Evaluation of the trueness and precision of eight extraoral laboratory scanners with a complete-arch model: a three-dimensional analysis

Effect of different intraoral scanners and scanbody splinting on accuracy of scanning implant-supported full arch fixed prosthesis

OBJECTIVE

This study evaluated the accuracy of different intraoral scanners (IOS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations with and without scanbodies splinting.

MATERIALS AND METHODS

Two maxillary models were designed and fabricated to receive an all-on-four implant retained. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30 and Group 2; 45). Each group was then divided into three subgroups according to the type of IOS used: Subgroup C; Primescan, subgroup T; Trios4, and subgroup M; Medit i600. Then each subgroup was divided into two divisions according to scanning technique; division S: splinted and division N: nonsplinted. Ten scans were made by each scanner for every division. Trueness and precision were analyzed using Geomagic controlX analysis software.

RESULTS

Angulation had no significant effect on both the trueness (p = 0.854) and precision (p = 0.347). Splinting had a significant effect on trueness and precision (p < 0.001). Scanner type had a significant effect on trueness (p < 0.001) and precision (p < 0.001). There was no significant difference between trueness of Trios 4 (112.15 ± 12.85) and Primescan (106.75 ± 22.58). However, there was a significant difference when compared to trueness of Medit i600 (158.50 ± 27.65). For the precision results Cerec Primescan showed the highest precision (95.45 ± 33.21). There was a significant difference between the three scanners, precision of Trios4 (109.72 ± 19.24) and Medit i600 (121.21 ± 17.26).

CONCLUSION

Cerec Primescan has higher trueness and precision than Trios 4 and Medit i600 in full arch implants scanning. Splinting the scanbodies improve the accuracy of full arch implants scanning.

CLINICAL SIGNIFICANCE

Cerec Primescan and 3Shape Trios 4 can be used for scanning of All-on-four implant supported prosthesis when scanbodies are splinted using a modular chain device.

Positional transfer accuracy of titanium base implant abutment provided by two different scan body designs: an invitro study

BACKGROUND

The variabilities in design and material of scan bodies have a major role in the positional transfer accuracy of implants. The purpose of this invitro study was to compare the 3D transfer accuracy (trueness and precision) of titanium base (TB) abutment position provided by 2 different scan bodies: one-piece scan body (SB) in comparison to two-piece healing abutment and scan peg (HA-SP).

METHODS

A maxillary model with a dummy implant in the 2nd premolar (Proactive Tapered Implant; Neoss) was 3D printed and TB (Ti Neolink Mono; Neoss) was tightened on the implant and scanned by using a laboratory scanner (inEos X5; Dentsply Sirona) (reference scan). An SB (Elos Medtech) and an HA-SP (Neoss) were subsequently connected to the implant and were scanned 10 times each by using the same scanner (test scans). All the scans were exported as STL files and imported into CAD software where the TBs were formed. Test scans were superimposed on reference scans for transfer accuracy analysis using 3D metrology software (GOM Inspect; GOM GmbH) in terms of angular deviation in vertical and horizontal directions, linear deviation in each XYZ axis of TBs and total linear deviation in all axes. Statistical analysis was done using independent sample t test. When Levene's test for equality of variances was significant, Welch's t-test was used. (P value < 0.05) RESULTS: Significant differences were found amongst the tested groups in both angular and linear deviation in terms of trueness with less deviation values for the SB group (P < 0.001). For the precision, significant differences were found amongst the tested groups in angular deviation in vertical direction with less deviation value for the SB group compared to HA-SP group (P < 0.001). However, no significant difference was found between the tested groups regarding the angular deviation in horizontal direction (P = 1.000). Moreover, significant differences were found amongst the tested groups in linear deviations with less linear deviations in XYZ axes for SB compared to HA-SP group (P = 0.020, < 0.001, = 0.010 respectively).

CONCLUSIONS

SB showed less angular and linear deviation values in the 3D positional transfer of TB than HA-SP indicating higher degree of accuracy of SB.

Assessment of guide fitting using an intra-oral scanner: An in vitro study

OBJECTIVES

The aim of this study was to evaluate the capacity of an intra-oral scanner (IOS) to assess the position of an endodontic guide in vitro.

