A Study of Tensile Bond Strengths of Three Bracket Base Surfaces

Abstract

The present study was designed to test the tensile bond strength of two new bracket base designs and compare the results with those of the study by Higgins using Ormesh brackets. It was hypothesized that the visible increase in surface roughness of the two new bracket bases over the conventional (Ormesh) mesh would increase the tensile bond strength of the bracket. Sixteen DuraLingual mesh brackets and the acid-etched bracket bases were fabricated and bonded to human maxillary bicuspid teeth with a Bis-GMA compound adhesive as described by Higgins. After 24 hours, the bases were subjected to tensile bond strength testing until failure in tension and 10 brackets tested from each group were used to calculate the results. The following results were recorded: (1) The mean tensile bond strength of DuraLingual mesh and acid-etched bracket bases were significantly greater than the Ormesh wire mesh. (2) The mean tensile bond strength of the acid-etched base was significantly greater than the DuraLingual mesh. The visually apparent surface roughness and intricate microscopic voids and pits created by electrolytically-etching a smooth bracket base surface may have contributed to greater mechanical retention in this bracket compared to a smooth wire mesh bracket base (Ormesh) and a cast mesh (DuraLingual).