Does ambient light affect the accuracy and scanning time of intraoral scans?

Impact of Cut-out-rescan and Data Exchange by Over-scanning Techniques on Marginal Fit of CAD/CAM Lithium Disilicate Crowns

OBJECTIVE

Evaluate the impact of adjustment procedures - cut-out-rescan (COR) and data exchange by over-scanning (DEOS) techniques - through CAD/CAM software on the marginal fit outcome of ceramic crowns.

METHODS AND MATERIALS

Twenty-eight de-identified teeth were adapted in a mandibular typodont set. Tooth #19 was prepared for a lithium disilicate crown and seven groups, G0 to G6 (n=10), were created based on the rescanned areas (mesial and/or buccal) on the typodont using an intraoral scanner through COR or DEOS techniques. A digital workflow was used to design and mill 70 crowns according to the groups. Each crown was temporarily cemented on tooth #19 and scanned with micro-computed tomography to measure the marginal fit. The data were analyzed statistically by the Kruskal-Wallis test followed by the Mann-Whitney test to compare the groups pairwise as a post-hoc (α=0.05).

RESULTS

Statistically significant differences were found for vertical misfit (μm) between the groups for Marginal Gap Buccal (MGB) and Marginal Gap Mesial (MGM) (p=0.003 and p=0.029, respectively). No significant difference was found for Finish Line Buccal (FLB) and Finish Line Mesial (FLM) (p=0.062 and p=0.092, respectively). G3 (COR buccal and mesial) had the highest MGB (57.75 μm), statistically different from all other groups. G4 (DEOS buccal) (41.60 μm) was different from G6 (DEOS buccal and mesial) (44.21 μm) (p=0.023). For MGM, G0 (control) (53.96 μm) was different from G5 (DEOS mesial) (45.76 μm) and G6 (DEOS buccal and mesial) (48.56 vm) (p=0.013 and p=0.041, respectively) and G2 (COR mesial) (58.43 μm) was different from G5 (DEOS mesial) (45.76 μm) (p=0.016).

CONCLUSIONS

Despite a statistically significant difference in certain groups for both techniques, COR and DEOS techniques are viable options for image editing during acquisition. Lithium disilicate crowns can be produced with satisfactory marginal gap values utilizing a chairside CAD/CAM system.

Influence of ambient light conditions on intraoral scanning: A systematic review

PURPOSE

To systematically assess the influence of ambient light on the accuracy and scanning time of intraoral scanning.

STUDY SELECTION

The present systematic review (CRD 42022346672) was registered at the International Prospective Register of Systematic Reviews (PROSPERO) and was performed based on the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020. Electronic searches were conducted using PubMed, Web of Science, and EMBASE, complemented by gray literature, references, and citations of the included studies. The primary outcome was accuracy, and the scanning time was a secondary outcome. Owing to the high heterogeneity, the pooled data were analyzed descriptively.

RESULTS

Six in vitro and two in vivo experiments were performed. Three in vitro studies reported both the accuracy and scanning time of the intraoral scans, whereas the remaining studies exclusively evaluated the accuracy. The studies mainly investigated the influence of illumination levels (0-11000 lux) on intraoral scanning. Intraoral scans revealed optimal accuracy at 1000-lux illumination for complete-arch dentition scans, whereas the influence of illumination levels on 4-unit or shorter scans was not clinically significant. The intraoral scans obtained using confocal microscopy were less affected by the illumination levels than those obtained using the active triangulation technique. Furthermore, the scanning time tended to increase with increasing illumination.

CONCLUSIONS

Evidently from the limited number of studies conducted, ambient light illumination had considerable influence on the accuracy and scanning time of intraoral scanning, which appeared to be related to the scanning range and imaging technology.

Accuracy of maxillary full-arch digital impressions of tooth and implant models made by two intraoral scanners

OBJECTIVES

Limited studies are available on the accuracy of intraoral scanners (IOSs) for full-arch implant and tooth models. This study aimed to assess the accuracy of maxillary full-arch digital impressions of tooth and implant models made by two IOSs.

