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

In vitro comparison between complete arch abutment-level implant impressions with photogrammetry, grammetry, and intraoral scanning

STATEMENT OF PROBLEM

Photogrammetry (PG) has emerged as a promising recording technique for fabricating implant-supported prostheses. However, the existing evidence on the accuracy of dental PG devices is still limited.

PURPOSE

The purpose of this in vitro study was to evaluate the trueness and precision of a newly introduced advanced PG device (MicronMapper; SIN 360) by comparing it with grammetry and intraoral scanning.

MATERIAL AND METHODS

Four implants (BioHorizons) were placed in an edentulous mandibular model. Multi-unit abutments (BioHorizons) were positioned and tightened to 30 Ncm. A digital reference cast (Control group) was obtained by scanning the model with a laboratory scanner (inEosX5; Dentsply Sirona). Three test groups were evaluated: PS (Primescan), PS-OS (Primescan and OptiSplint), and PG (MicronMapper; SIN 360). Test files were superimposed with the reference file (trueness) and pairwise within groups (precision) using a 3D evaluation software program (Geomagic Control X). Root mean square (RMS) values were calculated. Analysis of variance (ANOVA) was used to analyze differences in RMS values among groups (α=.05), followed by the Tukey post hoc test.

RESULTS

For trueness, group PG showed the lowest mean ±standard deviation RMS values (20.5 ±0.6 µm), followed by PS-OS (30.9 ±16.8 µm) and PS (56 ±0.7 µm). A statistically significant difference was found between groups PG and PS (P<.001), as well as PS-OS and PS (P=.004). For precision, the lowest RMS values were detected in group PG (6 ±1.2 µm), followed by PS (9.5 ±3.3 µm) and PS-OS (23.3 ±22.3 µm). No statistically significant differences were detected among the test groups in terms of precision (P=.192).

CONCLUSIONS

Photogrammetry obtained the best accuracy. Grammetry improves the trueness; however, it appears to have no positive impact on the precision of complete arch implant recordings.

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.

Assessing the feasibility of handheld scanning technologies in neonatal intensive care: Trueness, acceptability, and suitability for personalised medical devices

BACKGROUND

Nasal continuous positive airway pressure (CPAP) injuries are common for premature infants. Clinical use of three-dimensional (3D) scanning is established in adult medicine, but the possibilities in neonatal care are still emerging. Custom printed CPAP devices have the potential to reduce injuries and disfigurement in this vulnerable population.

AIM

We sought to identify the most feasible portable 3D scanner for use in the neonatal intensive care environment towards the development of custom-fitting CPAP devices for premature infants.

METHODS

Four handheld 3D scanners were assessed and compared, Artec Leo, Revopoint POP 2, iPad Pro/Metascan, and iPhone/Scandy Pro. Trained neonatal clinicians (medical and nursing) undertook mock scans in a simulated neonatal intensive care environment.

RESULTS

Sixty scans were performed by 13 neonatal clinicians (four medical/nurse practitioners and nine nurses). The median mean absolute error was 0.21 mm (interquartile range [IQR]: 0.19-0.26), 0.17 mm (IQR: 0.15-0.21), and 1.08 mm (IQR: 1.0-1.63) for Artec Leo, Revopoint POP 2, and Scandy Pro, respectively. Scan times were the quickest for Artec Leo at 22.9 sec (IQR: 18.5-27), followed by Revopoint POP 2 at 25.2 sec (IQR: 22-34.4). Artec Leo was rated most expensive, but Revopoint POP 2 was rated more ergonomic. Both app-based 3D scanners (Metascan and Scandy Pro) presented data security issues.

CONCLUSIONS

Artec Leo and Revopoint POP 2 were identified as most feasible for use to perform 3D scans on premature infants in the neonatal intensive care environment.

Impact of scanning interruptions on accuracy of implant-supported full-arch scans: An in-vitro pilot study

PURPOSE

To assess the impact of involuntary interruptions (simulating tracking loss by moving the scanner out of its focal distance) and voluntary interruptions (pressing the scanner's turn-on button) on the accuracy of implant-supported full-arch scans using an intraoral scanner (TRIOS 5, version 22.1.10; 3Shape; Copenhagen, Denmark).

MATERIALS AND METHODS

An edentulous model with four implants was digitized with an industrial scanner (Artec Micro II; Artec 3D) to create a reference scan. Four groups (n = 30) were established based on the number of interruptions during scanning: Zero Group (no interruptions; control group), 6-V Group (six voluntary interruptions), 6-I Group (six involuntary interruptions), and 12-I Group (twelve involuntary interruptions). Primary outcome was accuracy assessed by the Root Mean Square (RMS) method. Secondary outcomes included scanning time and the number of photograms. Data were analyzed using one-way ANOVA and post hoc Tukey multiple comparison tests (α=0.05).

