Impact of intraoral scanner, scanning strategy, and scanned arch on the scan accuracy of edentulous arches: An in vitro study

Analyzing the influence of scanning speeds and distances on digital intraoral scans: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the influence of scanning speed and distance on the precision and quality of digital intraoral scans.

DATA

The PICO strategy was employed to delineate the inclusion and exclusion criteria. The acquired records underwent filtration according to eligibility criteria, with essential information subsequently extracted. The meta-analysis, facilitated by Review Manager 5.4, utilized chi-square and the inconsistency index, along with forest plots. The standardized mean difference (SMD) was employed for the comparative analysis of study groups. Additionally, the study encompassed assessments of publication bias and the quality of included studies.

SOURCES

The search was conducted using three Internet databases: PubMed, ScienceDirect, and the Cochrane Library.

RESULTS

Among the evaluated scanners (Trios 3, Trios 4, iTero, Primescan, Medit i500), only TRIOS 3 exhibited a statistically significant sensitivity to scanning parameters (SMD = -4.03; 95% CI: -7.26 to -0.80; P = 0.01). Increased scanning distances and faster speeds markedly reduced its accuracy, likely due to its older optical technology lacking real-time error correction features present in newer models like TRIOS 4 and Primescan. No significant effects were observed for TRIOS 4, Primescan, or Medit i500 (P > 0.05), suggesting their advanced hardware/software mitigates parameter variability.

CONCLUSIONS

Clinicians using TRIOS 3 should prioritize shorter scanning distances (5-10 mm) and slower speeds to optimize accuracy, as its performance is highly dependent on operator-controlled parameters. In contrast, newer scanners (e.g., TRIOS 4, Primescan) demonstrate greater resilience to distance/speed variations, enabling flexible clinical workflows. These findings underscore the importance of device-specific protocols to enhance digital impression reliability in restorative and prosthetic dentistry.

Can digital scans replace conventional impressions for complete denture fabrication? A scoping review

STATEMENT OF PROBLEM

With the advent of digital technologies, a shift has taken place from conventional impressions (CIs) to digital scans (DSs). However, DSs of completely edentulous arches remain challenging.

PURPOSE

The purpose of this scoping review was to explore the literature aiming to answer the question of whether DSs can entirely replace CIs for complete denture fabrication.

MATERIAL AND METHODS

The review followed the recommendations of the preferred reporting items for systematic review and meta-analysis extension for scoping review statement (PRISMA-ScR). An electronic search was conducted in MEDLINE/PubMed, Scopus, Web of Science, and Cochrane library. The search strategy used a combination of terms for "completely edentulous arches" and "digital scans." Any study from 2010 to 2024 was considered and included if in English. Those on complete arch implant impressions were excluded. The null hypothesis was that DSs would be equivalent with CIs.

RESULTS

The initial search retrieved 1980 articles. After deleting duplicates and applying the inclusion criteria, 26 articles were included. Nine were clinical cross-over studies, 8 were studies that introduced methods to enhance the accuracy of DSs of edentulous arches, and 9 were in vitro studies that compared the accuracy of DSs made by different scanners. The methods introduced somewhat improved the stitching process. However, the difficulty in acquiring data of the functional morphology of mobile tissues remained a challenge, especially for mandibular arches. Intraoral scanner (IOS)-related factors (such as scanning technology, scanned area, scanned arch, and scan strategy) seemed to affect the accuracy of DSs.

CONCLUSIONS

The main challenges in recording edentulous arches digitally included the lack of anatomic indicators, difficulty in capturing vestibular tissues, and IOS-related factors. Currently, reliable evidence that DSs could entirely replace CIs in complete denture wearers is lacking.

Clinical precision of Aoralscan 3 and Emerald S on the palatal and dentition areas: Evaluation for forensic applications

OBJECTIVES

To compare the precision (repeatability and intermediate precision) of palatal and dentition scans taken with two different intraoral scanners.

METHODS

The maxillary arch of 23 individuals was scanned three times using the Aoralscan 3 (Shining 3D) and Emerald S (Planmeca), resulting in 6 scans per individual. The scans were segmented in Meshmixer into palatal and dentition areas. Each replicate of an individual was compared within the specific scanner (repeatability) and to the corresponding replicate of the other scanner (intermediate precision). The scans were aligned using the iterative closest-point algorithm in the Zeiss Inspect software. The mean absolute distance between the aligned surfaces was calculated. Statistical comparisons were made using Friedman's two-way analysis of variance. Data are presented in median (quartile 1; quartile 3) form.

RESULTS

No significant difference in repeatability was found between Emerald S and Aoralscan 3 for the palate (26 µm [22; 26] vs. 22 µm [18; 26]) and for dentition (37 µm [31; 44] vs. 38 µm [35; 48]. Intermediate precision of the palate (32 µm [26; 43]) and dentition (72 µm [63; 80]) was significantly lower than the repeatability of Emerald S (p < 0.05, p < 0.001) and of Aorlascan 3 (p < 0.001, p < 0.001). Both precision types of both scanners were significantly lower for the dentition than for the palate (p < 0.001).

