Easy Debonding of Ceramic Brackets Bonded with a Light-Cured Orthodontic Adhesive Containing Microcapsules with a CO₂...

An easy debonding method for ceramic brackets using a light-cured Bis-GMA resin containing heat-expandable microcapsules and CO₂ laser was investigated.

Ceramic brackets are used frequently in orthodontic treatment because of their desirable esthetic properties. However, the application of heavy force to ceramic brackets in debonding can fracture the tooth enamel and ceramic brackets, causing tooth pain.

In total, 60 freshly extracted bovine permanent mandibular incisors were divided randomly into 10 groups of 6 specimens each, corresponding to the number of variables tested. Ceramic brackets were bonded to bovine permanent mandibular incisors using an orthodontic bonding agent containing heat-expandable microcapsules at different levels (0-30 wt%) and resin composite paste, and cured by a curing device. The bond strengths were measured before and after CO₂ laser irradiation, and the temperature increase in the pulp chamber in fresh human first premolars was also evaluated.

With CO₂ laser irradiation for 5 sec 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 increase 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 and enamel damage.