Transfer Accuracy of Three Indirect Bonding Trays: An In Vitro Study with 3D Scanned Models.

Objective: The goal of the current study is to compare the transfer accuracy of two different conventional indirect bonding trays with 3D-printed trays. Methods: Twenty-two patients' upper dental models were duplicated, scanned and brackets were bonded digitally. Different indirect bonding trays (double vacuum formed, transparent silicone and 3D-printed) were prepared according to three groups. These trays were used for the transfer of the brackets to the patients' models, then models with brackets were scanned. GOM Inspect software was used for the superimposition of virtual bracket setups and models with brackets. A total of 788 brackets and tubes were analyzed. Transfer accuracies were determined according to the clinical limit of 0.5 mm for linear and 2° for angular measurements. Results: 3D-printed trays had significantly lower linear deviation values than other trays for all planes (p<0.05). 3D-printed trays have significantly lower torque and tip deviation values than other groups (p<0.05). Transfer deviations were within the clinically acceptable limit for all transfer trays in horizontal, vertical and transverse planes. Deviation values of the molars were higher than those of the other tooth groups for all trays in the horizontal and vertical planes (p<0.05). Brackets were generally deviated toward the buccal direction in all tray groups. Conclusion: The transfer accuracy of 3D-printed transfer trays was more successful than the double vacuum formed and transparent silicone trays in the indirect bonding technique procedure. Deviations in the molar group were greater than those in the other tooth groups for all transfer trays.

Accuracy of bracket position using thermoplastic and 3D-printed indirect bonding trays.

AIM: The positional accuracy of bracket placement planned through tooth setup vs actual placement was evaluated by means of conventional thermoplastic indirect bonding trays and customized 3D-printed indirect bonding trays. MATERIALS AND METHODS: A total of 280 bracket positions placed on the crowns of 10 dental plaster models were evaluated. The manual setup method and a thermoplastic indirect bonding tray were used for the manual group. For the CAD/CAM group, the bracket was positioned using a digital setup and a corresponding 3D-printed tray. The positional accuracy of the bracket placement on the duplicated gypsum model using the trays was evaluated by means of 3D software. Six errors of bracket position (height, depth, mesiodistal, torque, rotation, and tip errors), including linear and angular errors, were measured. Differences in variables were compared across subgroups using the independent t test or the Mann-Whitney U test. RESULTS: Only the height error differed significantly (P < 0.05) between groups (manual: 0.2 mm; CAD/CAM: 0.12 mm). For both incisors and molars, the manual group showed significantly greater height errors than the CAD/CAM group (P < 0.05). The analysis of variance of the position error to the whole bracket showed statistically significant differences between tooth positions, linear measurements, and angular measurements (P < 0.05). CONCLUSION: A 3D-printed indirect bonding tray showed accuracy similar to that of conventional methods for bracket placement, with slightly greater bracket height accuracy. Further studies should strive to improve accuracy in terms of tooth positions.

Comparison of the transfer accuracy of two digital indirect bonding trays for labial bracket bonding.

OBJECTIVES: To compare the transfer accuracy of two digital transfer trays, the three-dimensional printed (3D printed) tray and the vacuum-formed tray, in the indirect bonding of labial brackets. MATERIALS AND METHODS: Ten digital dental models were constructed by oral scans using an optical scanning system. 3D printed trays and vacuum-formed trays were obtained through the 3Shape indirect bonding system and rapid prototyping technology (10 in each group). Then labial brackets were transferred to 3D printed models, and the models with final bracket positioning were scanned. Linear (mesiodistal, vertical, buccolingual) and angular (angulation, torque, rotation) transfer errors were measured using GOM Inspect software. The mean transfer errors and prevalence of clinically acceptable errors (linear errors of ≤0.5 mm and angular errors of ≤2°) of two digital trays were compared using the Mann-Whitney U-test and the Chi-square test, respectively. RESULTS: The 3D printed tray had a lower mean mesiodistal transfer error (P < .01) and a higher prevalence of rotation error within the limit of 2° (P = .03) than did the vacuum-formed tray. Linear errors within 0.5 mm were higher than 90% for both groups, while torque errors within 2° were lowest at 50.9% and 52.9% for the 3D printed tray and vacuum-formed tray, respectively. Both groups had a directional bias toward the occlusal, mesial, and buccal. CONCLUSIONS: The 3D printed tray generally scored better in terms of transfer accuracy than did the vacuum-formed tray. Both types of trays had better linear control than angular control of brackets.