Comparison of adhesion forces developed by foil mesh of various dimensions applied in combination with composites of different viscosity

Abstract

The aim of this study was to determine what effect various combinations of particular bracket bases and composites of different viscosity have on adhesion force. Eighty extracted premolars, upper and lower, were randomly assigned to four groups of 20 teeth and the combinations of either flowable or paste composite and brackets with either 80-gauge or 100-gauge foil mesh were applied to their labial surfaces accordingly: group A: flowable composite+80-mesh base; group B: flowable composite+100-mesh base; group C: paste composite+80-gauge base; group D: paste composite+100-gauge base. Each sample was subjected to shear bond stress to failure using a Zwick Roell Z050 testing machine at 50N/min load. The load required to detach each bracket was recorded in N and subsequently converted to MPa. After debonding, each tooth was analysed under optical microscope at 12× magnification and photographed prior to calculation of the Adhesive Remnant Index (ARI). The paste composite showed greater adhesion strength than the flowable in all cases, but this was further increased when the 80-gauge, rather than the 100-gauge, mesh was used. No statistically significant difference in ARI values was found between the flowable groups (groups A and B), on the other hand, in the paste composite groups, a statistically significant difference was highlighted between the 80-gauge (group D) and 100-gauge (group C) mesh bracket bases. Both the density of the composite and the gauge of a mesh bracket base are able to influence bond strength and the bond failure interface.