Comparison of Shear Bond Strength of Two Bonding Agents for Recycled Self-Ligating Brackets

Introduction: Bracket dislodgment is a common orthodontic problem. The clinician might has
the option of reusing the old bracket after recycling rather than replacing it with a new one.
Purpose: This current invitro study was designed to compare the effect of recycling of selfligating
brackets on shear bond strength (SBS) of both flowable composite and self-etch primer.
Materials & Methods: Thirty extracted premolars were randomly divided into two groups of
15 teeth per each according to the type of adhesive used. In group I, self-ligating (Damon) Brackets
were bounded with flowable composite Grandio Flow (GF) and in group II were bonded with
Transbond plus self-etch primer (SEP). All the specimen were subjected to recycling by a low speed
carbide debonding burs. The Universal Testing Machine was used to measure SBS. The mode of
bond failure was evaluated by the adhesive remnant index (ARI). The data was analysed with T-test
while ARI scores were evaluated by Wilcoxon test.
Results: There was a significant difference between the two tested groups (P< 0.05). Flowable
composite (GF) showed a significantly higher SBS than self-etching primer (SEP), for both before
and after recycling. After recycling there was a nonsignificant difference in SBS of the two groups
(P > 0.05), for ARI, there was a nonsignificant difference between the two tested groups (P > 0.05).
Conclusion: Self-ligating Damon brackets bonded with (GF) and (SEP) could be successfully
recycled by low speed debonding bur. GF was superior in SBS.
Key words: bond strength, recycling, self ligating brackets, adhesives.