CONCLUSION

The precision of the dentition scan is lower than that of the palate. The precision of the Aoralscan 3 is similar to that of the Emerald S scanner.

CLINICAL SIGNIFICANCE

Novel intraoral scanners could be used with high precision for palatal soft tissue scans, expanding their clinical utility. Aligning scans from two different IOSs still has high precision, facilitating the interchangeable use of intraoral scanners for orthodontic, prosthetic, and forensic examinations.

Scan accuracy of recently introduced wireless intraoral scanners in different fixed partial denture situations

OBJECTIVE

To compare the in vitro scan accuracy (trueness and precision) of recently introduced wireless intraoral scanners (IOSs) to commonly used wired IOSs in different fixed partial denture (FPD) situations.

METHODS

Three partially edentulous maxillary models with implants located at different sites (lateral incisors [Model 1]; right canine and first molar [Model 2]; right first premolar and first molar [Model 3]) were digitized with wireless (Primescan 2 [P2] and TRIOS 5 [T5]) and wired (Primescan [P1] and TRIOS 3 [T3]) IOSs (n = 14 per IOS-model pair). The models were also digitized with an industrial-grade optical scanner for their reference scans. The IOS scans were superimposed over the reference scans to evaluate the 3D distance, angular, and 2D interimplant distance deviations (trueness). The variance of measured deviations was defined as the precision and all data were analyzed with bootstrap analysis of variance and Holm-corrected Welch tests (α = 0.05).

RESULTS

The IOS, FPD situation, and their interaction affected the scan accuracy (P < 0.001). P2 scans mostly had the highest and the scans of Model 2 mostly had the lowest 3D distance accuracy (P ≤ 0.030). P1 scans had the highest angular accuracy within each model, followed by the P2 scans in Models 1 and 2 (P ≤ 0.002). P1 scans mostly had higher 2D interimplant distance accuracy (P ≤ 0.047).

CONCLUSIONS

Digital impressions of tested FPD situations had high accuracy mostly with P1 and P2. The scans for a posterior 4-unit FPD might have higher inaccuracies, regardless of the tested IOSs.

Improving the accuracy of complete arch implant digital scans by using auxiliary clips for intraoral scan bodies: A dental technique

A technique to improve the accuracy of complete arch implant intraoral digital scans and the accuracy of their virtual casts is described. Obtaining accurate complete arch implant intraoral digital scans with an intraoral scanner is challenging because of the smooth and movable tissues of edentulous areas. The described technique uses auxiliary clips attached to intraoral scan bodies to cover interimplant edentulous spans with immobile tooth-like geometric references that are more favorable for intraoral scanning. The technique is designed to be user friendly and compatible with any intraoral scanner.

Improving the accuracy of complete arch implant intraoral digital scans by using horizontal scan bodies with occlusal geometry: A dental technique

A technique to improve the accuracy of complete arch implant intraoral digital scans and to obtain more accurate virtual casts with them is described. First, 2 complete arch intraoral digital scans were obtained with an intraoral scanner: a multiunit abutment digital scan and an implant digital scan with reusable horizontal intraoral scan bodies (ISBs) placed on the implants. These were previously created by combining the conventional ISBs compatible with the patient's implants with extensional structures with occlusal geometry. Once the digital scans had been acquired, the position of the implants was obtained by superimposing a virtual design of the conventional ISB onto each horizontal ISB of the complete arch implant digital scan. Finally, the virtual cast was obtained by superimposing the complete arch multiunit abutment digital scan on the complete arch implant digital scan.

Evaluation of the Accuracy of Digital Impression Techniques Based on an Integrated ADA Model

OBJECTIVE

The purpose of this in vitro study was to assess and compare the accuracy of three digital impression techniques based on an innovative integrated model.

MATERIALS AND METHODS

The integrated model was created by incorporating crown, inlay, and long-distance specimens from the American Dental Association (ADA) Standard No. 132. Digitized files of the model were acquired using three distinct impression techniques: intraoral scanner (IOS), extraoral scanner with negative cast (EOS_N), and extraoral scanner with positive cast (EOS_P). A coordinate measuring machine (CMM) was employed to establish the gold standard. The digital files of the model obtained via the extraoral scanner were designated the reference set for 3D fitting. Statistical analysis was performed using a one-way analysis of variance and Tukey's posthoc test.

RESULTS

For the crown specimen, the relative error of EOS_N for indices d1 and d2 was higher than that of IOS and EOS_P. For the inlay specimen, IOS showed the highest trueness for d3 and h2. For the long-distance specimen, IOS exhibited superior trueness for indices l1 and l3. EOS_N displayed the lowest trueness for l2. For l4, IOS had the largest relative error. No significant differences were observed among the three groups for l5 and l6. Notable deviations were evident in the 3D fitting maps at various locations in three experimental groups.

