1 Volume 22 2023 e238354 Original Article Braz J Oral Sci. 2023;22:e238354http://dx.doi.org/10.20396/bjos.v22i00.8668354 1 Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), School of Dentistry, Araraquara, São Paulo, Brazil. 2 Department of Health Sciences, Implantology Post Graduation Course, Dental School, University Center of Araraquara (UNIARA), Araraquara, São Paulo, Brazil Corresponding author: Lucas Portela Oliveira Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), School of Dentistry, Araraquara, São Paulo, Brazil. 1680 Humaitá Street, Zip Code 14801–903 Phone: +55(16) 33016424; Fax: +55(16) 33016406 Email: lp.oliveira@unesp.br Editor: Altair A. Del Bel Cury Received: February 08, 2022 Accepted: April 10, 2022 Implant digital impression accuracy using extraoral scanners: a three-dimensional analysis Grazielle Franco Gomes1 , Mónica Estefanía Tinajero Aroni1 , Lucas Portela Oliveira1* , João Neudenir Arioli Filho1 , Carolina Mollo Binda2 , Francisco de Assis Mollo Júnior1 Aim: To analyze the accuracy of extraoral systems (Ceramill Map400+, AutoScan-DS200+, and E2) in full implant- prosthetic rehabilitation three-dimensionally. Methods: A metallic edentulous maxilla with four implants was digitalized by a contact scanner (MDX-40 - Roland, control) and used as a control image to compare with other images generated by three laboratory scanners (10 samples per group). Letters identified all the four components: A and D angled 45º, and B and C parallel. The BioCAD software exported the images (.STL) to compare and verify deviations of the analogs on the X, Y, and Z axes. The nonparametric Kruskal-Wallis test and the two-way ANOVA on ranks with a post hoc Tukey test analyzed the data with 5% significance. Results: No statistical differences were observed in the accuracy between the extraoral scanners (p=0.0806). However, when analyzing only the components, component D was more accurate when scanned with Ceramill Map400+ compared with AutoScan DS200+ (p<0.001) and with E2 (p=0.002). Conclusions: All extraoral systems assessed showed digitalization accuracy but with more deviations in angled implants. The Ceramill Map400+ scanner showed the best results for the digital impression of a complete arch. Keywords: Dental impression technique. Dental implants. Dental prosthesis. Dental prosthesis, implant-supported. https://orcid.org/0000-0003-0474-7059 https://orcid.org/0000-0002-8346-5561 https://orcid.org/0000-0002-7136-3488 https://orcid.org/0000-0003-3582-9233 https://orcid.org/0000-0002-3675-4360 https://orcid.org/0000-0003-0742-2145 2 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Introduction The use of conventional complete dentures is one of the most common options for treatment in cases of complete edentulism1. Nevertheless, low retention and stabil- ity in patients with considerable bone resorption resulted in a greater demand for implants2. Therefore, the All-on-four concept is an option in cases of anatomical lim- itations and severe bone resorption. This protocol uses four implants, two parallel and two 45º angled, in the anterior and posterior region, respectively—this aim to reduce the cantilever length and improve the transmission of strength3. The implant impression technique has the objective of transferring intraoral posi- tions of implants. An accurate impression is vital to obtain a passive fit: a clinical condition in prosthetic rehabilitation which avoids static load on the prosthetic sys- tem or alveolar bone4-6. However, incompatibility may cause mechanical and biolog- ical failures, such as poor adjustment, fracture of screws or components, and loss of osseointegration7,8. The literature mentions several impression techniques, such as using stable impres- sion material, splinted or non-splinted, or even using only implants or with abut- ments9-11. However, the contraction of impression materials and clinical and laboratory processes, such as improper leakage time and the plaster type used, can influence the accuracy of the final impression9,12,13. In addition, impression on implants, distance, and angulation may negatively affect the final passivity14. Due to these problems caused by conventional impressions, CAD/CAM (Computer-aided-design/manufacturing) systems were introduced to eliminate impression materials and some laboratory processes15. CAD/CAM