PURPOSE. Surface finishing of a zirconia restoration is essential after clinical adjustment. Herein, we
investigated the effects of a surface finishing protocol for monolithic zirconia on final roughness and bacterial
adherence. MATERIALS AND METHODS. Forty-eight disk-shaped monolithic zirconia specimens were
fabricated and divided into four groups (n = 12) based on initial surface treatment, finishing, and polishing
protocols: diamond bur+polishing bur (DP group), diamond bur+stone grinding bur+polishing bur (DSP group),
no diamond bur+polishing bur (NP group), and no diamond bur+stone grinding bur+polishing bur (NSP group).
Initial and final surface roughness was measured with a profilometer, and shown using scanning electron
microscope. Bacterial adhesion was evaluated by quantifying Streptococcus mutans in the biofilm. Kruskal–
Wallis and Mann-Whitney U tests were used to compare results among groups, and two-way analysis of variance
was used to evaluate the effects of grinding burs on final roughness (α=.05). RESULTS. The DP group had the
highest final Ra value, followed by the DSP, NP, and NSP groups. Use of the stone grinding bur as a coarsefinishing
step significantly decreased final Ra values when a diamond bur was used (P<.001). Omission of the
stone grinding bur increased biofilm formation on specimen surfaces. Combining a stone grinding bur with
silicone polishing burs produced the smallest final biofilm values, regardless of the use of a diamond bur in
initial surface treatment. CONCLUSION. Coarse finishing of monolithic zirconia with a stone grinding bur
significantly decreased final Ra values and bacterial biofilm formation when surfaces had been roughened by a
diamond bur.