A guide for maximizing the accuracy of intraoral digital scans. Part 1: Operator factors

A novel protocol for evaluating and classifying tooth preparations being scanned by using intraoral scanners: A critical review of how tooth preparation factors affect intraoral scanning accuracy

OBJECTIVES

To describe the tooth preparation-related factors that reduce the accuracy of intraoral scanners (IOSs) and present a novel protocol for examining and classifying tooth preparation/s being scanned by using an IOS to identify possible accuracy outcomes based on the preparation characteristics.

DATA & SOURCES

A collection of published articles related to tooth preparation-related factors that impact IOS accuracy and investigations assessing IOS accuracy for fabricating tooth-supported restorations were reviewed. Four search engines were used: Medline/PubMed, Scopus, Web of Science, and Cochrane. A manual search was also conducted.

RESULTS

The characteristics of tooth preparation/s and its relationship with the surrounding tissues (soft tissue and adjacent teeth) impact IOS accuracy. Five tooth preparation-related factors have been identified: tooth preparation geometry (the more complex the geometry, the lower the IOS accuracy), restorations (build-up and restorations on adjacent teeth reduce IOS accuracy), surface finishing (air-particle abrasion maximizes IOSs accuracy when compared with bur finishing and immediate dentin sealing), finish line location (supragingival location improves IOS accuracy when compared with equagingival or intracrevicular) and design (chamfer design improves scanability and accuracy), and interdental space (the higher the space, the better the IOS accuracy).

CONCLUSIONS

A novel protocol to systematically examine tooth preparation/s being scanned by using an IOS is described. The novel protocol includes a classification based on each tooth preparation-related factor that aims to identify influencing factors, increase the accuracy, reliability, and efficiency of complete digital workflows for fabricating tooth-supported restorations by using IOSs.

CLINICAL RELEVANCE

Five tooth preparation-related factors decrease IOS accuracy, namely tooth preparation geometry, restorations, surface finishing, finish line location and design, and interdental space. The proposed novel protocol assists the systematic examination of tooth preparations being scanned by using IOSs, identifying and minimizing potential influencing factors, aiming to increase the accuracy, reliability, and efficiency of the complete digital workflow.

Intra Oral Photogrammetry: Trueness Evaluation of Novel Technology for Implant Complete-Arch Digital Impression In Vitro

OBJECTIVES

To investigate the trueness of intraoral photogrammetry (IPG) technology for complete-arch implant digital impression and evaluate the effect of implant number.

MATERIAL AND METHODS

All data were fully anonymized in compliance with ethical standards, and a total of 30 complete-arch patient models with 4 (n = 13), 5 (n = 9), or 6 (n = 8) implants were selected from the archive. Digital impressions were taken with IPG and a desktop scanner. Test and reference standard tessellation language (STL) files were superimposed using a best-fit algorithm. For each implant position, mean linear (ΔX, ΔY, ΔZ axes) and angular deviations (ΔANGLE) and three-dimensional (3D) Euclidean distances (ΔEUC) were measured as primary outcomes with a dedicated software program (Hyper Cad S, Cam HyperMill, Open Mind Technologies) and reported as descriptive statistics. Secondary aim was to determine using linear mixed models whether implant number affected trueness. All statistical analyses were conducted using Stata 18 (Stata Corp, College Station) and significance was set at 0.05.

RESULTS

A total of 30 definitive casts with 4 (n = 13), 5 (n = 8), and 6 (n = 9) multi-unit abutment (MUA) analogs were analyzed (n = 146 implant positions). The mean deviations along the X-axis were -3.97 ± 32.8 μm, while along the Y-axis, they were -1.97 ± 25.03 μm. For the Z-axis, a greater deviation of -33 ± 34.77 μm was observed. The 3D Euclidean distance deviation measured 57.22 ± 27.41 μm, and the angular deviation was 0.26° ± 0.19°. Statistically significant deviations were experienced for ΔZ, ΔEUC, and ΔANGLE (p < 0.01). Additionally, the number of implants had a statistically significant effect only on the Z-axis deviation (p = 0.03).

CONCLUSIONS

Within study limitations, IPG technology was feasible for complete-arch digital implant impression with mean linear, angular, and 3D deviations far below the acceptable range for a passive fit. Reported IPG trueness might avoid a rigid prototype try-in. The implant number had no influence on trueness except for Z-axis deviations. Integrating photogrammetry with intraoral optical scanning (IOS) improved practicality, optimizing the digital workflow. Further clinical trials are needed to confirm these findings.

Classification of Scanning Errors of Digital Scans Recorded by Using Intraoral Scanners

OBJECTIVES

The different scanning errors that can be caused by the operator handling an intraoral scanner (IOS) or the intraoral conditions of the patient being scanned have not been described. The purpose of this review was to describe and classify the scanning errors that can be identified in digital scans recorded by using IOSs.

OVERVIEW

The identification of scanning errors in an intraoral scan and understanding the cause of these scanning errors are fundamental procedures for successfully handling an IOS and integrating these digital data acquisition technologies in dental practices. There are two main types of scanning errors: the ones created by the operator and the ones caused by the intraoral conditions of the patient. There are seven operator-related scanning errors: mesh hole, stitching, tissue, reliability, umbrella, implant scan body geometry, and scanning noise errors. Additionally, there are four patient-related scanning errors: humidity, bridge, fuzzy finish line, and scanability noise errors.

CONCLUSIONS

The identification of scanning errors is fundamental for assessing the quality of an intraoral digital scan. The comprehensive reading of these scanning errors allows the dental professional to understand if the scanning error can be corrected or if it is related to hardware/software limitations of IOSs.

Implant Scanning Workflows for Fabricating Implant-Supported Prostheses Recorded by Using Intraoral Scanners With or Without Photogrammetry Technologies

OBJECTIVES

To classify complete-arch implant scanning workflows for registering implant position, tooth position, soft tissue information, and maxillomandibular relationship recorded by using intraoral scanners (IOSs) with or without photogrammetry (PG) technologies.

OVERVIEW

Implant scanning workflow has been defined as the procedures required to acquire the digital information needed to design an implant-supported prosthesis, including implant and tooth position, soft tissue information, and maxillomandibular relationship scans. As a part of the implant scanning workflow, different implant scanning techniques have been described for recording the 3-dimensional position of the implants being scanned by using IOSs. Alternatively, PG systems can also be used to record implant positions. However, dental literature lacks a classification of implant scanning workflows.

CONCLUSIONS

There are six main implant scanning workflows based on the reference landmarks used: worflows guided by existing teeth, fiducial markers, fixation references, implant scan bodies, auxiliary devices, and interim restorations.

CLINICAL SIGNIFICANCE

Understanding different implant scanning workflows allows dental professionals to efficiently capture all the digital data information needed to design and fabricate implant-supported prostheses by using an intraoral scanner with or without a photogrammetry system.

Evaluating the feasibility of conventional and digital impressions of full-arch by the absolute linear deviation method: an in vitro study

BACKGROUND

Intraoral scanners (IOS) facilitate dental treatment, but the efficacy in full-arch scanning remains controversial. The aim of this study was to compare arch deformations between conventional impressions (CIs) and digital impressions (DIs) across six distinct spans in the maxillary and mandibular models, using the absolute linear deviation method.

METHODS

Standard maxillary and mandibular models, each with seven cylindrical landmarks added, were used as the reference. CIs and DIs as test scans (n = 15 each) were performed on the models using silicone impression material and three IOSs: CS3600, Trios3, and Trios5. The trueness of the distances and angles between the remaining cylinders and initial scanning cylinder were evaluated. Data were analyzed using the Kruskal-Wallis and One-way ANOVA tests, with the Bonferroni test for post hoc analysis (α = 0.05).

RESULTS

Deviations of DIs increased gradually from smaller spans to full-arch spans, while deviations of CIs remained stable. Within a 5-tooth-units, DIs provided superior trueness compared to CIs (P < 0.05), except for ΔL8, where the results from four impression methods were comparable (P = 0.28). For other measurements, CIs exhibited significantly better trueness than three IOSs (P < 0.05).

CONCLUSIONS

The current accuracy of IOSs was insufficient for full-arch applications, but suitable for short scan ranges (fixed prostheses within a 5-unit span).

Techniques and accuracy for aligning facial and intraoral digital scans to integrate a 3-dimensional virtual patient: A systematic review

STATEMENT OF PROBLEM

The optimal method of aligning intraoral scans with facial scans to generate a 3-dimensional (3D) virtual patient remains unclear. Distortions in the alignment of intraoral and facial scans would lead to an inadequate virtual patient representation and, therefore, to inadequate diagnosis and treatment planning.

PURPOSE

The purpose of this systematic review was to evaluate the available techniques for generating a 3D virtual patient by aligning facial and intraoral scans and to assess their accuracy.

MATERIAL AND METHODS

A systematic search was conducted in 3 databases: Medline, Scopus, and Web of Science. A manual search was also conducted. Specific descriptors were used to identify alignment techniques. Two independent reviewers screened titles and abstracts, with a third independent reviewer resolving ambiguities. A qualitative analysis was performed, and interexaminer agreement was assessed using the Cohen kappa statistic.

RESULTS

After screening, 48 of the 2832 identified articles were included for qualitative analysis. They focused on 3 alignment techniques: guided by retracted facial scans, extraoral scan bodies, and perioral intraoral scans. Interexaminer agreement was high (kappa=0.82 to 0.88). Integration techniques guided by extraoral scan bodies, influenced by extraoral scan body design and protocols, showed the best accuracy. The outcome variables for the evaluation of the effectiveness of these protocols were heterogeneous.

CONCLUSIONS

Integrating facial and intraoral scans was found to enhance diagnosis and treatment planning by providing essential esthetic and functional parameters. Integration techniques guided by extraoral scan bodies and combination techniques showed higher accuracy, especially for complex implant-supported prostheses or edentulous patients.

Complete arch digital implant scan accuracy with screw-retained or snap-on scan bodies: A comparative in vitro study

STATEMENT OF PROBLEM

Different scan body types have been reported to influence intraoral scanning accuracy. Stiff implant connections allow the use of snap-on scan bodies. However, data on the influence of scan body retention type are lacking.

PURPOSE

The purpose of this in vitro study was to assess and compare the accuracy of complete arch digital scanning with that of screw-retained or snap-on scan bodies.

MATERIAL AND METHODS

An edentulous mandibular master model with 4 conical connection analogs was digitized with an extraoral optical scanner to achieve a reference file. Seventy-six test scans were obtained with an intraoral scanner: 38 using screw-retained and 38 using snap-on scan bodies. The resulting 76 test files were aligned to the reference file with a best fit algorithm. Linear (ΔX, ΔY and ΔZ- axis), and angular deviations (ΔANGLE) were evaluated for each implant position (n=304). Three-dimensional (3D) deviation was calculated for each position according to the Euclidean distance (ΔEUC). Descriptive analysis and multivariable analysis were stratified considering scan body type and implant position (α=.05).

RESULTS

Considering ΔEUC, scan body type showed no significant difference (P=.097), while implant position was statistically significant (P<.001), with the left second premolar as the most critical and the right lateral incisor the most accurate. Considering ΔANGLE, the snap-on scan bodies were significantly better (P=.033). The implant position also resulted in statistically significant differences (P<.001) with the left second premolar being the most critical and the right lateral incisor as the most accurate.

CONCLUSIONS

Snap-on scan bodies showed comparable 3D and higher angular accuracy compared with screw-retained scan bodies. Tilted posterior implants were the least accurate and resulted in more critical positions, especially the most distal position to be recorded.

