Biomechanical evaluation of attachment geometries for labio-lingual inclinations in maxillary incisors of Class II Division 2 malocclusion: A 3D finite element analysis.

BACKGROUND: Class II Division 2 malocclusion presents biomechanical challenges due to retroclined maxillary incisors, often complicated by soft tissue constraints. Clear aligner therapy (CAT), though patient-friendly, shows limitations in predictably modifying labiolingual inclination. Recent attachment design advancements offer potential solutions but require biomechanical validation. Finite element modelling (FEM) serves as an effective analytical tool to evaluate these mechanics. The present study aims to compare the efficacy of three attachment geometries in expressing labiolingual inclination of maxillary incisors in a FEM model simulating Class II Division 2 malocclusion EIC.

MATERIALS AND METHODS: A FEM of the maxilla was generated from CBCT data of a Class II Division 2 patient. Labiolingual inclinations of 5°, 10°, 15°, 20°, and 25° were simulated on maxillary central and lateral incisors. Three attachment designs were evaluated: labial horizontal attachments (LHA), palatal horizontal attachments with labial power ridges (PHALPR) and labial-palatal reciprocal power ridges (LPRPR). Displacement and von Mises stress were calculated for teeth and supporting structures.

RESULTS: LPRPR showed the highest displacement (0.1418 mm) and stress (384.89 MPa), followed by PHALPR (0.1211 mm; 327.35 MPa) and LHA (0.1048 mm; 204.65 MPa) respectively. Lateral incisors demonstrated greater displacement and stress than central incisors. Supporting structures showed peak stress under LPRPR conditions.

CONCLUSIONS: Attachment geometry significantly affects labiolingual inclination expression in CAT. Among the tested designs, the LPRPR configuration demonstrated superior biomechanical efficiency for managing labiolingual inclination in Class II Division 2 malocclusion.