MATERIALS AND METHODS

This in vitro, experimental study was conducted on two maxillary dentiform models: one with six prepared natural teeth and the other with six implants at the site of canine, first premolar, and first molar teeth, bilaterally. A highly accurate industrial scanner was used for actual measurements on the models that served as the reference scan. TS (Trios3) and CO (CEREC Omnicam) IOSs were then used to scan each model 10 times according to the manufacturer's instructions. All scans were saved in STL format. The GOM Inspect software was used according to the best-fit algorithm to compare the accuracy of measurements in the groups with the reference scan. The trueness and precision were calculated. Statistical analyses were carried out using SPSS by one-way analysis of variance and t-test (α = .05).

RESULTS

TS showed a significantly higher trueness than CO for both tooth and implant models (p < .05). TS also revealed significantly higher precision than CO for the tooth model; however, the difference in precision for the implant model was not significant between the two IOSs (p > .05).

CONCLUSIONS

TS showed higher accuracy than CO in both tooth and implant models.

'Gold' lost in restoration: Evaluation of core morphology of custom metal posts and cores, and analysis of precious metal debris

1 Objectives

To investigate the deviations between the morphological dimensions of finished cores and desired dimensions made by three available fabricating techniques. To assess the precious metal loss in custom precious metal post and core restorative treatment in the dental clinic.

2 Methods

Titanium posts and cores were fabricated using three different techniques: digital scanning impression technology, digital scanning wax-pattern technology, and the traditional lost-wax casting method. Geomagic Studio was used to fit the scanned model data to the digital design data of the expected preparation and to analyze the 3D deviations between the two. Precious metal debris from the precious metal post and core was collected, processed, weighed and analyzed for precious metal elements by energy-dispersive X-ray spectroscopy layered images.

3 Results

In all 48 pairs of models, there were positive and negative deviations, with the largest mean positive deviation of (0.752 ± 0.037 mm) for models made by the semi-digital scanning wax-pattern technique. A total of 7001.3 mg of metals was recovered from the waste streams collected, which contained precious metals-mainly gold, silver, and platinum.

4 Conclusions

There were discrepancies between the custom core and the expected preparation regardless of the fabrication process used. The digital scanning impression technology showed better dimensional rationality of crown cores. Custom precious metal posts and cores can have an average precious metal loss of 129.7 mg per case in the dental clinic.

Intraoral digital implant scans: Parameters to improve accuracy

PURPOSE

To report the means to maximize the predictability and accuracy of intraoral digital implant scans through the evaluation of operator and patient-related factors.

MATERIALS AND METHODS

A search of published articles related to factors that can decrease the scanning accuracy of intraoral digital implant scans was completed in four data sources:MEDLINE, EMBASE, EBSCO, and Web of Science. All studies related to variables that can influence the accuracy of intraoral digital implant scans obtained by using intraoral scanners (IOSs) were considered. These variables included ambient lighting, scanning pattern, implant scan body (ISB) design, techniques for splinting ISBs, arch location, implant position, and inter-implant distance.

RESULTS

Among operator-related factors, ambient lighting conditions, scanning pattern, and ISB design (material, geometry, and retention design) can impact the accuracy of intraoral digital implant scans. The optimal ISB for maximizing IOS accuracy is unclear; however, polymer ISB can wear with multiple reuse and sterilization methods. Among patient-related factors, additional variables should be considered, namely arch (maxillary vs. mandibular arch), implant position in the arch, inter-implant distance, implant depth, and angulation.

CONCLUSIONS

Ambient lighting conditions should be established based on the IOS selected to optimize the accuracy of intraoral digital implant scans. The optimal scanning pattern may vary based on the IOS, clinical situation, and the number of implants. The optimal ISB design may vary depending on the IOS used. Metallic implant scan bodies are preferred over polymer ISB designs to minimize wear due to multiple use and sterilization distortion. Among patient-related factors, additional variables should be considered namely the arch scanned, implant position in the arch, inter-implant distance, implant depth, and angulation. The impact of these factors may vary depending on the IOS selected.

