Trueness of intraoral scanners in digitizing specific locations at the margin and intaglio surfaces of intracoronal preparations

Conventional and digital complete arch implant impression techniques: An in vitro study comparing accuracy

STATEMENT OF PROBLEM

Varying complete arch digital-implant-scanning techniques have been described, but their accuracy remains uncertain.

PURPOSE

The purpose of this in vitro investigation was to assess the effect of the implant angulation and impression method (conventional, intraoral digital scan, intraoral scan with a splinting framework, and combining cone beam computed tomography [CBCT] and intraoral scan) on the accuracy of complete arch implant recording.

MATERIAL AND METHODS

The following 2 casts were obtained: one with 4 parallel (P group) and the other with 4 angled (up to 30 degrees) implant abutment analogs (NP group). Both the casts were digitized (7Series Scanner) (control file). The following 4 subgroups were created: conventional polyether impression with a splinted framework (CNV subgroup), intraoral scan (IOS subgroup), intraoral scan with a splinting framework (S-IOS subgroup), and intraoral scan combined with CBCT scan (CBCT-IOS subgroup) (n=10). For each file, an implant-supported bar was designed and imported into a program (Netfabb) to perform linear and angular interimplant abutment measurements. Two-way ANOVA (Analysis of Variance) and Tukey tests were selected to examine the data (α=.05).

RESULTS

Implant angulation (P=.010) and impression method (P=.003) significantly influenced the linear trueness. The P group (112 μm) obtained better linear trueness than the NP group (144 μm). The CNV subgroup obtained the best linear trueness, while the IOS and CBCT-IOS showed the worst trueness. Group (P<.001) significantly influenced angular trueness. Group (P=.009) and subgroup (P<.001) influenced the linear precision. The P group (72 μm) obtained better linear precision than the NP group (91 μm). The IOS subgroup obtained the best linear precision. Group (P=.034) significantly influenced the angular precision. The P group (0.46 degrees) had higher angular precision compared with the NP group (0.60 degrees).

CONCLUSIONS

Implant angulation and the impression methods tested, impacted the accuracy of the complete arch implant recording. Parallel implants had better trueness and precision values than nonparallel implants. The conventional impression method showed the best trueness and precision. Among the digital implant scan methods assessed, the S-IOS and CBCT-IOS subgroups acquired significantly better trueness and precision than the IOS subgroup.

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.

Beyond the surface: A comparative study of intraoral scanners in subgingival configuration scanning

OBJECTIVES

This study conducted a comprehensive comparative analysis of three intraoral scanners (CEREC Primescan, TRIOS, CEREC Omnicam) and a lab scanner (inEosX5) assessing their precision in simulating subgingival tooth preparations.

METHODS

Utilizing a dental simulation mannequin with a 3D-printed resin structure, 100 structures with depths ranging from 0.5 to 4.0 mm were created within a square mimicking a rectangular tank surface. Four scanner groups (A-D) and five subgroups were established. Two digitization methods, a customized parallelometer and an intraoral simulation, were applied, ensuring a standardized scanning sequence. Trueness was evaluated by comparing CAD-calculated surface areas with actual dimensions, and qualitative trueness analysis was conducted using MeshLab. Surface areas were computed using the formula SA = 2lw + 2lh + 2wh. Statistical analyses, including Pearson's correlation coefficient, Kolmogorov-Smirnoff and Levene's tests, three-way ANOVA, and paired sample t-tests, elucidated relationships and differences (a=0.05).

RESULTS

A robust correlation (r = 0.850, p < 0.001) between intraoral scanner choice and scanned area depth was found. Inverse correlations were noted for experimental methods. Three-way ANOVA demonstrated significant scanner-depth interaction (F(12,760) = 760.801, p < 0.001).

SIGNIFICANCE

Emphasizing high-resolution sensors and advanced technologies, the study underscores the optimal choice for subgingival digitization, acknowledging variations among scanners.

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.

