Comparative study on the accuracy of extraoral scanning versus intraoral scanning in digital impressions for implant restoration in edentulous jaws

BackgroundThe accuracy of digital impressions for fully edentulous cases is currently insufficient for routinely clinical application. To overcome the challenge, a modified scan body was introduced, which demonstrated satisfactory accuracy in vitro. The aim of this study was to evaluate the accuracy of digital impressions using the modified scan bodies with extensional structure versus scan bodies without extensional structure in mandible with two implants in beagle dogs.MethodsThe unilateral mandibular second premolar to second molar were extracted in four beagle dogs. Twelve weeks later, two implants were placed. Five repeated digital impressions were performed with an intraoral scanner on each dog using each of the two different scan bodies: Group I—scan body without extensional structure (SB); Group II—scan body with extensional structure (SBE). The scans were exported to Standard Tessellation Language (STL) files to serve as test data. The dogs were sacrificed and the dissected mandibles were digitalized with a lab scanner to provide reference data. Linear and angular deviations were calculated in an inspection software for accuracy assessment. Statistical analysis was performed with two-way ANOVA. The level of significance was set at α = 0.05.ResultsFor trueness assessment, the mean of absolute linear/angular deviations were 119.53 μm/0.75 degrees in Group I and 68.89 μm/0.36 degrees in Group II. SBE was more accurate than SB regarding both linear (p = 0.008) and angular (p = 0.049) deviations. For precision assessment, the mean of absolute linear/angular deviations were 63.01 μm/0.47 degrees in Group I and 38.38 μm/0.24 degrees in Group II. No significant difference was found.ConclusionsThe application of SBE significantly improved the trueness of digital impressions in mandible with two implants compared to SB. No significant difference was found in terms of precision.

Accuracy of completely edentulous arch scanning with implant scan bodies has not been completely validated for intraoral scanners. For desktop laboratory scanners validations were found in the literature. The aim of this in vitro study was to compare the dimensional accuracy of scanning with splinted and unsplinted scan bodies on a completely edentulous maxillary arch with 6 implants. A maxillary edentulous master cast with 6 implants was used as control for all implant level impressions. 6 implants were digitally planned and placed at different angulation of 0, 0 17° and 30°. A contact coordinate measuring machine (CMM) was used to generate baseline linear measurements of the master cast. Four test groups included: 2 intraoral scanners Trios (3shape, Copenhagen, Denmark) and True Definition (3M ESPE, St Paul, MN), one industrial scanner Atos (Core optical 3D scanner) and one conventional impression group scanned with laboratory scanner Dental Wings 7 Series. Each scan recording was made with splinted and unsplinted scan bodies. Digital datasets of all measurements were compared with the CMM baseline values using PolyWorks® InnovMetric Software in order to assess the linear and angular deviations and determine the accuracy of complete arch digital impression. Factorial ANOVA showed significant effect with splinting, scanner type, inter-implant distance and implant angulation for linear deviations. Splinted scan bodies revealed elevated linear and angular deviation values for all scanners with significantly highest deviations for True Definition scanner. Significant correlation was found between inter-implant distance and linear deviation (r =0.45, P =<0.001) with increased linear deviations among all scanners, regardless of splinting. ( P <0.05). Significant effect on accuracy was seen for angular deviation with splinting, scanner type and implant angulation; significant difference was found between 0° and 30° implant angulation ( P =0.035) with more deviation with 30° implant angulation. The accuracy of the complete arch implant digital impression using splinted scan bodies was significantly reduced for measurements that crossed the arch midline. The digital impression technique using a broad splint design to connect scan bodies was not found to improve the scan accuracy for intraoral scanners.