RESULTS

A total of 120 digital scans were conducted. The Zero group achieved a RMS error of 291 ± 47 µm, a scanning time of 68 ± 6s, and 1320 ± 129 photograms. 6-V group significantly reduced RMS error (MD -102 µm [IC 95 %: -141, -63]), decreased scanning time (MD -20s [IC 95 %: -25, -17]), and reduced photograms (MD -415 photograms [IC 95 %: -506, -324]) compared to the control group (P<.001). Simulations of 6 or 12 involuntary interruptions did not affect accuracy compared to the control group (P>.05).

CONCLUSIONS

Voluntary interruptions during scanning, achieved by pressing the scanner's turn-on button, appear to enhance accuracy due to image preprocessing, while involuntary interruptions had no significant impact on the accuracy of implant-supported full-arch scans.

CLINICAL SIGNIFICANCE

Voluntary stop during scanning implant-supported full-arches may result in better-fitting prostheses owing to higher scan accuracy and efficiency.

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.

Evaluation of the accuracy of digital impressions with different scanning strategies: An in vitro study

OBJECTIVES

To evaluate the effects of three different scanning strategies on the trueness and precision of optical impressions obtained with four intraoral scanners (IOSs).

METHODS

The reference maxillary dental arch model was fabricated using Telio CAD, and the reference digital reference cast was obtained using a computer numerical control machine and an optical scanner (E4, 3Shape, Copenhagen, Denmark). Test scans were performed with four different IOSs (TRIOS3, MEDIT i700, CS 3600, and iTero Element 5D) by an experienced operator and three different scanning strategies (S1: manufacturer-recommended, S2: optimal per previous literature, and S3: experimental). The scan duration was recorded for each scan. All scans were converted to standard tessellation language format and imported into Geomagic Control X. The accuracy was measured by absolute deviation/distance between aligned surfaces. Data of trueness and precision of each IOS and scan duration were statistically compared using analysis of variance for repeated measures and Bonferroni post-hoc test (p < .05).

RESULTS

No significant differences in trueness were found among strategies (S1: 9.98 µm, S2: 11.93 µm, S3: 8.84 µm; p = .388) in Trios 3 and iTero Element 5D (S1: 12.24 µm, S2: 11.53 µm, S3: 10.71 µm; p = p = .279). Scanning strategy S3 with MEDIT i700 achieved greater trueness (7.33 µm) than S2 (16.33 µm, p < .05), while no significant difference was noted between S1 (10.44 µm) and S3 (p = .291). S3 showed the highest trueness (16.28 µm) compared to S2 (24.05 µm) and S1 (24.78 µm, p < .001) for CS 3600, with no difference between S1 and S2 (p = .457). Trios 3 had higher precision with S2 (22.46 µm) than S3 (31.69 µm, p < .05), and no significant differences between S1 (25.67 µm) and S2/S3 (p > .05). MEDIT i700 with S3 (29.52 µm) was more precise than both S1 (39.52 µm) and S2 (46.24 µm) (p < .001) with no difference between the last two (p = .302). S2 yielded the highest precision (44.93 µm) compared to S3 (61.81 µm) and S1 (76.53 µm) (p < .001) for CS 3600, with S3 more precise than S1 (p < .001). Similarly, iTero Element 5D showed S2 as the most precise (30.19 µm) compared to S3 (42.80 µm) and S1 (44.45 µm) (p < .05), with no difference between S1 and S3 (p = .472). Scan durations were shorter for S3 and S1 compared to S2 in Trios 3 (p < .001), and S3 was faster than S1 and S2 for MEDIT i700 (p < .001). CS 3600 scans with S1 were quicker than S2 and S3 (p < .001). For iTero Element 5D, no significant differences were found between S1 and S3 (p = .511), but S2 was slower than both (p < .001).

CONCLUSIONS

Scanning strategies significantly affect the accuracy and scan duration of optical impressions. Specifically, S3 provided the best trueness with both the MEDIT i700 and the CS 3600 while the S2 strategy demonstrated the highest precision for most scanners. Overall, the S1 and S3 strategies resulted faster than S2 among the devices evaluated.

CLINICAL SIGNIFICANCE

The results suggest that the experimental scan strategy may optimize the use of intraoral scanners in clinical practice, potentially leading to more accurate and time-efficient dental impressions.