Optical impressions assessment for overlay restorations with rubber dam: A clinical trial

OBJECTIVE

The possibility of making impressions of teeth prepared with a rubber dam in place has been proposed; however, this requires trimming and rescanning the mesh, which has been described as a cause of accuracy loss. This study aims to clinically determine whether overlay restorations obtained from a scan with a rubber dam in place have equivalent marginal fit, contact points, and occlusal fit to the same type of restorations obtained from a scan without a rubber dam.

MATERIAL AND METHODS

Thirty patients who underwent overlay restoration of a molar with at least one neighbouring tooth were selected. After tooth preparation, two scans were performed: one without a rubber dam and the other with a rubber dam. Restorations were randomly created from one scan or another. The marginal fit, interproximal contact points, and occlusal fit were evaluated clinically. Two meshes, with and without rubber dams, were also compared.

RESULTS

No significant differences were observed in the clinical evaluation of the overlays made of the two meshes. The trueness of the mesh from the impression made with a rubber dam with respect to the mesh without a rubber dam was about 40 µm in the critical areas of the preparation (margins, intaglio, and interproximal contact points).

CONCLUSIONS

The results of this study show that under the conditions performed and with the equipment used, there are no significant clinical differences between overlay restorations made from a scan with a rubber dam and those made from a scan without a rubber dam.

CLINICAL SIGNIFICANCE

Scanning with a rubber dam in place may be a valid option for certain types of restorations under certain clinical conditions.

Accuracy, scanning time, and number of photograms of various scanning patterns for the extraoral digitalization of complete dentures by using an intraoral scanner

STATEMENT OF PROBLEM

The use of intraoral scanners (IOSs) has been described as a method of digitizing complete dentures (CDs) extraorally; however, accuracy, scanning time, and number of photograms remain unclear.

PURPOSE

The purpose of this in vitro study was to assess the accuracy, scanning time, and number of photograms of different scanning patterns for digitizing CDs extraorally with an IOS.

MATERIAL AND METHODS

The virtual design of a maxillary and mandibular CD was used to manufacture milled CDs. The maxillary (Mx group) and mandibular (Mb group) CDs were digitized extraorally by using an IOS (Medit i500). Three subgroups were created depending on the scanning pattern: using the protocol of the IOS selected (Medit Link) (ML subgroup), using the technique recommended by the implant manufacturer (DIOnavi) (DIO subgroup), and using a custom method (C subgroup). The design of the CDs (reference files) was used to compare the discrepancy between each virtual design and the corresponding scans by using the root mean square (RMS) error. The scanning time and number of photograms were recorded. Two-way ANOVA and Tukey tests were used to analyze the trueness data. The Bartlett test was used to analyze the precision values (α=.05).

RESULTS

The group (P<.001) was a significant predictor of trueness. The Mx group (RMS mean of 0.452 mm) obtained higher trueness than the Mb group (RMS mean of 0.536 mm). The Mx-C and Mb-DIO subgroups obtained the highest trueness, and the Mx-ML and Mb-ML subgroups showed the lowest trueness. Significant differences were found in precision among groups (P<.01) and across subgroups (P<.01). The Mb group obtained the highest precision mean (0.586 mm) and was significantly different from the Mx group that obtained the lowest precision mean (0.611 mm). The C subgroup obtained the highest precision mean (0.339 mm) and was significantly different from the DIO subgroup that obtained the lowest precision mean (0.425 mm). The group (P<.01) and scanning pattern (P<.01) were significant predictors of the scanning time and number of photograms obtained. The Mb group showed lower scanning time and number of photograms than the Mx group.

CONCLUSIONS

The scanning patterns tested significantly influenced the trueness and precision values, scanning time, and number of photograms of the extraoral digitalization of maxillary and mandibular CDs by using the IOS tested.

Effect of tooth color on the accuracy of intraoral complete arch scanning under different light conditions using a zirconia restoration model

STATEMENT OF PROBLEM

Information regarding the effect of tooth color under different light conditions on the accuracy of intraoral complete arch scanning is limited.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of color and ambient light conditions on the accuracy of mandibular complete arch scanning with an intraoral scanner (IOS) using a zirconia restoration model with different shades.