Image-guided photogrammetry accuracy: In vitro evaluation of an implant-supported complete arch digital scanning technology

STATEMENT OF PROBLEM

Complete arch digital scanning with intraoral scanners (IOSs) for implant-supported fixed dental prostheses (FDPs) is controversial with current technologies, and accuracy and consistency are insufficient. Stereophotogrammetry (SPG) may capture precise implant coordinates but unrelated to the patient anatomy. Conclusive data comparing IOS versus SPG are lacking.

PURPOSE

The purpose of this in vitro study was to investigate a novel image-guided photogrammetry (IGP) navigation technology for complete arch digital scanning with an artificial intelligence (AI) driven workflow to superimpose implant coordinates on preoperative patient data sets.

MATERIAL AND METHODS

After ethical approval had been received for the use of human-derived data, complete arch casts of actual patients with 4 and 6 implants were selected from an archive. Digital scans were made with IGP and a coordinate measuring machine (CMM) to generate standard tessellation language (STL) test and reference files for each cast, which were then superimposed with a best-fit algorithm. For each implant position, linear along x- (longitudinal), y- (lateral), and z- (vertical) axes (ΔX, ΔY, ΔZ) and angular (ΔANGLE) deviations were calculated. Three-dimensional (3D) deviation (ΔEUC) was measured as the Euclidean distance. Sample size was calculated assuming ΔEUC as the primary endpoint, significance level of.05, n=84 to ensure a minimum expected difference of 120 µm (standard deviation 150 µm), and test power of.95. A univariate descriptive analysis of study variables was performed and stratified by implant number (4 versus 6). An independent samples t test was used to assess whether ΔEUC and ΔANGLE differed significantly based on implant number (4 versus 6) and position on the arch (anterior versus posterior for 4-implant casts) and anterior, intermediate, and posterior for 6-implant casts) (α=.05).

RESULTS

A total of 26 complete arch casts, mandibular (n=16) and maxillary (n=10) with 4 (n=15) or 6 (n=11) implants, were investigated. A total of 126 implant positions were captured with IGP technology and compared with respective references (n=26 test, n=26 reference files). Mean deviations, standard deviation, range, and 75 percentiles were calculated for ΔX (-0.05 ±29.95; -75.17 - 68.00; 22,00 µm), ΔY (0.01 ±31.65; -68.0 - 93.93; 19,18 µm), ΔZ (-0.02 ±12.95; -39.0 - 43.5; 6,76 µm), ΔEUC (43.02 ±26.24; 3.41 - 190.23; 58,21 µm), and ΔANGLE (0.43 ±0.22; 0.03 - 0.86; 0,61 degrees). Lower deviations were found in 4-implant casts ΔEUC (P=.017), ΔANGLE (P=.003). Implant position did not affect accuracy, with the exception of ΔANGLE on 6-implant casts, and anteriors performed worse than posteriors and intermediate implants (P=.009).

CONCLUSIONS

Image-guided photogrammetry was feasible for implant-supported complete arch digital scanning with linear and 3D deviations lower than those of conventional SPG. Linear deviations were close to 0 µm and angular deviations about 0.4 degrees, with the 4-implant casts being more accurate. Implant position did not affect accuracy with the exception of anterior implants that showed higher angular deviations in the 6-implant casts. Even though actual patient casts were investigated, allowing the IGP outcomes to be generalized with caution, trials are needed to validate its clinical performance.

Complete arch implant scans with standard scan bodies versus scannable healing abutments on scanning accuracy, scanning time, and number of photograms: A comparative clinical study

STATEMENT OF PROBLEM

Digital scans for complete arch implant fixed dental prostheses are typically performed using implant scan bodies (ISBs). Scannable healing abutments may be an alternative to ISBs. However, evidence on the accuracy, scanning time, and number of photograms of digital scans using scannable healing abutments remains uncertain.

PURPOSE

The purpose of this clinical study was to evaluate the scanning accuracy, scanning time, and number of photograms of scannable healing abutments of several heights in comparison with standard ISBs.

MATERIAL AND METHODS

A reference stone cast was obtained from a patient with 7 maxillary implants from a splinted open-tray conventional impression. It was digitized by using a laboratory scanner (E4 Scanner). A milled titanium bar was manufactured, and passive fit was evaluated clinically and radiographically. Three groups (n=15) were determined based on the devices used during the intraoral scanning procedure (TRIOS 4): standard ISB (Scanbody 2800) (Group STD), 5-mm height scannable healing abutment (TissueShaper 5 mm) (Group TS5), and 7-mm height scannable healing abutment (TissueShaper 7 mm) (Group TS7). The implant abutment discrepancy between the platform of the abutments of the digitized reference cast and the intraoral scans from the different groups were calculated. Maximum deviation (highest value of misfit per scan) and overall deviations (mean of all the deviations of the scan) were considered. The scanning time and number of photograms were registered. The 1-way ANOVA and Tukey tests were used to analyze trueness. The Levene test was used to analyze the precision. ANOVA and the post hoc Tukey test were used to evaluate the scanning time and numbers of photograms (α=.05).

RESULTS

Significant trueness differences were found in the overall and maximum misfit among the groups (P<.05). Significant precision discrepancies were revealed in the maximum misfit (P<.05) but not in the overall misfit (P=.56). The highest deviations were in the STD group (overall: 94 ±6 µm; maximum misfit: 172 ±24 µm), followed by TS5 (overall: 72 ±10 µm; maximum misfit: 112 ±15 µm) and TS7 (overall: 63 ±9 µm; maximum misfit: 91 ±20 µm). Significant differences in scanning time and number of photograms were found between the STD group and both the TS5 and TS7 groups (P<.01). The longest scanning time (129.9 ±16.7 s) and highest number of photograms (1322 ±150 photograms) were in the STD group in comparison with TS5 (71.7 ±10.8 s; 805 ±104 photograms) and TS7 (77.3 ±0.9 s; 764 ±119 photograms).

CONCLUSIONS

The tested scannable healing abutments improved the accuracy and decreased the scanning time and number of photograms in complete arch implant digital scans recorded by using the IOS assessed.

Evaluation of impact of intraoral scanning technology and scan body design on the accuracy of maxillary complete arch digital scans: A clinical study

STATEMENT OF PROBLEM

Intraoral scanners (IOSs) can be used to digitize complete arches with multiple dental implants; however, the influence of intraoral scanning technology and scan body system selection on accuracy in maxillary complete arches remains unclear.

PURPOSE

The purpose of this clinical study was to evaluate the accuracy in the maxillary arch, encompassing both trueness and precision, of 2 distinct intraoral scanning systems and 2 diverse scan body systems in comparison with the conventional reference method.

MATERIAL AND METHODS

Two participants were recruited with 6 maxillary bone-level implants (JDEvolution Plus; JDentalCare) placed in positions corresponding to the right first molar, right canine, right central incisor, left central incisor, left canine, and left first molar. All implants had multiunit abutments (Conical Abutment Straight; JDentalCare) screwed to the implants. Definitive casts from 2 edentulous maxillary impressions were made using a conventional method. The casts were digitized to create reference models using a laboratory scanner (E3; 3Shape A/S). Two experimental groups were created based on the IOS used: the TRIOS 3 group (TR3) and the Primescan group (PS). Two subgroups were generated depending on the scan body system used to digitize the spatial position of the implants: IPD scan body (IPD) and DAS scan body (DAS). The digital implant scan discrepancies between the control group and experimental scans were calculated. The normality of the data was assessed using the Shapiro-Wilk test (α=.05). Two-way ANOVA and post hoc pairwise comparison tests were used to compare the trueness, precision, and interaction between the intraoral scanner and the scan body (α=.05) RESULTS: Statistically significant differences (P<.001) were found between the intraoral scanners tested. No significant differences were found between the IPD and DAS scan body systems (P=.649), and none were found for the interaction between the IOS and the scan body (P=.524). Significant differences were observed between the following groups: PS-IPD and TR3-IPD, PS-IPD and TR3-DAS, PS-DAS and TR3-IPD, and PS-DAS and TR3-DAS (all P<.001).

CONCLUSIONS

The combination of intraoral scanner and scan body system is crucial to improve the accuracy of digital complete arch intraoral implant scans. In the maxillary arch, the Primescan IOS obtained the highest accuracy when compared with the TRIOS 3 IOS, independently of the scan body system used.

Comparison of trueness, time, and number of images among different denture digitization protocols

PURPOSE

To compare trueness, time, and number of images of different denture digitization protocols.

MATERIALS AND METHODS

Maxillary and mandibular complete prostheses (n = 10) were fabricated and attached with four fiducial markers. Reference scans were obtained using a laboratory scanner. Test scans were obtained using three different protocols: intraoral scanner (IOS) with manufacturer's scanning pattern (MA), IOS with rolling scanning pattern (RO), and IOS- polyvinylsiloxane technique (IOS-PVS). The scan time and number of images taken were recorded for analysis. Using 3-dimensional (3D) inspection software (Geomagic control X), corresponding test scans were superimposed to the reference scan using overall best fit. For trueness analysis, the root mean square (RMS) value of the overall best-fit superimposition was calculated. One-way ANOVA followed by Games-Howell and Tukey post-hoc tests were applied to analyze trueness, scan time, and number of images. Qualitative analysis of trueness was performed using 3D color mapping.

RESULTS

The lowest RMS value was in the mandibular RO protocol (0.10 ±0.01 mm). The highest RMS value was mandibular scans of the IOS-PVS protocol (1.46 ± 0.09 mm). The longest digitization time was recorded in the maxillary MA group (3.34 ± 0.70 min), while the shortest was in the mandibular RO protocol (2.48 ± 0.56 min). Qualitative analysis revealed that deviation in IOS-PVS protocol occurred around the border area of the prosthesis.

CONCLUSION

The denture digitization protocols tested significantly affected trueness, total scanning time, and number of images. Digitizing dentures using the RO protocol improved trueness and reduced scanning time and the number of images.

Trueness and Passivity of Digital and Conventional Implant Impressions in Edentulous Jaws: A Prospective Clinical Study

AIM

To compare the linear and angular deviations of conventional implant (CI) and digital implant (DI) impression techniques in edentulous jaws with four or six implants.

MATERIALS AND METHODS

Twenty participants (12 men, 8 women; mean age 58.6 years) with complete edentulous maxillary (n = 8) or mandibular (n = 12) arches were included. Each patient received four or six dental implants (Straumann BLX). Both CI and DI were performed using randomized sequences. Linear and angular deviations were measured between the reference scan (coordinated measuring machine) and the CI (desktop scanner) and DI (intraoral scanner, IOS) using CATIA software (Dassault Systèmes). Framework passivity was evaluated using the Sheffield one-screw test. The Shapiro-Wilk test determined data normality (p < 0.05), and nonparametric statistical tests were applied using statistical software.

RESULTS

Descriptive statistics showed a mean linear discrepancy of 29.05 (84.80 μm) for CI and 6.95 (154.10 μm) for DI, with angular deviations of 0.06° (0.36°) for CI and 0.05° (1.40°) for DI. No statistically significant differences were found in linear (p = 0.38) or angular (p = 0.12) measurements between CI and DI. Framework passivity testing showed that both techniques achieved passive fit in 17 out of 20 cases (85%), with the reference scan achieving passivity in 18 (90%) cases. Distal implants, particularly in the upper jaw, exhibited greater discrepancies, but none were statistically significant.

CONCLUSIONS

No significant differences in trueness were found between CI and DI techniques. Both methods demonstrated comparable trueness and framework passivity, supporting the use of IOS as a reliable alternative to CI in edentulous jaws with multiple implants.

Substituting the Conventional Facebow With an Extraoral Scan Body System for Transferring the Maxillary Cast Into the Virtual Articulator: Manufacturing Procedures and Digital Clinical Protocol

CLINICAL CONSIDERATIONS

Conventional facebow records are used to transfer the maxillary cast into the analog articulator. Different reference planes have been described, including the true horizontal or gravity reference plane. A conventional facebow (Kois Dentofacial Analyzer; Panadent) allows the recording of the gravity plane for transferring the maxillary cast into the analog semi-adjustable articulator. Clinical procedures should also allow the maxillary scan transfer into the virtual articulator by using the true horizontal reference plane.