CONCLUSIONS

The three digital impression techniques exhibited varying capacities for capturing features of the integrated ADA model. For crown preparations, IOS and EOS_P are recommended, while for inlay preparations, no technology meets the standard requirements. IOS is recommended for partial impressions, while both EOS_N and EOS_P are suited for full-arch impressions.

Scan accuracy of wireless intraoral scanners while digitizing a combined scan body-healing abutment system

OBJECTIVES

To investigate the accuracy (trueness and precision) of wireless and wired intraoral scanners (IOSs) when scanning an implant with the combined healing abutment-scan body (CHA-SB) system.

METHODS

A partially edentulous mandibular model with a CHA-SB at the right first molar site was digitized with 2 wireless (NeoScan 2000 (NW) and TRIOS 4 wireless (T4 W)) and 2 wired (NeoScan 1000 (N) and TRIOS 4 wired (T4)) IOSs 44 times in total (n = 11). The reference scan file was generated by digitizing the same master model and CHA-SB with an industrial-grade optical scanner. All files were imported into a metrology-grade analysis software program to evaluate the surface (root mean square, RMS), linear, and angular deviations of the top part of the SB. The average deviation values defined the precision of the scans. The data were statistically analyzed (α = 0.05).

RESULTS

IOS type affected the surface and angular deviations and the precision (linear deviations on the x-axis) of the scans (p ≤ 0.043). T4 W had lower RMS than N and T4 (p ≤ 0.031). T4 had higher angular deviations than N on the XZ plane and had the lowest angular deviations on the YZ plane (p ≤ 0.011). T4 W scans had higher precision than N scans (p = 0.024).

CONCLUSION

Despite some differences in the trueness or precision of scans, tested IOSs mostly enabled similar scan accuracy. Regardless of the IOS, the implant scans had a tendency to tilt mesiobuccally, which can be considered clinically small.

CLINICAL SIGNIFICANCE

Tested wireless intraoral scanners may be suitable alternatives to their wired counterparts while digitizing an implant with a combined healing abutment-scan body system in the posterior region. However, the crowns fabricated from tested scans might require buccal, mesial, and occlusal surface veneering and distal surface adjustments.

A feasibility study on the use of an intraoral optical coherence tomography system for scanning the subgingival finish line for the fabrication of zirconia crowns: An evaluation of the marginal and internal fit

OBJECTIVES

This study aimed to evaluate the marginal and internal fit of zirconia crowns were fabricated using scan data from an intraoral optical coherence tomography (OCT) scanner and an intraoral scanner (IOS) for scanning the subgingival finish line.

METHODS

An extracted maxillary left central incisor was prepared for a zirconia crown. The prepared tooth was placed in artificial gingiva, created using silicone with a refractive index similar to that of the tooth, ensuring a subgingival depth of 0.50 to 0.70 mm from the labial finish line. Scanning data were obtained from four types of models as follows. (1) CAD reference model (CRM) excluding the gingiva and scanned using a laboratory scanner. (2) IOS group excluding the gingiva (IOS only, IOSO group). (3) IOS group with scanned attached artificial (IOS with gingiva, IOSG group). (4) OCT post-processed data of the subgingival finish line and IOSG data (OCT group). Zirconia crowns were fabricated based on these data, and their marginal and internal fit were evaluated using the silicone replica technique. Statistical analyses were conducted using one-way and two-way ANOVA (α = 0.05).

RESULTS

The OCT group exhibited a significantly smaller marginal gap than the IOSG group (P < 0.05). The marginal fit of the OCT group did not significantly differ from that of the CRM group (P > 0.05). The IOSG group exhibited a significantly larger chamfer gap, while both the IOSG and OCT groups had significantly larger axial gaps. Furthermore, the OCT group showed a significantly larger incisal gap (P < 0.05).

CONCLUSIONS

An intraoral OCT system can enhance the fabrication accuracy of zirconia crowns by achieving superior marginal fit for crowns with subgingival finish lines.

CLINICAL SIGNIFICANCE

The use of an IOS for subgingival finish lines without gingival displacement cords may result in a suboptimal marginal fit. However, integrating OCT technology can effectively address this issue, leading to improved clinical outcomes.