systems comprise three stages: data acquisition, prosthesis design, and manufacturing pro- cesses16,17. Besides, two scan modalities are available: extraoral and intraoral18,19. Intraoral digitalization is performed directly in the patient’s mouth. The advantages include eliminating impression material, patient comfort, and a faster treatment18,20-22. However, studies show that buccal humidity, patient’s head movement, and restric- tions in the scanner movement can limit the use of this technique23-25. However, there are two systems concerning extraoral scanners: (1) one allows the digitalization of a cast created from the conventional impression; (2) another digi- talizes the impression. Unfortunately, both modalities may have errors resulting from the impression, manufacture of the dental cast, or even failures in digitalization26. During the process, the scanning is performed with light sources, such as light rays, laser, infrared light, LED, or structured light16. For example, laser scanners use a pattern of one-dimensional lines, whereas structured light scanners project a two-dimensional light to obtain three-dimensional data of the scanned object27. In addition, scanners with blue LED technology have a shorter wavelength, resulting in better accuracy17. Thus, although digitalization is a simple process, the operating mechanism of scan- ners is complex and may influence its final accuracy, characterized by the combina- tion of trueness and precision28. Trueness is the scanner’s ability to digitalize an object 3 Gomes et al. Braz J Oral Sci. 2023;22:e238354 with its real dimensions. Precision is the scanner’s ability to create repeatable images using different measurements of the same object12,29. Other factors that can influence the extraoral scanner precision include device hardware, software algorithms, digita- lization technology, and the shape and size of the master model17; however, there is literature lacking about the accuracy of extraoral scanners in angled implants associ- ated with the all-on-four technique. Due to the importance of obtaining an accurate final impression, this study assessed, and three-dimensionally compared, the accuracy of different extraoral scanners (Ceramill Map400+, AutoScan-DS200+, and E2) in parallel and angled implants. Our null hypothesis states that different laboratory scanners do not present differences in accuracy. Materials and Methods Sample Size Estimation The sample size was calculated using a software program (GPower; Hein- rich-Heine-Universität Düsseldorf). In this study the parameters for analysis of vari- ance (ANOVA) were used, which effect size f = 3.60, α = 5%, power = 80%, number of groups= 3 (extraoral scannings). The sample size was calculated to be 6. Considering a loss of 30%, the final sample of this study consisted of 10 scanning for each extra- oral system analyzed. Obtaining the Master Impression Initially, an edentulous maxilla cast model was used to obtain a metallic model (Figure 1A) through the Lost-wax casting technique. Next, a precision lathe per- formed four 4.1-mm-diameter perforations in this metallic model and installed exter- nal hexagon implants with a regular platform (Conexão, Sao Paulo, Brazil). Then, two parallel perforations were done in the premaxilla region to install 13-mm-long implants; two other perforations angled 45º were conducted in the canine fossa’s posterior area, installing 15-mm-long implants. The implants were named A, B, C, and D (Figure 1A) to facilitate analysis. A B Figure 1. (A) Scheme of the metallic master cast. (B) A metallic model with scan bodies in position. 4 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Abutments with a 3-mm collar were installed on anterior implants (Micro Unit, Con- exão), and 30º angled abutments (Micro Unit) with a 3-mm collar were installed on 45º angled posterior implants, which compensated for implant angulation (a 15º final angulation). All abutments were applied a 20 N.cm torque, as recommended by the manufacturer. Digital Impression Due to high accuracy, the metallic master cast was initially digitalized with an indus- trial contact scanner (MDX-40, Roland, Centro de Tecnologia da Informação - CTI, Campinas, SP, Brazil) due to high accuracy30. The distance between the contact tip and the model surface was calibrated to 0.2 mm, resulting