Indirect bonding with a hydrophilic adhesive

Methods: Simulated patient models were prepared from mounting bovine incisors in stone. Split mouth cases of APC PLUS and APC II (control) Victory Series brackets were then bonded to stone models prepared from the simulated patient models. Primary curing of brackets took place for 10-minutes in a TRIAD curing unit. The hard tray was filled with impression material, placed over the brackets and then removed. Secondary curing of brackets took place for 2-minutes in the TRIAD. Trays were cleaned, rinsed, and microetched and the Sondhi Rapid-Set system was used to bond the brackets to the bovine teeth. The teeth were later mounted and an INSTRON was used to debond the brackets.

Results: The simulated patient models and indirect bonding trays were prepared uneventfully. However, after the bonding trays were detached from the stone model, rinsed and dried, the custom resin base of the APC PLUS samples appeared to have a thin, chalky surface not present in the APC II samples. SEM studies suggest that this is the result of oxygen inhibition during curing. A comparison of bond strength between APC PLUS and APC II, using both the microetching and toothbrush methods, showed mean values ranging from 14 to 18 MPa, indicating clinically acceptable bond strength using both preparation methods. Tukey's Test yielded a P-value of 0.33, indicating that differences in bond strength were not statistically significant.

Conclusions: While there is a visible opaque layer that appears on the APC PLUS resin base, there was no significant difference in bond strength observed between APC PLUS and APC II appliances bonded to bovine teeth using the Sondhi indirect bonding method.