OBJECTIVE

The present manuscript describes the step-by-step protocol to record the gravity plane and to transfer the maxillary scan into the virtual articulator by using an extraoral scan body system.

CONCLUSIONS

The extroral scan body device enables the substitution of the conventional facebow procedure. Additionally, this extraoral scan body is fabricated by using additive manufacturing technologies and eases the complete digital workflow for transferring the maxillary scan into the virtual articulator.

Accuracy of complete arch nonsplinting and noncalibrated splinting implant scanning techniques recorded by using five intraoral scanners

STATEMENT OF PROBLEM

Splinting implant scan bodies (ISBs) has been reported to improve the accuracy of intraoral scanners (IOSs) compared with nonsplinting methods. However, the accuracy of commercially available horizontal noncalibrated ISBs remains unknown.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of complete arch scans obtained using horizontal noncalibrated or standard ISBs recorded by using 5 different IOSs.

MATERIAL AND METHODS

An edentulous maxillary stone cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was used. The reference scan was obtained by digitizing the reference cast with a calibrated laboratory scanner (T710). Five groups were created based on the IOS tested: TRIOS 5, i700, Primescan, Aoralscan 3, and iTero. Two subgroups were defined based on the ISBs selected to record complete arch implant scans: standard ISBs (Stand subgroup) or horizontal noncalibrated ISBs (Apollo subgroup) (n=10). In the Stand subgroup, a standard ISB (Accurate Implant Body MUA) was positioned on each implant abutment, and experimental scans were captured. In the Apollo subgroup, a horizontal ISB (Apollo) was positioned on each implant abutment, connecting the implants horizontally following the arch shape. The standard tessellation language (STL) files of all the experimental scans were exported. A program (DentalCAD) was used to design a complete arch implant-supported bar from the control and each experimental scan. Then, another program (Geomagic) was used to perform linear and angular measurements of the implant interfaces of each bar. The measurements obtained in the control scan were used as a reference to measure the scanning distortion of each specimen. The 2-way ANOVA Welch and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were applied to analyze precision (α=.05).

RESULTS

Significant linear trueness differences were found between the subgroups (P<.001) with a significant interaction group×subgroup (P<.05). The iTero system demonstrated a significantly worse linear trueness compared with the other IOSs (P<.001). The TRIOS 5 obtained the worst linear precision. Significant angular trueness discrepancies were found between the groups (P<.001) and subgroups (P=.048) with a significant interaction group×subgroup (P=.041). The Apollo group obtained better angular trueness (P<.001) and precision (P<.001) compared with the Stand ISBs group.

CONCLUSIONS

Both the implant scanning technique and choice of IOS impacted the accuracy of complete arch implant scans.

Accuracy of a complete arch noncalibrated splinting implant scanning technique with a palatal orientation recorded by using different intraoral scanners

STATEMENT OF PROBLEM

The accuracy of noncalibrated splinting implant scanning techniques that include horizontal implant scan bodies (ISBs) positioned connecting the implants by following the shape of the dental arch have previously been analyzed. A novel horizontal ISB connected in the center of the arch has been introduced; however, the accuracy of this noncalibrated splinting implant scanning technique with a palatal orientation is unknown.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of a nonsplinting and noncalibrated splinting implant scanning technique recorded using 5 intraoral scanners (IOSs).

MATERIAL AND METHODS

A laboratory scan (reference scan) of an edentulous stone cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was acquired (T710). Five groups were created based on the IOS tested: TRIOS5, Primescan, i700, Aoralscan3, and iTero Element 5D. Two subgroups were defined based on the implant scanning technique used to record complete arch implant scans: a nonsplinted (NS-ISB subgroup) or noncalibrated splinting (NCS-IOC group) implant scanning technique (n=10). In the NS-ISB subgroup, an ISB (TrueScan Body) was positioned on each implant abutment, and complete arch implant scans were recorded and exported in standard tessellation language (STL) format. In the NCS-IOC subgroup, a horizontal ISB (IOConnect) was positioned on each implant abutment connecting them in the center of the palate. Implant scans were recorded, capturing only the section of the horizontal ISBs located in the center of the arch. Then, the scans were processed by a specific program (TruSuite), and the STL of the scans were exported. A program (Geomagic) was used to perform linear and angular measurements among the ISBs in the control scan and each specimen. The measurements obtained in the control scan were used as a reference to measure the scanning distortion of each specimen. The 2-way ANOVA Welch and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were used to analyze precision (α=.05).

RESULTS

Linear trueness discrepancies were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.002). The NCS-IOC group had significantly better linear trueness than the NS-ISB group. The TRIOS5, Primescan, and Aoralscan3 systems had significantly better linear trueness than the i700 device. The Levene test revealed that the NCS-IOC group had significantly better linear precision than the NS-ISB group. Additionally, angular trueness discrepancies were revealed among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P<.001). The NCS-IOC group had significantly better angular trueness than the NS-ISB group. The i700 and Aoralscan3 systems had the best angular trueness. Additionally, the NCS-IOC group had significantly better angular precision than the NS-ISB group. The TRIOS5 and Aoralscan3 had the best angular precision.

CONCLUSIONS

The implant scanning technique used and IOS selected impacted the trueness and precision of complete arch implant scans.

Influence of an artificial intelligence-based application on the accuracy of complete arch implant scans recorded by using an intraoral scanner

STATEMENT OF PROBLEM

Artificial intelligence (AI)-based applications have been integrated into intraoral scanner (IOS) programs aiming to assist the digitizing procedure, including the automatic alignment of the computer-aided design (CAD) file of the selected implant scan body (ISB). However, the impact of this AI-based application on the accuracy of complete arch implant scans remains unknown.

PURPOSE

The purpose of this in vitro study was to assess the impact of an AI-based application on the accuracy of complete arch implant scans recorded by using an IOS.

MATERIAL AND METHODS

A maxillary edentulous stone cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was obtained. Three groups were created based on the technique used to record complete arch implant scans by using an IOS (i700): prescan with the posterior ISB scan activating (Pre-AI group) or disabling the AI-based application (Pre-NoAI group) or obtaining a complete arch implant scan without prescan (NoPre group) (n=10). A complete arch scan involving the implant abutments was obtained (prescan) and duplicated 20 times. Then, an ISB (Elos Accurate IO 2C-A) was hand tightened into each implant abutment analog. In the Pre-AI group, for each duplicated prescan, each ISB was scanned until each scanned ISB was automatically aligned with the CAD file by the AI-based program. In the Pre-NoAI group, for each duplicated prescan, the ISBs were digitized to obtain the experimental complete arch implant scans. In the NoPre group, a complete arch implant scan was obtained. Lastly, a laboratory scan (reference scan) was obtained (T710). For each scan, an implant-supported bar was designed by using a program (DentalCAD). The bar designs were imported into another program (Geomagic), and linear and angular measurements among the implants were made. The measurements obtained in the control scan were used as a reference to measure the scanning distortion of each specimen. A 1-way Welch ANOVA test followed by the post hoc pairwise multiple comparison Tukey test was used to analyze trueness (α=.05). The Levene test was used to analyze precision (α=.05).

RESULTS

Significant linear (P<.001) trueness discrepancies were found among the groups. The Pre-AI group obtained significantly worse linear trueness than the other 2 groups. Additionally, significant angular trueness (P<.001) and precision (P<.001) discrepancies were revealed among the groups. The Pre-AI group obtained significantly worse angular trueness and precision than the other groups tested.

CONCLUSIONS

The implant scanning technique impacted the 3-dimensional implant positions recorded by using the IOS tested.

Accuracy of Intraoral Scanner Systems for Fabricating Inlay, Onlay, and Veneer Restorations: A Systematic Review and Meta-Analysis

PURPOSE

To evaluate the accuracy of intraoral scanners (IOSs) for fabricating inlay, onlay, and veneer restorations.

MATERIALS AND METHODS

A literature search was completed in five databases: PubMed/Medline, Scopus, Embase, Web of Science, and Cochrane. A manual search was also conducted. Two methods have been used to assess the accuracy of IOSs for fabricating inlay, onlay, and veneer restorations: accuracy of the definitive virtual casts and the marginal and internal discrepancies of inlay, onlay, and veneer restorations fabricated by using IOSs. Included articles were classified into two groups: definitive virtual casts accuracy and restoration fit. Two investigators evaluated the studies independently by applying the Joanna Briggs Institute critical appraisal. A third examiner was consulted to resolve any lack of consensus.

RESULTS

Thirty four articles were included: 17 analyzed the accuracy of definitive virtual casts and 17 assessed the marginal and internal discrepancies. Regarding the accuracy of definitive virtual casts, a trueness of 27.47 μm (p < 0.001) in the inlay subgroup and 64.15 μm (p < 0.001) in the onlay subgroup were found among the IOSs tested. For digitizing inlay preparations, a trueness of 12.29 μm (p < 0.001) in the Primescan, 69.34 μm (p < 0.001) in the Omnicam, 38.39 μm (p < 0.001) in the Trios 3, 52.96 μm (p < 0.001) in the Trios, and 28.90 μm (p < 0.001) in the CS3500 were found. A trueness of 53.00 μm (I2 = 99%, p < 0.001) in the Omnicam. Also, a precision of 19.88 μm (p < 0.001) in the inlay subgroup and 19.69 μm (p < 0.001) in the onlay subgroup was obtained. Furthermore, a nonsignificant test result for subgroup differences (p = 0.06) in the marginal discrepancy between conventional and IOS methods was found with a significant heterogeneity (I2 = 99%, p < 0.001). However, a significant test result for subgroup differences (p < 0.001) in the internal discrepancy values was found with a significant heterogeneity (I2 = 72%, p < 0.001).

CONCLUSIONS

IOSs and restoration type influenced the accuracy of the definitive virtual casts. A Better trueness and worse precision was found on the definitive virtual cast of inlay restorations when compared with those of onlay restorations. The impression method used did not impact the marginal discrepancy of inlay and onlay restorations. However, a higher internal discrepancy was found in the inlay and onlay restorations fabricated by using conventional methods, but the discrepancy was not significant. Studies are needed to assess the accuracy of definitive virtual casts for fabricating veneer restorations captured by using IOSs and to measure the fit of the veneer restorations fabricated by using IOSs.

CLINICAL SIGNIFICANCE

Intraoral scanners provide a reliable method for fabricating inlay and onlay restorations. The accuracy of IOSs for fabricating veneer restorations remains uncertain.

Evolution of Dental Occlusion: Integrating Digital Innovations

The landscape of dental occlusion is undergoing a transformative shift with the integration of digital technologies offering accuracy, efficiency, and improved patient outcomes. This article explores the advancements in digital innovations that have reshaped occlusal analysis and management. By examining tools such as three-dimensional (3D) scanning, virtual articulators, and occlusal diagnostic software, we highlight their impact on treatment planning and clinical workflows. These technologies enable dental professionals to analyse occlusal relationships with a level of detail previously unattainable, paving the way for more accurate and individualised treatment plans. The implementation of digital approaches also enhances patient engagement, as visual data aids in understanding treatment processes. This article also reviews the available research on the reliability of these innovations, providing an evidence-based perspective on their clinical application.

Effect of relative humidity on the accuracy, scanning time, and number of photograms of dentate complete arch intraoral digital scans

STATEMENT OF PROBLEM

Intraoral scanners (IOSs) have been used in dentistry for diagnostic and treatment purposes; however, the influence of environmental factors such as humidity or temperature on the accuracy of intraoral scanning is uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of relative humidity and ambient temperature on the accuracy, scanning time, and number of photograms of dentate complete arch intraoral digital scans.

