Accuracy of Digital Dental Implants Impression Taking with Intraoral Scanners Compared with Conventional Impression Techniques: A Systematic Review of In Vitro Studies

Research progress on accuracy of intraoral digital impressions for implant-supported full-arch prostheses

With the rapid development of implant techniques and digital technology, digital impressions have become a commonly used impression method in implant restoration. At present, the accuracy of intraoral digital impressions directly applied to implant-supported full-arch prostheses remains inadequate, which is due to the high accuracy requirement of full-arch implant impressions, while there are still technical challenges in intraoral digital impressions about recognition and stitching. In this regard, scholars have proposed a variety of scanning strategies to improve the accuracy of intraoral scan, including mucosal modifications, auxiliary devices and novel scan bodies. At the same time photogrammetry, as a new digital impression technique, has been developing steadily and exhibits promising accuracy. This article reviews the research progress on the accuracy of edentulous full-arch implant impressions and techniques which can improve the accuracy of intraoral digital impressions, to provide reference for clinical application.

Comparison between Conventional and Digital Impressions for Determining Axes and Distances of Three Implants in Straight and Curved Lines: An In Vitro Study

Background: In this study, we aimed to compare the effects of conventional and digital impressions on several parameters (inter-implant distance, intra-implant distance, inter-implant axis, and intra-implant axis) of three implants in curved lines and straight lines by using a laboratory scanner (LBS) versus an intra-oral scanner (IOS). Methods: Two 3D models were fabricated using a printer, each model with three internal hex implants analogues at the positions of 15#,16#,17# (straight line) and 12#,13#,14# (curved line). Standard intra-oral scan bodies (ISBs) were used, and the two models were scanned using 7 Series dental wings (LBS, reference model), followed by ten scans with Primescan (digital method). Standard Tessellation Language (STL) files were created. Five polyether impressions were taken from each model (straight and curved), and gypsum type 4 models were poured; each model was scanned five times to create a total of 25 STL files for each group (conventional method). The comparison between all the STL files (conventional and digital) was made by superimposition of the STL files on the STL reference model laboratory file using a 3D analyzing software. A Kolmogorov-Smirnov test was performed, followed by Mann-Whitney tests and Wilcoxon signed-rank tests. (p < 0.05). Results: For the conventional method, the mean errors were significantly higher for the curved line model (12-14) compared to the straight line model (15-17) for most parameters (p < 0.05). For the digital method, the mean errors were significantly higher for the curved-line model (12-14) compared to the straight line model (15-17) in half of the parameters (p < 0.05). Within the curved line model (12-14) and the straight line model (15-17), the mean errors between the conventional method and the digital method were not significant for most variables. Conclusions: The difference between curved lines and straight lines has an impact on the mean error of the conventional method. Both methods are reliable for straight and curved lines in partially dentate situations.

Conventional Dental Impressions vs. Impressions Reinforced with Rigid Mouthguards

The impression materials utilized today in dental medicine offer a good reproducibility and are easily accepted by patients. However, because they are polymer-based, they have issues regarding their dimensional stability. In this respect, the present work proposes a new type of dental impression, which is reinforced with rigid mouthguards. The aim of the study is to test the performances of such new impressions by comparing them to conventional ones-from this critical point of view, of the dimensional stability. Three types of polymeric materials were considered for both types of impressions: alginate, condensation silicone, and addition silicone. In order to obtain the new type of impressions, a manufacturing technique was developed, comprising the following phases: (i) conventional impressions were made; (ii) a plaster model was duplicated, and 15 rigid mouthguards were obtained; (iii) they were inserted in the impression technique, with each mouthguard positioned on the cast before the high-consistency material was inserted in the tray and the practitioner took the impression; (iv) the mouthguard remained in the tray and the low-viscosity material was inserted over the mouthguard; (v) the impression was positioned on the model, and after the material hardened, the mouthguard-reinforced impression was analyzed. In the evaluation of the dimensional stability, rigorous statistical analysis was essential to discern the performance differences between conventional and mouthguard-reinforced dental impressions. Statistical analyses employed non-parametric Mann-Whitney U tests because of the non-normal distribution of the data. They indicated a statistically significant improvement in the dimensional stability of addition silicone impressions when reinforced with mouthguards (p < 0.05), showcasing superior performance over conventional methods. Conversely, alginate and condensation silicone reinforced impressions did not exhibit the same level of stability improvement, suggesting the need for further optimization of these materials. In conclusion, from the three considered elastomers, addition silicone was found to be the prime candidate for high-precision dental impressions, with the potential to improve their quality from conventional impressions by utilizing the proposed reinforcing technique.