MATERIAL AND METHODS

Five mandible dentition models with zirconia restorations of different shades were fabricated by computer-aided design and computer-aided manufacturing (CAD-CAM). The spectral reflectance and transmittance curves were collected with a spectrophotometer to determine color parameters (Rb, T, S+A, L*, a*, b*, C*, and h). Under 4 different lighting conditions: no light (ZL), natural light (NL), room light (RL), and chair light (CL), each model was scanned 10 times by using an IOS (TRIOS 3). Three-dimensional (3D) deviation analysis and a linear deviation analysis were performed for an accurate quantitative measurement of intraoral scanning. The multivariate test was used to determine significant differences in 3D deviation and linear deviation among groups. The multiple linear regression test was conducted to investigate the relevant independent factors of mean absolute 3D deviation.

RESULTS

The 3D deviation analysis showed that the mean absolute 3D deviation of 3M2 model scanning was the lowest (P<.001). Moreover, under CL and RL, the accuracy results from the 3M2 model scan were demonstrated as significantly better than the tested scans under other light conditions (P=.021). The result of the linear deviation analysis indicated that the variation in distance was only significant between the bilateral canines (P=.032). Ambient light conditions, C*, and h were factors influencing mean absolute 3D deviation (R2=0.593, P<.001).

CONCLUSIONS

Color change influenced the accuracy of intraoral mandibular complete arch scanning under different light conditions. This effect may be attributable to the interaction between the ambient light condition and color parameters such as C* and h.

Influence of implant angulation and clinical implant scan body height on the accuracy of complete arch intraoral digital scans

STATEMENT OF PROBLEM

The accuracy of digital implant scans can be affected by the implant angulation, implant depth, or interimplant distance. However, studies analyzing intraoral scanning accuracy with different implant angulations and different scan body heights are scarce.

PURPOSE

The purpose of this in vitro study was to determine the influence of the implant angulation and clinical implant scan body height on the accuracy of complete arch scans.

MATERIAL AND METHODS

Two definitive implant casts with 6 implant analogs (Zimmer Biomet) were obtained: 1 cast had all the implant analogs parallel (GP group), and 1 cast had the implant analogs with divergence of up to 30 degrees (GD group). A coordinate measurement machine (Global Evo 09.15.08) was used to measure the positions of the implant analogs. Each group was divided into 3 subgroups depending on the clinical implant scan body height: 10, 6, and 3 mm. An implant scan body (Elos Accurate Scan Body Brånemark system) was positioned on each implant analog. A total of 10 scans of each subgroup were recorded by using an intraoral scanner (TRIOS 3). Each STL file obtained was imported into a reverse engineering software program (Geomagic), and linear and angular Euclidean measurements were obtained. The Euclidean calculations between the implant analog positions of the definitive implant casts were used as a reference to calculate the discrepancies among the corresponding subgroups. The Kolmogorov-Smirnov test revealed that the lineal measurements were not normally distributed, so the Kruskal-Wallis and pairwise comparison Dunn tests were used (α=.05). The Kolmogorov-Smirnov test revealed that the angular measurements were normally distributed. Therefore, the 2-way ANOVA and pairwise comparison Tukey tests were used (α=.05).

RESULTS

The Kruskal-Wallis test revealed significant differences in the linear Euclidean medians between the GP and GD groups with different clinical implant scan body heights (H(5)=23.18, P<.001). Significant differences in the linear Euclidean medians were computed between the GP-6 and GD-10 subgroups (P=.009), GD-3 and GD-6 subgroups (P=.029), and GD-3 and GD-10 subgroups (P=.001). Two-way ANOVA revealed that the implant angulation (F(1, 3.3437)=28.93, P<.001) and clinical implant scan body height (F(2, 0.4358)=3.77, P=.029) were significant predictors of discrepancies in the angular measurement.

CONCLUSIONS

Implant angulation and clinical scan body height influenced scanning accuracy. The lowest clinical implant scan body height tested had the lowest accuracy in both parallel and angled implants, but statistically significant differences were found only in the angled group.

Considerations for predictable outcomes in static computer- aided implant surgery in the esthetic zone

OBJECTIVE

To provide technical and clinical recommendations for implementing a digital workflow in Static Computer-Aided Implant Surgery in the anterior maxilla.