Enhancing Effective Scanning Techniques for Digital Impression in Neonates with Cleft Lip and/or Palate: A Laboratory Study Investigating the Impact of Different Scanners, Scanning Tip Sizes, and Strategies

Background/Objectives: Digital impressions are increasingly used to manage Cleft lip and/or palate (CL/P), potentially offering advantages over traditional methods. This laboratory investigation sought to evaluate the impact of scanning tip sizes, different scanners, and scanning strategies on intraoral scanning in neonates with CL/P. Methods: Ten soft acrylic models were used to simulate the oral anatomy of neonates with CL/P, evaluating parameters such as the ability of different scanning tips to capture alveolar cleft depth, scanning time, number of scan stops, and scan quality. The study utilised various scanning tips, including the Carestream normal tip, Carestream side tip, and Trios 4 scanner tip to assess the alveolar cleft depth measurements. The Trios 4, Carestream, and iTero scanners were evaluated for the time taken, number of scan stops during cleft-unobstructed scanning and cleft-obstructed scanning. The quality of all scanned images was analysed. Results: The findings showed comparable accuracy in capturing alveolar cleft depth with the three-scanning tip (p > 0.05). Scanning time and the number of scan stops did not significantly differ across the three scanners and various scanning strategies employed (p > 0.05). However, scanning with the cleft obstructed required less time and resulted in fewer scan stops compared to cleft -unobstructed scanning. Despite these results, all scanners failed to record the deepest part of the alveolar cleft, highlighting a limitation in current scanning technology for neonates with CL/P. Conclusions: The study recommends enhancing intraoral scanning in this population by adjusting tip size, improving clinician training, optimizing protocols, and conducting further research to improve techniques.

In vitro evaluation of the impact of intraoral scanner, scanning aids, and the scanned arch on the scan accuracy of edentulous arches

PURPOSE

To assess the accuracy of complete maxillary and mandibular edentulous arch scans obtained using two different intraoral scanners (IOSs), with and without scanning aids, and to compare these results to those obtained using conventional impression methods.

MATERIALS AND METHODS

Two IOSs were used (TRIOS 4 [TRI] and Emerald S [EMR]) to scan maxillary and mandibular typodonts. The typodonts were scanned without scanning aids [TRI_WSA and EMR_WSA groups] (n = 10). The typodonts were then scanned under four scanning aid conditions (n = 10): composite markers [TRI_MRK and EMR_MRK groups], scanning spray [TRI_SPR and EMR_SPR groups], pressure indicating paste [TRI_PIP and EMR_PIP groups], and liquid-type scanning aid [TRI_LQD and EMR_LQD groups]. Conventional impressions of both arches were also made using irreversible hydrocolloids in stock trays [IHC] and using polyvinyl siloxane (PVS) impression material in custom trays (n = 10) which were digitized using a laboratory scanner. Using a metrology software program, all scans were compared to a reference scan in order to assess trueness and to each other to assess precision. Trueness and precision were expressed as the root mean square (RMS) of the absolute deviation values and the statistical analysis was modeled on a logarithmic scale using fixed-effects models to meet model assumptions (α = 0.05).

RESULTS

The main effect of arch (p = 0.004), scanner (p < 0.001), scanning aid (p = 0.041), and the interaction between scanner and scanning aid (p = 0.027) had a significant effect on mean RMS values of trueness. The arch (p = 0.015) and scanner (p < 0.001) had a significant effect on the mean RMS values of precision. The maxillary arch had better accuracy compared to the mandible. The TRIOS 4 scanner had better accuracy than both the Emerald S scanner and conventional impressions. The Emerald S had better precision than conventional impressions. The scanning spray and liquid-type scanning aids produced the best trueness with the TRIOS 4 scanner, while the liquid-type scanning aid and composite markers produced the best trueness for the Emerald S scanner.

CONCLUSION

The scanned arch and the type of scanner had a significant effect on the accuracy of digital scans of completely edentulous arches. The scanning aid had a significant effect on the trueness of digital scans of completely edentulous arches which varied depending on the scanner used.

Evaluating the influence of palate scanning on the accuracy of complete-arch digital impressions-An in vitro study

OBJECTIVES

To assess the impact of including the palate and the number of images recorded during intraoral digital scanning procedure on the accuracy of complete arch scans.

METHODS

An experienced operator conducted 40 digital scans of a 3D printed maxillary model and divided them into two groups: 20 with inclusion of the palate (PAL) and 20 without (NPAL). Each set of scans was performed using an intraoral scanner (IOS) (Trios 5; 3Shape A/S; Copenhagen, Denmark). The resulting STL files were imported into the Geomagic Control X software (3D Systems, Rock Hill, SC, USA) for accuracy comparison. A reference STL file was created using a 3Shape E3 laboratory scanner (3Shape Scanlt Dental 2.2.1.0; Copenhagen, Denmark). The number of images captured was recorded during the scanning procedure.

RESULTS

In the case of the right side no statistically significant difference in trueness was detected (84 µm ± 45.6 for PAL and 80.4 ± 40.4 µm for NPAL). In the case of the left side no significant difference in trueness was observed (215.1 ± 70.2 µm for PAL and 233.9 ± 70.7 µm for NPAL). In the case of the arch distortion a statistically significant difference in trueness was seen between the two types of scans (135.3 ± 71.9 µm for PAL and 380.4 ± 255.1 µm for NPAL). The average number of images was 831.25, and 593.8 for PAL and NPAL, respectively.