To assess the accuracy of intraoral digital impressions for gingival contour captured in the esthetic zone in vivo. Five participants with full upper dentition were recruited. For each participant, three scans were taken using two intraoral scanning (IOS) systems (3Shape TRIOS Color, TRC; CEREC Omnicam, OC) respectively; three conventional impressions (CIs) were taken using vinyl polysiloxane materials. The CIs of all participants were casted and then digitized with a model scanner (IScan D103i, Imetric). Precision was evaluated by superimposing three repeated STL datasets per participant within each group and calculating the (90th-10th)percentile/2 values. The CIs were the reference for evaluating the level of system error of the two IOS systems from the true value. Digital models from CI and each IOS group were superimposed and (mean positive deviation-mean negative deviation)/2[mean negative deviation, mean positive deviation] were calculated to assess trueness level of the two IOS systems. For the soft tissue acquisition, precision results of each group were 45.10 ± 12.54 μm in TRC, 66.04 ± 13.46 μm in OC, and 63.66 ± 17.19 in CI (TRC vs OC, p < 0.001; TRC vs CI, p = 0.001; OC vs CI, p = 0.66). Trueness results were 80.12 ± 8.69[- 112.10 ± 9.88, 48.13 ± 13.79] μm in TRC and 82.70 ± 8.85[- 121.41 ± 15.40, 43.98 ± 11.86] μm (p > 0.05). In dentate situations, the two tested IOS systems achieved a clinically satisfying accuracy for capturing gingival contour in anterior maxilla, with a comparable or superior precision to the CI. TRC achieved a similar trueness and a higher precision level compared with OC. Intraoral digital impressions could be a recommended method for recording 3-dimensional gingival contour in the esthetic zone.

ObjectiveEvaluation of the effect of preparation type (inlay, onlay, and crown) on the accuracy of different intraoral scanning (IOS) systems at the preparation and arch segment levels.Materials and MethodsThree molars were prepared for inlay, onlay, and crown. Each preparation was scanned 10 times by CEREC Omnicam, Trios 3 (TS), and Medit i500 scanners. Each image was trimmed twice. The first trimming produced a preparation image (PI), and the second trimming extracted a segment image (SI) that involved the preparation with the adjacent teeth. Trueness and precision were calculated at the PI and SI levels.ResultsAt the PI level, all IOS systems had similar trueness pattern for all preparations, where the inlay had the best trueness followed by the crown and onlay. At the SI level, the different preparations showed similar trueness. The precision did not show a clear pattern of superiority for any preparation. The TS was significantly more precise than other IOS systems at the PI and SI levels, for every preparation. The proximal areas suffered from the greatest errors, regardless of preparation type.ConclusionsThe preparation type influenced PI trueness, and the IOS system affected PI and SI precisions.Clinical SignificanceThe smaller and less complex preparations have greater IOS accuracy than larger and more complex preparations. As the proximal areas are more affected regardless of the preparation, a more accessible proximal area for scanning is desirable.

BackgroundGuided endodontics technique has been introduced for years, but the accuracy in different types of teeth has yet to be assessed. The aim of this study is to evaluate the accuracy of three dimensional (3D)-printed endodontic guides for access cavity preparation in different types of teeth, and to evaluate the predictive ability of angular and linear deviation on canal accessibility ex vivo.MethodEighty-four extracted human teeth were mounted into six jaw models and categorised into three groups: anterior teeth (AT), premolar (P), and molar (M). Preoperative cone beam computed tomography (CBCT) and surface scans were taken and matched using implant planning software. Virtual access cavity planning was performed, and templates were produced using a 3D printer. After access cavities were performed, the canal accessibility was recorded. Postoperative CBCT scans were superimposed in software. Coronal and apical linear deviations and angular deviations were measured and evaluated with nonparametric statistics. The receiver operating characteristic (ROC) curve was used to evaluate the predictive ability of angular and linear deviation for canal accessibility in SPSS v20.ResultsA total of 117 guided access cavities were created and 23 of them were record as canal inaccessibility, but all canals were accessible after canal negotiation. The average linear deviation for all groups was 0.13 ± 0.21 mm at coronal position, 0.46 ± 0.4 mm at apical position, and 2.8 ± 2.6° in angular deviation. At the coronal position, the linear deviations of the AT and P groups were significantly lower than M group deviation (P < 0.05), but no statistically significant difference between AT group and P group. The same results were found in linear deviation at the apical position and in angular deviation. The area under the ROC curve was 0.975 in angular deviation, 0.562 in linear deviation at the coronal position, and 0.786 at the apical position. Statistical significance was noted in linear deviation at the apical position and in angular deviation (P < 0.001).ConclusionsIn conclusion, this study demonstrated that the accuracy of access cavity preparation with 3D-printed endodontic guides was acceptable. The linear and angular deviations in the M group were significantly higher than those in the other groups, which might be caused by the interference of the opposite teeth. Angular deviation best discriminated the canal access ability of guided access cavity preparation.Graphical

