Three-Dimensional Analysis of Upper and Lower Arches Using Digital Technology: Measurement of the Index of Bolton and Correspondence between Arch Shapesand Orthodontic Arches

INTRODUCTION

Thanks to the great development of digital technology, viaCAD (computer-aided design) and CAM (computer-aided manufacturing) systems, digital models canbe used as an aid for orthodontic planning decision-making processes as there are numerous studies in the literature that support the validity ofthe digital model measurements of anterior teeth and the total coefficient of Bolton analysis. The aim of the present study isto compare the average length value of the current upper and lower arches with that of a hypothetical nickel-titanium wire and to confirm the reliability and accuracy of digitally taken measurements of the anterior and total Bolton coefficients.In this retrospective study, dental casts of 138 Caucasian adolescent patients were scanned with an extraoral scanner, and Ortho3Shape software was adopted for the following dental cast measurements: actual and ideal lengths of the lower arches and anterior and total Bolton coefficients.In the present study, we found that the mean value of the anterior coefficients of the Bolton index was compatible with those of previous studies, confirming the reliability of digital measurements.Therefore, digital CAD/CAM models may be a viable alternative to plaster models, as they can facilitate model preservation and recovery. For future studies, it would be better to use intraoral scanners (IOSs) to ensure greater accuracy, since they only require one step and allow obtaining better results for the patients.

An overview of three-dimensional imaging devices in dentistry

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL SIGNIFICANCE

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

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL SIGNIFICANCE

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

Evaluation of the Accuracy of Digital Impressions Obtained from Intraoral and Extraoral Dental Scanners with Different CAD/CAM Scanning Technologies: An In Vitro Study

PURPOSE

To compare the accuracy of intraoral and extraoral scanners (IOSs and EOSs) with different scanning technologies.

MATERIAL AND METHODS

A phantom cast was used to simulate the patient's mouth. Polyether impression was made of the phantom cast and poured to fabricate stone casts. The stone casts were scanned by two IOSs (3shape Trios 3, 3S and Dental Wings, DW) and two EOSs (S600 Arti Zirkonzahn, ZK and Ceramill map 600 Amann Girrbach, AG) to obtain digital casts. Reference teeth (canines, premolar, and molars) dimensions were measured on the digital casts by Geomagic software and compared to measurements of the stone cast done by stereomicroscope. The dimensions were occluso-cervical mesio-distal, and bucco-lingual and their average was calculated. Differences between digital and stereoscopic measurements were assessed using paired t-test. Discrepancies between these measurements were calculated as differences and were compared among the four scanners using ANOVA.

RESULTS

The differences among the discrepancies of the four scanners were not significant overall (p = 0.969), in premolars (p = 0.932) or molars (p = 0.069) but significant in canines (p = 0.025). The discrepancies of the EOSs were ≤0.01 mm in canines and molars. DW had the greatest discrepancy in canines and molars.

CONCLUSIONS

The IOSs and EOSs had similar accuracy except in canines where EOSs performed better. The accuracy of scanning is affected by the smoothness and regularity of the teeth surfaces as in case of the canine.

A comparative evaluation of intraoral and extraoral digital impressions: An in vivo study

Aim:

The accuracy of a dental impression is determined by two factors: “trueness” and “precision.” The scanners used in dentistry are relatively new in market, and very few studies have compared the “precision” and “trueness” of intraoral scanner with the extraoral scanner. The aim of this study was to evaluate and compare accuracy of intraoral and extraoral digital impressions.

