The Effect of Different Finishing and Polishing Protocols On The Surface Roughness and Flexural Strength of Anatomic Contour Zirconia
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INTRODUCTION: This study evaluated the effect of three different finishing and polishing protocols on the surface roughness and flexural strength of anatomic contour zirconia material. MATERIALS AND METHODS: 1: Surface roughness; One hundred and five bars of Yttria-Stabilized tetragonal zirconia polycrystals (Y-TZP) were prepared from Zenostar zirconia blocks (Ivoclar Vivadent). Fifteen bars were distributed into one of seven groups (n=15/group). Three rotary systems were assessed for finishing and polishing zirconia. 1) Control, 2) Brasseler wet, 3) Brasseler dry, 4) Axis wet, 5) Axis dry, 6) Komet wet , 7) Komet dry. After surface preparation surface roughness was measured using a non-contact profilometer (NPFlex Light interferometer, Bruker Corp., Tucson, AZ). 2: Flexural Strength; Flexural strength of the bars was determined using a three point bending test in a Universal Testing Machine (Instron). RESULTS: 1: Surface roughness; one-way ANOVA (Brown-Forsythe) indicated a statistically significant difference in surface roughness by group, (p<0.005). Two-way ANOVA demonstrated statistically significant main effects of grinding condition (wet/dry) (P=0.001) and polishing kit (P < .005) on surface roughness. A significant interaction was demonstrated between grinding condition and polishing kit (P = .001). 2: Flexural Strength; one-way ANOVA (Tukey HSD) indicated a statistically significant difference in flexural strength between groups, (p<0.005). Two-way ANOVA was used to determine the relationship between polishing kit and grinding condition in relation to flexural strength. The analysis demonstrated statistically significant main effects for both grinding condition (P=0.001) and polishing kit (P < 0.05). There was no significant interaction effect (P = 0.869). CONCLUSIONS: Wet grinding yielded a smoother surface when using Brasseler and Komet adjustment kit. Dry grinding resulted in lower flexural strength compared to wet grinding, irrespective of the kit being used. A polished surface comparable to that of the control group was achieved using Brasseler’s zirconia polishing kit with water.