Evaluation and comparison of the accuracy of three intraoral scanners for replicating a complete denture

STATEMENT OF PROBLEM

Technological advances in digital acquisition tools have increased the scope of intraoral scanners (IOSs), including scanning a removable complete denture (RCD) to replicate it. However, studies assessing the accuracy of IOSs for replicating a maxillary or mandibular RCD are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy (trueness and precision) of 3 IOSs while replicating a maxillary and mandibular RCD.

MATERIAL AND METHODS

One maxillary and 1 mandibular RCD were scanned with a desktop scanner (D2000) to obtain the reference model. Two operators scanned each RCD 5 times with 3 different IOSs (TRIOS 4, Primescan, and IS3800), following a predefined acquisition protocol. The 60 study models obtained were compared with the reference model using the Geomagic software program. For each comparison, the mean and standard deviation of discrepancy were calculated. Distances were measured on both the reference and the study model, and differences were calculated to assess whether sagittal or transverse deformations were present. The tolerance percentage of the volume of the digital model compared with the volume of the reference model was determined (difference tolerance was set at 0.1 mm). A univariate analysis of variance followed by a post hoc analysis using the Student-Newman-Keuls (α=.05) test was performed to determine the truest and the most precise IOS.

RESULTS

The TRIOS 4 and Primescan IOSs had comparable trueness, with mean dimensional variations of 47 ±27 µm and 57 ±8 µm respectively compared with the reference model. The IS3800 had a lower trueness (98 ±35 µm). Primescan was significantly more precise with a mean standard deviation of 64 ±15 µm (P<.05). The TRIOS 4 (141 ±48 µm) and IS3800 (129 ±24 µm) had comparable precision. Primescan showed the least sagittal and transverse deformation.

CONCLUSIONS

This study determined that an RCD can be replicated using an IOS, although all IOSs did not have equal accuracy. An in vivo study needs to assess whether this procedure is clinically acceptable.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

Obtaining more accurate complete arch implant digital scans with the aid of a geometric pattern: A dental technique

A technique to obtain more accurate complete arch implant digital scans and virtual casts is described. In order to obtain complete arch implant digital scans with greater accuracy, short-span intraoral digital scans are superimposed with the aid of a geometric pattern. Therefore, the technique takes advantage of the accuracy of intraoral scanners to obtain digital scans of reduced spans. Two virtual designs of the geometric pattern have been made available online: one for maxillary arches and one for mandibular arches. From these virtual designs, new virtual designs of geometric patterns of different sizes and shapes can be created to better fit different arch forms and implant positions.

A comprehensive review and update on the current state of computer-assisted rehabilitation in implant dentistry

AIM

This paper provides a comprehensive review of the established concepts and newer developments related to computer-assisted implant rehabilitation.

METHODS

Two independent researchers searched the English literature published to 31st December 2023 in the PubMed/Medline database for primary and secondary research and related publications on computer-assisted implant planning, computer-assisted implant placement and computer-assisted implant restoration.

RESULTS

A total of 58,923 papers were identified, 198 relevant papers were read in full text and 110 studies were finally included. Computer-assisted implant rehabilitation was found to result in more precise implant positioning than freehand placement. Advantages include reduced trauma and surgery time; disadvantages include reduced primary implant stability and higher cost.

CONCLUSION

Computer-assisted surgery is particularly indicated in cases of critical anatomy, but may encounter limitations in terms of cost, restricted mouth opening, visibility and adjustment of the surgical guides and the need for prior familiarisation with the procedure. Nonetheless, this surgical technique reduces the post-implant placement complication rate.

3D printed indirect bonding trays: Transfer accuracy of hard versus soft resin material in a prospective, randomized, single-blinded clinical study

OBJECTIVES

This prospective clinical study aimed to compare transfer accuracy and immediate loss rate of hard versus soft transfer trays utilizing a CAD/CAM workflow.

