Effect of Multiple-step versus Reduced-step Polishing Systems on Composite Surface-properties

Objectives: To compare the surface gloss and surface roughness of two contemporary composites when polished with four reduced-step finishing & polishing systems or a conventional multiple-step technique.
Methods: Sample discs of 8mm ø x 2mm thickness (n=50 for each material) were fabricated from two nanohybrid composites; Essentia (ES), GC and BRILLIANT EverGlow (EG), Coltene. 10 specimens of each composite were randomly assigned to one of the 5 polishing systems used. The ‘gold standard’ multiple-steps system consisted of coarse to fine Orange Sof-Lex XT discs (3M) followed by DiaPolisher diamond paste (GC). The single-step systems used were; ProGloss (Kerr) and OneGloss (Shofu) and two-step systems were DIATECH ShapeGuard (Coltene) and Polishettes (KENDA Dental). Surface gloss was measured using a glossmeter (Microgloss 155/SO, Sheen), surface roughness by a white light profilometer (Proscan 2000, UK) and polished surfaces were also evaluated using scanning electron microscopy (Hitachi). Statistical analysis was conducted using One-Way ANOVA and post-hoc Tukey tests using SPSS 21.
Results: Interestingly, whilst there was no difference in the surface roughness (R_a) of both composites when the multiple-step system was used (p>0.05), ES had a significantly higher surface gloss than EG (p<0.05). The lowest surface roughness (R_a 0.08 µm) and highest gloss (90.7 GU) were obtained from EG composite polished with DIATECH ShapeGuard (p<0.05). Each composite group polished with the ProGloss system had the same surface roughness and gloss as when polished with the multiple-step system (p>0.05). Polishing with OneGloss and Polishettes resulted in highest surface roughness and lowest surface gloss in both composites (p<0.05).
Conclusions: The lowest surface roughness and highest surface gloss were achieved when the EG composite material was matched with the same manufacturer’s polishing system (EG and DIATECH ShapeGuard). ProGloss system was able to produce similar surface roughness and gloss in both composite groups as when polished with a more time consuming system.