Efficacy Of Invisalign On Upper Molar Distalization Via CBCT Evaluation

Objective:Toevaluate the efficacy of Invisalignonuppermolardistalizationvia CBCT 3-dimensional measurement.Methods:Orthodontic patients who needed upper molar distalization and treated by Invisalign were enrolled in this study. During the treatment, mini-implant or CII elastics were used to reinforce the anchorage.CBCT images were obtained before and after upper molars were fully distalized. The actual molar movements on 3 dimensions were quantified by Sim Plant 11.04 software and compared with the planned value in Clin Check.The effects of attachments on molar distalization and the anchoragemovement of incisors were also evaluated. SPSS 19.0 software was used for statistical analysis.Results: 15 patients with mean age of 27 years and 8 monthswere included(5 male, 10 female).There were significant differences between the actual and planned movement valuesfor all the molars.Upper first molars moved distally 1.83±1.01 mm on average with an efficacy of 81.33%(actual movement / planned movement in mesial-distal direction); Upper second molars distalized2.02±1.00 mm on average,and the efficacy of distalizationwas83.82%.Compared to the planned movement, upper first molar had extra intrusion of0.99 mm, distal tipping of3.57°and buccal inclination of 3.61°. The second molar showed a similar tooth movement with a significant more intrusion of 0.89 mm compared to the first molar. No significant difference was observed between the groups with and without attachments. Incisors showed no significant proclination compared to the planned movement.Conclusion: Upper molar distalization could be effectively achieved by Invisalign appliances, withminorintrusion, distal tipping and buccal inclination. Attachments had no influence onmolar movements. Mini-implants or CII elastics are sufficient to support the anchorage.