CLINICAL CONSIDERATIONS

An optimal 3D implant position is crucial for achieving satisfying results in implant rehabilitation in the esthetic area. Due to its complexity, implant placement in the esthetic zone should be executed with precision and predictability. Static Computer-Aided Implant Surgery requires thorough planning and detailed attention to every step of the digital workflow protocol.

CONCLUSIONS

Implant positioning in the esthetic zone using Static Computer-Aided Implant Surgery is a technique-sensitive procedure that requires precise execution of each step. This approach ensures accurate prosthetically driven 3D implant placement and prevents potential errors that could lead to inaccurate positioning.

CLINICAL SIGNIFICANCE

The proper implementation of Static Computer-Aided Implant Surgery may increase the level of agreement between the planned and definitive implant 3D positions in the esthetic zone, thus enhancing the esthetic outcomes of implant rehabilitation.

Influence of ambient temperature changes on intraoral scanning accuracy

STATEMENT OF PROBLEM

Different variables that decrease the accuracy of intraoral scanners (IOSs) have been identified. Ambient temperature changes can occur in the dental environment, but the impact of ambient temperature changes on intraoral scanning accuracy is unknown.

PURPOSE

The purpose of this in vitro study was to assess the impact of ambient temperature changes on the accuracy (trueness and precision) of an IOS.

MATERIAL AND METHODS

A complete arch maxillary dentate Type IV stone cast was obtained. Four 6-mm-diameter gauge balls were added to the maxillary cast to aid future evaluation measurements. The maxillary cast was digitized by using an industrial scanner (GOM Atos Q 3D 12M). The manufacturer's recommendations were followed in obtaining a reference scan. Then, the maxillary cast was digitized by using an IOS (TRIOS 4) according to the scanning protocol recommended by the manufacturer. Four groups were created depending on the ambient temperature change assessed: 24 °C or room temperature (24-D or control group), 19 °C or a 5-degree temperature drop (19-D group), 15 °C or a 9-degree temperature drop (15-D group), and 29 °C or a 5-degree temperature rise (29-D group). The Shapiro-Wilk and Kolmogorov-Smirnov tests revealed that the data were not normally distributed (P<.05). For trueness, the nonparametric Kruskal-Wallis followed by the Dwass-Steel-Critchlow-Fligner pairwise comparison tests were used. Precision analysis was obtained by using the Levene test based on the comparison of the standard deviations of the 4 groups with 95% Bonferroni confidence intervals for standard deviations (α=.05).

RESULTS

The Kruskal-Wallis test revealed significant differences in the trueness values among all 4 groups (P<.001). Furthermore, significant differences between the linear discrepancy medians between the control and 19-D groups (P<.001), control and 15-D groups (P=.002), control and 29-D groups (P<.001), 19-D and 29-D groups (P=.003), and 15-D and 29-D groups (P<.001) were found. The Levene test for the comparison of the variances among the 4 groups did not detect a significant difference (P>.999), indicating that precision wise the 4 groups were not significantly different from each other.

CONCLUSIONS

Ambient temperature changes had a detrimental effect on the accuracy (trueness and precision) of the IOS tested. Ambient temperature changes significantly decreased the scanning accuracy of the IOS system tested. Increasing the ambient temperature has a greater influence on the intraoral scanning accuracy of the IOS selected when compared with decreasing the ambient temperature.

Comparing the accuracy of distinct scanning systems and their impact on marginal/internal adaptation of tooth-supported indirect restorations. A scoping review

OBJECTIVE

To summarize the existing scientific evidence on the effect of distinct intraoral (IOS) and extraoral (EOS) scanners in terms of their accuracy for image acquisition and the marginal/internal adaptation of indirect restorations.

METHODS

The protocol of this scoping review is available online (https://osf.io/cwua7/). A structured search, with no date restriction, was performed in LILACS, MEDLINE via Pubmed, EMBASE, Web of Science, and Scopus, for articles written in English. The inclusion criteria were studies that considered at least two scanners, regardless of method (intra or extraoral), for the production of tooth-supported restorations. Two independent and blinded researchers screened the studies, collected and analyzed the data descriptively.