Effect of scanning strategies on the accuracy of digital intraoral scanners: a meta-analysis of in vitro studies

PURPOSE

This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis.

MATERIALS AND METHODS

This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05.

RESULTS

The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16).

CONCLUSION

The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.

Impact of color temperature and illuminance of ambient light conditions on the accuracy of complete-arch digital implant scans

OBJECTIVE

The purpose of the present study was to assess the influence of color temperature and illuminance of ambient light on the accuracy of different intraoral scanners (IOSs) in complete-arch implant scans.

METHODS

An edentulous model with six implants and scan bodies was digitized by using a laboratory scanner (DW-7-140; Dental Wings) to obtain a reference mesh. Fifteen scans were performed employing two intraoral scanners (Trios 4;3Shape A/S and i700; Medit Co) at two illuminances (500 and 1000 lux) and three color temperatures (3200, 4400, and 5600 K). Scanning accuracy was measured by using a 3D metrology software program (Geomagic Control X). Kruskal-Wallis, one-way ANOVA, and pairwise comparison tests were used to analyze the data (α = .05).

RESULTS

Significant differences in trueness and precision values were found among the different IOSs under the same ambient lighting condition and among the different lighting conditions for a given IOS (p < .05) except for trueness in i700 groups (p > .05).

CONCLUSIONS

The influence on the accuracy of color temperature and illuminance varied depending on the intraoral scanner. An optimal ambient scanning light condition was not found; this should be adjusted based on the specific IOS system used. 3200 K of ambient light influences the precision of i700 when performed at 1000 lux, decreasing the accuracy. The variation of color temperature at the same illuminance does not affect the scanning accuracy of TRIOS 4, which obtained better accuracy in all scans at 1000 lux.

Effect of substrate adjacent to the scan region on the trueness of four intraoral scanners: An in vitro study

OBJECTIVES

The purpose of this in vitro study was to evaluate the trueness of four commercially available intraoral scanners (IOSs) on scanning different substrates that existed in the adjacent proximal contact area.

METHODS

Four IOSs (TRIOS 4, TRIOS 3, Primescan, Omnicam) were used for scanning the intact enamel surface of a molar tooth, and six restorative materials (zirconia, lithium disilicate glass-ceramic, composite resin, hybrid ceramic, feldspathic ceramic, metal) that were located at the adjacent proximal contact area of the same tooth. Reference scans were obtained using an extraoral scanner (inEos X5). A 3-dimensional analyzing software (Geomagic Control X) was used to compare the reference and tested scans. The two-way analysis of variance (ANOVA) followed by Bonferroni correction was performed for statistical analyses (α=0.05).

RESULTS

TRIOS 3 and TRIOS 4 showed higher trueness than Primescan, and Primescan showed higher trueness than Omnicam (p<0.001), while there were no differences between TRIOS 3 and TRIOS 4. Metal showed significantly higher Root Mean Square values (0.273 ± 0.24 mm) than other substrates. No difference was found between the scanners' zirconia, lithium disilicate glass-ceramic, composite, and feldspathic ceramic scans (p > 0.05). For the metal, TRIOS 3 and TRIOS 4 showed higher trueness than Primescan and Omnicam, while Omnicam showed lower trueness among all scanners. For the hybrid ceramic, TRIOS 3 showed higher trueness than Omnicam (p<0.001). For the enamel, TRIOS 3 showed higher trueness than Primescan and Omnicam (p<0.001).

CONCLUSIONS

The trueness of IOSs can be affected by the substrates that exist in the proximal contact area. Amongst all, the metal substrate affected most the trueness of the IOSs.

CLINICAL SIGNIFICANCE

The clinician should decide on the impression system, taking into account that the IOS and the surfaces to be scanned affect the trueness of the digital data. The deviation of the digital impression would be high in the presence of a metal restoration on the adjacent proximal surface.

