Purpose: This study investigated the bracket placement accuracy of a digital indirect bonding (dIDB) technique utilizing 3D-printed trays and the effects of dental crowding and tooth type on bracket placement accuracy. Material and Methods: Thirty digital mandibular models of various amounts of arch length discrepancy (ALD) were categorized into 3 groups according to the amount of ALD. Digital bracket placement was performed from second molar to second molar using Indirect Bonding Studio (3ShapeTM, Copenhagen, Denmark) and this virtual model was used as the control. Indirect bonding trays were designed using Appliance Designer (3ShapeTM) and 3D-printed with the SprintRayTM Pro (SprintRayTM, Los Angeles, CA). After the IDB procedure was performed on the printed models, models were scanned and digitized using a TRIOSTM Intraoral Scanner (3ShapeTM). The digitized experimental model was aligned with the digital control model. Bracket positions were analyzed for linear and angular discrepancies along the x-, y-, and z-axes using GeomagicTM Wrap v.2021.0.0: 64 Bit Edition (3D SystemsTM, Rockhill, SC). Statistical analysis was performed using the Wilcoxon Signed-Rank test, Kruskal-Wallis test, and Pairwise Comparisons (< 0.05) to assess if any significant differences existed between control and experimental bracket positions and to assess if dental crowding or tooth type (Incisor, Canine, Premolar, Molar) had any effect on bracket placement accuracy. Results: A total of 419 brackets were analyzed. No statistically significant difference was found between planned bracket positions and experimental bracket positions. Statistically significant differences were found among ALD Groups in the mesial-distal dimension. Statistically significant differences were found among tooth types in all dimensions – the Molar group displayed significantly higher mean angular discrepancies. Conclusion: This dIDB technique was highly accurate in all linear and angular dimensions, and least accurate in torque. The amount of ALD and Tooth Type did not have any clinically significant effects on dIDB accuracy. Care should be taken when designing the tray, bonding in the molar areas, and when placing occlusal pressure during bonding to avoid tray flexure.
Phillip Ha (Wed,) studied this question.