in a high-precision digital model, which was then exported as an STL file to be used as a control image and compared with the other scanners. Subsequently, we used three laboratory scanners, including two structured light (Ceramill map400+, Amann Girrbach Charlotte USA; AutoScan DS200+, SHINING 3D, Zhejiang China) and a multilinear blue LED light (E2, 3Shape Copenhagen, Denmark) (Table 1), to digitalize the metallic master model and generate the STL images. In addi- tion, scan bodies were installed on the abutments of the master cast (Scan-Connect Micro Unit, Conexão) (Figure 1B), which allowed the components to shift position. Table 1. Experimental groups System Scanner Technology Manufacturer Country MDX-40 Control Contact scanner Ronald São Paulo, Brazil Ceramill Map400+ Scanner 1 Structured light Lab scanner Amann Girrbach Charlotte, USA AutoScan-DS200+ Scanner 2 Structured light Lab scanner SHINING 3D Zhejiang, China E2 Scanner 3 Multilinear blue LED light 3Shape Copenhagen, Denmark Scanners used (laboratory scanner and contact scanner) and their features. A thin, uniform layer of titanium dioxide powder (D70, Metal Chek, Uberaba, Brazil; SKD-S2 Spotcheck, Magnaflux, Glenview, USA) was used on the surface of the master model to be digitalized by all three scanners to generate an opaque surface and avoid the reflection of light on the metallic model, thus preventing interferences on the final accuracy of the digital model. Subsequently, each scanner performed 10 scans fol- lowing the manufacturer’s instructions, and STL images were obtained (n=30). After obtaining the digital models, the digitalization system replaced the scan bodies present in the digital images for mini pillars available at the digital library, generating the images to be analyzed; we then used interest areas (pyramid and components) for a subsequent 3D analysis. The professionals trained in each system used conducted the digitalization processes: NB for Ceramill Map400+, APS for AutoScan DS200+, and NP for E2. 5 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Determining the Distances between the Pyramids and the Components All models were digitalized in STL files, including one control image (contact scanner) and 30 experimental (extraoral scanners), and then these files were imported to a Bio-CAD program (Computer Assisted Design; Rhino3D, Rhinoceros, USA) to deter- mine measures to be later compared (Figure 2). Initially, each image was imported to select the reference points and build references between the pyramid (creating schemes to represent the pyramidal geometry and obtain the pyramid’s edges and apex) and the components to measure distances (Figure 3A). Contact Scanner MDX-40 (Control Group) Reference Model 31 Digital Images in STL Bio-CAD Software Reference Model Reference Model Reference Model n = 1 n = 10 n = 10 n = 10 2 3 1 Ceramill Map400+ Extraoral Scanner E2 AutoScan DS200+ Figure 2. Flowchart of the steps performed. 6 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Figure 3. (A) Selection of reference points of the components. (B) Measurements of the distances between the origin and the center of the analogs. (C) X, Y, and Z axes to determine the measurements of all three axes. After obtaining the reference points in the experimental images (extraoral scan- ners), we imported the control image to the Bio-CAD program, repeating the pre- vious steps described to create the reference points to analyze the images. The pyramid’s apex was used as the origin of the coordinate systems of models to calculate the distance between the origin and the centers of analogs (Figure 3B), generating the measurements necessary for verifying the deviations. These mea- surements were performed in the axes of the pyramid (X, Y, and Z), the X-axis being the vertical deviation, the Y-axis being the anteroposterior deviation, and the Z-axis being the lateral deviation (Figure 3C). As a result, we obtained three measurements for each component. The process was conducted with all 30 images generated by the laboratory scanners and compared with the control image generated by the contact scanner. 