MATERIAL AND METHODS

A completely dentate mandibular typodont was digitized by using a dental laboratory scanner. Four calibrated spheres were attached following the International Organization for Standardization (ISO) standard 20 896. A watertight box was designed to simulate 4 different relative humidity conditions (50%, 70%, 80%, and 90%) (n = 30). An IOS (TRIOS 3) was used to obtain a total of 120 complete arch digital scans (n = 120). Scanning time and number of photograms of each specimen were recorded. All the scans were exported and compared with the master cast by using a reverse engineering software program. The linear distances among the reference spheres were used to calculate trueness and precision. A unifactorial analysis of variance (ANOVA) and Levene tests followed by the post hoc Bonferroni test were used to analyze trueness and precision data, respectively. A unifactorial ANOVA followed by a post hoc Bonferroni test was also conducted to analyze scanning time and the number of photogram data.

RESULTS

Statistically significant differences were found in trueness, precision, number of photograms, and scanning time (P<.05). Regarding trueness and precision, significant differences were found between the 50% and 70% relative humidity groups and the 80% and 90% relative humidity groups (P<.01). Regarding scanning time and number of photograms, significant differences were obtained among all groups, except between the 80% and 90% relative humidity groups (P<.01).

CONCLUSIONS

The relative humidity conditions tested influenced accuracy, scanning time, and number of photograms in complete arch intraoral digital scans. High relative humidity conditions resulted in the decreased scanning accuracy, longer scanning time, and greater number of photograms of complete arch intraoral digital scans.

Accuracy (trueness and precision) of 3-dimensional virtual patients: An in vitro investigation of different facial scanners and digital integration techniques

OBJECTIVES

To investigate the influence of different facial scanners and integration approaches on the accuracy of virtual dental patients (VDPs).

METHODS

Forty VDPs were generated using a head mannequin and two facial scanners: 1) an industrial scanner and 2) a smartphone scanner. For each scanner, two integration methods were applied: 1) integration by virtual facebow scan and 2) integration by nose-teeth scan. This resulted in four VDP groups, with ten repetitions for each group (n = 10). A cone beam computed tomography (CBCT) scan of the mannequin served as the reference. The linear deviations of the maxillary arches at teeth #16, #21, and #26, as well as the angular deviations of the occlusal planes, were measured to assess accuracy.

RESULTS

No significant trueness differences were found between the scanners (p = 0.78 for tooth #16, p = 0.84 for tooth #21, p = 0.35 for tooth #26, p = 0.18 for angular deviations) or between the integration techniques (p = 0.42 for tooth #16, p = 0.29 for tooth #21, p = 0.76 for tooth #26, p = 0.61 for angular deviations). In terms of precision, the industrial facial scanner demonstrated superior outcomes (p < 0.001 for teeth #16, #21, #26, and angular deviations). No significant precision differences were found between the two integration techniques for teeth #16 (p = 0.17) and #26 (p = 0.25), or for angular deviations (p = 0.27); however, the nose-based integration technique showed higher precision for tooth #21 (p = 0.01).

CONCLUSIONS

The smartphone-based facial scanner exhibited trueness comparable to that of the industrial facial scanner, though with reduced precision. The nose-based integration technique demonstrated better accuracy compared to the virtual facebow-based technique.

CLINICAL SIGNIFICANCE

The smartphone-based facial scanner achieves trueness comparable to the industrial facial scanner for VDP integration. Additionally, the nose-based integration technique offers a viable alternative to the virtual facebow-based approach, with a simplified scanning and integration process.

Influence of fabrication method on the manufacturing accuracy and internal discrepancy of removable partial dentures: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Removable partial dentures (RPDs) can be fabricated with conventional casting procedures or computer-aided design and computer-aided manufacturing (CAD-CAM) technologies; however, the manufacturing accuracy and internal discrepancy differences among these manufacturing methods remain uncertain.

PURPOSE

The purpose of this systematic review and meta-analysis was to assess the influence of the fabricating method (casting, milling, or additive manufacturing) on the accuracy and internal discrepancy of RPDs.

MATERIAL AND METHODS

An electronic search of the literature was performed in 6 databases: PubMed/Medline, Embase, Web of Science, Scopus, Cochrane, and Google Scholar. The studies that assessed the accuracy and internal discrepancy of RPDs fabricated from casting, milling, and additive manufacturing were included. Studies reporting gaps (mean) and standard deviations were included in the meta-analysis. Publication bias was identified using funnel plot asymmetry and the Egger test.

RESULTS

A total of 25 articles were included. The internal discrepancy of the additively manufactured RPDs ranged from 14.4 to 511 μm and from 7 to 419 μm in conventionally fabricated RPDs. For the milling method, 20 to 66 μm horizontal and 17 to 59 μm vertical discrepancies were reported. The Egger tests indicated no publication bias among the studies that were included in the meta-analysis. Four included studies resulted in more than the acceptable clinical gap (311 μm) for the CAD-CAM method. Independently of the manufacturing method, the greatest internal discrepancies reported were observed under the major connectors. RPDs fabricated by using CAD-CAM techniques required fewer clinical appointments, the RPD design was easier to reproduce, and laboratory time was less than with conventional procedures. However, the reviewed studies described several disadvantages, including limited RPD design programs, difficulties in defining the occlusal plane, expensive materials, and increased laboratory cost.

CONCLUSIONS

Additive and subtractive technologies provide accurate methods for RPD fabrication; however, all challenges, including limited design software programs have not yet been overcome, and casting is still needed when the framework pattern is milled or printed.

Implant scanning workflows: Accuracy of registration methods for integrating intraoral scans containing soft tissue and tooth position information

STATEMENT OF PROBLEM

An implant scanning workflow involves recording different intraoral scans containing all the information needed to fabricate an implant-supported prosthesis. The accuracy of these implant scanning workflow registration methods remains unknown.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of different implant scanning workflows for registering the soft tissue and tooth position information scans recorded by using 5 intraoral scanners (IOSs).

MATERIAL AND METHODS

A maxillary edentulous stone cast with 6 implant abutment analogs (MultiUnit Abutment Replica) and 2 screw-retained implant-supported interim restorations (from the right first molar to the left canine and from the left first premolar to the left first molar) were obtained. Three markers were attached on the palatal surface of the cast on the anterior palatine raphe and right and left first molar positions, and 4 markers were attached on the palatal surface of the right and left second premolar and right and left lateral incisor of the interim prostheses. Afterwards, 5 composite resin (CR) reference landmarks were created on the palatal surface of the cast on the anterior palatine raphe, right and left first premolar, and right and left first molar. Additionally, a screw was placed in the posterior palatine raphe, simulating a temporary anchorage device (TAD). The interim prostheses were positioned in the implant analogs of the cast and digitized by using a laboratory scanner (T710). Five groups were created depending on the IOS: TRIOS 5, i700, Elite, iTero, and Primescan groups. A tooth position, soft tissue information, and soft tissue with existing teeth scans were obtained by using each IOS. Six subgroups were created depending on the reference landmarks used to register the scans: 3 or 5 CR landmarks (3CR or 5RC subgroup, respectively), existing teeth (teeth subgroup), existing teeth combined with 2 CR landmarks (teeth+2CR subgroup), TAD (TAD subgroup), TAD combined with 1 CR landmark (TAD+1CR subgroup). Twelve linear measurements were performed on the control scans and on each specimen among the 7 markers. Trueness was analyzed by using 2-way ANOVA and the pairwise comparison Tukey tests (α=.05). Precision was evaluated by using the Levene and pairwise comparisons tests (α=.05).

RESULTS

Trueness discrepancies were found among the groups (P<.001) and subgroups (P<.001), with a significant group*subgroup interaction (P=.004). The Tukey test showed that the Primescan and iTero systems obtained worse trueness than the other groups. Also, the TAD and Teeth subgroups obtained worse trueness than the other subgroups tested. All the groups and subgroups were significantly different from each other (P<.05).

CONCLUSIONS

The IOS and reference landmarks tested impacted the trueness and precision of the registration of soft tissue and tooth position information scans.

Influence of scan extension on the accuracy of maximum intercuspal position recorded by using intraoral scanners or an artificial intelligence-based program

STATEMENT OF PROBLEM

Intraoral scanners (IOSs) and artificial intelligence (AI) based programs can be used to locate the maximum intercuspal position (MIP). However, the influence of scan extension on the accuracy of the MIP located by using these technologies is uncertain.

PURPOSE

The purpose of this in vitro study was to analyze the effect of scan extension on the accuracy of the MIP located by using 3 IOSs and an AI-based program.

MATERIAL AND METHODS

Stone casts mounted in an articulator in MIP were digitized (T710). Two groups were created: complete- (CA group) and half arch (HA group) scan. In the CA-group, complete arch scans of the reference casts were captured with each IOS tested. The nonarticulated scans were duplicated 20 times. In the HA-groups, the right half arch scans of the reference casts were captured with each IOS tested. Six subgroups were generated: 3 IOS (Primescan-IOS, i700-IOS, and Aoralscan3-IOS) and 3 AI (Primescan-AI, i700-AI, and Aoralscan3-AI) subgroups. In the CA-Primescan-IOS subgroup, 10 duplicated scans were articulated in MIP by recording a bilateral occlusal record. In the CA-Primescan-AI subgroup, 10 duplicated scans were articulated in MIP by using an AI-based program (Bitefinder). In the CA-i700-IOS, CA-Aoralscan3-IOS, CA-i700-AI, and CA-Aoralscan3-AI subgroups, the same procedures as in the CA-Primescan-IOS and CA-Primescan-AI subgroups were completed, respectively. In the HA-Primescan-IOS subgroup, 10 duplicated scans were articulated in MIP by capturing a right occlusal record. In the HA-Primescan-AI subgroup, 10 duplicated scans were articulated in MIP by using the AI-based program. In the HA-i700-IOS, HA-Aoralscan3-IOS, HA-i700-AI, and HA-Aoralscan3-AI subgroups, the same procedures as in the HA-Primescan-IOS subgroups were completed, respectively. A program (Geomagic) was used to calculate 36 interlandmark measurements on the virtual articulated casts (control) and each specimen. Three-way ANOVA and Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison tests were used to analyze precision (α=.05).

RESULTS

MIP trueness discrepancies were found between the IOS (P<.001), groups (P<.001), and subgroups (P<.001), with a significant interaction IOS×subgroup (P<.001), group×subgroup (P<.001), and IOS×group×subgroup (P<.001). The Primescan and i700 (P=.014) and the Primescan and Aoralscan3 (P<.001) were different from each other. The CA and HA groups (P<.001) were different from each other. The IOS and AI subgroups (P<.001) were different from each other. The Levene test showed significant precision discrepancies between the groups (P<.001) and subgroups (P<.001). The HA scans demonstrated significantly worse precision than the CA scans (P<.001). Additionally, the AI-based program obtained significantly worse precision than the IOS programs tested (P<.001).

CONCLUSIONS

Scan extension and program impacted the trueness and precision of the MIP. CA groups demonstrated better MIP trueness and worse precision than the HA groups. Primescan obtained better MIP trueness than the i700 and Aoralscan3 systems. The IOSs revealed better MIP trueness and precision than the AI-based program tested.

Effect of different preparation designs of minimally invasive occlusal onlays on the accuracy of different intraoral scanners: An in vitro study

PURPOSE

The aim of this in vitro study was to assess and compare three different preparation designs of minimally invasive occlusal onlays on the trueness and precision of three different intraoral scanners under two different scanning conditions.