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.

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.

Influence of scan extension and starting quadrant on the accuracy of four intraoral scanners for fabricating tooth-supported crowns

STATEMENT OF PROBLEM

Multiple factors can influence the accuracy of intraoral scanners (IOSs). However, the impact of scan extension and starting quadrant on the accuracy of IOSs for fabricating tooth-supported crowns remains uncertain.

PURPOSE

The purpose of the present in vitro study was to measure the influence of scan extension (half or complete arch scan) and the starting quadrant (same quadrant or contralateral quadrant of the location of the crown preparation) on the accuracy of four IOSs.

MATERIAL AND METHODS

A typodont with a crown preparation on the left first molar was digitized (T710) to obtain a reference scan. Four scanner groups were created: TRIOS 5, PrimeScan, i700, and iTero. Then, 3 subgroups were defined based on the scan extension and starting quadrant: half arch (HA subgroup), complete arch scan starting on the left quadrant (CA-same subgroup), and complete arch scan starting on the right quadrant (CA-contralateral subgroup), (n=15). The reference scan was used as a control to measure the root mean square (RMS) error discrepancies with each experimental scan on the tooth preparation, margin of the tooth preparation, and adjacent tooth areas. Two-way ANOVA and pairwise multiple comparisons were used to analyze trueness (α=.05). The Levene and pairwise comparisons using the Wilcoxon Rank sum tests were used to analyze precision (α=.05).

RESULTS

For the tooth preparation analysis, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.002). The iTero and TRIOS5 groups obtained better trueness than the PrimeScan and i700 groups (P<.001). Moreover, half arch scans obtained the best trueness, while the CA-contralateral scans obtained the worst trueness (P<.001). The iTero group showed the worst precision among the IOSs tested. For the margin of the tooth preparation evaluation, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.005). The iTero group obtained best trueness (P<.001), but the worst precision (P<.001) among the IOSs tested. Half arch scans obtained the best trueness and precision values. For the adjacent tooth analysis, trueness and precision differences were found among the groups (P<.001) and subgroups tested (P<.001), with a significant interaction group×subgroup (P=.005). The TRIOS 5 obtained the best trueness and precision. Half arch scans obtained the best accuracy.

CONCLUSIONS

Scan extension and the starting quadrant impacted the scanning trueness and precision of the IOSs tested. Additionally, the IOSs showed varying scanning discrepancies depending on the scanning area assessed. Half arch scans presented the highest trueness and precision, and the complete arch scans in which the scan started in the contralateral quadrant of where the crown preparation was obtained the worst trueness and precision.

Influence of connected and nonconnected calibrated frameworks on the accuracy of complete arch implant scans obtained by using four intraoral scanners, a desktop scanner, and a photogrammetry system

STATEMENT OF PROBLEM

Different techniques have been proposed for increasing the accuracy of complete arch implant scans obtained by using intraoral scanners (IOSs), including a calibrated metal framework (IOSFix); however, its accuracy remains uncertain.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of complete arch scans obtained with connecting and non-connecting the implant scan bodies (ISBs) recorded using intraoral scanners (IOSs), a laboratory scanner (LBS), and photogrammetry (PG).

MATERIAL AND METHODS

A cast with 6 implant abutment analogs was obtained. Six groups were created: TRIOS 4, i700, iTero, CS3800, LBS, and PG groups. The IOSs and LBS groups were divided into 3 subgroups: nonconnected ISBs (ISB), splinted ISBs (SSB), and calibrated framework (CF), (n=15). For the ISB subgroups, an ISB was positioned on each implant abutment analog. For the SSB subgroups, a printed framework was used to connect the ISBs. For the CF subgroups, a calibrated framework (IOSFix) was used to connect the ISBs. For the PG group, scans were captured using a PG (PIC Camera). Implant positions of the reference cast were measured using a coordinate measurement machine, and Euclidean distances were used as a reference to calculate the discrepancies using the same distances obtained on each experimental scan. Wilcoxon squares 2-way ANOVA and pairwise multiple comparisons were used to analyze trueness (α=.05). The Levene test was used to analyze precision (α=.05).

RESULTS

Linear and angular discrepancies were found among the groups (P<.001) and subgroups (P<.001). Linear (P=.008) and angular (P<.001) precision differences were found among the subgroups.

CONCLUSIONS

The digitizing method and technique impacted the trueness and precision of the implant scans. The photogrammetry and calibrated framework groups obtained the best accuracy. Except for TRIOS 4, the calibrated framework method improved the accuracy of the scans obtained by using the IOSs tested.