METHODS

Fourteen extracted human teeth were placed into a maxillary model and scanned using computed tomography and a reference laboratory scanner. An ideal endodontic guide was then created and modified by adding defects of different thicknesses to simulate incorrect positions: 50 μm, 150 μm, 400 μm, and 1000 μm. For each thickness, guides were printed three times and each guide was scanned by three experimented operators using a Trios 4 IOS (3Shape, Copenhagen, Denmark). The 36 scans were compared using a best-fit alignment to the master model without defect to define the accuracy of the method and the positioning error.

RESULTS

The IOS presented a mean trueness of 1.28 μm (SD= 12.70) and a mean precision of 11.52 μm (SD= 62.17). Considering all sizes of defect, the mean measured position of the endodontic guide was highly correlated (R>0.99) with the expected position. Compared to the ideal guide, there was a mean linear deviation of 46.11 μm (SD= 23.21) and a mean angular deviation of 5.9° (SD= 1.2); this deviation was not influenced by the operator.

CONCLUSION

The present study found that an IOS had good performance to detect a positioning error of the endodontic guide in vitro.

CLINICAL SIGNIFICANCE

This new application of IOS has a promising potential in clinical practice to assist practitioners during the fitting of guides.

Comparison of intraoral scanning and CBCT to generate digital and 3D-printed casts by fused deposition modeling and digital light processing

OBJECTIVES

to evaluate trueness and precision of digital casts from intraoral scanning (IOS) and cone beam computed tomography (CBCT); trueness and precision of 3D-printed casts using digital light processing (DLP) and fused deposition modeling (FDM); the influence of digitizing method in the 3D-printed casts and, to compare STL data after DICOM segmentation and conversion.

METHODS

a reference cast was digitized with IOS and CBCT, and 3D-printed using FDM and DLP. Linear measurements of occlusocervical (OC), interarch (IEA), and mesiodistal (MD) dimensions were taken on reference, digital and 3D-printed casts. Trueness was observed as the distortion, and precision was observed as the variation of measurements. One and Two-way ANOVA, Student t-test, and Chi-Square were applied to analyze data.

RESULTS

distortion varied between digital casts for all dimensions; at OC, both showed expanded dimensions with IOS being significantly greater; in turn, CBCT digital casts showed higher distortion at IEA and MD. Dimensions of 3D-printed casts showed a predominance of shrinkage, DLP presented higher distortion compared to FDM for both digitizing methods. Digitizing methods influenced the 3D-printing of casts, especially for DLP. Regarding precision, no statistical difference was found. STL converted from DICOM showed statistical difference in IEA (p < 0.001).

CONCLUSIONS

digital casts showed distortion depending on the digitizing method. IOS was better in IEA and MD, and CBCT in OC dimensions. Overall, DLP casts presented higher distortion compared to FDM. The digitizing method influences trueness on 3D-printed casts. File conversion from DICOM to STL per se could change the dimension.

CLINICAL SIGNIFICANCE

This investigation showed that digital casts from IOS and CBCT as well 3D-printed casts from FDM and DLP can show different trueness. It is clinically relevant as clinicians have various workflows available in Digital Dentistry which involve these digitizing and manufacturing methods.

An overview of three-dimensional imaging devices in dentistry

OBJECTIVE

To review four types of three-dimensional imaging devices: intraoral scanners, extraoral scanners, cone-beam computed tomography (CBCT), and facial scanners, in terms of their development, technologies, advantages, disadvantages, accuracy, influencing factors, and applications in dentistry.

METHODS

PubMed (National Library of Medicine) and Google Scholar databases were searched. Additionally, the scanner manufacturers' websites were accessed to obtain relevant data. Four authors independently selected the articles, books, and websites. To exclude duplicates and scrutinize the data, they were uploaded to Mendeley Data. In total, 135 articles, two books, and 17 websites were included.

RESULTS

Research and clinical practice have shown that oral and facial scanners and CBCT can be used widely in various areas of dentistry with high accuracy.