This study aimed to evaluate the influence of the presence of adjacent teeth on the accuracy of intraoral scanning (IOS) systems for class II inlay preparation. The mesio-occlusal inlay preparation was prepared in an anatomical model of the maxillary molar. The prepared tooth was secured to a typodont with the mesial adjacent tooth removed or in situ. Ten digital impressions of the inlay preparation were acquired using three IOS systems (CEREC Primescan, 3Shape TRIOS 3, and Medit i500). A laboratory scanner (3Shape E3) was used to obtain the reference scan data. The mean absolute deviation values were calculated to evaluate the accuracy of the digital models. The group with the adjacent teeth present showed lower trueness and precision compared to that without the adjacent tooth (p <.05). Significant differences were observed among the IOS systems (p <.05). Primescan showed the highest accuracy, irrespective of the presence of adjacent teeth. The presence of the adjacent tooth negatively affected the accuracy of all the IOSs tested. Although the performance of Primescan was superior to that of TRIOS 3 and i500, each IOS system showed clinically acceptable levels of accuracy for class II inlay preparation. The adjacent tooth can be a confounding factor for accurate digital impressions of class II inlay preparation.

Accuracy of different digital scanning techniques and scan bodies for complete-arch implant-supported prostheses

Accuracy of digital and conventional implant impressions in edentulous jaws: A clinical comparative study.

Aim:The aim is to assess and compare angular, linear, and depth deviation and difference in bone density of dental implants placed using computer aided design/computer aided manufacturing (CAD/CAM) fabricated surgical guides versus implants placed using Bone Pen Kit. Till now, no original research exists in the search engines such as Pubmed, Google Scholar, Science Direct, and Research Gate on this kit.Settings and Design:In vivo- Randomised control trial.Materials and Methods:Twenty clinical cases were selected and split into two distinct groups. Group 1 involved the placement of 10 implants using CAD/CAM fabricated three dimensional guides and Group 2 involved the placement of 10 implants using Bone Pen Kit. Four deviation parameters were evaluated, which included: (a) Angular deviation, (b) Linear deviation at implant platform, (c) Linear deviation at implant apex, and (d) Depth deviation and difference in bone density before and after implant placement was also evaluated.Statistical Analysis Used:SPSS software version 23 was utilized for the analysis of the data. The comparison was made using the Whitney test, and Wilcoxon signed rank test.Results:When comparing angular deviation, the results indicated a statistically significant difference with a P < 0.05. The values observed for angular and linear deviation in Group 2 were significantly greater than those in Group 1. No statistically significant difference in depth and linear deviation was found at the implant platform among the two groups. Bone density before and after implant placement was significantly higher in Group 1.Conclusions:(1) Angular and linear deviation at the apex in Group 2 exhibited higher values in comparison to Group 1, (2) No difference in depth and linear deviation at the implant platform was found among the two groups, and (3) There was no difference in change in bone density among two groups.