CONCLUSIONS

Scanning of the palatal area can significantly improve the accuracy of dental scans in cases of complete arches. In terms of the number of images, based on the current results, obvious conclusions could not be drawn, and further investigation is required.

CLINICAL SIGNIFICANCE

Scanning the palate may be beneficial for improving the accuracy of intraoral scans in dentate patients. Consequently, this should be linked to an appropriate scanning strategy that predicts palatal scanning.

Accuracy of Complete-Arch Scans Obtained by Intraoral Scanner and Smartphone Three-Dimensional Scanning Applications With Different Smartphone Position Setups: An In Vitro Study

INTRODUCTION

The high cost of intraoral scanners (IOS) for complete-arch scans makes them less accessible for many dental practitioners. As a viable alternative, smartphone scanner applications (SMP) provide comparable scanning capabilities at a significantly low cost. However, there is limited data on the accuracy of SMP, especially when used in various smartphone positions. This study aimed to compare the three-dimensional (3D) and linear accuracy of complete-arch scans acquired by an IOS and SMP (KIRI Engine, KIRI Innovations, Guangdong, China) at three shooting angles (0°, 45°, and 90° for SMP_3A) and two shooting angles (30° and 60° for SMP_2A).

METHODS

A stone dental cast was scanned with a laboratory scanner as a reference, with 11 scans performed by an IOS, SMP_2A, and SMP_3A. In 3D analysis, trueness and precision were evaluated through superimposition with the reference scan and within each group, respectively, using the best-fit algorithm of Geomagic Wrap software (3D Systems, Inc., Rock Hill, SC). Trueness in linear discrepancy was assessed by comparing the occlusal-cervical and mesiodistal dimensions of reference teeth (canine, premolar, and molar), intercanine width, and intermolar width on the digital casts to measurements of the stone cast, while precision was measured using the coefficient of variance. Differences between groups were analyzed using the Friedman test, followed by the Dunn-Bonferroni post hoc test with a significance level set at 0.05.

RESULTS

IOS exhibited significantly lower trueness than SMP_2A (p = 0.003) with significantly greater width discrepancies on canines (p = 0.001) and molars (p < 0.001). Discrepancy patterns differed among the three scanning methods. The IOS showed greater discrepancies on the occlusal surfaces of posterior teeth. While SMP_3A demonstrated higher variation on the palatal surfaces and interproximal areas of posterior teeth. For precision, SMP_3A (p = 0.028) and SMP_2A (p = 0.003) showed a significantly lower precision in 3D analysis, but a comparable reproducibility in linear measurement to IOS.

CONCLUSION

TRIOS IOS (3Shape, Copenhagen, Denmark) exhibited lower trueness in 3D and linear accuracy analyses for complete-arch scans. The positions of the smartphone significantly enhanced trueness at the undercut region. SMP_2A and SMP_3A can be a potential alternative for precise linear measurement in complete-arch scans with selective use.

Accuracy and time efficiency of conventional and digital outlining of extensions of denture foundation on preliminary casts

PURPOSE

The purpose of this diagnostic study was to assess the accuracy and time efficiency of a digital method to draw the denture foundation extension outline on preliminary casts compared with the conventional technique.

MATERIALS AND METHODS

A total of 28 preliminary edentulous casts with no anatomical landmarks were digitized using a laboratory scanner. The outlining of the entire basal seat of the denture was performed on preliminary casts and digitized. Casts with no extension outline were digitized and outlines were drawn using software (DWOS, Straumann). The accuracy of the extension outlined between both techniques was evaluated in the software (GOM Inspect; GOM GmbH) by file superimposition. Specificity and sensitivity tests were applied to measure accuracy. The paired t-test (95% CI) was used to compare the mean total area and the working time.

RESULTS

The accuracy ranged from 0.57 to 0.92. The buccal and labial frenulum showed a lower value in the maxilla (0.57); while the area between the retromolar pad and buccal frenulum (0.64) showed a lower score in the mandible. The maxillary denture foundation and the working time for both arches were significantly longer for the digital method (P < .001).

CONCLUSION

The denture foundation extension outline exhibited a sufficiently excellent accuracy for the digital method, except for the maxillary anterior region. However, the digital method required a longer working time.

Effect of using scan body accessories and inter-implant distances on the accuracy of complete arch implant digital impressions: An in vitro study

PURPOSE

To introduce a novel design for scan body accessory parts that are reusable, easy to attach and detach without permanent change of the scan body, and can be used with different inter-implant distances to enhance the accuracy of complete arch implant scans.

MATERIALS AND METHODS

A maxillary polymethylmethacrylate (PMMA) model with a soft tissue replica was fabricated with four implant analogs located at tooth positions 17, 13, 22, and 27 with 18, 25, and 30 mm inter-implant distances. Four scan bodies (SBs) were attached to the implants. The model was scanned with a laboratory scanner to be used as a reference scan. A total of 40 scans were made with the same intraoral scanner and they were divided equally into two groups. Group A: Complete arch implant scans without scan body accessories (n = 20), and Group B: Complete arch implant scans with scan body accessories (n = 20). Intraoral scans were exported and superimposed on the reference scan using reverse engineering inspection software to be evaluated for 3D deviations, angular deviations, and linear deviations. Statistical analysis was performed with student t-test and analysis of variance (ANOVA) with repeated measures followed by post hoc adjusted Bonferroni test. The level of significance was set at P = 0.05.

