Comparative Shear Bond Strengths of Orthodontic Adhesives with sealants/bonding resin

Objectives: : The purpose of this study was to (1) determine the in vitro debond shear strength of brackets bonded with medium-filled fluorescent adhesive OpalBond MV or heavily-filled Transbond XT;  in presence of sealants Opal Seal(OS), ProSeal(PS),  or bonding resin Transbond XT primer(TP); at different storage times and conditions, and (2)  examine the bond failure interfaces.

Methods: 144 extracted third molars were randomly divided into six groups. Groups 1-3: brackets were bonded to teeth with Opal Bond MV  and one of the three sealants or bonding resin (OS, PS or TP), Groups 4-6: brackets were similarly bonded with Transbond XT in presence of one of the three sealants or bonding resin. Transbond XT and TP served as the control. In each group, half of the brackets (n=12) were debonded after 30–mins and half were debonded after 24-hrs and 500 thermocycles. Debonding forces were determined using an Instron machine with crosshead speed of 1mm/min. Bond failure interface was scored (0-5) using the modified adhesive remnant index (ARI).  Bond strength and ARI data were analyzed using multi-factor ANOVA and Tukey-Kramer multiple comparisons test (p=0.05)

Results: ANOVA revealed significant differences among adhesives, sealants/bonding resin, debond times/storage; and some of their interactions (p<.05).  Significant differences were found between debond strength (MPa) of OpalBond MV (11.87) and Transbond XT (14.12), at p<.01. Among the three sealants or bonding resin,TP (14.48 MPa) yielded significantly higher bond strength than OS (12.85) and PS (11.52) with the adhesives (p<.01). ARI scores were above 3 in all groups, representing mixed adhesive and cohesive failures.

 Conclusions: These results indicate that Opal Bond MV and Transbond XT adhesives can be used with sealant or bonding resin from different manufacturers. Heavily-filled adhesive yields a higher bond strength but all groups resulted in clinically acceptable bond strengths. Similar bracket failure interface in all groups may also suggest similar ease of resin removal after debonding.