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

Background and Objectives: This study aimed to investigate the effect of the intraoral scanner, scanning technique, and implant position on the trueness measured by linear and angular deviations. Materials and Methods: An edentulous maxillary model with four implants was scanned using four intraoral scanners (Trios 5, Trios 3, Primescan, Medit i700) and four scanning techniques (unmodified, composite, eugenol, dental floss). Each intraoral scanner–scanning technique combination was repeated ten times, producing 160 test datasets. Master reference files were generated with a laboratory scanner. Linear and angular deviations were calculated after superimposing each test scan with its master file. A three-way ANOVA followed by Tukey’s HSD test was used to determine statistical differences. Significance was set at p < 0.05. Results: Significant effects of intraoral scanner, scanning technique, and implant position were found for both linear and angular deviations (p < 0.001). Trios 5 showed the highest linear deviation values, although these remained within clinically acceptable limits, while Primescan showed the lowest. Dental floss produced the highest linear and angular deviations, whereas eugenol demonstrated the lowest. Medit i700 demonstrated the lowest angular deviation. Conclusions: All intraoral scanners showed deviations within clinically acceptable thresholds, although Trios 5 showed the highest linear deviation. Among scanning techniques, dental floss resulted in the highest linear and angular deviations. Deviations were lower between adjacent implants and higher across 1–3, 1–4, and 2–4.

Statement of problemThe type of intraoral scanner (IOS), region of the implant, and extent of the scanned area have been reported to affect scan accuracy. However, knowledge of the accuracy of IOSs is scarce when digitizing different partially edentulous situations either with complete or partial arch scans. PurposeThe purpose of this in vitro study was to investigate the scan accuracy and time efficiency of complete and partial arch scans of different partially edentulous situations with 2 implants and 2 different IOSs. Material and methodsThree maxillary models with implant spaces at the lateral incisor sites (anterior 4-unit), right first premolar and right first molar sites (posterior 3-unit), or right canine and right first molar sites (posterior 4-unit) were fabricated. After placing implants (Straumann S RN) and scan bodies (CARES Mono Scanbody), models were digitized by using an optical scanner (ATOS Capsule 200MV120) to generate reference standard tessellation language (STL) files. Complete or partial arch scans (test scans) of each model were then performed by using 2 IOSs (Primescan [PS] and TRIOS 3 [T3]) (n=14). The duration of the scans and the time needed to postprocess the STL file until the design could be started were also recorded. A metrology-grade analysis software program (GOM Inspect 2018) was used to superimpose test scan STLs over the reference STL to calculate 3D distance, interimplant distance, and angular (mesiodistal and buccopalatal) deviations. Nonparametric 2-way analysis of variance followed by Mann-Whitney tests with Holm correction were used for trueness, precision, and time efficiency analyses (α=.05). ResultsThe interaction between IOSs and scanned area only affected the precision of the scans when angular deviation data were considered (P≤.002). Trueness of the scans was affected by IOSs when 3D distance, interimplant distance, and mesiodistal angular deviations were considered. The scanned area affected only 3D distance deviations (P≤.006). IOSs and scanned area significantly affected the precision of scans when 3D distance, interimplant distance, and mesiodistal angular deviations were considered, while only IOSs significantly affected buccopalatal angular deviations (P≤.040). Scans from PS had higher accuracy when 3D distance deviations were considered for the anterior 4-unit and posterior 3-unit models (P≤.030), when interimplant distance deviations were considered for complete arch scans of the posterior 3-unit model (P≤.048), and when mesiodistal angular deviations were considered in the posterior 3-unit model (P≤.050). Partial arch scans had higher accuracy when 3D distance deviations of the posterior 3-unit model were considered (P≤.002). PS had higher time efficiency regardless of the model and scanned area (P≤.010), while partial arch scans had higher time efficiency when scanning the posterior 3-unit and posterior 4-unit models with PS and the posterior 3-unit model with T3 (P≤.050). ConclusionsPartial arch scans with PS had similar or better accuracy and time efficiency than other tested scanned area-scanner pairs in tested partial edentulism situations.

