The Effect of Sintering Time on the Marginal Fit of Zirconia Copings.

PURPOSE: This study analyzed the effect of different sintering times on the marginal adaptation of zirconia ceramic copings.

MATERIALS AND METHODS: Thirty copings of pre-sintered 3Y-TZP blanks were milled and subsequently sintered in a special furnace for three different durations (n = 10 per group). The sintering time was 1 hour, 15 minutes for IPS e.max ZirCAD, 4 hours 20 minutes for Speed ZrO2, and 7 hours 20 minutes for the conventional ZrO2 group. The marginal gaps of specimens were measured at 18 spots on the master die by employing a digital microscope. One-way ANOVA test compared the mean differences among the 3 groups (α = 0.05).

RESULTS: The mean values for the marginal gap of the IPS e.max ZirCAD, Speed ZrO2 , and conventional ZrO2 groups were 41.06 ± 14.03, 43.03 ± 11.67, and 39.88 ± 15.23 μm, respectively. There was no statistically significant difference among the groups regarding the marginal gap.

CONCLUSION: Different sintering times did not alter the marginal fit of the zirconia copings. The mean values of the marginal gap were within the clinically acceptable level for all three groups.