RESULTS

The scan body accessories decreased both the 3D and linear deviations, with a statistically significant difference at SB4 for the 3D deviation (P = 0.043) and the linear inter-implant discrepancies between SB1-SB2 and SB3-SB4 (P = 0.029 and < 0.001), respectively. However, there was no statistically significant difference in angular deviation between the study groups. Implant positions had significant differences within each group.

CONCLUSIONS

 A significant improvement in the accuracy of the complete arch implant digital impression was achieved by using the scan body accessories, particularly in reducing the 3D and linear deviations at the most distant implant positions.

Novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit

OBJECTIVES

This article presents a novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit for implant-supported fixed complete dental prostheses (IFCDPs).

MATERIAL AND METHODS

The novel system presents a 3-unit toolset comprising intraoral scan bodies (ISBs), lateral pillar attachments (LPAs) and occlusal pillar attachments (OPAs). A 2-stage single visit workflow by an intraoral scanner (Trios 5) was introduced. The first stage "Screw-Scan-Done" was used to describe complete-arch intraoral implant scanning using LPAs. The second stage "Screw-Occlude-Done" involved virtual occlusal recording using OPAs. Two patients with one single edentulous arch were selected for this study. In the first patient, 6 bone level implants (Bone Level Tapered, Straumann) were placed in the edentulous maxilla at positions 12, 14, 16, 22, 24 and 26. In the second patient, 4 bone level implants (NobelActive CC, Nobel Biocare) were placed in the edentulous mandible at positions 32, 35, 42 and 45. A CAD-CAM procedure was initiated with the acquired IOS data to fabricate an interim IFCDP at the same day. Periapical radiographs were obtained of the implant-prosthetic connection of the definitive IFCDPs to verify the passive fit. Metrology software (Geomagic Qualify, 3D Systems - Matlab, Mathworks) was used to assess the implant analogs position in the 3D-printed casts used for fabricating the definitive IFCDPs. A quantitative occlusal relationship analysis was performed with IOS.

RESULTS

Radiographic examination revealed no gaps at implant-prosthetic connection of the definitive IFCDPs. The 3D-printed casts showed an overall average distance deviation within the clinically acceptable range of errors of 150 µm. Quantitative occlusal relationship analysis with IOS showed well-distributed contacts.

CONCLUSION

Within the limitations of this study, the following conclusions can be drawn: (1) A 3-unit toolset with ISBs, LPAs and OPAs allows to register the implant position and maxillomandibular relationship in one single visit; (2) the 2-stage clinical workflow with the CAPS system facilitates the IOS data acquisition for fabrication of an interim IFCDP at the same day; (3) a passive fit was demonstrated for the interim and the definitive IFCDPs.

CLINICAL SIGNIFICANCE

The CAPS system can help clinicians to register the implant position and the maxillomandibular relationship in one single visit for the fabrication of an IFCDP.

Evaluation and comparison of the accuracy of three intraoral scanners for replicating a complete denture

STATEMENT OF PROBLEM

Technological advances in digital acquisition tools have increased the scope of intraoral scanners (IOSs), including scanning a removable complete denture (RCD) to replicate it. However, studies assessing the accuracy of IOSs for replicating a maxillary or mandibular RCD are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy (trueness and precision) of 3 IOSs while replicating a maxillary and mandibular RCD.

MATERIAL AND METHODS

One maxillary and 1 mandibular RCD were scanned with a desktop scanner (D2000) to obtain the reference model. Two operators scanned each RCD 5 times with 3 different IOSs (TRIOS 4, Primescan, and IS3800), following a predefined acquisition protocol. The 60 study models obtained were compared with the reference model using the Geomagic software program. For each comparison, the mean and standard deviation of discrepancy were calculated. Distances were measured on both the reference and the study model, and differences were calculated to assess whether sagittal or transverse deformations were present. The tolerance percentage of the volume of the digital model compared with the volume of the reference model was determined (difference tolerance was set at 0.1 mm). A univariate analysis of variance followed by a post hoc analysis using the Student-Newman-Keuls (α=.05) test was performed to determine the truest and the most precise IOS.

RESULTS

The TRIOS 4 and Primescan IOSs had comparable trueness, with mean dimensional variations of 47 ±27 µm and 57 ±8 µm respectively compared with the reference model. The IS3800 had a lower trueness (98 ±35 µm). Primescan was significantly more precise with a mean standard deviation of 64 ±15 µm (P<.05). The TRIOS 4 (141 ±48 µm) and IS3800 (129 ±24 µm) had comparable precision. Primescan showed the least sagittal and transverse deformation.