CONCLUSION

Although further advancement of these devices is desirable, there is no doubt that digital technology represents the future of dentistry. Furthermore, the combined use of different devices may bring dentistry into a new era. These four devices will play a significant role in clinical utility with high accuracy. The combined use of these devices should be explored further.

CLINICAL SIGNIFICANCE

The four devices will play a significant role in clinical use with high accuracy. The combined use of these devices should be explored further.

Accuracy of different laboratory scanners for scanning of implant-supported full arch fixed prosthesis

OBJECTIVE

This study evaluated the accuracy of different laboratory scanners (LS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations.

MATERIALS AND METHODS

Two maxillary models that are designed to receive an all-on-four implant retained prosthesis were fabricated then scanned using five different LS. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30° and group 2; 45°). Each group was then subdivided into five subgroups according to the type of LS, subgroup T; Medit T710, subgroup I; IneosX5, subgroup E; 3ShapeE4, subgroup A; Autoscan DS-Mix, and subgroup M; Ceramill Map600. An industrial 3D scanner was used as reference scanner, then each model was scanned with 5 LS 10 times. Trueness and precision were analyzed using Geomagic 3D analysis software.

RESULTS

Both scanner type and implant angle had a significant effect on the trueness (p < 0.001). Significant interaction was found between the scanner type and implant angle (p < 0.001). For scanner type tukeys post hoc test revealed highest trueness with the 3Shape E4 (21.3 ± 2.1) and the medit T710 (22.6 ± 2.1) and least trueness with the shining 3D autoscan ds-mix (33.8 ± 3.0). Significantly better trueness was observed with the 30° than the 45° angle. Regarding precision, two-way ANOVA revealed significant effect of the scanner type only (p < 0.001). There were no significant differences between the 3Shape E4, medit T710, Ineos X5, and the Ceramill map600. However, all showed significantly higher precision values when compared to shining 3D autoscan ds-mix.

CONCLUSIONS

All tested scanners showed results within the clinically acceptable range with 3ShapeE4 and Medit T710 showing the highest accuracy.

CLINICAL SIGNIFICANCE

Tested scanners can be used for scanning of All-on-four implant supported prosthesis.

Comparison of the virtual techniques in registering single implant position with a universal-coordinate system: An in vitro study

OBJECTIVES

The aim of this in-vitro study was to compare the virtual techniques for registering single-implant position to the physical gold standard using a universal-coordinate system.

MATERIALS AND METHODS

Thirty dentate maxillary resin models with a dental implant inserted in the incisor region were prepared. On each model, a tooth-supported acrylic stent with a 1 cm x 1 cm x 1 cm cubic-corner (CC) was prepared. The Cartesian x,y,z-coordinate of the implant neck and apex were measured physically by a coordinate-measuring machine (CMM) with reference to this CC and served as the gold-standard. The resin models were scanned by a benchtop scanner (Group BS), cone-beam computed tomography (Group CBCT), and intraoral scanner (Group IOS). Stone casts, poured from open-tray polyether impression of the resin models, were scanned by the benchtop scanner (Group BS-cast). The implant neck and apex coordinates with reference to the CC were measured and the differences in the coordinates (∆x, ∆y, ∆z) and distance r from the gold standard were calculated. The data were analyzed by one-sample t-test and one-way ANOVA/Kruskal-Wallis test with the level of significance set at 0.05.

RESULTS

The implant neck and apex positions of Group BS were statistically different from that of the CMM, r>0 (p<0.001). Group IOS showed a significant less ∆z and r at the implant neck than Group BS-cast (p = 0.006). No significant difference was found in the coordinates and distance at implant apex among Groups BS, CBCT, IOS and BS-cast.

CONCLUSIONS

The physical measurements could be adopted as the gold standard in assessing the single-implant positions. The IOS was more accurate in registering the single-implant neck positions than scanning of the cast.

CLINICAL SIGNIFICANCE

A universal-coordinate system defined by the cubic-corner allows comparing the virtual techniques in registering single-implant positions to the physical gold standard.

