Comparison of different bonding materials for laser debonding.

The laser-aided removal of ceramic brackets from enamel surfaces was compared between two different adhesives. The selected bonding materials were Bis-GMA composite resin and 4-META MMA resin. Debonding forces were measured as the shear bond strength, perpendicular to the brackets. Debonding force, debonding time, total illuminated laser energy, and Modified Adhesive Remnant Index were discussed. Laser illumination was very effective for debonding in both resin groups. Enamel fracture was not observed in either laser illuminated groups, whereas two teeth were cracked in the Bis-GMA control group. For MMA resin, debonding force was sufficiently decreased at 3 watts output, whereas 7 watts output was needed for Bis-GMA resin samples. Total illuminated energies until the removal of the brackets were statistically lower in the MMA groups than in the Bis-GMA groups. Laser-focused adhesives tended to be removed with the brackets in the Bis-GMA groups, whereas they tended to remain on the tooth surface in the MMA groups. We concluded that debonding MMA resin with a laser is safer than debonding Bis-GMA resin with a laser.