Efficacy of in-house clear aligner therapy mechanics on root torque: an in-vitro study

Abstract

Abstract Background This study aimed to evaluate the torque effectiveness of different attachment types and power ridges used in clear aligner therapy (CAT) on the upper lateral incisors. Methods A typodont model simulating oral conditions was developed. Two hundred lateral incisor samples were divided into five groups based on attachment types and clear aligner modifications: no attachments (NA), horizontal ellipsoid attachment (HEA), vertical ellipsoid attachment (VEA), buccal power ridge (BPR), and buccal and palatal power ridge (BPPR). Subsequently, a 5° palatal torque moment was applied to the lateral incisors. In-house clear aligners were inserted, and 3D scanning was performed after each aligner step. Post-treatment 3D models were compared with pre-treatment models. The lateral incisors were assessed for torque, tipping, and rotational movements. Results The HEA group (41.6%) and the BPPR group (40.8%) showed significantly higher torque effectiveness than the NA group (20%) when 5° of torque was delivered. The planned movement was approximated when 1° and 2° of torque were applied in the NA group (114% and 98%, respectively). The NA and BPR groups showed the highest loss of anchorage. Conclusions When more than 3° of torque was applied, HEA and BPPR were more effective than NA in achieving the CAT’s planned torque of the upper lateral incisors, although with an efficacy rate of approximately 40%. Highlights It is challenging to achieve torque movement using CAT. When less than 3° of torque was required, additional mechanics were not necessary. BPPR and HEA showed higher effectiveness when 5° of torque was applied. The efficacy of BPR was similar to that of NA.