Influence of Simulated Clinical Finishing/Polishing Protocols and Thermocycling on the Surface Integrity and Mechanical Performance of 3Y‐TZP

PURPOSE: This in vitro study evaluated the influence of different finishing and polishing protocols associated with thermocycling aging on surface roughness, flexural strength, and topography of 3Y-TZP. METHODS AND MATERIALS: Two hundred and eighty-six specimens (16 × 3 × 1 mm) were distributed into 22 groups (n = 13) according to the finishing/polishing protocol and thermocycling aging (with [18,000 cycles at 5°C and 55°C] or without aging). The groups included: control (no finishing or polishing), polishing with an intraoral polishing kit without previous finishing, positive control (laboratory polishing/glazing), and a factorial combination of finishing procedures performed using either high-speed rotation or a multiplier contra-angle, associated or not with irrigation and intraoral polishing. Surface roughness and flexural strength tests were performed, and representative specimens from each group were analyzed by scanning electron microscopy (SEM) to assess surface topography. Data were analyzed using two-way ANOVA followed by Tukey's post hoc test (α = 0.05). RESULTS: Surface roughness was significantly affected by the finishing/polishing protocols (p < 0.0001). The multiplier contra-angle promoted significantly greater roughness than the control (p = 0.0237) and positive control groups (p < 0.0001). No significant differences were observed in flexural strength among the groups (p > 0.05). Thermocycling aging did not significantly affect either surface roughness or flexural strength (p > 0.05). SEM analysis corroborated the roughness findings, demonstrating more irregular surface patterns after intraoral adjustment procedures. CONCLUSION: Finishing/polishing protocols influenced the 3Y-TZP surface integrity, whereas its flexural strength remained unaffected, even after thermocycling aging. Although laboratory glazing remained the most effective approach for producing smooth zirconia surfaces, careful intraoral polishing represented a clinically acceptable alternative following conservative adjustment.