POROUS CERAMIC LAMELLAE FOR ORTHODONTIC CERAMIC BRACKETS .1. FABRICATION AND CHARACTERIZATION

This study was undertaken to test a new and original orthodontic brack et base, consisting of a porous lamella, which was designed to facilit ate removal of ceramic brackets from the enamel surface after treatmen t. In the phase of the study presented here, porous pellets were made by bonding coarse alumina particles (calcined or fused) with mullite, formed by their reaction with fine quartz particles during firing of t he mixture at 1700 degrees C. After machining the pellets to the desir ed shape, nine types of lamellae with different porosities were attach ed to the brackets using two different adhesive resins, and also bonde d to bovine enamel using the same adhesives. The tensile bond strength s for the assemblies were determined so that the lamellae a nd the bon ding adhesive that might be suitable for clinical application could be selected for testing in vitro in the second phase of the study.