influence of sintering temperature on the marginal fit and compressive strength of monolithic zirconia crowns

Statement of the problem: increasing the sintering temperature is suggested by some man-ufacturers as a way to enhance the translucency of monolithic zirconia crowns. meanwhile, its effect on the marginal fit and compressive strength of the restoration is not fully under-stood. purpose: this study aimed to evaluate the effect of sintering temperature on the marginal fit and compressive strength of monolithic zirconia crowns. materials and method: in this in vitro study, thirty crowns of pre-sintered monolithic zir-conia were milled and sintered in a special furnace at either 1450°c or 1550°c (n=15 per group). the marginal gaps were measured at 18 spots on the dies with a digital microscope. to evaluate the compressive strength, the specimens were cemented on brass dies by using conventional glass ionomer cement. vertical load was applied by a universal testing ma-chine until fracture. one-way anova test was used to analyze the results (α=0.05). results: the marginal gap was not significantly different between the two groups (p= 0.062). a significantly higher mean value of compressive strength was observed in crowns sintered at 1550°c (1988.27±635.09 n) than those sintered at 1450 °c (1514.27±455.11 n) (p= 0.026). conclusion: although increasing the sintering temperature would not affect the marginal gap of monolithic zirconia crowns, it could significantly improve the compressive strength of zirconia restorations.