RESULTS

103 studies were included (55 on marginal/internal adaptation, 33 on accuracy, 5 on both outcomes, and 10 reviews). Most of them, shown clinically acceptable adaptation (<120 μm). Factors commonly related to the performance of scanners are: use of anti-reflection powders, method of image acquisition, and restoration/tooth characteristics. The need of anti-reflection powders was controversial. Different scanning principles seems to result on similar performance; IOS that combine them could be promising. The most explored systems were Omnicam - IOS, and inEos X5 - EOS, which showed similar performance on marginal/internal adaptation. Scarce studies explored the performance of EOS systems, especially in terms of accuracy. Different restoration designs as single-unit seemed not to modify the performance of scanners. Limited information is available regarding the planned cement space, restorative material and design (multi-unit restorations), as also techniques to measure adaptation.

CONCLUSIONS

Digital scanners are valid approaches to obtain accurate impressions resulting in clinically acceptable restorations. Systems that uses combined principles of image acquisition seems promising for optimal performance. Based on high discrepancy, the quality of evaluated evidence is low, and well-designed studies are still encouraged, especially considering validated IOS/EOS as a control comparison condition.

Influence of arch location and scanning pattern on the scanning accuracy, scanning time, and number of photograms of complete-arch intraoral digital implant scans

OBJECTIVES

To measure the influence of arch location and scanning pattern on the accuracy, scanning time, and number of photograms of complete-arch implant scans acquired using an intraoral scanner (IOS).

MATERIALS AND METHODS

A maxillary (maxillary group) and mandibular (mandibular group) model with 6 implant abutments on each cast was digitized using a desktop scanner (control scans). Six subgroups were created based on the scanning pattern used to acquire the scans using an IOS (Trios 4): occluso-buccal-lingual (OBL subgroup), occluso-linguo-buccal (OLB subgroup), bucco-linguo-occlusal (BLO subgroup), linguo-buccal-occlusal (LBO subgroup), zigzag (ZZ subgroup), and circumferential (C subgroup). The control scans were used as a reference to measure the discrepancy with the experimental scans calculating the root mean square error. Two-way ANOVA and the pairwise comparison Tukey tests were used to analyze the data (α = .05).

RESULTS

Significant discrepancies in trueness (p < .001), precision (p < .001), scanning time (p < .001), and number of photograms (p < .001) were found. The maxillary group obtained poorer trueness and precision values, higher scanning times, and a larger number of photograms than the mandibular group. The C subgroup obtained the best trueness and precision values, but was not significantly different from the OLB, BLO, and LBO subgroups. The ZZ subgroup obtained the worst trueness and precision values (p < .05). The C subgroup obtained the lowest scanning time and number of photograms (p < .05).

CONCLUSIONS

Arch location and scanning pattern influenced scanning accuracy, scanning time, and number of photograms of complete-arch implant scans.

Accuracy of the maxillomandibular relationship at centric relation position recorded by using 3 different intraoral scanners with or without an optical jaw tracking system: An in vivo pilot study

PURPOSE

To measure the accuracy (trueness and precision) of the maxillomandibular relationship at centric relation position recorded by using 3 different intraoral scanners with or without an optical jaw tracking system.

MATERIAL AND METHODS

A completely dentate volunteer was selected. Seven groups were generated: conventional procedure (control group), 3 IOSs: Trios4 (Trios4 group), Itero Element 5D Plus (Itero group), i700 (i700 group), and 3 groups with a jaw tracking system for each corresponding IOS system (Modjaw-Trios4, Modjaw-iTero, and Modjaw-i700 groups) (n = 10). In the control group, casts were mounted on an articulator (Panadent) using a face bow and a CR record captured with the Kois deprogrammer (KD). The casts were digitized by using a scanner (T710) (control files). In the Trios4 group, intraoral scans were obtained by using the corresponding IOS and duplicated 10 times. The KD was used to obtain a bilateral occlusal record at CR position. These same procedures were followed for the Itero and i700 groups. In the Modjaw-Trios 4 group, the intraoral scans acquired by using the corresponding IOS at MIP were imported into the jaw tracking program. The KD was used to record the CR relationship. For acquiring the specimens in the Modjaw-Itero and Modjaw-i700 groups, the same procedures were followed as in the Modjaw-Trios4 group, with the scans obtained with the Itero and i700 scanners respectively. The articulated virtual casts of each group were exported. Thirty-six inter-landmark linear measurements were used to calculate the discrepancies between the control and experimental scans. The data were analyzed by using 2-way ANOVA followed the pairwise comparison Tukey tests (α=0.05).