The question about the numerical value and quantitative data transfer of implant prosthodontics-orom experience guidance to digital guidance

The correct implant site design and placement are the basic clinical techniques that must be known for implant restoration. For a long time, most implants have been placed by free hands, and the choice of site is mostly dependent on the accumulation of long-term experience of the surgeon. The selection of implant site guided by this experience analogy logic is often based on the surgeon's level of experience,which often makes it very easy to produce complications related to the implant restoration of the incorrect site. In contrast, a clinical program using digital guidance and real-time measurable verification has emerged based on the restoration-oriented implantation concept, which marks the formation of an accurate, measurable and verifiable whole-process digital implant prototype. Furthermore, from the perspective of surveying, the numerical requirements that digital implant restoration relies on are actually incomplete to the four elements of measurement, which leading to the doubts about its authenticity. This article will question the numbers in implant restoration, and conduct a preliminary demonstration, and propose a new reliable actual measurement and verification method of the correct location and the numerical requirements of the restoration space and a new clinical program that relies on numbers from the perspective of the evolution of digital restoration, guided implantology and actual measurement technology. And this article further discusses the current mainstream implant restoration technology based on experience analogy which cannot effectively support the whole process of digital implant restoration and provides a new logical cognitive basis for the final realization of the entire process of digital implant restoration.

The accuracy of single implant scans with a healing abutment-scanpeg system compared with the scans of a scanbody and conventional impressions: An in vitro study

PURPOSE

To compare the accuracy of polyvinylsiloxane (PVS) impressions and intraoral scans when a healing abutment-scanpeg system (HASP) or a conventional scanbody (CSB) was used on a single implant.

MATERIALS AND METHODS

A maxillary model with an implant (4.0 × 11 mm) (Neoss) and a CSB or an HASP (Neoss) was scanned by using a laboratory scanner (Ceramill Map 600; Amann Girrbach) (reference scans) and an intraoral scanner (Trios 3) (n = 10). PVS open-tray impressions were also made and stone casts of the model with a CSB were digitized with the laboratory scanner. Intraoral scanner and cast scans were superimposed to their reference scans. On superimposed scans, points were selected on HASP and CSB to calculate distance deviations (at points 1-4) and angular deviations (at points 5 and 6 on CSB and PVS, and 5-8 on HASP) between scans (trueness), and their variation (precision). The deviation data was analyzed with ANOVA and pairwise comparisons (trueness) with Tukey's adjustment, and F-tests (precision).

RESULTS

At point 1, PVS had lower trueness than CSB (difference in means (DIMs) = 0.184 mm, p = 0.006) and HASP (DIMs = 0.122 mm, p = 0.042). At point 3, CSB had higher trueness than HASP (DIMs = 0.134 mm, p = 0.001). Angular deviations with PVS were higher than with CSB (DIMs = 0.6°, p = 0.013) and HASP (DIMs = 0.7°, p = 0.005). CSB had higher precision than PVS (p < 0.05). HASP had higher precision than PVS for distance (Point 1)(p < 0.001) and angular deviations (p < 0.05). Deviation differences within the HASP parts were not significant.

CONCLUSION

The accuracy of intraoral scans and PVS impressions of an implant was similar.

CLINICAL RELEVANCE

The combined healing abutment-scanpeg system and the conventional scanbody can be recommended for scans of anterior single implants with the intraoral scanner used.

In vitro Comparison of the Accuracy (Precision and Trueness) of Seven Dental Scanners

Statement of the Problem:

The mechanisms of operation of dental scanners are based on different technologies. Considering these differences, there are many types of scanners available in the market.

Purpose:

This in vitro study aimed to compare the accuracy (precision and trueness) of seven commonly used dental scanners.

Materials and Method:

In this in vitro experimental study, the accuracy of 7 common extra oral scanners (Sirona ineos inLab, Sirona X5, Dentium, Imes Icore 350I, Amann Girrbach, 3shape D700, and 3Shape E3) were evaluated. Each of scanners performed 7 scans of implant abutment of SIC (SIC MAX.GH1). Data from each scanner were then compared to data received from 3Shape Trios intra oral scanner as a reference. For evaluating the accuracy of each scanner, trueness and precision was evaluated. Collected data were analyzed using Kruskal Wallis and Bonferroni tests via SPSS version 22.

