Stress Analysis in Orthodontics using Finite Element Modelling

Objective: To improve the understanding of the use of brackets directly bonded to teeth and their impact on a tooth in translation regarding intrinsic stresses and strains, by hypothetically viewing the effect of a bracket on a canine, and the stress distributions attained with typical archwire configurations in the initial stages of correction, where the teeth are to be consequently aligned within the mandibular arch. Methods:Using finite element analysis (Ansys 12.0), a canine with a bonded bracket was modeled and the typical load induced by the arch wire (40g-Force) was placed in the center of the crown at different orientations with respect to the modeled bracket. The four initial load cases were at 0, 45, 90 and 135 degree angles with respect to the bracket. Results:The peak stress response is seen to occur in the enamel at lower angles, but gradually shifts to the dentin and surrounding gingiva when the perpendicular load is applied, leading to the optimal orientation for effective osseointegration and tooth alignment. There is also a higher stress in the labial section of the cementum in all load cases. Conclusions: This analysis provides a clear indication of the stress distribution within the tooth structure for a given force, further work applying a range of loading and alternate placing of the bracket will help to optimise tooth movement using fixed appliances.