Surface roughness of acrylic resins submitted to an alternative chemical polishing method

Abstract

This study evaluated the effect of chemical polishing on the surfa- ce roughness of an self-curing (AU, Jet-Clássico), conventional -heat- cured (TP, Clássico) and a micro- wave-cured (MI, Ondacryl) acrylic resin, all manufactured by A.O. Clássico Ltda., Brazil. Twenty dis- coid specimens (30 mm diameter x 5.0 mm thick) made with each of the resins were equally divided into four groups (n =5 ) and re- ceived the following finishing/po- lishing procedures: NC (negative control, Edenta 1513 tungsten carbide bur), PC (positive control, 600-grit polishing paper + pomes stone and chalk for 15 s each), PQ1 (CN + 10-s immersion in che- mical polishing liquid [Poli-Quim, A.O. Clássico Ltda.] heated at 80 °C) and PQ2 (similar to PQ1, but heated at 65°C). Three roughness measurements were taken for each specimen. Kruskall-Wallis test de- tected statistical significant diffe- rences (p < 0.05). The conventional mechanical polishing (NC) differed from the other methods for all re- sins, giving the lowest roughness value. When compared to AM, the PQl method exhibited similar (AU material), superior (TP material) or inferior (IM material) rough- ness. PQ2 method gave superior (AU and TP materials) and infe- rior (1M material) roughness va- lues compared to AM.The methods PQ1 and PQ2 differed among each other for AU resin, with PQ2 sho- wing a higher roughness value. It may be concluded that the chemi- cal polishing was more efficient for the microwave-cured acrylic resin. Heating the chemical polishing li- quid at a temperature below the conventional one did not affect the effectiveness of the polishing and may help to prevent distortion of the polished device. Key words: polishing, acrylic re- sin, roughness.