POROUS CERAMIC LAMELLAE FOR ORTHODONTIC CERAMIC BRACKETS .2. IN-VITROPERFORMANCE TESTING

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, two types of lamella and the adhesive resin used to bond them to brackets and teeth, were evalu ated in vitro. Two types of test were carried out on bracketed teeth. The tensile bond strength was measured for specimens that had been eit her kept in water for 24 h at 37 degrees C or subjected to 18 000 cycl es in water between 6 degrees C and 55 degrees C. The stress required to remove brackets with debracketing pliers was measured and the mode of failure recorded for specimens that had been kept in water for 24 h at 37 degrees C. The results indicate that bracket/lamella assemblies can be bonded to enamel sufficiently strongly for clinical applicatio n and can be safely removed without damage to enamel.