CONCLUSIONS

This study determined that an RCD can be replicated using an IOS, although all IOSs did not have equal accuracy. An in vivo study needs to assess whether this procedure is clinically acceptable.

Clinician- and Patient-Centred Outcomes of Digital Impressions in Infants with Cleft Lip and Palate: A Systematic Review

This systematic review examines the effectiveness of digital impressions in infants with cleft lip and palate (CLP), focusing on accuracy, operator preferences, and parents' perceptions. The PICO-formulated focused questions assessed the accuracy and operator preference of digital impressions compared to conventional impressions in infants with cleft lip and palate, while also exploring parents' perceptions as patient-centred outcomes. Electronic and manual searches were conducted in five databases including PubMed, Scopus, Web of Science, Embase, and Cochrane Library; to acquire grey literature, Google Scholar was also consulted. Both experimental and observational studies that used digital impressions in the clinical care of infants with CLP were included. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess the quality of the included studies. Out of 503 records, 12 studies met the inclusion criteria. The accuracy assessment included surface discrepancy and intra-arch measurements. Surface discrepancy studies showed variations in the premaxillary segments, while intra-arch measurements revealed no significant differences. Operators preferred digital impressions, citing reduced stress and streamlined workflows. Parents expressed a clear preference for digital over conventional impressions. The conclusions drawn were substantiated by weak evidence due to the limited number and the high risk of bias of the included studies. Challenges remain here, warranting continued research to enhance accuracy and assess parents' preferences, ensuring optimal outcomes for infants with CLP.

Effect of different intraoral scanning strategies on the marginal and internal fit of CAD-CAM inlay restorations: An in vitro study

STATEMENT OF PROBLEM

Whether the scanning strategy of intraoral scanners (IOSs) affects the accuracy of the digital recording for an indirect ceramic inlay restoration is unclear. Furthermore, which strategy would be optimal and most effective is uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate the impact of 3 different scanning strategies using the Carestream CS 3700 IOS on the marginal and internal fit of a mesio-occluso-distal (MOD) ceramic inlay restoration.

MATERIAL AND METHODS

A typodont master model (ANA-4 VCER; Frasaco) was used with a standardized preprepared MOD inlay maxillary first molar typodont tooth (ANA-4 ZP16 CER99-008; Frasaco) (N=30). These inlay preparations were scanned with the CS 3700 IOS using 3 different scanning strategies: linear, wave, and S-figure scanning strategies. Each scan strategy group was scanned 10 times for all groups to obtain 30 standard tessellation language (STL) files. Thirty restorations were milled from lithium disilicate CAD blocks (IPS e.max; Ivoclar AG) and cemented into their typodont-prepared inlay cavities. A single examiner used a stereomicroscope to measure the marginal and internal gaps at the predetermined points. A 1-way ANOVA was used for the statistical analysis, followed by the Tukey post hoc test with Bonferroni adjustment. All tests were 2-tailed (α=.05).

RESULTS

All scanning strategy groups demonstrated statistically significant differences for the marginal and internal fit of the inlay restorations (P<.001). Overall, the linear scanning strategy showed the lowest mean marginal and internal gap values (29.2 ±3.6 µm and 39.0 ±6.4 µm), followed by the wave scanning strategy, which had comparable mean marginal and internal gap values: 49.1 ±3.6 µm and 48.2 ±6.0 µm, respectively. The S-figure scan strategy had the highest mean marginal and internal gap values: 50.2 ±12.6 µm and 71.3 ±7.7 µm, respectively.

CONCLUSIONS

Inlay restorations scanned by the linear scan strategy had the best marginal and internal fit when scanned with the CS 3700 IOS.

Comparison of tissue displacement in edentulous arches among three-dimensional files obtained through different impression-making methods: A retrospective study

PURPOSE

To retrospectively compare and analyze differences in tissue displacement of edentulous arches among three-dimensional (3D) files obtained using various impression-making techniques.

MATERIALS AND METHODS

Fourteen patients who underwent prosthodontic treatment for edentulous arches at Yonsei University Dental Hospital between June 2020 and April 2023 were included in the study. Three types of 3D files were used for the evaluation of each arch: a 3D scan file of a definitive cast (Group DEF), a preliminary cast (Group PRE), and an intraoral scan file (Group IOS). The files were superimposed on a reference 3D scan file of the definitive cast group through best-fit matching using metrology software. Seventeen measurement points (MP1-4, RC1-6, TB1-2, and PPS1-5 for the maxilla and RP1-2, RC1-7, BS1-4, and LS1-4 for the mandible) were selected for both the maxillary (n = 13) and mandibular arches (n = 6). The deviation considering the direction (DD) between the three groups and the absolute deviation (AD) between the three groups were recorded. Kruskal-Wallis and post-hoc Mann-Whitney tests were used for statistical analyses (α = 0.05 and α = 0.0167, respectively).

