DEBONDING ORTHODONTIC CERAMIC BRACKETS BY ULTRASONIC INSTRUMENTATION

Breakage of ceramic brackets because of brittleness may cause such pro blems as aspiration of fragments and injury by flying debris. Portions remaining on the tooth must be laboriously ground off with a handpiec e. This study investigated a potential method of lowering the force re quired to remove ceramic brackets, i.e., use of an ultrasonic chisel. Ceramic brackets were bonded to extracted incisors and canines. The de gree of cure of a light-activated cement was systematically varied wit h different exposure times to a curing light. The brackets were sheare d from the teeth with a universal testing machine and a chisel tip on a Cavitron. The ultrasonic chisel markedly reduced the force required to debond the brackets; however, the time of application averaged 16.6 seconds. Reducing the degree of cure of the cement had only a slight effect on the time required and the forces generated. This method of d ebonding is not recommended without further development.