Surface roughness of three resin restorative materials after finishing and polishing

The surface roughness of 3 different resin restorative materials polymerized with a halogen and a plasma arc curing light, following finishing and polishing was evaluated in vitro.

Using a metal mold, 10 block specimens were prepared from each material. A Mylar strip was placed on both sides of the mold. Five specimens from each material were cured with the halogen lamp, while the other 5 were polymerized with the plasma arc lamp. In both groups the surface exposed to curing light was finished and polished with the Enhance system (Dentsply). The opposite surface was not treated and served as a control. Both surfaces of each specimen were analyzed with a laser profilometer: the roughness average (R(a)) was evaluated. The Vickers microhardness of the polished surfaces was also calculated. All data were statistically analyzed with the Mann-Whitney test. A regression test was carried out to evaluate the possible correlation between roughness and microhardness.

The smoothest surfaces were obtained when composites were cured against a Mylar strip. Roughness was significantly increased in both groups in the treated surfaces. A significant correlation between roughness and microhardness could not be demonstrated.

This study demonstrated that the surface polymerized against a Mylar strip was the smoothest surface produced, while the roughness of the Mylar-formed surface was significantly increased by finishing and polishing. Surface roughness following polishing is material-dependent.