MATERIALS AND METHODS

Three maxillary premolars were prepared in three different designs and divided accordingly into three groups, Group 1: Anatomical (n = 60), Group 2: Flat (n = 60), and Group 3: Ferrule (n = 60). The samples were then further divided into subgroups according to scanners as subgroup A: Medit i500 (n = 20), subgroup B: 3Shape TRIOS 4 (n = 20), and subgroup C: Cerec Primescan (n = 20). Last, the samples were further divided according to scanning conditions: Division i: As prepared (n = 10) and Division ii: Sprayed - scan spray (n = 10). An industrial 3D scanner was used to obtain the reference STL files. Accuracy was assessed in terms of trueness and precision and recorded in terms of root mean square in micrometers. Numerical data were explored for normality using Shapiro-Wilk test and were analyzed using 3-way ANOVA followed by Tukey's post hoc test.

RESULTS

Regarding trueness, 3-way ANOVA showed that all tested variables had a significant effect on trueness. Significant interactions were found between the different variables (p < 0.001). For preparation design the highest value was found in ferrule preparation (27.88 ± 7.11), followed by flat preparation (22.99 ± 7.56), while the lowest value was found in anatomical preparation (18.83 ± 5.71) (p < 0.001). For scanner type, the highest value was found in Primescan (25.36 ± 10.66), followed by TRIOS 4 (22.75 ± 5.98), while the lowest value was found in Medit i500 (21.59 ± 5.03) (p < 0.001). As for the scanning condition, sprayed samples (26.54 ± 8.24) had a significantly higher value than non-sprayed samples (19.93 ± 5.53) (p < 0.001). Regarding precision, both preparation design and scanner type had a significant effect on precision. Scanning conditions had no significant effect. There was a significant interaction between the three tested variables (p = 0.012).

CONCLUSIONS

Anatomical preparation of minimally invasive occlusal onlays produced the most accurate scans. Within the tested preparation designs, Medit i500 and 3Shape TRIOS 4 have better trueness than Cerec Primescan. Cerec Primescan is more precise than 3Shape TRIOS 4 and Medit i500 Scan spray application causes a higher deviation in the trueness of the tested intraoral scanners while it does not affect their precision.

A Retrospective Cohort Study on Scan Quality of Implant Scanbodies Matched With CAD Libraries

PURPOSE

To assess the effect of scanbody (SB)-type, edentulous site, and restoration-type on the scan quality of SBs used in the treatment of short-span edentulism.

MATERIALS AND METHODS

The cohort consisted of SBs with different specifications connected to bone-level implants for intraoral digitalization in the fabrication of fixed restorations. SBs matched with library CAD files for digital implant position transfer into dental CAD software were enrolled in the study group. Intraoral implant digital records were categorically evaluated to assess the quality of SB scans. In statistical analyses, the chi-squared test was used to describe the clinical variables, and logistic regression models were constructed to reveal the association between the clinical variables and SB scan quality.

RESULTS

A total of 243 SBs were eligible for scan quality evaluation. Scan quality did not differ statistically (p > 0.05) in the SB reference area, while texture in the representation of SB was significantly affected (p < 0.05) by the variables SB-type and edentulous-site. Cylindrically designed SBs without specific geometrical features presented remarkably higher risks for reduced scan quality in SB representation.

CONCLUSION

SBs successfully aligned with library CAD files based on a software algorithm may not consistently present similar scan quality. Intraoral scanning of a SB is highly vulnerable with regard to scan deterioration in texture and geometry.

Influence of the ambient color lighting on the accuracy of complete arch implant scans recorded by using two intraoral scanners

STATEMENT OF PROBLEM

The influence of different ambient factors including lighting has been previously studied. However, the influence of ambient color lighting settings on intraoral scanning accuracy remains uncertain.

PURPOSE

The purpose of this in vitro study was to assess the influence of ambient color lighting on the accuracy of complete arch implant scans recorded by using 2 intraoral scanners (IOSs).

MATERIAL AND METHODS

An edentulous maxillary cast with 6 implant scan bodies was digitized by using a laboratory scanner (DW-7-140) to obtain a reference file. Two groups were created based on the IOS tested: TRIOS 4 (IOS-1) and i700 (IOS-2). Seven subgroups were developed depending on the ambient color lighting (red, green, blue, yellow, cyan, magenta, and white) (n=15). Scanning accuracy was analyzed by using a metrology software program (Geomagic Control X). The Kruskal-Wallis, 1-way ANOVA, and pairwise comparisons were used to analyze the data (α=.05).

RESULTS

Significant trueness and precision values were found across the groups (P<.05) and subgroups (P<.05). For IOS-1, blue ambient lighting obtained the best trueness (19.8 ±1.8 µm) (P<.05); in precision, white light (20.8 ±7.3 µm) and blue light (22.1 ±13.5) showed the best results (P<.05). For IOS-2, white light showed the best trueness (51.9 ±16.7 µm); the best precision was obtained under magenta (38.6 ±10.4 µm) and yellow light (52.6 ±24.0 µm) (P<.05).

CONCLUSIONS

The optimal ambient color lighting varied between the IOSs assessed. As the best condition for maximizing accuracy was not found, ambient color lighting must be individualized for the IOS system used.

Influence of edentulous areas on the accuracy of the maximum intercuspal position recorded by using different intraoral scanners or an artificial intelligence-based program

STATEMENT OF PROBLEM

Intraoral scans can be articulated in maximum intercuspal position (MIP) by using an artificial intelligence (AI) based program; however, the impact of edentulous areas on the accuracy of the MIP located using this AI-based program is unknown.

PURPOSE

The purpose of this in vitro study was to assess the impact of edentulous areas (0, 1, 2, 3, and 4 posterior mandibular teeth) on the accuracy of the MIP located using 3 intraoral scanners (IOSs) and an AI-based program.

MATERIAL AND METHODS

Stone casts articulated in MIP in an articulator were digitized (T710). Five groups were created: no edentulous area (Group 0) or edentulous area of 1 (Group 1), 2 (Group 2), 3 (Group 3), or 4 (Group 4) posterior mandibular teeth. A maxillary and mandibular scan were obtained from the reference casts with 3 IOSs: Primescan, Aoralscan3, and i700. The nonarticulated scans were duplicated 20 times. Six subgroups were created based on the program used to locate the MIP: 3 IOS subgroups: PrimeScan, AoralScan3, and i700 and 3 subgroups for the AI-based program (Bitefinder) (Primescan-AI-articulated, Aoralscan3-AI articulated, and i700-AI articulated) (n=10). In the Group 0-Primescan subgroup, the 10 duplicated corresponding scans were articulated by recording a bilateral occlusal record. In the Group 0-Primescan-AI articulated subgroup, the 10 duplicated corresponding scans were automatically articulated in MIP by the AI-based program. In the Group 0-Aoralscan3 and Group 0-i700 subgroups, the same procedures were completed as in the Group 0-Primescan. In the Group 0-Aoralscan3-AI articulated and Group 0-i700-AI articulated subgroups, the same procedures were accomplished as in the Group 0- Primescan-AI articulated. For the data acquisition of Groups 1, 2, 3, and 4, the right mandibular posterior teeth were removed sequentially. The same procedures were completed as in Group 0. A program (Geomagic Wrap) was selected to compute interlandmark measurements on the digitized articulated casts (control) and each articulated specimen. Two-way ANOVA and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were used to analyze precision (α=.05).

RESULTS

Trueness and precision discrepancies were found between the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P<.001). Groups 0, 1, and 2 obtained the best trueness and precision, while Group 4 demonstrated the worst trueness and precision. Primescan and Aoralscan3 obtained better trueness than the i700. The AI-based program obtained lower MIP trueness and precision when compared with the IOSs tested. The AI-based program revealed the best MIP accuracy when articulating scans recorded by using the i700 and the worst with the Aoralscan3.

CONCLUSIONS

Edentulous areas impacted the trueness and precision of the MIP recorded by using the IOSs or AI-based program tested. Edentulous spaces involving 1 or 2 posterior teeth did not impact the MIP accuracy. An edentulous space of 4 teeth revealed the worst accuracy values captured by using the IOSs assessed or AI-based program. The performance of the AI-based program was influenced by the IOS system used to record the nonarticulated digital scans.

Influence of implant reference on the scanning accuracy of complete arch implant scans captured by using a photogrammetry system

STATEMENT OF PROBLEM

Photogrammetry has been reported to be a reliable digital alternative for recording implant positions; however, the factors that may impact the accuracy of photogrammetry techniques remain unknown.

PURPOSE

The purpose of this in vitro study was to assess the influence of the implant reference on the accuracy of complete arch implant scans acquired by using a photogrammetry system.

MATERIAL AND METHODS

An edentulous cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was obtained and digitized by using a laboratory scanner (T710; Medit). A photogrammetry system (PIC System) was selected to obtain complete arch implant scans. An optical marker (PIC Transfer, HC MUA Metal; PIC Dental) was positioned on each implant abutment of the reference cast. Each optical marker code and position was determined in the photogrammetry software program. Three groups were created based on the implant reference selected before acquiring the photogrammetry scans: right first molar (IPR-3 group), left canine (IPR-11 group), and left first molar (IPR-14 group) (n=30). Euclidean linear and angular measurements were obtained on the digitized reference cast and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and the Tukey tests were used to analyze the trueness data. The Levene test was used to analyze the precision values (α=.05 for all tests).

RESULTS

One-way ANOVA revealed significant linear (P=.003) and angular (P=.009) trueness differences among the groups tested. Additionally, the Tukey test showed that the IPR-11 and IPR-14 groups had significantly different linear (P<.001) and angular trueness (P<.001). The Levene test showed no significant precision linear (P=.197) and angular (P=.235) discrepancies among the groups tested. The IPR-3 group obtained the highest trueness (P<.001) and precision (P<.001) values among the groups tested.

CONCLUSIONS

Implant reference impacted the accuracy of complete arch implant scans obtained by using the photogrammetry system tested. However, a trueness ±precision linear discrepancy of 6 ±3 µm and an angular discrepancy of 0.01 ±0.01 degrees were measured among the groups tested; therefore, the impact of the discrepancy measured should not be clinically significant.

Influence of operator experience on the complete-arch accuracy and time-based efficiency of three intraoral scanners

Background/purpose

The performance of intraoral scanners (IOSs) relies on the operator's skills. However, whether operator experience influences IOS accuracy remains unclear. This study investigated the effect of operator experience on the trueness accuracy and time-based efficiency of IOSs.

Materials and methods

Thirty operators were equally divided into two groups on the basis of their IOS-handling experience. Each operator performed simulation scans of a maxillary model in a training dummy by using three IOSs: CEREC Omnicam, Primescan, and Aoralscan 3. A total of 90 scans were generated, and the scan time for image acquisition and the render time required for an IOS to generate a three-dimensional image were recorded. The trueness of each scan was calculated by comparing with a reference scan obtained from an industrial high-precision scanner. The t test and the ANOVA followed by the Tukey post hoc test were used to determine statistical differences. Significance was set at P < 0.01.

Results

For the three IOSs, no significant difference was noted in trueness accuracy, scan time, or render time between inexperienced and experienced operators. For both inexperienced and experienced operators, Omnicam had significantly less accuracy and longer scan time than did the other IOSs; the render time was significantly shorter for Aoralscan 3 than for the other IOSs.

Conclusion

Operator experience does not substantially influence the trueness accuracy and time-based efficiency of IOSs; these factors vary across IOS types. The render time for obtaining three-dimensional images is a significant feature for improving the time-based efficiency of IOSs.

Classification of Complete-Arch Implant Scanning Techniques Recorded by Using Intraoral Scanners

OBJECTIVES

To classify the complete-arch implant scanning techniques recorded by using intraoral scanners (IOSs).

