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 (alpha = 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 mu m, 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.