RESULTS

Significant trueness and precision discrepancies were found among the groups tested (P<.001). The Modjaw-i700, Modjaw-iTero, Modjaw-Trios4, and i700 groups obtained the best trueness and precision among the groups tested, and the iTero and Trios4 groups obtained the worst trueness. The iTero group obtained the worst precision among the groups tested (P>.05).

CONCLUSIONS

The maxillomandibular relationship recorded was influenced by the technique selected. Except for the i700 IOS system, the optical jaw tracking system tested improved the trueness value of the maxillomandibular relationship recorded at CR position when compared with the corresponding IOS.

The effect of different tooth preparation finishing procedures and immediate dentin sealing on the scanning accuracy of different intraoral scanners

PURPOSE

To measure the effect of different tooth preparation finishing procedures (super-coarse grit, fine grit, and air-particle abrasion) and immediate dentin sealing (IDS) on the scanning accuracy of 4 intraoral scanners (IOSs).

MATERIAL AND METHODS

A tooth preparation for a full-coverage restoration was performed on an extracted mandibular molar using super-coarse diamond burs. Four groups were created depending on the tooth preparation finishing procedure: super-coarse grit (bur with a grit size of 150 µm) (SCG group), fine grit (bur with a grit size of 30 µm) (FG), air-particle abrasion with 27-µm aluminum oxide particles (APA group), and IDS (IDS group). Each group was divided into 5 subgroups according to the scanning system used to digitize the tooth preparation: laboratory scanner (control subgroup) (T710; Medit), Trios 4 (Trios subgroup), CS 3800 (CS subgroup), i700 wireless (i700 subgroup), and iTero Element 5D Plus (iTero subgroup) (n=20). For each subgroup, the control file was aligned with each experimental scan using the best-fit algorithm and an engineering program (Geomagic Control X). The discrepancy between the control and experimental files of each subgroup was computed by measuring the root mean square (RMS) error. Two-way ANOVA and Tukey tests were used to analyze the data (α=.05).

RESULTS

Tooth preparation finishing procedures (P<.001) and the IOS assessed (P<.001) were significant predictors of the trueness and precision values obtained. The highest trueness and precision values were measured in the APA group, while the IDS group had the lowest trueness and precision. Additionally, the i700 subgroup obtained the highest trueness and precision values, while the CS and Trios subgroups had the lowest trueness and precision values.

CONCLUSIONS

The different tooth preparations finishing procedures tested influenced on the scanning accuracy of the 4 IOSs considered. The air-particle abrasion procedure obtained the best accuracy values. The trueness discrepancies measured among all the subgroups was 19µm and the precision discrepancies measured among all the subgroups was 4.69 µm.

CLINICAL SIGNIFICANCE

The tooth preparation finishing procedure used can reduce the intraoral scanning accuracy of any of the intraoral scanners tested. The air-particle abrasion finishing procedure might be recommended for maximizing the scanning accuracy of the IOSs tested.

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.

A guide for maximizing the accuracy of intraoral digital scans: Part 2-Patient factors

OBJECTIVES

To describe the factors related to patient intraoral conditions that impact the scanning accuracy of intraoral scanners (IOSs). A new classification for these influencing factors is proposed to facilitate dental professionals' decision-making and maximize the accuracy and reliability of intraoral digital scans.

OVERVIEW

Variables related to intraoral conditions of the patient that can influence the scanning accuracy of IOSs include tooth type, presence of interdental spaces, arch width variations, palate characteristics, wetness, existing restorations, characteristics of the surface being digitized, edentulous areas, interimplant distance, position, angulation, and depth of existing implants, and implant scan body selection.