7 Gomes et al. Braz J Oral Sci. 2023;22:e238354 A B 40 30 20 10 0 A A A A A A B AutoScan DS200+ Ceramill Map400+ E2 150 100 50 0 D ev ia tio n (R an k) D ev ia tio n (µ m ) E2 Au to Sc an D S2 00 + Co m po ne nt A Co m po ne nt B Co m po ne nt C Co m po ne nt D Ce ra m ill M ap 40 0+ Figure 4. (A)Deviations of scanners related to manufacturers compared with the master model. (B) Components A, B, C, and D, when compared with the master model, about manufacturers of extraoral scanners. The components were analyzed individually and with no multiple comparisons between A, B, C, and D. Same letters represent no statistical difference (a=0.05). Statistical Analysis This study has one dependent variable (accuracy) and two independent (extraoral scanning and components). However, before performing a statistical test, the data were treated: the master model deviation values were subtracted from all images, and the value of each sample was acquired. Next, two variables were analyzed: Scanners and Components. When analyzing scanners, an average of the values (from the four components, con- sidering all axis) was used to obtain a mean of each model. Besides, a mean of the components for each model was performed to analyze the components. A normality test (Shapiro-Wilk) analyzed the measurements, and the nonparametric Kruskal-Wallis test was applied to analyze the scanners. The average values of components A, B, C, and D were determined by a two-way ANOVA on ranks and a post hoc Tukey test. All the tests with a 5% significance level. GraphPad Prism6 software (San Diego, CA, USA) was used to perform the statistical tests. Results Considering the scanners variable, this study did not find any difference (p=0.0806). However, when analyzing by component (A, B, C, and D) and the different scanners technologies (Figure 4A), there is an interaction (p<0.001) between component (p=0.001) and scanner (p=0.262). 8 Gomes et al. Braz J Oral Sci. 2023;22:e238354 This interaction is related to scanners accuracy in each component, as observed in component D, despite greater deviations, was more accurate for the Ceramill Map400+ model when compared with AutoScan DS200+ (p<0.001) and E2 (p=0.002) (Figure 4B). However, all the other components (A, B, and C) presented no statistical differences, independent of the scanners. Discussion Our null hypothesis was partially accepted, as we did not find statistically significant differences in accuracy among the laboratory scanners; however, we found such dif- ferences between the components. Component D was the only one to present a statistical difference in digitalization accuracy, as the Ceramill Map400+ scanner had a better performance than AutoScan DS200+ and E2. Probably the difference found in the last quadrant to be scanned, precisely the component D, occurred due to an increase in the area to be digitalized. Vecsei et al.31 found that the digitalization accuracy of laboratory scanners was influ- enced by the length of the arch included in the impression - the longer the arch to be scanned, the lower the accuracy of the digital impression32,33. Several images are merged when digitalizing a more extensive area, leading to progressive distortion and more significant errors17. Thus, the digital impression of a complete-arch is less accu- rate due to the overlapping of partial scans of quadrants12. Our results showed greater deviations in all extraoral systems, in components A and D: Ceramill Map400+ (93.7 mm / 32.4 mm), AutoScan-DS200+ (113.1 mm/ 144.11 mm), and E2 (64.3 mm / 97.8 mm), respectively. These errors may be related to the interaction between the angulation of implants and the distance between the scan bodies, as both implants are positioned in the reference model extremities. These extremities might distort the last components in a complete scan. Concern- ing the distance between scan bodies, only four implants in a completely edentulous arch result in a greater distance between the pillars. Additionally, distal angulation of posterior implants may increase the final interimplant distance. Referring to angulation, Pan et al.34, using an experimental block that simulates the All-on-four concept, found that laboratory scanners had a significant distortion in tilted sites. In addition, sizeable interimplant distance magnified the errors induced by the 45° implants. Pan et al.34 explained this finding based on light scattering and rotation. In a 3D structured light scan, light patterns are projected on the target sur- face and captured by cameras. Therefore, minimal