Does the Miniscrew Length, Insertion Level, and Insertion Force Make a Difference on the Stress and Strain Distribution Across the Alveolar Bone? A Finite Element Study

Abstract

Objective The aim of this study was to evaluate, using the finite element method (FEM), the stresses generated on various parts of the mini-screw and on the bone resulting from the insertion of mini-screws of varying lengths and under different forces. Materials and Methods Three-dimensional models of mini-screws (1.6 × 6, 8, and 10 mm) and bone (mandible cortical bone thickness of 2 mm) were constructed and simulated using FEM. The mini-screws were inserted using force loads of 10 and 20 Ncm, and stress evaluation was carried out on screws and bone. The stress evaluation was also performed across different levels of insertion (at the point of insertion, half-insertion, and full insertion). Results A direct correlation between the force applied and the stresses on the body of the screws was observed. There was an inverse relationship between the length of the mini-screw and the resulting stress on the bone with the highest stress of 14.58 Mpa with 6 mm long and the minimum stress of 3.81 Mpa with longer mini-screws. On application of different force magnitudes, the stress levels increased linearly with a change in the length. The highest stresses on the bone were observed only when the screw was fully inserted in the bone. Conclusion When mini-screws of different lengths were inserted using different magnitudes of forces, the stress levels increased linearly on the bone. A combination of longer mini-screw and lesser force magnitude used during insertion produced less stress on the bone.