RESULTS

Concerning the DD values, at the RC4 point of the maxillary arch, Group PRE exhibited significantly higher values than Groups IOS (p = 0.006) and DEF (p < 0.001), and at the RC5 point of the maxillary arch, Group IOS exhibited significantly lower values than Groups PRE (p = 0.016) and DEF (p < 0.001). Group IOS showed significantly lower DD values in the mandibular arch than Group DEF at the RP2 and RC3 points (p < 0.167). The AD values in Groups PRE and IOS significantly differed from those in Group DEF (all p < 0.001) at all measurement points but did not exhibit significant differences between each other (p > 0.05).

CONCLUSIONS

Different impression-making methods yielded different amounts of tissue displacement. The tendency of 3D files regarding tissue displacement varied at certain residual ridge crest areas and retromolar pad areas. The absolute amount of tissue displacement observed in the intraoral scan data was comparable to that observed in the preliminary casts.

Assessment of distortion of intraoral scans of edentulous mandibular arch made with a 2-step scanning strategy: A clinical study

STATEMENT OF PROBLEM

Manufacturers of several intraoral scanners have recommended a 2-step strategy for scanning the edentulous mandible. The 2-step technique requires scanning one side first and then moving to the other side. However, whether inconsistency in stitching occurs that results in loss of accuracy or distortion is unclear.

PURPOSE

The purpose of this clinical study was to measure the potential distortion of intraoral scans of edentulous mandibular arches made with a 2-step scanning strategy and to assess their differences with conventional impressions.

MATERIAL AND METHODS

Twenty mandibular edentulous arches were scanned by 1 investigator with an intraoral scanner using a 2-step scanning strategy, and a corresponding polysulfide conventional impression was obtained. The conventional impression was then immediately scanned with the same intraoral scanner. The obtained standard tessellation language (STL) files were superimposed with a surface-matching software program. After a preliminary alignment, the STL meshes were trimmed and reoriented; then, the final alignment was carried out and meshes moved to a metrology software program where their mean distance was measured. In addition, a surface curve (SIOS) was traced on the intraoral scan from the right to left retromolar pad along the residual ridge and automatically projected onto to the conventional impression scan to obtain a new curve (SC). The mean distance between SIOS and SC was measured and recorded as an indicator of the distortion by considering the X-, Y-, and Z-axes and the overall 3-dimensional (3D) deviation. The analysis was performed for the full curve length and after dividing it into 6 regions of interest. Univariate and multivariate statistical analyses were used to investigate the significance of the extent of the mean 3D distance, as well as the effects of measurement positions (side and region) between and within patients on differences along the X-, Y-, and Z-axes (α=.05).

RESULTS

The mean (-0.08 mm; standard error: 0.025) 3D distance between the intraoral scan and conventional impression was significantly different from zero (P=.003). No significant effect of the factor "side" was found by using generalized estimated equation models for the X-, Y-, and Z-axes, and global 3D deviations between SIOS and SC (P>.05), which appeared to exclude distortion. Conversely, a significant effect was found for the factor "region" (P<.05), with no significant differences (P>.05) between corresponding regions on the 2 sides.

CONCLUSIONS

Intraoral scans of the edentulous mandibular arch made in a 2-step procedure did not exhibit significant distortion in comparison with conventional impressions.

Validation of Digital Impressions' Accuracy Obtained Using Intraoral and Extraoral Scanners: A Systematic Review

BACKGROUND

At present, the evidence regarding digital impressions' accuracy recorded by using digital scanners is lacking. This systematic review aimed to evaluate whether the type of scanning (intraoral/extraoral) affects the Accuracy of Digital Impressions.

METHOD

Two independent reviewers performed a systematic search in the database both electronically and manually (PubMed, Ebsco HOST, the Cochrane Library, and Google Scholar) for articles published from 1 January 2010 to 1 December 2022. This study was registered with the International Prospective Register of Systematic Reviews (PROSPERO CRD42020188765) and followed the PRISMA statement. The question in focus was as follows: Does the type of scanning (intraoral or extraoral) affect the accuracy of digital impression?

RESULTS

A total of 449 papers were obtained by searching electronically and manually. In total, 15 complete-text papers qualified for assessment based on eligibility criteria. After reading the full-text articles, five studies were excluded. Ten studies were selected for the qualitative analysis. The qualitative data reported that the accuracy of both types of scanners (intraoral and extraoral) lies within the range of clinical acceptability. Nevertheless, the intraoral scanners seem to be more accurate when compared to the extraoral scanners for a partial arch situation.

CONCLUSIONS

Scanning type affects the accuracy of the digital impression. Various factors influence the scanning ability. Intraoral scanners seem to be more accurate compared to extraoral scanners for a partial arch situation. More studies comparing the accuracy of the intraoral scanner and extraoral scanner for a complete arch scan and in an in vivo study setting are needed.