light obstruction from projectors to cameras is fundamental for such a difference in accuracy. Thus, the undercut areas of angulated implants might be avoided because the cameras did not receive sufficient signals due to shadows, affecting scanning accuracy34. Studies assessing implant angulation on digital models of intraoral scanners showed that ≤ 15º angulation does not affect scanning accuracy9,35. Furthermore, regarding the distance between scan bodies, studies showed that the accuracy of laboratory scanners was not affected by interimplant distances31,33. Nevertheless, according to Vandeweghe et al.32, if the distance between scan bodies increases, scanning pro- cesses would become more complex, which would decrease scanning accuracy. 9 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Scan bodies B and C positioned parallel to each other in the anterior region showed minor deviations in scanning accuracy, probably due to the morphology of the ante- rior arch, which presents a linear scan path. Concerning scanners, Ceramill Map400 showed the best results for the digital impression of a complete-arch, considering even the extremities quadrant with minor deviations. Furthermore, we did not find differences between the structured light and blue LED technologies. Emir and Ayyıldız17 analyzed the accuracy of eight different extraoral scanners and their respective technologies. The authors concluded that the blue light scanners had more accurate results than white light ones17. Structured light scanners project a bi-dimensional pattern and have good scanning velocity; however, they lack repeat- ability and may present errors in narrow and deep areas. On the other hand, LED light scanners have better scanning repeatability and fewer errors due to short wave- lengths17. In this study, the scanners or the product software technology might have reduced this repeatability error in structured light scanners. Despite our results, some limitations must be considered. Because this is an in vitro study whose methodology was standardized, in everyday clinical practice, several variables may influence accuracy in the CAD/CAM method, such as the stage of the impression, material used, and scanning procedures31, as well as the device hardware, software algorithms, and scanning technology. Even the shape and size of a model may significantly impact the accuracy of an extraoral scanner17. Some scanners use powder during digitalization, and its thickness may contribute to differences between scanners in the final accuracy of digital impression16,23,36. Although there are advances in the launch of laboratory scanners on the market, few studies have approached the accuracy of extraoral scanners in complete-arch implant rehabilitation. Scientific literature is scarce, and results are divergent, meaning there is no agreement on the best extraoral systems. In conclusion, all extraoral systems showed accuracy in digitalization. However, the angulated components may result in insufficient scanning accuracy. The Ceramill Map400+ scanner showed the best results for the digital impression of a com- plete-arch, which suggests that the AutoScan DS200+ and E2 scanners should be used for single or partial prostheses. Acknowledgment The work was supported by São Paulo Research Foundation – FAPESP (Grazielle Franco Gomes was supported by FAPESP grant #2019/22509-9) and CAPES (Coordi- nation for the Improvement of Higher Education Personnel - Finance Code 001). Data Availability Datasets related to this article will be available upon request from the corresponding author. Conflicts of interest None. 10 Gomes et al. Braz J Oral Sci. 2023;22:e238354 Author Contribution All authors declare that they actively participated in the discussion of the results, reviewed, and approved the final version for submission. Grazielle Franco Gomes: Substantial contributions to the conception of the work; the acquisition, analysis, interpretation of data and final approval of the version to be published. Mónica Estefanía Tinajero Aroni: Drafting the work and revised it critically for import- ant intellectual content and and final approval of the version to be published. Lucas Portela Oliveira: Substantial contributions to the conception of the work; the acquisition of data, analysis and final approval of the version to be published. João Neudenir Arioli Filho: Interpretation of data and final approval of the version to be published. Carolina Mollo Binda: Interpretation of data and final approval of the version to be published. Francisco de Assis Mollo Júnior: Substantial contributions to the conception of the work, acquisition, analysis, interpretation of data and final approval of the version to be published. References 1. Carlsson GE, Omar R. The future of complete dentures in oral rehabilitation. A critical review. J Oral Rehabil. 