EFFECT OF FINISHING &POLISHING PROCEDURES ON THE SURFACE ROUGHNESS &MICROHARDNESS OF RESIN COMPOSITE RESTORATIVE MATERIALS

Abstract

Aim: To evaluate the effect of three different finishing and polishing (F&P) systems; Fine diamond bur, Sof-lex discs and Astropol® cups & discs on the surface roughness and microhardness of four resin composites. Materials and Methods: A total of 160 disc-shaped specimens (10 mm x 2 mm) were prepared in metal mold using four resin composite materials and stored in distilled water at 37˚C for 24 h. The specimens were then divided into four experimental groups (n=40) according to the type of resin composite. Group1: Microhybrid composite (Dynamic Plus), Group2: Nanohybrid (Nexcomp), Group3: Supernano composite (ESTELITE Σ QUICK), and Group4: Nanoceram composite (ZENIT). For each type of resin composite the forty specimens were divided into four sub-groups (A, B, C, & D) based on the type of finishing and polishing procedure as follow; A: Sandpaper, B: Fine diamond bur C: Astropol® cups & discs (two–step) F&P system, and D: Sof-lex discs (four–step) F&P system. The surface roughness measurements were made for all resin composite specimens using USB digital surface profile gauge and data were recorded using computer software (Elcomaster 2, Elcometer Instruments). Surface Micro-hardness of the specimens was determined using Digital Display Vickers Micro-Hardness Tester. The measurements were calculated and the obtained data statistically analyzed using SPSS software. Two-way ANOVA were applied to assess significant differences among composite materials using different F&P systems. Tukey`s Post hoc test was used for pair-wise comparisons between the means. Results: Significant differences in surface roughness and microhardness were found according to the type of F&P systems and resin composites (P<0.05). The smoothest surface value was recorded for nanoceramic composite. The highest microhardness value was obtained with microhybrid composite finished with the Soflex discs (four-step) F&P systems. Conclusions: Based on the obtained results it can be conclude that F&P procedure greatly affect the surface roughness and microhardness of the tested resin composite materials. Nanoceram and supernano composite exhibited the lowest surface roughness values, while nanohybrid composite exhibited the highest surface roughness value among the tested composites when finished with Soflex F&P system. Microhybrid composite exhibited the highest microhardness. The smoothest surface finish was obtained when using fine diamond bur particular with supernano and nanoceramic composites. The one step procedures exhibited the best result. Keywords: Resin composites, finishing and polishing system, surface roughness, microhardness.