Results:

Descriptive statistics showed the best trueness was for 3Shape E3 scanner with the average of 35.37µm and the worst trueness belonged to Sirona x5 scanner with the average of 51.75µm. Furthermore, the best precision was achieved for 3Shape E3 scanner with the average of 35.34, while the lowest precision was detected in 3Shape D700. The scanners had statistically significant differences with each other in terms of trueness and precision (p<0.05).

Conclusion:

Based on the results of this study, the extra oral scanner, 3shape E3, had the best trueness and precision. The lowest amount of trueness among the studied scanners was for the extra oral scanner, Sirona x5, and the lowest precision was for scanner 3shape D700.

Accuracy and Precision Evaluation of International Standard Spherical Model by Digital Dental Scanners

With the popularization of digital technology and the exposure of traditional technology's defects, computer-aided design and computer-aided manufacturing (CAD/CAM) has been widely used in the field of dentistry. And the accuracy of the scanning system determines the ultimate accuracy of the prosthesis, which is a very important part of CAD/CAM, so we decided to evaluate the accuracy of the intraoral and extraoral scanners. In this study, we selected the sphere model as the scanning object and obtained the final result through data analysis and 3D fitting. In terms of trueness and precision, the scanner of SHINING was significantly different from that of others; however, there was no significant difference between TRIOS and CEREC. SHINING showed the lowest level of accuracy, with CEREC slightly lower than TRIOS. The sphere model has also been proven to be scanned successfully.

Accuracy evaluation of complete-arch models manufactured by three different 3D printing technologies: a three-dimensional analysis

Purpose This study aimed to evaluate the trueness and precision of complete-arch models printed with three-dimensional printers via three different printing technologies.Methods An arch-shaped master model was designed using software (RapidForm XOR2, 3D Systems Inc., USA), and the digital master model was printed 10 times with three-dimensional printers using stereolithography (SLA), direct light processing (DLP), and Polyjet technology (n = 30). The printed models were then scanned with an industrial scanner to create the respective digital models. All digital models were compared with the master model, and an evaluation of the trueness was performed by model superimposition with Geomagic Control software (3D Systems, Rock Hill, SC, USA). Precision was determined for each case by superimposing some combination of the 10 datasets in each group.Results The trueness of the printed models was 46.2 µm for the DLP printer, 51.6 µm for the SLA printer, and 58.6 µm for the Polyjet printer. The DLP models were significantly better than the Polyjet models (p = .005). However, the Polyjet models (30.4 µm) were more precise than the SLA (37.6 µm) and DLP (43.6 µm) models (p < .001, p = .016). Furthermore, the SLA (11.8 µm) was the most accurate printer in the Z-direction (p = .016, p = .002).Conclusions The 3D printing technologies showed significant differences in the precision and trueness of complete-arch measurements. Although DLP was more accurate other tested 3D printers, the accuracy of all 3D printed models was within clinical tolerance, and they were clinically acceptable and could be used for the production of fixed restorations.

Accuracy and its impact on fit of injection molded, milled and additively manufactured occlusal splints

Occlusal devices to reduce symptoms of bruxism and temperomandibular disorders can nowadays be manufactured in a digital workflow but studies comparing the accuracy of those occlusal devices are still limited. Therefore, the aim of this investigation was to investigate the accuracy of injection molding compared with four computer-aided design (CAD) and computer-aided manufacturing (CAM) techniques for the manufacturing of occlusal devices. In addition, the number of contact points and retention were evaluated to assess clinical relevance. A conventional workflow consisting of alginate impression, wax-up, and injection molding (IM) and digital workflows including intraoral scanning, digital design, and subtractive manufacturing (SM) or additive manufacturing by using stereolithography (SLA), digital light processing (DLP), and material jetting (Polyjet) were investigated. Sixteen splints were fabricated with each method. The intaglio surfaces of the splints were laser scanned and superimposed with the reference data sets to analyze the surface deviations. In addition, the number of contact points after repositioning the splints on the reference model was evaluated with occlusal foil. Finally, the retention was measured in a tensile test. One-way ANOVA with post hoc Tukey tests were used for statistical analyses (α = .05). IM and SM splints demonstrated the highest manufacturing accuracy without significant differences to each other (P > .985). Additive manufactured splints revealed greater deviations with equal results for SLA and Polyjet (P > .949) and significantly higher deviations for DLP compared to all other groups (P < .002). Comparable retention force was measured for IM, SM, and SLA (P > .923), whereas Polyjet splints showed the greatest variability. IM and SM splints presented the most contact points (P = .505). Additive manufactured splints demonstrated fewer contacts without significant difference to each other (P > .116). It can be concluded, that there is no difference in manufacturing accuracy, retention, and number of contacts between IM and SM splints. AM splints demonstrated higher, however, clinically acceptable deviations.

