RESUMO
OBJECTIVE: The aim of this study was to find out whether Er:YAG laser can aid in debonding ceramic brackets, and to see what kind of method will be the most appropriate for debonding. METHODS: One hundred and ninety teeth, monocrystalline brackets (MISO(TM), HT, Ansan-Si, Korea), polycrystalline brackets (Transcend(TM) series 6000, 3M Untek, Monrovia, CA, USA) and the KEY Laser3 (KavoDental, Biberach, Germany) were used. Experimental groups were classified according to the type of ceramic brackets, and the amount of laser energy (0, 140, 300, 450, 600 mJ). After applying laser on the bracket at two points at 1 pulse each, the shear bond strength was measured. The effect of heat caused by laser was measured at the enamel beneath the bracket and pulp chamber. After measuring the shear bond strength, adhesive residue was evaluated and enamel surface was investigated using SEM. RESULTS: All ceramic bracket groups showed a significant decrease in shear bond strength as the laser energy increased. The greatest average temperature change was 3.78degrees C on the enamel beneath the bracket and 0.9degrees C on the pulp chamber. Through SEM, crater shape holes caused by the laser was seen on the enamel and adhesive surfaces. CONCLUSIONS: If laser is applied on ceramic brackets for debonding, 300 - 450 mJ of laser energy will be safe and efficient for monocrystalline brackets (MISO(TM)), and about 450 mJ for polycrystalline brackets (Transcend(TM) series 6000).