Objective: To evaluate the accuracy of a self-developed extraoral scanning system based on photogrammetry technology, and to provide evidence for advancing the development and clinical application evaluation of domestically produced scanning devices. Methods: This research group developed a photogrammetry-based implant extraoral scanning system with customized scan bodies. Two distinct edentulous implant resin models were designed and three-dimensional (3D)-printed by Center of Digital Dentistry, Peking University School and Hospital of Stomatology, containing 6 (Model 1) and 8 (Model 2) abutment analogs respectively. Reference data acquisition was performed using a high-precision denture 3D scanner with scan caps mounted on the analogs. Specialized scan bodies were then mounted on the analogs for 3D positional data acquisition using both the self-developed system (experimental group) and the clinically established system (control group). Each system conducted 10 repeated scans per model. Trueness was assessed through root mean square error (RMSE), linear deviation (LD), and angular deviation (AD) relative to reference data, while precision was determined through intra-group RMSE analysis. Systematic comparisons included inter-group performance on identical models and intra-group variability across different models. Results: For Model 1, the experimental group showed statistically significant advantages over controls in intra-group RMSE [(3.10±0.71) μm vs (4.61±1.51) μm, P<0.001], reference-data RMSE [(21.48±0.60) μm vs (32.50±0.63) μm, P<0.001], linear deviation [23.64 (32.35) μm vs 44.86 (55.73) μm, P<0.001], and angular deviation [0.29° (0.29°) vs 0.23° (0.33°), P<0.001]. In Model 2, significant improvements were observed in intra-group RMSE [(4.47±1.58) μm vs (6.21±2.07) μm, P<0.001], reference-data RMSE [(38.84±0.86) μm vs (43.69±1.34) μm, P<0.001], and linear deviation [37.95 (50.68) μm vs 49.71 (58.89) μm, P<0.001]. Both groups exhibited model-dependent variability, with RMSE of precision and trueness of both groups, linear deviation of experimental group, angular deviation of control group showing statistically significant increases (all P<0.001) corresponding to abutment analog quantity. Conclusions: The self-developed scanning system demonstrates superior accuracy in 3D positional acquisition of abutment analogs compared to the contral group system, with implant number identified as a critical determinant of extraoral scanning accuracy.

Accuracy of intraoral optical scan versus stereophotogrammetry for complete-arch digital implant impression: An <i>in vitro</i> study

In implant dentistry, the advent of intraoral scanning technology has revolutionized traditional clinical processes by streamlining procedures and ensuring predictable treatment outcomes. However, achieving accurate virtual implant positions using intraoral scanners and scan bodies can be influenced by various clinical and laboratory factors. This study aims to investigate the impact of scan body image capture deficiency and scan body alignment methods in computer-aided design (CAD) software on the accuracy of virtual implant positions, particularly in different implant depths. Three stereolithographic half-arch implant models with different implant depths were prepared, representing three scenarios of scan body exposure: full exposed scan body, 2/3 exposed scan body, and 1/3 exposed scan body. The scan body image capture deficiency and alignment methods were simulated using CAD software. The deviation of virtual implant positions obtained from different scenarios were evaluated using 3D analysis software. The highest angular and linear deviation (0.237±0.059 degrees, 0.084±0.068 mm) were found in the 1/4 upper and lower part scan body deficiency using the 1-point alignment method in the 1/3 exposed scan body. Two-way ANOVA analysis revealed significant effects of scan deficiency on virtual implant position deviations across all scan body exposures, except for the linear deviation when the scan body was exposed 2/3 of its length. Furthermore, scan deficiencies in the 1/4 upper and lower parts of the scan body significantly affected implant angular deviation regardless of scan body exposure, while implant linear deviation was specifically affected when the scan body was exposed to only 1/3 of its total length. Deficiencies in scan body acquisition, particularly in deep soft tissue situations, can lead to deviations in both angular and linear positioning of virtual implants. Employing appropriate scan body alignment methods such as a 3-point alignment approach demonstrates better accuracy compared to a 1-point alignment.