METHODS

We performed virtual bracket placement on intraoral scans of adolescent patients to create individual indirect bonding trays. Orthodontic software (Appliance Designer, 3Shape, Copenhagen, Denmark) was used to design the trays, which were then produced using 3D printing technology. Patients were randomly assigned to the hard or soft resin groups with a 1:1 allocation. Subgroups were determined based on the Little's Irregularity Index and distributed equally.

RESULTS

552 brackets were bonded onto adolescent patients using 46 CAD/CAM indirect bonding trays. The linear mean transfer errors ranged from -0.011 mm (soft) to -0.162 mm (hard) and angularly -0.255° (hard) and -0.243° (soft). No statistically significant differences were found between the subgroups or soft and hard resin groups. However, the transfer accuracy of molar brackets was significantly lower in the transversal and horizontal directions. All mean transfer errors were within the limits of clinical acceptability. The loss rate was 2.4 % in the hard resin group and 2.3 % in the soft resin group. The Intra Observer Correlation was excellent.

SIGNIFICANCE

CAD/CAM technology for indirect bracket bonding has been proven reliable in a randomized clinical trial. Both hard and soft resin showed a low rate of immediate loss compared to the current literature. Soft resin was more favorable than hard resin in terms of accuracy and usability. However, the indirect bonding of molar brackets is significantly less accurate than incisor brackets.

Intraoral Scan Accuracy and Time Efficiency in Implant-Supported Fixed Partial Dentures: A Systematic Review

The digital implant impression technique (DIT) and conventional implant impression technique (CIT) workflows in implant-supported fixed partial dentures (FPDs) have not been extensively compared in prior studies. Moreover, there is no agreement on the more accurate method that entails less time in the laboratory and during the clinical phases of fabrication and delivery of the prosthesis, respectively. This review aimed to assess the precision of the imaging procedure and overall fabrication time of the DIT and CIT for the implant-supported FPDs. An electronic search was performed using PubMed, Scopus, EMBASE, Cochrane Oral Health Group, and Dentistry and Oral Science Source databases through EBSCO for relevant studies from January 2014 to April 2023. Following the preliminary screening, the studies that met the inclusion criteria underwent full-text review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Cochrane Collaboration risk of bias appraisal tool and Newcastle-Ottawa scale were applied to assess the quality of randomized controlled trials (RCTs) and non-randomized prospective clinical studies, respectively. The initial search yielded 332 studies, and after excluding duplicates, 241 papers were available for screening. Titles and abstracts were reviewed, and 97 articles were chosen for full-text review by two authors independently. Furthermore, 89 articles were excluded in compliance with the PICOS question, and eight studies were chosen for qualitative analysis. Hence, the review comprised two RCTs and six prospective clinical studies. The time efficiency of the implant-supported FPDs was examined in four investigations, three of which used the Trios 3 scanner and one used the Intero scanner. The three-dimensional accuracy of DIT and CIT was compared in six clinical comparative studies. One of the RCTs was rated to have a high risk of bias and the other with a moderate quality of evidence. The six prospective studies were rated to have high-quality of evidence. The findings of this review indicate the prospective applicability of future intraoral scanning systems. The DIT was reported to be outstanding in terms of patient preferences and total fabrication time efficiency. Additional in vivo studies are needed to establish the therapeutic usefulness and time efficiency of integrating DIT in more comprehensive settings.

Accuracy of different digital acquisition methods in complete arch implant-supported prostheses: An in vitro study

STATEMENT OF PROBLEM

Digital methods such as intraoral scanners for recording the location of implants supporting complete arch prostheses have limitations. Photogrammetry devices should be able to digitize implant positions accurately, but standardized comparisons between different digital acquisition methods are lacking.

PURPOSE

The purpose of this in vitro study was to compare the repeatability of different digital acquisition methods for complete arch prostheses supported by 6 and 4 implants.

