[Effects of pins and bonding agents on the tensile strengths of Ni/Cr alloy bonded to enamel].

OBJECTIVE

To evaluate the effects of pin retention form and different bonding agents on the tensile bond and re-bond strength of Ni/Cr alloy to the enamel.

METHODS

Sixty bovine permanent incisors were randomly divided into 6 equal groups by the variables of the numbers (0, 1 or 2) of pins to be prepared and bonding agents (Panavia F and Super-Bond C&B). The pin 1mm in diameter and 1mm in depth was prepared vertically to each enamel surface in the groups to be with pins. Cast Ni/Cr alloys cylinders were made and bonded to respective enamels using two different agents. Tensile strengths were tested. After residual visible resin on the debond surfaces being removed, specimens were re-bonded and tested in the same way as initial bonding.

RESULTS

The tensile strength of Super-Bond C&B groups (11.82 MPa) was significantly higher than those of Panavia F groups (9.28 MPa, P<0.001). There was no significant difference of the tensile strength among the groups with one pin, two pins or without pins (P=0.394). There was no significant difference between the bond and re-bond tensile strength (P=0.969).

CONCLUSION

Super-Bond C&B has significantly higher tensile strength than Panavia F, and is good for the retention of resin bonded fixed partial denture. Pins, which are vertical to the bonding surfaces have little effect on the tensile strength. The re-bonding can be successfully achieved by removing the residual visible resin and sandblasting the metal surfaces and the tensile strength is unchanged.