CONCLUSIONS

The knowledge and understanding of the patient's intraoral conditions that can impact the scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs.

CLINICAL SIGNIFICANCE

The patient's intraoral conditions, or patient factors, can significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing patient factors to maximize the accuracy of IOSs.

Influence of the implant scan body geometry bevel feature position, implant angulation, and position on intraoral scanning accuracy: An in vitro study

PURPOSE

To assess the influence of the scan body geometry bevel position and implant angulation and position of complete-arch implant digital scans.

MATERIAL AND METHODS

Two definitive casts with 4 implant analogs placed parallel (P group) or angulated up to 30 degrees (NP group) were fabricated. Five subgroups were created based on the scan body geometry bevel position: facial, mesial, distal, lingual, or random (F, M, D, L, and R subgroup). Casts were digitized using a laboratory scanner (reference) (7Series Desktop Scanner) and an intraoral scanner (TRIOS 3). The implant position discrepancies between the reference and experimental scans were calculated. Data was analyzed using 3-way ANOVA and Tukey tests (α=.05).

RESULTS

The scan body geometry bevel position (P<.001) and the inter-implant distance (P<.001) were shown as significant predictors of the linear discrepancies obtained. The L subgroup had a significantly lower discrepancy compared with the other subgroups. Implant angulation (P<.001), the scan body geometry bevel position (P<.001), and the inter-implant distance (P<.001) were all significant predictors on the angular discrepancies obtained.

CONCLUSIONS

The scan body geometry bevel feature position and implant angulation and position influenced the accuracy of the IOS tested. The lingual orientation obtained significantly better accuracy values compared with the other positions. The parallel implant analog position obtained better accuracy than the angulated positions. Lastly, the implant positioned in the dental arch where the intraoral digital scan was started obtained significantly higher distortion than the contralateral implant.

Influence of rescanning mesh holes on the accuracy of an intraoral scanner: An in vivo study

OBJECTIVES

To evaluate whether the cutting-off and rescanning procedures have an impact on the accuracy (trueness and precision) of the intraoral digital scan.

METHODS

A right quadrant digital scan (reference scan) of a participant was obtained using an intraoral scanner (IOS) (TRIOS 4; 3Shape A/S, Copenhagen, Denmark). The reference scan was duplicated 135 times and divided into 3 groups based on the number of rescanned mesh areas: 1 (G1 group), 2 (G2 group), and 3 (G3 group) mesh holes. Each group was subdivided into 3 subgroups depending on the mesh hole diameter: 2 mm- (G1-2, G2-2, and G3-2), 4 mm- (G1-4, G2-4, and G3-4), and 6 mm- (G1-6, G2-6, and G3-6) (n = 15). A software program (Geomagic; 3D Systems, Rock Hill, SC, USA) was used to assess the discrepancy between the reference and the experimental scans using the root mean square (RMS). Kruskal-Wallis and post hoc multiple comparison Dunn's tests were used to analyze the data (α=0.05).

RESULTS

Trueness ranged from 5 to 20 µm and precision ranged from 2 to 10 µm. For trueness assessment, Kruskal-Wallis test revealed significant differences on the RMS error values among the groups tested (P<.05). The G3-6 group obtained the lowest trueness and lowest precision values, while the G1-2, G1-4, G2-2, G2-4, and G3-2 groups computed the highest trueness and precision values. When comparing groups with the same number of rescanned mesh holes but with different diameter, the higher the diameter of the rescanned mesh hole, the lower the trueness values computed; however, when comparing groups with the same diameter of the rescanned mesh hole but with differing number of rescanned mesh holes, no significant differences were found in the RMS values among the groups. For the precision evaluation, Levene's test showed a lack of equality of the variances, and therefore of the standard deviations. The F-test with Bonferroni correction identified significant differences between the SDs between group G3-6 and all the other groups. When comparing instead the interquartile range (IQRs) due to the non-normality of the data, groups G1 and G2 also showed lower IQR values or higher precision than groups G3.

CONCLUSIONS

Cutting-off and rescanning procedures decreased the accuracy of the IOS tested. The higher the number and diameter of the rescanned areas, the lower the accuracy.

