Running Time: 15 min
We investigated an easy debonding method for ceramic brackets using a light-cured Bis-GMA resin adhesives containing thermal expansion microcapsules and CO2 laser.
In order to debond the ceramic bracket, a heavy force must be applied physically to the bracket; this can sometimes cause fractures of the enamel and intense tooth pain. An orthodontic adhesive therefore must have contradictory properties that firmly bond the tooth and bracket during treatment but can easily separate them after treatment. To find out the CO2 laser irradiation conditions (Operalaser PRO, YOSHIDA), the bracket surface was irradiated with the laser and the bracket base temperature and inside temperature of the pulp chamber under various conditions were evaluated using thermocouple sensor. Sixty brackets, bonded with paste and bonding agent containing microcapsule contents 0, 10, 20, 25 and 30 wt% were irradiated with CO2 laser. Shear bond strength tests were performed at 10 min after irradiation with a dental material universal testing machine.
With CO2 laser irradiation for 5s to the bracket, the bond strength in the 25% microcapsule group decreased significantly, to ̃ 0.17 fold, compared with that of the no-laser group(P<0.05). The maximum temperature rise in the pulp chamber was 5.3°C with laser irradiation, which was less than the level that induces pulp damage. From these results, it seems likely that the combined use of a light-cured orthodontic bonding agent containing microcapsules and a CO2 laser is a simple debonding system for ceramic brackets, with less debonding time, enamel damage, and tooth pain.
Release Date: 13-11-2020Subtitle: