An evaluation of the quality of orthodontic attachment offered by single- and double-mesh bracket bases using the finite element method of stress analysis

The objective of this study was to evaluate the influence of bracket base m esh geometry on the stresses generated in the bracket-cement-tooth continuu m by a shear/peel load case. A validated three-dimensional finite element m odel of the bracket-cement-tooth system was constructed consisting of 15,32 4 nodes and 2971 finite elements. Cement geometric and physical properties were held constant and bracket base geometry was varied, representing a var iety of single-mesh configurations and 1 double-mesh design. For the single -mesh designs, increasing wire diameter (100-400 mum) resulted in a decreas e in enamel and cement stresses. Increases in wire mesh spacing (200-750 mu m) increased the major principal stress recorded in the enamel and adhesive at all wire diameters. Within the bracket, the major principal stress incr eased significantly at wire spacing above 400-500 mum However, within the i mpregnated wire mesh (IWM), the major principal stress decreased as wire sp ace increased. When the double-mesh bracket base was considered, the combin ed mesh layers resulted in a decrease in the stresses recorded in the most superficial (coarse) mesh layer and an increase in the stresses recorded in the deepest (fine mesh) layer when compared with the single-layer designs in isolation. Modification of single-mesh spacing and wire diameter influen ces the magnitude and distribution of stresses within the bracket-cement-to oth continuum. The use of a double-mesh design results in a reduction in th e stresses recorded in the most superficial mesh. Mesh design influenced st ress distribution in this study, primarily by determining the flexibility o f the bracket base.