2010;37(2):143-56. doi: 10.1111/j.1365-2842.2009.02039.x. 2. Fluegge T, Att W, Metzger M, Nelson K. A Novel method to evaluate precision of optical implant impressions with commercial scan bodies-an experimental approach. J Prosthodont. 2017;26(1):34-41. doi: 10.1111/jopr.12362. 3. Horita S, Sugiura T, Yamamoto K, Murakami K, Imai Y, Kirita T. Biomechanical analysis of immediately loaded implants according to the “All-on-Four” concept. J Prosthodont Res. 2017;61(2):123-32. doi: 10.1016/j.jpor.2016.08.002. 4. Bilmenoglu C, Cilingir A, Geckili O, Bilhan H, Bilgin T. In vitro comparison of trueness of 10 intraoral scanners for implant-supported complete-arch fixed dental prostheses. J Prosthet Dent. 2020;124(6):755-60. doi: 10.1016/j.prosdent.2019.11.017. 5. Amin S, Weber HP, Finkelman M, El Rafie K, Kudara Y, Papaspyridakos P. Digital vs. conventional full-arch implant impressions: a comparative study. Clin Oral Implants Res. 2017;28(11):1360-7. doi: 10.1111/clr.12994. 6. Arcuri L, Pozzi A, Lio F, Rompen E, Zechner W, Nardi A. Influence of implant scanbody material, position and operator on the accuracy of digital impression for complete-arch: A randomized in vitro trial. J Prosthodont Res. 2020;64(2):128-36. doi: 10.1016/j.jpor.2019.06.001. 7. Alikhasi M, Alsharbaty MHM, Moharrami M. Digital implant impression technique accuracy: a systematic review. Implant Dent. 2017;26(6):929-35. doi: 10.1097/id.0000000000000683. 8. Stimmelmayr M, Güth JF, Erdelt K, Edelhoff D, Beuer F. Digital evaluation of the reproducibility of implant scanbody fit--an in vitro study. Clin Oral Investig. 2012;16(3):851-6. doi: 10.1007/s00784-011-0564-5. 11 Gomes et al. Braz J Oral Sci. 2023;22:e238354 9. Papaspyridakos P, Gallucci GO, Chen CJ, Hanssen S, Naert I, Vandenberghe B. Digital versus conventional implant impressions for edentulous patients: accuracy outcomes. Clin Oral Implants Res. 2016;27(4):465-72. doi: 10.1111/clr.12567. 10. Moura RV, Kojima AN, Saraceni CHC, Bassolli L, Balducci I, Özcan M, et al. Evaluation of the Accuracy of Conventional and Digital Impression Techniques for Implant Restorations. J Prosthodont. 2019;28(2):e530-e5. doi: 10.1111/jopr.12799. 11. Alsharbaty MHM, Alikhasi M, Zarrati S, Shamshiri AR. A Clinical comparative study of 3-dimensional accuracy between digital and conventional implant impression techniques. J Prosthodont. 2019;28(4):e902-e8. doi: 10.1111/jopr.12764. 12. Lee SJ, Kim SW, Lee JJ, Cheong CW. Comparison of intraoral and extraoral digital scanners: evaluation of surface topography and precision. Dent J (Basel). 2020;8(2):52. doi: 10.3390/dj8020052. 13. Ahrberg D, Lauer HC, Ahrberg M, Weigl P. Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial. Clin Oral Investig. 2016;20(2):291-300. doi: 10.1007/s00784-015-1504-6. 14. Menini M, Setti P, Pera F, Pera P, Pesce P. Accuracy of multi-unit implant impression: traditional techniques versus a digital procedure. Clin Oral Investig. 2018;22(3):1253-62. doi: 10.1007/s00784-017-2217-9. 15. Nedelcu R, Olsson P, Nyström I, Rydén J, Thor A. Accuracy and precision of 3 intraoral scanners and accuracy of conventional impressions: A novel in vivo analysis method. J Dent. 2018;69:110-8. doi: 10.1016/j.jdent.2017.12.006. 16. Vafaee F, Firouz F, Mohajeri M, Hashemi R, Ghorbani Gholiabad S. In vitro comparison of the accuracy (precision and trueness) of seven dental scanners. J Dent (Shiraz). 2021;22(1):8-13. doi: 10.30476/dentjods.2020.83485.1047. 17. Emir F, Ayyıldız S. Evaluation of the trueness and precision of eight extraoral laboratory scanners with a complete-arch model: a three-dimensional analysis. J Prosthodont Res. 2019;63(4):434-9. doi: 10.1016/j.jpor.2019.03.001. 18. Gherlone E, Capparé P, Vinci R, Ferrini F, Gastaldi G, Crespi R. Conventional versus digital impressions for “All-on-Four” restorations. Int J Oral Maxillofac Implants. 