In vitro study of the accuracy and efficiency of wireless intraoral scanners at various battery levels

OBJECTIVES

To determine the trueness and precision of 2 wireless intraoral scanners (IOSs) under various battery levels, and assess scanning efficiency.

METHODS

A maxillary cast with 4 metal spheres attached was fabricated. Two wireless IOSs (TRIOS 3 and TRIOS 4) were evaluated under 3 battery levels (1-30%, 31-60%, and 61-100%; n = 30). Six horizontal distances and 1 vertical distance were measured between 4 spherical centers and 1 generated plane. The distance deviations were determined with a coordinate-measuring machine data set. Kruskal-Wallis and Levene tests were used to analyze trueness and precision. Scan time and the number of three-dimensional (3D) images captured were analyzed by using a 2-way analysis of variance.

RESULTS

In terms of trueness and precision, no significant differences were found at various battery levels over the majority of the measured distances. TRIOS 4 demonstrated better trueness than TRIOS 3 for cross-arch scan. The 61-100% battery level resulted in the shortest scan time and the least number of 3D images captured (p < 0.001). Scan time and number of 3D images captured were strongly correlated for TRIOS 3 (r = 0.66) and TRIOS 4 (r = 0.89).

CONCLUSIONS

Changes in battery level had no impact on the trueness and precision of TRIOS 3 and TRIOS 4. High battery level IOSs resulted in faster scans and fewer 3D images captured with less storage space. TRIOS 4 scanned faster, captured fewer images, and demonstrated better trueness than TRIOS 3.

CLINICAL SIGNIFICANCE

Although all battery levels of wireless IOSs provide comparable trueness and precision, a wireless IOS with a high battery level is more time efficient than one with a low battery level in complete-arch scan.

A Comprehensive Review of Factors That Influence the Accuracy of Intraoral Scanners

Intraoral scanners (IOSs) have become increasingly popular in the field of dentistry for capturing accurate digital impressions of patients' teeth and oral structures. This study investigates the various factors influencing their accuracy. An extensive search of scholarly literature was carried out via PubMed, utilizing appropriate keywords. Factors evaluated in the included studies were categorized into three primary divisions: those related to the operator, the patient, and the IOS itself. The analysis demonstrated that the accuracy of intraoral scanning is influenced by various factors such as scanner selection, operator skill, calibration, patient's oral anatomy, ambient conditions, and scanning aids. Maintaining updated software and understanding factors beyond scanner resolution are crucial for optimal accuracy. Conversely, smaller IOS tips, fast scanning speeds, and specific scanning patterns compromise the accuracy and precision. By understanding these factors, dental professionals can make more informed decisions and enhance the accuracy of IOSs, leading to improved final dental restorations.

Validation of Digital Impressions' Accuracy Obtained Using Intraoral and Extraoral Scanners: A Systematic Review

BACKGROUND

At present, the evidence regarding digital impressions' accuracy recorded by using digital scanners is lacking. This systematic review aimed to evaluate whether the type of scanning (intraoral/extraoral) affects the Accuracy of Digital Impressions.

METHOD

Two independent reviewers performed a systematic search in the database both electronically and manually (PubMed, Ebsco HOST, the Cochrane Library, and Google Scholar) for articles published from 1 January 2010 to 1 December 2022. This study was registered with the International Prospective Register of Systematic Reviews (PROSPERO CRD42020188765) and followed the PRISMA statement. The question in focus was as follows: Does the type of scanning (intraoral or extraoral) affect the accuracy of digital impression?

RESULTS

A total of 449 papers were obtained by searching electronically and manually. In total, 15 complete-text papers qualified for assessment based on eligibility criteria. After reading the full-text articles, five studies were excluded. Ten studies were selected for the qualitative analysis. The qualitative data reported that the accuracy of both types of scanners (intraoral and extraoral) lies within the range of clinical acceptability. Nevertheless, the intraoral scanners seem to be more accurate when compared to the extraoral scanners for a partial arch situation.

