Incisor Torque Control in CAD-CAM Customized Lingual Appliances
Se Yun Kang1 , Jae-Hong Choi2 , Yoon-Ji Kim1,3, Sang-Jin Sung1,3
1 Department of Orthodontics, Asan Medical Center, Seoul
2 Korea University Graduate School of Clinical Dentistry, Seoul
3 University of Ulsan College of Medicine, Seoul, Korea
Purpose: This study aims to compare the 3-dimensional position of bracket slots using an intraoral scanner in labial fixed appliances, conventional prefabricated lingual appliances, and computer assisted design-computer assisted manufactured fully customized lingual appliances and analyze the dimensional accuracies of fully customized lingual archwires.
Materials & Methods: The digital impression data of patients treated with Damon (Ormco, Orange, CA, USA), Clippy-L (TOMY, Tokyo, Japan), and Incognito (3M Unitek, Monrovia, CA, USA) brackets were acquired, and the distance from the incisal edge to the bracket slot was measured. Dimensions of custom archwires of Incognito and Harmony (American Orthodontics, Sheboygan, WI, USA) were measured using a digital caliper. Differences in the slot-incisal edge distance among appliances were compared.
Results: A total of 40 subjects (mean age 23.9±2.1 years) were included for analysis of bracket slot-incisal edge distance. A statistically significant difference was observed in the bracket slot-incisal edge distance in the maxillary central and lateral incisors, mandibular lateral incisor, and mandibular canine. For both maxillary central and lateral incisors, the distance for Clippy-L was significantly greater than that for Damon and Incognito. Clippy-L showed greater distance than the Damon and Incognito in the mandibular lateral incisors and canines. Both fully customized lingual appliance systems had undersized archwires with a mean error of 0.053±0.005 mm for the Incognito system and 0.055±0.016 mm for the Harmony system. Furthermore, no statistically significant difference was observed between the two systems (p=0.455).
Conclusion: Fully customized lingual brackets may have the advantage of controlling torque and vertical position of the incisors compared to conventional lingual appliances attributing to the bracket slot position that is close to the tooth surface.
Key words: Incisor inclination, Incisor torque control, Customized brackets, Torsional play
Korean J Lingual Orthod 2021;10(1):10-17