OVERVIEW

Different implant scanning techniques have been described for recording complete-arch implant scans by using IOSs. However, dental literature lacks on a classification of these implant scanning techniques. Implant scanning techniques aim is to record the 3-dimensional position of the implants being scanned, while implant scanning workflows require additional scans to record all the information needed for designing an implant prosthesis. This additional information includes soft tissue information, tooth position, antagonist arch, and maxillomandibular relationship.

CONCLUSIONS

There are five complete-arch implant scanning techniques captured by using IOSs: non-splinting, non-calibrated splinting, calibrated implant scan bodies, calibrated frameworks, and reverse impression methods. The digital workflow varies depending on the implant scanning technique selected.

CLINICAL SIGNIFICANCE

The understanding of the varying implant scanning techniques and the main differences among them may ease the decision criteria for recording digital implant scans by using intraoral scanners.

Parameters to Improve the Accuracy of Intraoral Scanners for Fabricating Tooth-Supported Restorations

OBJECTIVES

To review the factors that impact the accuracy of intraoral scanners (IOSs) when fabricating tooth-supported restorations.

OVERVIEW

Factors can have a different impact on IOS accuracy depending on the scanning purpose. If the goal is to fabricate tooth-supported restorations, it is essential to review the following operator-related factors: IOS technology and system, scan extension and starting quadrant, scanning pattern, scanning distance, and rescanning methods. Additionally, it is critical to interpret the following patient-related factors differently: edentulous spaces, presence of existing restorations on adjacent teeth, and characteristics of the tooth preparation (build-up material, geometry, total occlusal convergence [TOC], finish line location, and surface finishing), and interdental spaces (between tooth preparations or between preparation and the adjacent tooth).

CONCLUSIONS

For crown or short-span fixed dental prostheses, a reduced scan extension is recommended. For complete-arch scans, it is advisable to start the scan in the same quadrant as the preparation. If the IOS permits locking the scan, rescanning may be indicated. Restorations on tooth preparations and adjacent teeth reduce accuracy. The simpler the geometry and the larger the TOC, the higher the IOS accuracy. Intracrevicular finish lines result in lower accuracy than equigingival or supragingival positions. Air-particle procedures showed better accuracy than coarse and fine grit and immediate dentin sealing. The greater the space between a preparation and the adjacent tooth, the better the accuracy.

CLINICAL IMPLICATIONS

Dental professionals must understand and handle the factors that impact the scanning accuracy of intraoral scanners differently depending on the purpose of the scan.

Accuracy of digital jaw relation determination in different occlusal conditions - an in vitro study

OBJECTIVES

In orthodontics, accurate registration of jaw relationships is essential for correct diagnosis and treatment planning. Therefore, accuracy of the digital spatial registration of maxillary and mandibular models and - for the first time-the influence of dentition stage and malocclusion type on this procedure were investigated under controlled conditions.

MATERIALS AND METHODS

Eight pairs of jaw models, representing different occlusal and developmental statuses (m1-m8), were scanned using two IOS types (PS: Primescan; TR: Trios4). Buccal scans for registering maxillary and mandibular models were repeated (n = 3). Reference scans were obtained using a desktop scanner (RDS; Ceramill Map 600). Arch-specific 3D coordinate systems were used to calculate the linear and angular deviations among different registrations. Trueness of registration by PS and TR was calculated using a statistical mixed-effect model (random-effect: model-type). Precision values of IOS registrations across m1-m8 were characterized as standard deviations (SDs).

RESULTS

As maximum deviations compared to RDS, PS showed caudal translation (0.11 ± 0.02 mm), while TR showed ventral translation (0.08 ± 0.06 mm), of the maxillary relative to the mandibular model. Maximum rotational values were calculated for tilting around the transverse axis (PS: anteinclination (0.25 ± 0.16°), TR: retroinclination (0.27 ± 0.16°)). These deviations varied with the malocclusion type. The lowest IOS precision was recorded for sagittal translation (PS: 0.013 ± 0.005 mm, TR: 0.021 ± 0.010 mm) and rotation around the transverse axis (PS: 0.051 ± 0.013°, TR: 0.076 ± 0.031°).

CONCLUSIONS AND CLINICAL RELEVANCE

Registrations using buccal IOS scans showed quantifiable but clinically negligible 3D deviations from reference scan registrations, whereby the type of tooth and jaw misalignment did not appear to have a clinically relevant influence. Therefore, the examined IOSs appear to be suitable for digital jaw relation determination in everyday clinical orthodontic practice.

An overview of the different digital facebow methods for transferring the maxillary cast into the virtual articulator

OBJECTIVES

The purposes of this study were to classify the described digital facebow techniques for transferring the maxillary cast into the semi-adjustable virtual articulator based on the digital data acquisition technology used and to review the reported accuracy values of the different digital facebow methods described.

OVERVIEW

Digital data acquisition technologies, including digital photographs, facial scanners, cone beam computed tomography (CBCT) imaging, and jaw tracking systems, can be used to transfer the maxillary cast into the virtual articulator. The reported techniques are reviewed, as well as the reported accuracy values of the different digital facebow methods.

CONCLUSIONS

Digital photographs can be used to transfer the maxillary cast into the virtual articulator using the true horizontal reference plane, but limited studies have assessed the accuracy of this method. Facial scanning and CBCT techniques can be used to transfer the maxillary cast into the virtual articulator, in which the most frequently selected references planes are the Frankfort horizontal, axis orbital, and true horizontal planes. Studies analyzing the accuracy of the maxillary cast transfer by using facial scanning and CBCT techniques are restricted. Lastly, optical jaw trackers can be selected for transferring the maxillary cast into the virtual articulator by using the axis orbital or true horizontal planes, yet the accuracy of these systems is unknown.

CLINICAL IMPLICATIONS

Digital data acquisition technologies, including digital photographs, facial scanning methods, CBCTs, and optical jaw tracking systems, can be used to transfer the maxillary cast into the virtual articulator. Studies are needed to assess the accuracy of these digital data acquisition technologies for transferring the maxillary cast into the virtual articulator.

An overview of artificial intelligence based applications for assisting digital data acquisition and implant planning procedures

OBJECTIVES

To provide an overview of the current artificial intelligence (AI) based applications for assisting digital data acquisition and implant planning procedures.

OVERVIEW

A review of the main AI-based applications integrated into digital data acquisitions technologies (facial scanners (FS), intraoral scanners (IOSs), cone beam computed tomography (CBCT) devices, and jaw trackers) and computer-aided static implant planning programs are provided.

CONCLUSIONS

The main AI-based application integrated in some FS's programs involves the automatic alignment of facial and intraoral scans for virtual patient integration. The AI-based applications integrated into IOSs programs include scan cleaning, assist scanning, and automatic alignment between the implant scan body with its corresponding CAD object while scanning. The more frequently AI-based applications integrated into the programs of CBCT units involve positioning assistant, noise and artifacts reduction, structures identification and segmentation, airway analysis, and alignment of facial, intraoral, and CBCT scans. Some computer-aided static implant planning programs include patient's digital files, identification, labeling, and segmentation of anatomical structures, mandibular nerve tracing, automatic implant placement, and surgical implant guide design.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of select 2023 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertize in their subject areas that include (in order of appearance here): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine, oral and maxillofacial surgery, and oral radiology; and dental caries and cariology. The authors have focused their efforts on presenting information likely to influence the daily dental treatment decisions of the reader with an emphasis on current innovations, new materials and processes, emerging technology, and future trends in dentistry. With the overwhelming volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to inform and update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope readers find this work helpful in providing evidence-based care to patients seeking healthier and happier lives.

Influence of scanning pattern on accuracy, time, and number of photograms of complete-arch implant scans: A clinical study

OBJECTIVES

To measure the influence of scanning pattern on the accuracy, time, and number of photograms of complete-arch intraoral implant scans.

METHODS

A maxillary edentulous patient with 7 implants was selected. The reference implant cast was obtained using conventional methods (7Series Scanner). Four groups were created based on the scanning pattern used to acquire the complete-arch implant scans by using an intraoral scanner (IOS) (Trios4): manufacturer's recommended (Occlusal-Buccal-Lingual (OBL)), zig-zag (Zig-zag), circumferential (Circumf), and novel pattern that included locking an initial occlusal scan (O-Lock group) (n = 15). Scanning time and number of photograms were recorded. The linear and angular measurements were used to assess scanning accuracy. One-way ANOVA and Tukey tests were used to analyze trueness, scanning time, and number of photograms. The Levene test was selected to assess precision (α=0.05).

RESULTS

Statistically significant differences in trueness were detected among OBL, Zig-zag, Circumf, and O-Lock regarding linear discrepancy (P<0.01), angular discrepancy (P<0.01), scanning time (P<0.01), and number of photograms (P<0.01). The O-Lock (63 ± 20 µm) showed the best linear trueness with statistically significant differences (P < 0.01) with Circumferential (86 ± 16 µm) and OBL (87 ± 19 µm) groups. The O-Lock (93.5 ± 13.4 s, 1080 ± 104 photograms) and Circumf groups (102.9 ± 15.1 s, 1112 ± 179 photograms) obtained lower scanning times (P < 0.01) and number of photograms (P < 0.01) than OBL (130.3 ± 19.4 s, 1293 ± 161 photograms) and Zig-zag (125.7 ± 22.1 s, 1316 ± 160 photograms) groups.

CONCLUSIONS

The scanning patterns tested influenced scanning accuracy, time, and number of photograms of the complete-arch scans obtained by using the IOS tested. The zig-zag and O-Lock scanning patterns are recommended to obtain complete-arch implant scans when using the selected IOS.

Effects of the intraoral scanner and implant library on the trueness of digital impressions in the full-arch implant scan: A comparative in vitro study

OBJECTIVE

To evaluate the effect of intraoral scanners (IOSs) and implant libraries (ILs) on the trueness of digital impressions for the fabrication of implant-supported full-arch (FA) prostheses.

METHODS

A stone cast of an edentulous maxilla with 6 implant analogues and cylindrical scanbodies (IPD ProCam®, Matarò, Barcelona, Spain) was probed using a coordinate measuring machine to capture a reference model (RM). The cast was mounted on a mannequin and scanned with 3 different IOSs (iTERO Element 5D Plus®, Align Technologies, San José, CA, USA; IS 3800®, Dexis, Quackertown, PN, USA; and i-700®, Medit, Seoul, South Korea). Ten scans were performed by an experienced operator using each IOS, first capturing only the occlusal surfaces, then the buccal and finally the palatal surfaces (less than 45 s per scan). In each scan, the meshes of the SBs were replaced by the corresponding IL file, with and without increment, to obtain the best correction for the mesh growth. The positions of the SBs in each file were compared with those in the RM, to evaluate the linear and cross distances between them. The final outcome was the trueness of the different IOSs, evaluating the effect of using different ILs on the quality of the impressions.

RESULTS

Significant differences were found between the different IOS scans and the RM, and among the different IOSs, in the different segments. The correction of the mesh growth through incremental ILs did not affect the final trueness of the IOS scans.

CONCLUSIONS

Different levels of trueness were found among the IOSs evaluated, in the different scan segments, but with the cylindrical SBs used herein, the correction of the mesh growth with incremental ILs did not affect the final quality of the digital impressions.

STATEMENT OF CLINICAL RELEVANCE

There are still errors with IOS in the FA impressions. IOS have an effect on the quality of the digital impressions, and apparently the library has not, with purely cylindrical SBs: further studies are needed to confirm this aspect.

Accuracy of intraoral scanning using modified scan bodies for complete arch implant-supported fixed prostheses

STATEMENT OF PROBLEM

The accuracy of intraoral scanning techniques for complete arch implant-supported prostheses remains unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of complete arch intraoral scanning using newly modified scan bodies.