CONCLUSIONS

Scanning type affects the accuracy of the digital impression. Various factors influence the scanning ability. Intraoral scanners seem to be more accurate compared to extraoral scanners for a partial arch situation. More studies comparing the accuracy of the intraoral scanner and extraoral scanner for a complete arch scan and in an in vivo study setting are needed.

Comparative analysis on efficiency and accuracy of parallel confocal microscopy and three-dimensional in motion video with triangulation technology-based intraoral scanner under influence of moisture and mouth opening - A crossover clinical trial

Aim

The intraoral scanners are digital devices used to digitise the oral tissues. The accuracy of the intraoral scanners has been studied under different environmental conditions, but there might be differences that occur in the actual oral environment, which is still in question. The aim of the study was to evaluate the accuracy and efficiency of Parallel Confocal Microscopy and 3D in motion video with triangulation technology-based intraoral scanners under the influence of moisture and mouth opening.

Settings and Design

This was an Cross over clinical controlled study.

Materials and Methods

The controlled in vivo study included healthy subjects who were in need of CBCT for the purpose of locating the position of unerupted third molars before going abroad for a job. The subjects were exposed to scans in the upper and lower jaws with two intraoral scanners based on 3D motion video technology with triangulation (Medit) and parallel confocal microscopy (Trios) under the influence of two oral conditions, which were moisture (presence and absence of moisture) and mouth opening (30 mm and 50 mm, respectively). A total of 96 scans were obtained and superimposed individually over the reference CBCT scans to find the deviations in the Geomagic Rapidform (version 2020, USA) software. The efficiency of the scanners was calculated by recording the time taken and the number of images obtained after each scan.

Statistical Analysis Used

The significance was calculated by using the independent and paired sample t test in SPSS software (IBM, version 23).

Results

Based on the surface analysis, the trueness of the intra-oral scanners had statistically significant differences when compared between 3D in motion video technology with Triangulation and Parallel Confocal Microscopy (P < 0.05) whereas no statistical significance was observed in precision. There was a significant difference observed in the efficiency of the intra-oral scanners (P < 0.05).

Conclusion

There is a significant difference in the accuracy and efficiency of the intraoral scanners under the influence of oral conditions, such as different moisture levels and mouth opening conditions. 3D in motion video technology with Triangulation showed better results with the least deviation than Parallel Confocal Microscopy.

Comparison of the learning curve of intraoral scanning with two different intraoral scanners based on scanning time

BACKGROUND

The appearance of intraoral scanners (IOSs) in dental offices was an important milestones for the digital innovations in dentistry. Knowing the learning curve for intraoral scanning is crucial, because it can serve as a guideline for clinicians before buying a new IOS. The aim of the present in vivo study was to determine the learning curve required by dental students for intraoral scanning with the 3Shape Trios 4 IOS and the CEREC Primescan IOS, based on scanning time.

METHODS

A total of 20 dental students with no previous experience in intraoral scanning participated in the present study. 10 students scanned with Trios 4® IOS (TRI) and 10 students took digital impressions with Primescan® IOS (CER). Every student created 15 digital impressions from patients. Prior to taking the impressions, theoretical and practical education was provided. The total scanning time included the upper and lower arches as well as bite registration, for which average values were calculated. Statistical analysis was performed using the Stata package with a mixed-effects generalized least squares regression models.

RESULTS

The average total scanning times were the following: TRI - 205 s for the 1st impression, 133.6 s for the 15th, CER - 289.8 s for the 1st impression, 147 s for the 15th. The model-based estimate of the difference between the two in case of TRI was 57.5 s, and in CER was 144.2 s which is a highly significant improvement in both cases (P < 0.0001). The slope of the scanning time vs. learning phase curve gradually approached flatness, and maintained a plateau: TRI - from the 11th measurement and CER - from the 14th measurement onward.

