Evaluation of different lower incisor decompensation methods with clear aligners in class III orthognathic surgery patients by three di̇mensional finite element analysis method

In the preparation for Class III orthognathic surgery, the correct positioning of lower incisors during decompensation is crucial for determining function, stability, and the boundaries of the surgical procedure. In traditional orthodontic treatments, one of the most critical stages in orthognathic surgery preparation involves moving the incisors to their ideal positions within the alveolar bone and optimizing their angulation. Different mechanics and anchorage protocols are applied during the decompensation of incisors. Clear aligner technology is currently used today for treating many malocclusions. In the context of orthognathic surgery preparation, decompensation of lower incisors using clear aligners is a developing field with limited studies available. Finite element analysis, due to its ability to provide close-to-reality results when accurate data is input and its non-invasiveness, is frequently used in dentistry and orthodontics. Our study aims to determine the stress distribution in teeth and periodontal ligaments (PDL) and the amount of displacement in teeth caused by six different mechanics used for decompensation of lower incisors in Class III orthognathic surgery preparation, employing finite element analysis. These mechanics were investigated using transparent aligners in six groups: (1) control group, (2) buccal power ridge applied on the aligner, (3) buccal power ridge on the aligner with additional lingual attachment on the tooth, (4) lingual attachment on the tooth, (5) both buccal and lingual power ridge on the aligner, and (6) both buccal and lingual attachment on the tooth. All groups used 0.75 mm thick aligners, examining a 0.2 mm tooth movement. Our findings revealed buccal movement of incisor crowns and lingual movement at root apices across all lower incisors. Intrusion was observed in all groups except Group 6. Maximum tipping during decompensation was noted in Groups 5 and 2. Group 5 exhibited the highest degree of displacement among lower incisors, whereas Group 6 showed the least amount of displacement.