The effect of various composite polishing systems on the surface roughness and micro hardness of nanofill and nanohybrid composite resin restoratives” An in vitro study

Context: The key to esthetic and biologic integrity of restorations for a long term, lies in the finishing and polishing, which is the most often neglected procedure.Various finishing and polishing systems are available in the market, however, the polishing regimen for the newer nano-based composites have not been adequately investigated. Aims: The purpose of this current study is to evaluate and compare the effect of two different polishing systems (Diamond Impregnated Compomaster and Aluminium oxide discs Super Snap Xtreme) on the surface roughness and micro hardness of a nanofill(Filtek Z 350 XT )and a nanohybrid composite resin(Filtek Z 250 XT). Methods and Material: A total of 60 composite discs of which, 30 specimens of each restorative material , were fabricated (8 mm in diameter and 2 mm in thickness). The respective finishing and polishing procedures were carried out and all the specimens were subjected to Surface roughnesss measurement using a Profilometer and micro hardness measurement using a Vickers Micro hardness testing Machine. Statistical analysis used: Means and Standard Deviation (Descriptive), one and two way ANOVA, Independent Sample t test, Pearson's correlation co efficient. Results: The nanofill Z350 XT and Super Snap Xtreme aluminium oxide discs showed least roughness values and Nanohybrid composite specimens had a higher microhardness value. Conclusions: Z350 XT showed least roughness values overall in comparison.For both nanohybrid and nanofill composites resins, the multistep polishing system-aluminium oxide discs (Supersnap Xtreme Shofu Inc.) provided significantly lower surface roughness .Nanohybrid composite specimens had a higher microhardness value when compared with nanofill specimens.