CLINICAL SIGNIFICANCE

Cutting-off and rescanning procedures should be minimized in order to increase the accuracy of the IOS evaluated. The intended clinical use of the intraoral digital scan is a critical factor that might determine the scanning workflow procedures.

Intraoral scanners: An American Dental Association Clinical Evaluators Panel survey

BACKGROUND

Dentists may choose to integrate intraoral scanners (IOSs) into their practices, but there are many different IOS technologies and system generations to choose from, posing a challenge for dentists who want to invest in them.

METHODS

A survey of IOS use rates, advantages, satisfaction, and training was developed and deployed through Qualtrics to the 968 members of the American Dental Association Clinical Evaluators (ACE) Panel on February 19, 2021. Nonrespondents were sent reminders, and data were analyzed in SAS Version 9.4 (SAS).

RESULTS

A total of 369 panelists responded to the survey. IOS use was split among the ACE Panel; 53% indicated they use one in their practice. The top reason respondents began using IOSs was to improve clinical efficiency (70%). Ninety percent of respondents use IOSs for single tooth-supported crowns, and 58% began using IOSs less than 4 years ago. Most users are at least mostly satisfied (91%) with the results. Among nonusers, the top reason for not using an IOS was the high level of financial investment (66%); 34% and 40% of nonusers are thinking of buying or training with IOSs in 2021, respectively.

CONCLUSIONS

Uptake of IOSs is split; most users are satisfied with their results, and nonusers cited financial barriers as the most common reason for not investing in one.

PRACTICAL IMPLICATIONS

As IOSs continue to penetrate the market and dentists are faced with a decision whether to invest in one, they will need guidance on how to choose the most appropriate device for their patients.

Influence of rescanning mesh holes and stitching procedures on the complete-arch scanning accuracy of an intraoral scanner: An in vitro study

PURPOSE

To measure the impact of different scanning patches on the accuracy (trueness and precision) of an intraoral scanner (IOS).

MATERIAL AND METHODS

A typodont was digitized using an industrial optical scanner (GOM Atos Q 3D 12 M) to obtain a reference mesh. The typodont was scanned using an IOS (TRIOS 3). Three groups were generated based on the rescan areas created: no mesh holes (G0 group), 3 mesh holes distributed on the digital scan (G1 group), and 3 mesh holes located on the left quadrant of the digital scan (G2 group). In the G0 group, a digital scan was completed following the manufacturer's scanning protocol. In the G1 group, a digital scan was obtained following the same protocol as G0 group. Three 12-mm diameter holes were created in the occlusal surfaces of the left second first molar, incisal edges of the central incisors, and right first molar of the digital scan using the IOS software. In the G2 group, a digital scan was obtained following the same protocol as G0 group. Three 12-mm diameter holes in the digital scan were created in the occlusal surface of the left first molar and left second and first premolars using the IOS software program. The discrepancy between the control and the experimental digital scans was measured using the root mean square calculation. The Kolmogorov-Smirnov test demonstrated that data were normally distributed. One-way ANOVA followed by post hoc multiple comparison Bonferroni test were used to analyze the data (α = .05).

RESULTS

Trueness values ranged from 15 to 26 μm and the precision ranged from 21 to 150 μm. Significant differences in trueness mean values were found among the groups tested (F(2, 42) = 6.622, P = .003); the Bonferroni test indicated significant mean differences between the G0 and G2 groups (mean difference=0.11, SE=0.003, and P = .002). For precision evaluation, significant precision differences were found between the groups tested (F(2, 39)=9.479, P < .001); the Bonferroni test revealed significant precision differences between G0 and G2 groups (mean difference=-0.12, SE=0.030, and P = .001).

CONCLUSIONS

Rescanning mesh holes and stitching procedures decreased the trueness and precision of the IOS tested; furthermore, the number and dimensions of mesh holes rescanned represented an important factor that influenced the scanning accuracy of IOS tested.

CLINICAL SIGNIFICANCE

It is a fundamental procedure obtaining intraoral digital scans without leaving mesh holes, so the rescanning techniques are minimized and, therefore, the scanning accuracy of the intraoral scanner tested is maximized.