Accuracy evaluation of 3D printed interim prosthesis fabrication using a CBCT scanning based digital model

OBJECTIVES

This study aimed to evaluate the marginal and internal gaps in 3D-printed interim crowns made from digital models of cone-beam computed tomography (CBCT) conversion data.

MATERIALS AND METHODS

Sixteen polyvinylsiloxane impressions were taken from patients for single crown restorations and were scanned using CBCT. The scanning data were converted to positive Standard Triangulation Language (STL) files using custom-developed software. The fabricated stone models were scanned with an intraoral optical scanner (IOS) to compare the surface accuracy with the STL data obtained by CBCT. The converted STL files were utilized to fabricate interim crowns with a photopolymer using a digital light-processing 3D printer. The replica method was used to analyze the accuracy. The marginal and internal gaps in the replica specimen of each interim crown were measured with a digital microscope. The Friedman test and Mann-Whitney U test (Wilcoxon-signed rank test) were conducted to compare the measurements of the marginal and internal gaps with a 95% level of confidence.

RESULTS

The root-mean-square values of the CBCT and IOS ranged from 41.00 to 126.60 μm, and the mean was 60.12 μm. The mean values of the marginal, internal, and total gaps were 132.96 (±139.23) μm, 137.86 (±103.09) μm, and 135.68 (±120.30) μm, respectively. There were no statistically significant differences in the marginal or internal gaps between the mesiodistal and buccolingual surfaces, but the marginal area (132.96 μm) and occlusal area (255.88 μm) had significant mean differences.

CONCLUSION

The marginal gap of the fabricated interim crowns based on CBCT STL data was within the acceptable range of clinical success. Through ongoing developments of high-resolution CBCT and the digital model conversion technique, CBCT might be an alternative method to acquire digital models for interim crown fabrication.

Dentistry 4.0 Concept in the Design and Manufacturing of Prosthetic Dental Restorations

The paper is a comprehensive but compact review of the literature on the state of illnesses of the human stomatognathic system, related consequences in the form of dental deficiencies, and the resulting need for prosthetic treatment. Types of prosthetic restorations, including implants, as well as new classes of implantable devices called implant-scaffolds with a porous part integrated with a solid core, as well as biological engineering materials with the use of living cells, have been characterized. A review of works on current trends in the technical development of dental prosthetics aiding, called Dentistry 4.0, analogous to the concept of the highest stage of Industry 4.0 of the industrial revolution, has been presented. Authors’ own augmented holistic model of Industry 4.0 has been developed and presented. The studies on the significance of cone-beam computed tomography (CBCT) in planning prosthetic treatment, as well as in the design and manufacture of prosthetic restorations, have been described. The presented and fully digital approach is a radical turnaround in both clinical procedures and the technologies of implant preparation using computer-aided design and manufacturing methods (CAD/CAM) and additive manufacturing (AM) technologies, including selective laser sintering (SLS). The authors’ research illustrates the practical application of the Dentistry 4.0 approach for several types of prosthetic restorations. The development process of the modern approach is being observed all over the world. The use of the principles of the augmented holistic model of Industry 4.0 in advanced dental engineering indicates a change in the traditional relationship between a dentist and a dental engineer. The overall conclusion demonstrates that it is inevitable and extremely beneficial to implement the idea of Dentistry 4.0 following the assumptions of the authors’ own, holistic Industry 4.0 model.