Materials and Methods:

Ten dentulous participants (male/female) aged 18–45 years with an asymptomatic endodontically treated mandibular first molars with adjacent teeth present were selected for this study. The prepared test tooth was measured using a digital Vernier caliper to obtain reference datasets. The tooth was then scanned using the intraoral scanner, and the extraoral scans were obtained using the casts made from the impressions. The datasets were divided into four groups and then statistically analyzed. The test tooth preparation was done, and dimples were made using a round diamond point on the bucco-occlusal, mesio-occlusal, disto-occlusal, and linguo-occlusal lines angles, and these were used to obtain reference datasets intraorally using a digital Vernier caliper. The test tooth was then scanned with the IO scanner (CS 3500, Carestream dental) thrice and also impressions were made using addition silicone impression material (3M™ ESPE) and dental casts were poured in Type IV dental stone (Kalrock-Kalabhai Karson India Pvt. Ltd., India) which were later scanned with the EO scanner (LAVA™ Scan ST Design system [3M™ ESPE]) thrice. The Datasets obtained from Intraoral and Extraoral scanner were exported to Dental Wings software and readings were obtained. Repeated measures ANOVA test was used to compare differences between the groups and independent t-test for comparison between the readings of intraoral and extraoral scanner. Least significant difference test was used for comparison between reference datasets with intraoral and extraoral scanner, respectively. A level of statistical significance of P < 0.05 was set.

Results:

The precision values ranged from 20.7 to 33.35 μm for intraoral scanner and 19.5 to 37 μm for extraoral scanner. The mean deviations for intraoral scanner were 19.6 μm mesiodistally (MD) and 16.4 μm buccolingually (BL) and 24.0 μm MD and 22.5 μm BL for extraoral scanner. The mean values of the intraoral scanner (413 μm) for trueness were closest to the actual measurements (459 μm) than the extraoral scanner (396 μm).

Conclusion:

The intraoral scanner showed higher “precision” and “trueness” values when compared with the extraoral scanner.

Intraoral versus extraoral digital occlusal records: a pilot study

The aim of the present pilot study was to analyze the reliability of interocclusal contact records generated with an intraoral scanner (TRIOS Standard) and an extraoral scanner (Zfx Evolution). Ten patients were selected. The number of occlusal contacts was first determined with the conventional method using 8-µm articulating paper (gold standard) (control). These conventional records were then compared with the intra- and extraoral digital records. Diagnostics tests (sensitivity, specificity, predictive values for positives and negatives), receiver operating characteristic (ROC) curve, and Cohen's kappa coefficient were performed to analyze the data. The kappa index of the extraoral scanner (40.7%) was considered to be 'moderate,' and better than that of the intraoral scanner (26.1%), which was considered to be 'low.' The extraoral scanner showed better results in the diagnostic test and in the ROC curve. The first results suggest that the extraoral scanner is more reliable for recording occlusal contacts than the intraoral scanner.

Marginal fit of all-ceramic crowns fabricated using two extraoral CAD/CAM systems in comparison with the conventional technique

Objective

The purpose of this study was to determine the effect of two extraoral computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, in comparison with conventional techniques, on the marginal fit of monolithic CAD/CAM lithium disilicate ceramic crowns.

Study design

This is an in vitro interventional study.

Place and duration of study

The study was carried out at the Department of Prosthodontics, School of Dentistry, Prince Sattam Bin Abdul-Aziz University, Saudi Arabia, from December 2015 to April 2016.

Methodology

A marginal gap of 60 lithium disilicate crowns was evaluated by scanning electron microscopy. In total, 20 pressable lithium disilicate (IPS e.max Press [Ivoclar Vivadent]) ceramic crowns were fabricated using the conventional lost-wax technique as a control group. The experimental all-ceramic crowns were produced based on a scan stone model and milled using two extraoral CAD/CAM systems: the Cerec group was fabricated using the Cerec CAD/CAM system, and the Trios group was fabricated using Trios CAD and milled using Wieland Zenotec CAM. One-way analysis of variance (ANOVA) and the Scheffe post hoc test were used for statistical comparison of the groups (α=0.05).

Results

The mean (±standard deviation) of the marginal gap of each group was as follows: the Control group was 91.15 (±15.35) µm, the Cerec group was 111.07 (±6.33) µm, and the Trios group was 60.17 (±11.09) µm. One-way ANOVA and the Scheffe post hoc test showed a statistically significant difference in the marginal gap between all groups.

Conclusion

It can be concluded from the current study that all-ceramic crowns, fabricated using the CAD/CAM system, show a marginal accuracy that is acceptable in clinical environments. The Trios CAD group displayed the smallest marginal gap.