Is surface roughness of resin composites affected by operator's performance?

To assess intra-individual and inter-individual differences in applying finishing diamonds and rubber polishers to composite specimens with special reference to surface roughness.

The composite Herculite XRV was used to fabricate 120 specimens. Four human operators with varying experience (Operators 1 to 4) and an automatic mechanical device (Operator 5) were selected for the task of preparation. At baseline, six specimens were prepared by each operator using a 30 microm finishing diamond and six other specimens were prepared by each operator using Astropol polishing cups. After 48 hours, the entire procedure was repeated using new specimens and instruments. All the specimens were assessed for surface roughness by optical profilometry. Average roughness (Ra) and profile-length ratio (LR) were calculated. Intra-individual (baseline/48 hours) and inter-individual (Operators 1 to 5) differences were statistically analyzed by two-way and one-way ANOVA.

With respect to finishing, there was a significant interindividual effect between the four human operators and the mechanical device in terms of Ra (P = 0.007) but not in terms of LR. With respect to polishing, the five test groups had a significant effect on Ra and LR values (P < 0.001 in both cases). Overall, finishing and polishing performed at baseline or after 48 hours had no significant effect on surface roughness values.