MATERIAL AND METHODS

A master cast was created with 6 and 4 dental implants with multiunit abutments to obtain the master digital casts. The evaluated devices were the industrial high-resolution 12-megapixel scanner (reference) Atos Compact Scan 12M (GOM), the laboratory scanners D2000 (3Shape A/S) and S900 Arti (Zirkonzahn), the photogrammetry devices iCam (iMetric4D) and PIC (PIC Dental), and the intraoral scanners TRIOS 3 (3Shape A/S) and iTero Element 5D (Align Technology). The resulting files were imported to a computer-aided design software program (exocad GmbH) to obtain the implant replicas as standard tessellation language (STL) files. These files were imported into a software program (Geomagic Control X) and superimposed per group through the best-fit algorithm to determine repeatability, defined as the closeness of agreement between each group's scanned results as root mean square (RMS) values. The normality of distribution was tested by the Shapiro-Wilk normality test, and the Kruskal-Wallis test with adjustment with the Bonferroni correction method was used accordingly (α=.05).

RESULTS

The repeatability means and 95% confidence intervals for the 4 implant scans were: 1.07 µm (0.86; 1.29) for GOM, 2.05 µm (1.89; 2.21) for D2000, 3.61 µm (3.23; 3.99) for S900, 7.01 µm (6.11; 7.91) for iCam, 5.18 µm (4.6; 5.76) for PIC, 20.52 µm (18.33; 22.72) for TRIOS3, and 20.5 µm (17.37; 23.63) for iTero. Statistically significant differences were found between devices, except for iCam versus PIC, GOM versus S900, iCam versus D2000, PIC versus D2000, and TRIOS3 versus iTero. The repeatability means and 95% confidence intervals for the 6 implant groups were: 1.36 µm (1.08; 1.65) for GOM, 3.17 µm (3.01; 3.33) for D2000, 2.15 µm (2.04; 2.25) for S900, 8.67 µm (8.06; 9.28) for iCam, 13.88 µm (12.62; 15.14) for PIC, 40.32 µm (36.29; 44.36) for TRIOS3, and 38.86 µm (34.01; 43.71) for iTero. Statistically significant differences were detected between devices, except for S900 versus GOM, PIC versus iCam, and iTero versus TRIOS 3.

CONCLUSIONS

The results suggest that photogrammetry could be a suitable alternative for recording implant locations of complete arch prostheses supported by 4 or 6 implants, with better repeatability than intraoral scanners. Increasing the number of implants decreased the repeatability of every device tested except the laboratory scanners.

Optimal impression materials for implant-supported fixed complete dentures: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Although polyvinyl siloxane (PVS) materials and polyether (PE) materials have been the recommended materials for making impressions for implant-supported fixed complete dentures (IFCDs), a consensus regarding the optimal impression materials has yet to be established.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the effect of impression materials on the accuracy of conventional impressions for IFCDs and to provide guidance for selecting the optimal impression material.

MATERIAL AND METHODS

The PubMed, Web of Science, and Embase databases were searched and supplemented via hand searches. Studies comparing the accuracy of conventional impressions for IFCDs by using PVS and PE materials with either direct (open-tray) or indirect (closed-tray) techniques were included. Linear distance deviations and angular deviations between adjacent implants were evaluated. The mean difference (MD) with a 95% confidence interval (CI) was calculated for continuous data. A subgroup analysis was conducted to evaluate the impact of implant angulation (α=.05).

RESULTS

Among the 597 publications identified, 27 in vitro studies were included for qualitative analysis, and 12 were included for quantitative analysis. The general analysis revealed no significant differences in linear distance and angular deviations between the 2 impression materials with the direct or indirect technique. The subgroup analysis found that a statistically significant difference in linear distance deviations was found when implants were placed at an angle greater than 15 degrees, favoring PE materials when using the direct technique (P=.010, MD: 32.54 µm; 95% CI: 6.83 to 58.24) and indirect technique (P=.020, MD: 138.15 µm, 95% CI: 19.17 to 257.13). However, only 2 relevant studies assessed the indirect technique.

CONCLUSIONS

When providing IFCDs, conventional impressions obtained by using PVS and PE materials were found to have similar accuracy in most scenarios. PE materials yielded better outcomes when implants were placed at an angle greater than 15 degrees.

Evaluation of the accuracy of digital and conventional implant-level impression techniques for maxillofacial prosthesis

Objectives

This study aims to evaluate the accuracy of digital impression making based on trueness and precision measurements of dental implants placed in maxillofacial lesions to produce Maxillofacial prosthesis substructures.