MATERIAL AND METHODS

A definitive cast with 6 parallel dental implants (6-246 subgroup, right first molar, right first premolar, right lateral incisor, left lateral incisor, left first premolar, and left first molar) was fabricated. By masking the implants with artificial gingiva, 2 other distinct definitive casts were obtained for 2 subgroups: the 4-24 subgroup, which included 4 implants (right first premolar, right lateral incisor, left lateral incisor, and left first premolar) and the 4-26 subgroup, which also included 4 implants (right first molar, right lateral incisor, left lateral incisor, and left first molar). Three methods were used to record implant location in these 3 subgroups: conventional impression making using the open-tray splinted technique (group CNV), intraoral scanning with the use of conventional scan bodies (group IOS-C), and intraoral scanning using newly modified scan bodies (group IOS-M). To assess accuracy, the best-fit algorithm was used, and root mean square (RMS) values were calculated. Descriptive statistics, including the median, interquartile range, and minimum and maximum values, were used to summarize the variables. Accuracy among different groups was compared, and the influence of the number of implants and the scan distance on the accuracy of group IOS-M was investigated. Appropriate methods were chosen based on the examination of normal distribution and homogeneity of variance, with 1-way analysis of variance (ANOVA) and the Tukey multiple comparison test for data normally (or log-normally) distributed and having equal variances and the Brown-Forsythe ANOVA test and Dunnett T3 multiple comparisons test for data normally (or log-normally) distributed but having unequal variances (α=.05). For data that did not follow a normal or log-normal distribution, the nonparametric Kruskal-Wallis test and Dunn multiple comparisons test was used.

RESULTS

The trueness of group IOS-M ranged from 15.5 to 37.5 µm, with a median (Q1, Q3) of 22.8 (20.3, 25.5) μm, better than that of group IOS-C (P<.001), ranging from 10.1 to 110.0 µm, with a median (Q1, Q3) of 32.1 (26.3, 47.6) μm. Although the trueness of group IOS-M was worse than group CNV (P<.001), ranging from 6.7 to 22.5 µm, with a median (Q1, Q3) of 14.9 (10.5, 17.8) μm, it was within the threshold deemed acceptable to produce clinically suitable complete arch restorations (<59 to 72 µm). The precision of group IOS-M, ranging from 7.2 to 40.8 µm, with a median (Q1, Q3) of 19.5 (16.4, 23.0) μm, was better than that of group IOS-C (P<.001), ranging from 9.8 to 86.8 µm, with a median (Q1, Q3) of 33.7 (25.2, 44.5) μm, but not as good as group CNV (P<.001), ranging from 7.0 to 34.3 µm, with a median (Q1, Q3) of 18.8 (14.3, 21.4) μm. No significant difference in accuracy was found in group IOS-M among subgroups 6-246, 4-26, and 4-24 (P>.05).

CONCLUSIONS

For complete arch implant scans, the modified scan body significantly improved the accuracy of intraoral scanning, with trueness <59 to 72 µm (threshold deemed acceptable to produce clinically suitable complete arch restorations). The accuracy of intraoral scanning using the modified scan bodies was not affected by the number of implants or the scan distance.

Influence of limited mouth opening in children on intraoral scanning accuracy: An in vitro study

BACKGROUND

Although intraoral scanning is highly reliable, little is known about its accuracy in young children with limited mouth-opening ability.

AIM

To determine the accuracy of intraoral scans based on the degree of mouth opening.

DESIGN

To simulate mouth opening in children with primary dentition, three groups (n = 5 per group) were allocated by maximum mouth opening of 30, 37 and 40 mm. After the primary dentition model was connected to a dental phantom, intraoral scanning was performed using iTero and TRIOS4. The scanned files were digitally evaluated. Root mean square values were calculated to assess trueness and precision.

RESULTS

iTero showed deviations of three-dimensional trueness of 0.067 ± 0.008, 0.063 ± 0.001 and 0.065 ± 0.005 mm, and TRIOS4 of 0.07 ± 0.002, 0.064 ± 0.003 and 0.066 ± 0.002 mm in the 30, 37 and 40 mm groups, respectively. There were no significant differences in either mouth opening (p > .017) or the intraoral scanners (p > .05). The same statistical results were obtained for precision, with the exception of the 30 mm of mouth opening.

CONCLUSIONS

Within the limits of this study, limited mouth opening hardly influenced the accuracy of intraoral scanning.

Differences in maxillomandibular relationship recorded at centric relation when using a conventional method, four intraoral scanners, and a jaw tracking system: A clinical study

STATEMENT OF PROBLEM

Digital systems including intraoral scanners (IOSs) and optical jaw tracking systems can be used to acquire the maxillomandibular relationship at the centric relation (CR). However, the discrepancy of the maxillomandibular relationship recorded at the CR position when using digital methods remains uncertain.

PURPOSE

The purpose of this clinical study was to compare the accuracy of the maxillomandibular relationship recorded at the CR position using a conventional procedure, 4 different IOSs, and an optical jaw tracking system.

MATERIAL AND METHODS

A completely dentate volunteer was selected. A Kois deprogrammer (KD) was fabricated. Six groups were created based on the technique used to obtain diagnostic casts and record the maxillomandibular relationship at the CR position: conventional procedures (CNV group), 4 IOS groups: TRIOS4 (TRIOS4 group), iTero Element 5D (iTero group), i700 wireless (i700 group), Primescan (Primescan group), and a jaw tracking system (Modjaw) (Modjaw group) (n=10). In the CNV group, conventional diagnostic stone casts were obtained. A facebow record was used to mount the maxillary cast on an articulator (Panadent). The KD was used to obtain a CR record for mounting the mandibular cast, and the mounted casts were digitized by using a scanner (T710) to acquire the reference scans. In the TRIOS group, intraoral scans were obtained and duplicated 10 times. The KD was used to obtain a bilateral virtual occlusal record at the CR position. To acquire the specimens of the iTero, i700, and Primescan groups, the procedures in the TRIOS4 group were followed, but with the corresponding IOS. In the Modjaw group, the KD was used to record and export the maxillomandibular relationship at the CR position. Articulated virtual casts of each group were exported. Thirty-six interlandmark linear measurements were computed on both the reference and experimental scans. The distances obtained on the reference scan were used to calculate the discrepancies with the distances obtained on each experimental scan. The data were analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey tests (α=.05).

RESULTS

The trueness and precision of the maxillomandibular relationship record were significantly affected by the technique used (P<.001). The maxillomandibular relationship trueness values from high to low were iTero (0.14 ±0.09 mm), followed by the Modjaw (0.20 ±0.04 mm) and the TRIOS4 (0.22 ±0.09 mm) groups. However, the iTero, Modjaw, and TRIOS4 groups were not significantly different from each other (P>.05). The i700 group obtained the lowest trueness and precision values (0.40 ±0.22 mm) of all groups tested, followed by the Primescan grop (0.26±0.13 mm); however, the i700 and Primescan groups had significantly lower trueness and precision than only the iTero group (P<.05).

CONCLUSIONS

The trueness and precision of the maxillomandibular relationship recorded at the CR position were influenced by the different digital techniques tested.

Augmented reality assisted intraoral scanning of mandibular arch: A proof-of-concept pilot clinical study

OBJECTIVES

To investigate whether the scanning time, trueness and number of photos are influenced when augmented reality (AR) heads-up display (HUD) is utilized during the intraoral scan of fully dentate mandibular arches.

METHODS

A total of 10 patients (6 females and 4 males) were included. The mandibular arch of each patient was scanned twice using an intraoral scanner (Trios4 Pod IOS: 3Shape): one with and one without AR-HUD (ML2; Magic Leap). Further, alginate impression was taken, and the cast was digitized to acquire the reference model for trueness comparison (T310, Medit). The scan time and number of photos were recorded. Trueness was evaluated qualitatively and quantitatively using colored heat maps and RMSE values respectively. t-test was used to evaluate the difference in scan time, trueness, and number of photos between the two groups (α = .05).

RESULTS

AR-assisted IOS resulted in significantly faster scan time (44 s) compared to the time consumed following conventional scan method without AR-HUD (63 s) (P = <0.001). The number of photos was also significantly less with AR-assisted IOS (836) compared to IOS using conventional technique without AR-HUD (1209) P = <0.001. No statistical difference was detected in RMSE between the test groups.

CONCLUSIONS

Integration of AR technology with IOS process represents a promising potential to acquire digital impressions with reduced scan acquisition time and reduced images count while simultaneously maintaining the trueness of the acquired scans.

CLINICAL SIGNIFICANCE

Augmented Reality presents an emerging potential in Prosthodontics to acquire digital impressions with decreased number of images and acquisition time.

Effect of preparation design and scan pattern on the accuracy of intraoral scans for complete arch laminate veneers under simulated intraoral variables

PURPOSE

The purpose of the study was to investigate the influence of different preparation designs and scan patterns on the accuracy of intraoral scans for complete-arch maxillary laminate veneers.

MATERIALS AND METHODS

Three maxillary typodonts were used to obtain reference models with three different laminate veneer preparation designs: windows (W), beveled (B), and incisal overlap (IO). Reference scans were obtained with a desktop scanner. A total of 90 complete arch intraoral scans were made with an intraoral scanner (Medit i700) following three different scan patterns: straight motion (SM), zigzag motion (ZM), and combined motion (CM). Ten scans were made in each subgroup and exported as standard tessellation language (STL) files. Assessment of accuracy was conducted with a 3D software analysis program (Geomagic Control X). Each STL file was individually aligned with the reference scan using the best fit algorithm tool, and 3D differences were calculated using the root mean square (RMS) value. Two-way analysis of variance (ANOVA) followed by post hoc comparison tests were applied to analyze precision and trueness data (α = 0.05).

RESULTS

Two-way ANOVA and post hoc comparison tests revealed significant differences among different preparation designs and scan patterns (p < 0.05). Regarding trueness, the IO when scanned with SM presented higher mean RMS than the other preparation designs (W and B) scanned with the same scanning pattern (p < 0.05). Regarding precision, the groups of W and IO presented significantly higher mean RMS than the group of B when scanned with ZM (p < 0.05).

CONCLUSIONS

Accuracy of intraoral scans for complete-arch laminate veneers was affected by different laminate veneer preparation designs and scan patterns.

CLINICAL SIGNIFICANCE

Modifying scan pattern according to preparation design helps to improve scan accuracy for complete-arch laminate veneers.

Do intraoral scanning technologies affect the trueness of dental arches with crowding, diastema, and edentulous spaces? A clinical perspective

OBJECTIVES

To evaluate the trueness of dental arches digitised by two intraoral scanning (IOS) technologies from patients presenting crowding, diastema, and bilateral posterior edentulous space with tilted molar.

METHODS

Conventional impressions and dental stone models were generated from three patients presenting the aforementioned dental arch conditions. These models were digitised on a desktop scanner, and the resulting mesh was used as reference. Subsequently, the patients were scanned using confocal based (CF; iTero Element 2) and blue laser-multiscan (BLM; Virtuo Vivo) imaging IOS technology, totalling thirty scans. The meshes from the scans were exported in Standard Tessellation Language format and analysed using Geomagic Control X software. Root mean square (RMS) indicated deviation magnitude. Differences in IOS technologies were evaluated with paired t-tests, and dental arch conditions compared using ANOVA and post-hoc Tukey tests (α=0.05).

RESULTS

Digital dental arch from blue laser-multiscan technology showed lower trueness compared to confocal based technology for crowding (p = 0.0084) and edentulous spaces (p = 0.0025) conditions. When the types of oral condition were compared, discrepancies were significantly different for both IOS technologies, featuring the arch with diastema showing the lowest trueness, followed by edentulous spaces and crowding.

CONCLUSION

Dental arches presenting crowding and edentulous spaces digitised by blue laser-multiscan technology exhibited greater discrepancies compared to confocal based imaging technology. Furthermore, trueness varied among the dental arch conditions.