CONCLUSIONS

Given the limitations of the present study, we found difference between the learning curve of scanner types which are operate various principle of imaging. In case of the TRI fewer digital impressions (11 repeating) were sufficient to reach the average scanning time of an experienced user than using CER (14 repeating).

TRIAL REGISTRATION

The permission for this study was given by the University Ethics Committee of Semmelweis University (SE RKEB number: 184/2022).

Reverse impression technique: A fully digital protocol for the fabrication of the definitive fixed prosthesis for completely edentulous patients

In complete arch implant rehabilitation, one of the greatest difficulties still encountered in the digital workflow is the deviation of the implant position during intraoral scanner (IOS) data acquisition. As a result, the passivity of a definitive prosthesis fabricated using IOS data might be compromised. Thus, an implant position verification method is essential, either digitally or conventionally executed. A fully digital protocol for the fabrication of the definitive fixed prosthesis for completely edentulous patients, without the interference of any conventional step within the digital process, is presented. For the verification of the captured position of the scan-bodies, novel scan analogs were connected to the interim prosthesis extraorally and scanned. The virtual superimposition of the interim prosthesis intraorally with the same prosthesis extraorally served as a verification device for the position of the implants.

Influence of planning software and surgical template design on the accuracy of static computer assisted implant surgery performed using surgical guides fabricated with material extrusion technology: An in vitro study

OBJECTIVES

This in vitro study aimed to assess the influence of the planning software and design of the surgical template on both trueness and precision of static computer assisted implant surgery (sCAIS) performed using surgical guides fabricated using material extrusion (ME).

METHODS

Three-dimensional radiographic and surface scans of a typodont were aligned using two planning software (coDiagnostiX, CDX; ImplantStudio, IST) to virtually position the two adjacent oral implants. Thereafter, surgical guides were created with either an original (O) or modified (M) design with reduced occlusal support and were steam sterilized. Forty surgical guides were used to instal 80 implants equally distributed among four groups: CDX-O, CDX-M, IST-O, and IST-M. Thereafter, the scan bodies were adapted to the implants and digitised. Finally, inspection software was used to assess discrepancies between the planned and final positions at the implant shoulder and main axis level. Multilevel mixed-effects generalised linear models were used for statistical analyses (p = 0.05).

RESULTS

In terms of trueness, the largest average vertical deviations (0.29 ± 0.07 mm) could be assessed for CDX-M. Overall, vertical errors were significantly dependent on the design (O < M; p ≤ 0.001). Furthermore, in horizontal direction, the largest mean discrepancy was 0.32 ± 0.09 mm (IST-O) and 0.31 ± 0.13 mm (CDX-M). CDX-O was superior compared to IST-O (p = 0.003) regarding horizontal trueness. The average deviations regarding the main implant axis ranged between 1.36 ± 0.41 ° (CDX-O) and 2.63 ± 0.87 ° (CDX-M). In terms of precision, mean standard deviation intervals of ≤ 0.12 mm (IST-O and -M) and ≤ 1.09 ° (CDX-M) were calculated.

CONCLUSIONS

Implant installation with clinically acceptable deviations is possible with ME surgical guides. Both evaluated variables affected trueness and precision with negligible differences.

CLINICAL SIGNIFICANCE

The planning system and design influenced the accuracy of implant installation using ME-based surgical guides. Nevertheless, discrepancies were ≤ 0.32 mm and ≤ 2.63 °, which may be considered within the range of clinical acceptance. ME should be further investigated as an alternative to the more expensive and time-consuming 3D printing technologies.

A guide for maximizing the accuracy of intraoral digital scans. Part 1: Operator factors

OBJECTIVES

To describe the factors related to the operator skills and decisions that influence the scanning accuracy of intraoral scanners (IOSs). A new classification for these factors is proposed to facilitate dental professionals' decision making when using IOSs and maximize the accuracy and reliability of intraoral digital scans.