Methods

Two intra-oral scanners (Trios 3 and CS 3700) and one Desktop scanner (open technology) were examined in this study. A Model of a patient with a lesion in the ear region was created as a reference. The reference model was scanned by each scanner 10 times. Standard Tessellation Language files were provided from each scanner and were examined in terms of Trueness and Precision aspects.

Results

In Distance 1, in the one-way analysis of variance test, there was a significant difference between the three scanners. The Trios group has less deviation than the Open Technology group (P = 0.015) compared with the CareStream (CS) group that showed more deviation (P < 0.000). There is a statistically significant difference in distance 2 among scanners. The Trios group showed more deviation as compared with the Open Technology group (P < 0.000). While this deviation is not statistically significant compared with the CS group (P = 0.0907). Open Technology Group compared with the CS group also has less deviation in distance 2, which has been statistically significant (P < 0.000). The preparation of a precise model of maxillofacial lesions is still difficult for some Intraoral scanners.

Conclusion

There were significant statistical differences in Trueness and Precision among scanners. Used scanners can be applied as an alternative to conventional impression methods.

Digital workflow in implant prosthodontics: The critical aspects for reliable accuracy

INTRODUCTION

This paper is a comprehensive treaty about the variables that influence the transfer of the position of an implant to the laboratory when using a digital workflow.

OBJECTIVE

The aim is to provide operators and manufacturers with a guide on how to improve certain aspects of the digital workflow specific to the fabrication of implant-supported restorations.

OVERVIEW

It addresses intraoral scanning issues and CAD software issues. In the former, the variables that play a part in the quality of the scan file are investigated: the implant scan body, the IOS and the operator. For the latter, instead, the focus is on those aspects that still today may create inaccuracies in the workflow and in the final product being fabricated: the identification of the specific implant placed in the patient and the generation of a virtual model with the representation of that implant platform correctly positioned in the three dimensions of space. Suggestions and recommendations are given to improve the control on the quality of the digital workflow's output.

CONCLUSION

In a digital workflow for the fabrication of an implant-supported restoration, the selection and use of the implant scan body, the use of an effective scan strategy and the appropriateness of the best fit function in the CAD software, that is, the procedure of superimposing the library of geometric shapes of the ISB linked to the implant with the shape acquired intraorally, are variables that can influence the positional precision of the FDP.

CLINICAL SIGNIFICANCE

Fully understanding the importance of the information enclosed in the ISBs themselves can be crucial in the digital workflow. A proper ISB's selection, a correct scan of the ISB's shape and an accurate CAD superimposition of the ISB's library can lead the clinician to reduce the variables that affect the final result in daily practice.

Digital assessment of the accuracy of implant impression techniques in free end saddle partially edentulous patients. A controlled clinical trial

Objectives

This in vivo study aims to assess the accuracy of the digital intraoral implant impression technique, the conventional closed-tray impression technique, and open-tray impression techniques in a standardized method of data segmentation along with the best-fit algorithm to overcome the inconsistency of results of previous studies regarding implant impression techniques.

Materials and methods

Sixteen implants were placed in eight patients. Each patient has undergone four impression techniques: direct intraoral scanning of the stock abutment, intraoral scanning using a scan body, conventional closed tray impression technique, and the conventional open tray impression technique. The conventional impressions were poured into stone casts with analogues and stock abutments and scanned using a desktop scanner. In intraoral scanning of the scan body, computer-aided design software was used for the replacement of the scan body with a custom-made abutment that is identical to the stock abutment, allowing comparison with the other impression techniques. The deviation in implant position between the groups was measured using special 3D inspection and metrology software. Statistical comparisons were carried out between the studied groups using a one-way analysis of variance (ANOVA) test.

Results

The total deviation between groups was compared to the reference group represented by the intraoral scanning of the abutment. The total deviation was statistically significantly different (P = 0.000) among the different studied groups. The mean deviation was recorded as 21.45 ± 3.3 μm, 40.04 ± 4.1 μm, and 47.79 ± 4.6 μm for the intraoral scanning of the scan body, the conventional closed, and open tray, respectively.