CLINICAL SIGNIFICANCE

The IOS technology and patient's dental arch condition can influence the trueness of dental arch digitisation. Being aware of these effects allows clinicians to take them into account during scanning procedures, digital planning and manufacturing.

Accuracy Analysis of Digital Models from Intraoral Scanners and 3D-Printed Casts in Children and Teenagers

PURPOSE

The aim was to analyze the accuracy of digital models and 3D-printed casts from full-arch digital impressions using two intraoral scanners (iTeroTM and PrimescanTM).

MATERIALS AND METHODS

A crossover reliability study was designed, scanning children and teenagers with iTeroTM and PrimescanTM. Accuracy was evaluated by measuring intercanine, intermolar, and ipsilateral canine-molar distances intraorally and comparing these measurements with those from plaster casts, digital models obtained with intraoral scanners, and 3D-printed casts. A paired comparison and a general linear model with a one-way repeated measures ANOVA procedure were carried out with a confidence level of 95% (p ≤ 0.05).

RESULTS

A total of 51 subjects were analyzed (mean age 12.35 ± 2.57). Statistical differences (p < 0.05) were found in the upper and lower arch regarding accuracy in comparison to intraoral measurements, except for the iTeroTM-printed cast and canine-molar upper right and intercanine lower distances (p > 0.05 for all comparisons). Regarding a comparison between reproduction methods, the plaster cast oversized the intercanine upper distance in comparison with both intraoral scanners' digital models and the PrimescanTM-printed cast (p = 0.001), but there were no differences in the lower arch (p > 0.05 for all comparisons).

CONCLUSION

Intraoral scanners reproduce tooth structures with similar accuracy to conventional methods.

Evaluating the accuracy of CEREC intraoral scanners for inlay restorations: impact of adjacent tooth materials

BACKGROUND

The accuracy of intraoral scanning is critical for computer-aided design/computer-aided manufacturing workflows in dentistry. However, data regarding the scanning accuracy of various adjacent restorative materials and intraoral scanners are lacking. This in vitro study aimed to evaluate the effect of adjacent restorative material type and CEREC's intraoral scanners on the accuracy of intraoral digital impressions for inlay cavities.

METHODS

The artificial tooth was prepared with an occlusal cavity depth of 2 mm, a proximal box width at the gingival floor of 1.5 mm, and an equi-gingival margin extended disto-occlusally at the transition line angle on both the lingual and buccal sides for an inlay restoration. The adjacent teeth were veneered with crowns made of gold and zirconia, and an artificial tooth (resin) was utilized as the control group. The inlay cavity and adjacent teeth (Gold, Zirconia, and resin) were scanned 10 times using Chairside Economical Restoration of Esthetic Ceramics (CEREC) Primescan (PS), Omnicam (OC), and Bluecam (BC). A reference scan was obtained using a laboratory scanner (3-shape E3). Scanning was performed according to the manufacturer's instructions, including powder application for the BC group. Standard tesselation language files were analyzed using a three-dimensional analysis software program. Experimental data were analyzed using a two-way analysis of variance and the Tukey's post-hoc comparison test.

RESULTS

The restorative materials of the adjacent teeth significantly affected the accuracy of the intraoral digital impressions (p < .05). The zirconia group exhibited the highest trueness deviation, followed by the resin and gold groups, with each demonstrating a statistically significant difference (p < .05). The resin group demonstrated the highest maximum positive deviation and deviation in precision. Gold exhibited the lowest average deviation value for trueness compared with those of the other adjacent restorative materials. Intraoral scanner type significantly influenced the trueness and precision of the scan data (p < .05). The average deviation of trueness according to the intraoral scanner type increased in the following order: BC > PS > OC. The average deviation in precision increased in the following order: PS>OC>BC (p < .05).

CONCLUSION

The restorative materials of the adjacent tooth and the type of intraoral scanner affect the accuracy of the intraoral digital impression. The trueness of the digital images of the BC group, obtained by spraying the powder, was comparable to that of the PS group. Among the adjacent restorative materials, zirconia exhibited the lowest trueness. In contrast, PS demonstrated the highest precision among the intraoral scanners, while resin displayed the lowest precision among the adjacent restorative materials.

Digital workflow for the fabrication of custom-fit additively manufactured sports mouthguards with balanced occlusion using an optical jaw tracking system: A dental technique

Custom sports mouthguards are used in various sports to protect teeth, temporomandibular joints, and soft tissues from impact forces. The present article demonstrates a digital workflow to fabricate a 3-dimensionally (3D) printed individualized sports mouthguard. An optical jaw tracking system is used to record a repeatable reference position, and mandibular excursive movements to achieve a completely balanced occlusion. The technique simplifies the fabrication of a custom-fit mouthguard over the conventional approach by providing increased thickness accuracy, control of design, and integration of jaw motion.

True horizontal or gravity plane registration for transferring the maxillary scan into the virtual articulator by using a facial scanner without the need for an additional device

Different reference planes can be used to transfer the maxillary cast into the analog articulator, including the true horizontal or gravity reference plane. Different techniques have been described to record the gravity reference plane for transferring the maxillary scan into the virtual articulator by using facial scanning techniques. However, these digital facebow procedures require the use of an extraoral scan body system, printed reference device, or orientation reference board. This manuscript describes a technique for recording the gravity reference plane by using a facial scanner without the use of an additional device. This technique aims to reduce the clinical time needed to capture a patient's digital data and minimize the laboratory time needed to integrate the virtual patient and transfer the maxillary scan into the virtual articulator.

Influence of apical finish line location of tooth preparations on the scanning accuracy of intraoral scanners with various focal lengths and scanning technologies

STATEMENT OF PROBLEM

Limited studies have reported the influence of finish line location on the accuracy of intraoral scanners (IOSs). Focal length is a hardware characteristic of IOSs. Whether there is a relationship between scanning accuracy of tooth preparations with the finish located at different apical positions and focal length and IOS technology or system remains uncertain.

PURPOSE

The purpose of the present in vitro study was to assess the influence of the apical finish line location of tooth preparations on the accuracy of 4 IOSs with various focal lengths and scanning technologies.

MATERIAL AND METHODS

A maxillary typodont with a crown preparation on the left first molar was digitized (T710). Afterwards, a removable die was created on the prepared first molar of the virtual cast and duplicated to create 4 dies with different apical finish line locations: 2- or 1-mm supragingival, 0-mm or equigingival, and -0.5-mm or intracrevicular. The cast and die designs were additively fabricated (Asiga Pro 4K with Keystone Model Ultra). Each die was independently scanned by using the same laboratory scanner (reference scans). Four groups were created: TRIOS 5, i700, iTero, and Primescan. Four subgroups were developed depending on the apical position of the finish line (n=15). In each subgroup, the cast was assembled by positioning the corresponding die into the cast. The cast was then scanned by using the corresponding IOS. The reference scans were used as a control to compute the root mean square (RMS) error discrepancies with each experimental scan on the preparation and margin of the preparation areas. Two-way ANOVA and pairwise comparisons were used to analyze trueness (α=.05). The Levene and pairwise comparisons using the Wilcoxon Rank sum test were used to analyze precision (α=.05).

RESULTS

Trueness discrepancies in the preparation area were found among the groups (P=.010) and subgroups (P<.001), with a significant interaction between group×subgroup (P<.001). The -0.5 mm location obtained significantly worse trueness in the preparation area. The TRIOS 5 and i700 obtained the best trueness in the preparation area. Trueness discrepancies in the margin area were found among the groups (P=.002) and subgroups (P<.001), with a significant interaction between group×subgroup (P=.004). The -0.5 mm location obtained the worst trueness in the margin area. The i700 and Primescan obtained the best trueness in the margin area. Precision discrepancies were found in the preparation area (P<.001). The TRIOS 5 obtained the best precision in the preparation area (P=.001). Precision discrepancies in the margin area were obtained (P<.001). The 1-mm subgroup obtained the best precision (P=.001).

CONCLUSIONS

The apical position of the finish line of the tooth preparation tested affected the trueness and precision of the IOSs tested.

Impact of color temperature and illuminance of ambient light conditions on the accuracy of complete-arch digital implant scans

OBJECTIVE

The purpose of the present study was to assess the influence of color temperature and illuminance of ambient light on the accuracy of different intraoral scanners (IOSs) in complete-arch implant scans.

METHODS

An edentulous model with six implants and scan bodies was digitized by using a laboratory scanner (DW-7-140; Dental Wings) to obtain a reference mesh. Fifteen scans were performed employing two intraoral scanners (Trios 4;3Shape A/S and i700; Medit Co) at two illuminances (500 and 1000 lux) and three color temperatures (3200, 4400, and 5600 K). Scanning accuracy was measured by using a 3D metrology software program (Geomagic Control X). Kruskal-Wallis, one-way ANOVA, and pairwise comparison tests were used to analyze the data (α = .05).

RESULTS

Significant differences in trueness and precision values were found among the different IOSs under the same ambient lighting condition and among the different lighting conditions for a given IOS (p < .05) except for trueness in i700 groups (p > .05).

CONCLUSIONS

The influence on the accuracy of color temperature and illuminance varied depending on the intraoral scanner. An optimal ambient scanning light condition was not found; this should be adjusted based on the specific IOS system used. 3200 K of ambient light influences the precision of i700 when performed at 1000 lux, decreasing the accuracy. The variation of color temperature at the same illuminance does not affect the scanning accuracy of TRIOS 4, which obtained better accuracy in all scans at 1000 lux.

Discrepancies of centric occlusion located by using a conventional method and four intraoral scanners combined with a computer-aided design program: A pilot investigation

STATEMENT OF PROBLEM

Intraoral scanners (IOSs) can be used to record the maxillomandibular relationship at centric relation (CR). The articulated digital scans can be imported into a dental computer-aided design (CAD) program and used to locate centric occlusion (CO); however, the accuracy of the CO recorded by using IOSs and a dental CAD program remains unknown.

PURPOSE

The purpose of this clinical study was to compare the position of the CO located by using a conventional method and 4 IOSs combined with a dental CAD program.

MATERIAL AND METHODS

A patient volunteered to participate in this study. Conventional diagnostic stone casts were obtained. A facebow record (Kois Dentofacial Analyzer) was used to transfer the maxillary cast into a semi-adjustable articulator (Panadent PCH Articulator). A Kois deprogrammer (KD) was used to record the maxillomandibular relationship at CR and to transfer the mandibular cast into the articulator. Afterwards, CO was located in the articulated casts by removing the incisal pin and using an 8-µm articulating foil. CO was marked in the casts by using a blue articulating paper (control). Three groups were created based on the IOS used: TRIOS 4, iTero Element 5D Plus, i700, and Primescan. In each IOS group, a maxillary and mandibular scan were obtained. The scans were duplicated 10 times. Afterwards, a bilateral occlusal record captured with the KD was used to articulate each pair of duplicated scans. Each articulated specimen was imported into a CAD program (DentalCAD) and CO was virtually located. The teeth contacting at the CO of each specimen were compared with the control group. Categorical data were analyzed by using the chi-squared test (α=.05).

RESULTS

The chi-squared test revealed a significant association between the IOS system and the location of the CO (P=.004). The highest association was found between the TRIOS 4 and CO position, in which 100% of the specimens obtained the same CO position as in the conventional group. The lowest association was found between the i700 and CO position. In the i700 group, 20% of the specimens showed the same CO position as in the control group. A similar outcome was obtained in the iTero and Primescan groups. In both groups, 60% of the specimens demonstrated the same CO position as the control group.

CONCLUSIONS

The IOS system used to acquire articulated scans at CR impacted the CO position located by using the evaluated digital methods. The TRIOS 4 system was the only IOS that consistently reproduced the same CO position as the conventional method.