2016;31(2):324-30. doi: 10.11607/jomi.3900. 19. Rego MR, Kitahara FM, Santiago LC. [Acrylic resin: relation between surface treatment and bacterial adhesion]. Cienc Odontol Bras. 2005;8(3):92-8. Portuguese. 20. Papaspyridakos P, Vazouras K, Chen YW, Kotina E, Natto Z, Kang K, et al. Digital vs conventional implant impressions: a systematic review and meta-analysis. J Prosthodont. 2020;29(8):660-78. doi: 10.1111/jopr.13211. 21. Türker N, Büyükkaplan US, Sadowsky SJ, Özarslan MM. Finite element stress analysis of applied forces to implants and supporting tissues using the “All-on-Four” Concept with different occlusal schemes. J Prosthodont. 2019;28(2):185-94. doi: 10.1111/jopr.13004. 22. Mennito AS, Evans ZP, Nash J, Bocklet C, Lauer Kelly A, Bacro T, et al. Evaluation of the trueness and precision of complete arch digital impressions on a human maxilla using seven different intraoral digital impression systems and a laboratory scanner. J Esthet Restor Dent. 2019;31(4):369-77. doi: 10.1111/jerd.12485. 23. Rudolph H, Salmen H, Moldan M, Kuhn K, Sichwardt V, Wöstmann B, et al. Accuracy of intraoral and extraoral digital data acquisition for dental restorations. J Appl Oral Sci. 2016;24(1):85-94. doi: 10.1590/1678-775720150266. 24. Resende CCD, Barbosa TAQ, Moura GF, Tavares LDN, Rizzante FAP, George FM, et al. Influence of operator experience, scanner type, and scan size on 3D scans. J Prosthet Dent. 2021;125(2):294-9. doi: 10.1016/j.prosdent.2019.12.011. 12 Gomes et al. Braz J Oral Sci. 2023;22:e238354 25. Keul C, Güth JF. Accuracy of full-arch digital impressions: an in vitro and in vivo comparison. Clin Oral Investig. 2020;24(2):735-45. doi: 10.1007/s00784-019-02965-2. 26. Serag M, Nassar TA, Avondoglio D, Weiner S. A Comparative study of the accuracy of dies made from digital intraoral scanning vs. elastic impressions: an in vitro study. J Prosthodont. 2018;27(1):88-93. doi: 10.1111/jopr.12481. 27. Piedra-Cascón W, Methani MM, Quesada-Olmo N, Jiménez-Martínez MJ, Revilla-León M. Scanning accuracy of nondental structured light extraoral scanners compared with that of a dental-specific scanner. J Prosthet Dent. 2021;126(1):110-4. doi: 10.1016/j.prosdent.2020.04.009. 28. Atieh MA, Ritter AV, Ko CC, Duqum I. Accuracy evaluation of intraoral optical impressions: A clinical study using a reference appliance. J Prosthet Dent. 2017;118(3):400-5. doi: 10.1016/j.prosdent.2016.10.022. 29. Imburgia M, Logozzo S, Hauschild U, Veronesi G, Mangano C, Mangano FG. Accuracy of four intraoral scanners in oral implantology: a comparative in vitro study. BMC Oral Health. 2017;17(1):92. doi: 10.1186/s12903-017-0383-4. 30. González de Villaumbrosia P, Martínez-Rus F, García-Orejas A, Salido MP, Pradíes G. In vitro comparison of the accuracy (trueness and precision) of six extraoral dental scanners with different scanning technologies. J Prosthet Dent. 2016;116(4):543-50.e1. doi: 10.1016/j.prosdent.2016.01.025. 31. Vecsei B, Joós-Kovács G, Borbély J, Hermann P. Comparison of the accuracy of direct and indirect three-dimensional digitizing processes for CAD/CAM systems - An in vitro study. J Prosthodont Res. 2017;61(2):177-84. doi: 10.1016/j.jpor.2016.07.001. 32. Vandeweghe S, Vervack V, Dierens M, De Bruyn H. Accuracy of digital impressions of multiple dental implants: an in vitro study. Clin Oral Implants Res. 2017;28(6):648-53. doi: 10.1111/clr.12853. 33. Pan Y, Tam JMY, Tsoi JKH, Lam WYH, Pow EHN. Reproducibility of laboratory scanning of multiple implants in complete edentulous arch: effect of scan bodies. J Dent. 2020;96:103329. doi: 10.1016/j.jdent.2020.103329. 34. Pan Y, Tam JM, Tsoi JK, Lam WY, Huang R, Chen Z, et al. Evaluation of laboratory scanner accuracy by a novel calibration block for complete-arch implant rehabilitation. J Dent. 2020;102:103476. doi: 10.1016/j.jdent.2020.103476. 35. Giménez B, Özcan M, Martínez-Rus F, Pradíes G. Accuracy of a digital impression system based on parallel confocal laser technology for implants with consideration of operator experience and implant angulation and depth. Int J Oral Maxillofac Implants. 2014;29(4):853-62. doi: 10.11607/jomi.3343. 36. Runkel C, Güth JF, Erdelt K, Keul C. Digital impressions in dentistry-accuracy of impression digitalisation by desktop scanners. Clin Oral Investig. 2020;24(3):1249-57. doi: 10.1007/s00784-019-02995-w.