OVERVIEW

Each IOS system is limited by the hardware and software characteristics of the selected device. The operator decisions that can influence the accuracy of IOSs include the scanning technology and system selection, scanning head size, calibration, scanning distance, exposure of the IOS to ambient temperature changes, ambient humidity, ambient lighting conditions, operator experience, scanning pattern, extension of the scan, cutting off, rescanning, and overlapping procedures.

CONCLUSIONS

The knowledge and understanding of the operator factors that impact scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs and for successfully integrating IOSs in daily practices.

CLINICAL SIGNIFICANCE

Operator skills and clinical decisions significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing operator factors for maximizing the accuracy of IOSs.

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.

Understanding the effect of scan spans on the accuracy of intraoral and desktop scanners

OBJECTIVES

This study aimed to measure and compare the accuracy (trueness and precision) of intraoral scanners and desktop scanners when scanning different spans.

METHODS

Three plaster models representing different spans (full arch, half arch, and three teeth) were obtained from conventional silicone impressions of a maxillary typodont and used as the scanning objects. An industrial scanner (ATOS III Triple Scan) was used to scan the three plaster models to obtain reference digital models. The plaster models were then scanned using two intraoral scanners (Trios 3 and Primescan) and two desktop scanners (LS3 and D2000) to obtain test digital models. The reference and test models were imported into professional reverse engineering software for processing and analysis. The root mean square value indicated differences between the reference and test models. Two-way ANOVA and Bonferroni multiple comparison tests were used for statistical analysis.

RESULTS

Two-way ANOVA tests revealed significant differences in trueness and precision for different scan spans (p < 0.001) and different scanners (p < 0.001), which indicates that the scanner types and scan spans affect the accuracy of the scanner. There was no significant difference in the accuracy of the D2000 at three different scan spans (trueness: 23.82 ± 0.22 µm, 21.53 ± 0.18 µm, and 21.02 ± 0.27 µm respectively; precision: 7.86 ± 0.83 µm, 7.87 ± 1.11 µm, and 7.82 ± 0.84 µm respectively). For the LS3 and the two intraoral scanners, the accuracy of the full arch scan (LS 3, trueness: 33.35 ± 0.47 µm, precision:15.36 ± 3.10 µm; Trios 3, trueness: 46.92 ± 9.23 µm, precision:20.79 ± 3.08 µm; Primescan, trueness: 28.73 ± 0.77 µm, precision:15.74 ± 2.45 µm) was significantly lower than that of the half arch (LS 3, trueness: 27.27 ± 0.43 µm, precision:5.62 ± 0.88 µm; trios 3, Trueness: 22.29 ± 1.50 µm, precision:14.12 ± 2.25 µm; Primescan, trueness: 18.91 ± 0.70 µm, precision:7.94 ± 1.09 µm) and three teeth scans (LS 3, trueness: 24.68 ± 0.36 µm, precision:5.29 ± 0.62 µm; Trios 3, trueness: 16.92 ± 0.78 µm, precision:11.95 ± 2.22 µm; Primescan, trueness: 15.79 ± 0.65 µm, precision:7.68 ± 0.62 µm).

CONCLUSIONS

The scan span affected the accuracy of the intraoral scanners, but not necessarily the accuracy of the desktop scanners.

Accuracy of Digital Impression Taking with Intraoral Scanners and Fabrication of CAD/CAM Posts and Cores in a Fully Digital Workflow

