In vitro evaluation of bond strength and surface roughness of a resin-paint material

This study investigated the stability of a resin-paint material (Master Palette)--which was developed for chairside shade modification of composite restorations--by evaluating its bond strength to indirect resin composite and surface degradation. Bond strength was evaluated with four surface treatments including an application of methylene chloride, airborne particle abrasion with 50 microm aluminum oxide, and additional applications of bonding agents after air-abrasion. The surface roughness (Rz value) of both the resin-paint and indirect resin composite before and after thermo-cycling (4-60 degrees C, 50,000 cycles) was also evaluated. All data were statistically analyzed by two-way ANOVA and Boneferroni's test (p=0.05). It was found that bond strength was improved by bonding agent application (14.9+/-1.9 MPa to 18.6+/-2.2 MPa, p<0.0054) after thermo-cycling. As for surface roughness, its results after thermo-cycling (2.7+/-0.2 microm, p<0.001) demonstrated that the resin-paint needed further improvements to maintain the original surface texture.