The effects of load misalignment on tensile load testing of direct bonded orthodontic brackets--a finite element model.

A finite element model (FEM) of an orthodontic bracket bonded to enamel with glass ionomer cement was developed. The loading on the model simulated tensile loading conditions associated with the testing of bonding system strength. The primary purpose of this project was to ascertain the effects of load misalignment on the calculated stresses within the cement layer. The results indicate that peak stress values increase as the load deflection angulation increases. If the tensile load is inadvertently applied entirely on one wing of the bracket, the stress components nearly double in magnitude.