Conclusion

For implant impressions in partially edentulous patients, intraoral oral scanning using a scan body significantly improves scanning and overall accuracy. Regarding conventional impressions, the closed-tray impression techniques showed more accuracy than conventional open-tray impressions.

Clinical relevance

Intraoral digital implant impression using scan body offers more accuracy than conventional implant impression techniques for recording posterior implant position in free-end saddle partially edentulous patients.

Enamel Wear of Antagonist Tooth Caused by Dental Ceramics: Systematic Review and Meta-Analysis

BACKGROUND

This systematic review and meta-analysis aimed to evaluate the wear of the antagonist tooth in ceramic restorations.

MATERIAL AND METHODS

This study was carried out based on Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) recommendations; it was also registered in PROSPERO (register number: CRD42022316252). Three databases were consulted in the literature search, Embase, Scopus, and Web of Science. The citation searching was conducted by two researchers independently. The clinical studies that evaluated wear in antagonist teeth concerning ceramic restoration were included. Twelve articles were selected after eliminating duplicates ones and applying the inclusion criteria, and two were chosen through citation. Fourteen articles were considered for the qualitative and quantitative analysis (meta-regression and meta-analysis).

RESULTS

The mean linear wear of the antagonist tooth in relation to feldspathic was 8.914 μm, for lithium disilicate it was 0.018 μm, and for zirconia it was 0.257 μm. The mean volumetric wear of the antagonist tooth in relation to feldspathic was 0.273 mm3, for hybrid ceramic it was 0.030 mm3, for lithium disilicate it was 0.018 mm3, and for zirconia it was 0.014 mm3. The mean natural tooth wear was 0.7974 μm per month. Tooth wear caused by zirconia at six months was 31.755 μm, at 12 months it was 24.648 μm, and at 24 months it was 20.662 μm.

CONCLUSIONS

Feldspathic produces greater wear of the antagonist tooth from ceramic restorations linearly and volumetrically. In addition, zirconia generates the least wear that will decrease over time, and it will be equal to or less than the natural wear in the tooth.

Accuracy of digital impressions for three-unit and four-unit implant supported fixed dental prostheses using a novel device

Background/ purpose

Accuracy of digital implant impressions was considered questionable due to the lack of anatomical reference points between implants and the similarities in scan body morphology, which lead to the purpose of this research is to propose a simple and convenient technique to improve the accuracy of scanning.

Materials and methods

Four implant analogues (teeth: 15, 17, 24, and 27) were inserted into a stone model of a partially edentulous maxilla; two implants were inserted on each side, creating a three-unit span and a four-unit span. The model was scanned using a 3Shape E4 dental laboratory scanner for reference and a TRIOS 3 intraoral scanner for testing. Each side was scanned 10 times, both with and without the novel device attached to the scan bodies. The trueness and precision of interimplant distances (linear deviations), and interimplant angulations (angle deviations) between the scan bodies were determined using software. A Mann-Whitney U test was used to determine statistical differences between subgroups.

Results

Significant differences were discovered in the trueness of angular deviations (-0.20° ± 0.15° vs. -0.01° ± 0.11º) and precision of linear deviations (11.14 ± 6.35 vs. 3.10 ± 2.14 μm) for the four-unit groups.

Conclusion

The novel device significantly improved scanning accuracy for a four-unit groups (approximately 22.93 mm) compared to three-unit groups.

Influence of Implant Impression Methods, Polymer Materials, and Implant Angulation on the Accuracy of Dental Models

The paper presents the influence of impression methods, polymer materials, and implant angulation on the accuracy of the definitive working model for the production of implant-supported dental restorations, based on the analysis of results obtained using different impression methods, materials, and parallel and angulated implants. The study findings indicate that all aforementioned factors impact the accuracy of the definitive working model. Specifically, 20° implant angulation in relation to the vertical plane has a greater impact on the impression accuracy compared to parallel implants. The open and splint method in combination with addition silicone, as well as the splint method and polyether combination yielded more accurate results when using implants under 20° angulation compared to other method and material combinations. The splint method in combination with addition silicone resulted in the smallest mean deviations from the center of the parallel implant base compared to other combinations of methods and materials. Analysis results further revealed statistically significant differences in the measured indicators across impression methods, implants, and polymer materials.