Shear bond strength and FEM of a resin-modified glass ionomer cement--effects of tooth enamel shape and orthodontic bracket base configuration.

The objective of this study was to evaluate the influences of enamel shape and bracket base configuration on shear bond strength from a biomechanical point of view. To this end, shear bond test and stress analysis using finite element method (FEM) were performed. Results obtained from both tests were then comprehensively investigated. Maxillary incisors were prepared for plane specimens, while mandibular premolars were prepared for curvature specimens. Shear bond test was carried out with three different test conditions. Two finite element models of enamel shape and bracket base configuration were also created. An approximate mean load of 200 N was applied. Results revealed that the shear bond strength of plane model was higher than that of curvature model. In conclusion, the present study revealed that shear bond strength was significantly influenced by enamel shape and bracket base configuration, whereby a curvature configuration tended to have lower bond strength.