Finite Element Analysis of Maxillary Molar Intrusion Using Temporary Anchorage Devices: A Comparison of Direct and Indirect Force Loading.

OBJECTIVE: This study aimed to evaluate and compare the efficacy of maxillary molar intrusion using the modified C-palatal plate (MCPP) and conventional temporary anchorage devices (TADs) through finite element analysis (FEA). METHODS: Three-dimensional models of the maxilla were constructed from computed tomography images of a skull study model. FEA models were developed to simulate two different modalities. In the first modality (M1), the MCPP was evaluated by applying forces from three distinct hook locations: 3 mm coronal to the center of resistance of the first molar (M1-A), at the level of the center of resistance (M1-B), and 5 mm apical to the center of resistance (M1-C). In the second modality (M2), maxillary first molar intrusion was evaluated using TADs with an elastic band directed between buccal and palatal miniscrews contacting the tooth occlusal surface. Tooth displacement and stress distribution were analysed for both modalities. RESULTS: M1-A, distalization of the tooth occurred, accompanied by extrusion. M1-B demonstrated distalization with negligible vertical changes, while M1-C resulted in the least distalization but with intrusion. Comparing M1-C with the TADs, M1-C showed similar intrusion as in M2 with the same magnitude of force but with less Von Mises stress at the root surfaces. CONCLUSION: FEA revealed that the MCPP is a versatile appliance that allows tooth movement with selective control of extrusion or intrusion. The MCPP with indirect force loading can induce the same intrusive movement of the maxillary molar as TADs with less stress on the root surface.