Current intraoral scanners (IOS) enable direct impression taking for computer-aided de-sign/computer-aided manufacturing (CAD/CAM) posts and cores (P+C) with subsequent milling out of monolithic materials. The aim of this in vitro study was to systematically investigate the accuracy of CAD/CAM-P+C in a fully digital workflow, considering different IOS impression methods (Primescan (PRI), Trios4 without (TRI) and with scanpost (TRI+SP)) (Part A), and CAD/CAM milling of zirconium dioxid (ZIR) and resin composite (COM)-P+C (Part B). Five human models were developed in this study. Micro-CT imaging was used as a reference (REF). For Part A, the models were scanned 12 times for each impression method. Then, IOS datasets (n = 180) were superimposed with REF, and scan accuracy was determined using 3D software (GOMInspect). For Part B, one CAD/CAM-P+C (n = 30) was milled for each model, impression method, and material. The triple-scan method was applied using an industrial scanner (ATOS) to determine the accuracy of the fit. Statistical analysis was performed using analysis of variance (ANOVA, p < 0.05). Part A showed for PRI significantly lower accuracy than TRI and TRI+SP (p < 0.05). The data of Part B revealed significantly higher accuracy for ZIR than for COM (p < 0.05). Within the limitations of this study, CAD/CAM-P+C of the ZIR can be recommended for fabrication in a fully digital workflow regarding the accuracy of fit.

Scanning Distance Influence on the Intraoral Scanning Accuracy—An In Vitro Study

Intraoral scanners (IOS) have reached a point where their impact in the dental office cannot be denied. The distance between the tip of the IOS and the preparation may have implications on the accuracy of the digital model. The objective of this study was to evaluate the differences in accuracy between digital impressions in the scenario of different scanning distances. Twenty consecutive scans were performed at five predetermined distances: 5 mm, 10 mm, 15 mm, 20 mm and 23 mm by a single operator. The scanning distance of 10 mm displayed the best accuracy with an overall trueness value of 23.05 μm and precision value of 4.2 μm. The drawn conclusion was that increased scanning distances can decrease the accuracy of a digital impression.

New Caries Diagnostic Tools in Intraoral Scanners: A Comparative In Vitro Study to Established Methods in Permanent and Primary Teeth

The aim of this in vitro study was to systematically investigate new caries diagnostic tools, including three intraoral scanners, and compare them to established diagnostic methods. For a standardized analysis of occlusal and proximal caries lesions, human permanent and primary teeth (n = 64) were embedded in models and investigated in a phantom head using six different caries diagnostic methods: visual examination, bitewing radiography, Diagnocam (KaVo, Biberach, Germany), Trios 4 (3Shape, Copenhagen, Denmark), iTero Element 5D (Align Technology, San José, CA, USA), and Planmeca Emerald S (Planmeca, Helsinki, Finland). The diagnostic methods were investigated and compared to reference µ-CT for permanent and primary teeth separately. For occlusal caries diagnostics in permanent teeth, the best agreement to the reference (reliability) was obtained for Planmeca Emerald S (ĸ = 0.700), whereas in primary teeth, for visual examination (ĸ = 0.927), followed by Trios 4 (ĸ = 0.579). Regarding proximal caries diagnostics, bitewing radiography, as the gold standard, exhibited the highest agreement for permanent (ĸ = 0.643) and primary teeth (ĸ = 0.871). Concerning the analysis of the diagnostic quality (sensitivity and specificity) using receiver operating characteristic (ROC) curve analysis, comparable findings were obtained for area under curve (AUC) values as for reliability. No diagnostic method could be identified that is generally suitable for occlusal and proximal lesions in both dentitions. Overall, caries diagnostics with intraoral scanners seem to be interesting tools that should be further investigated in clinical studies.

Can Dental Office Lighting Intensity Conditions Influence the Accuracy of Intraoral Scanning?

The aim of this study was to evaluate the influence of different settings of ambient light intensity inside the dental office on the accuracy (trueness and precision) of an intraoral scanner (IOS). A full crown preparation was conducted on a resin molar which was scanned using a high resolution extraoral scanner to obtain a reference model. Six light settings were chosen based on the most clinically relevant light conditions inside the workspace, and the preparation was scanned using an intraoral scanner (PlanScan, Planmeca). The obtained data was analyzed using a professional 3D quality control software (Geomagic Control X). There was no statistically relevant difference between the groups when regarding trueness, although a slight influence of the light intensity could be observed on the trueness values. Regarding precision, the best results were obtained in the 3800 lux group, with the other groups presenting close values, excepting the extreme values (400 lux and 11 000 lux) groups that proved to be the most deficient.