Open AccessEffect of Different Sintering Cycles on the Surface Hardness of Full Contour Monolithic Zirconia – An In Vitro Comparative Study
Author(s) -
Sanath Kumar Shetty,
Feba Maria Varghese,
Mohammed Zahid,
Savitha Dandekeri,
Fowzaan Feroz
Publication year - 2021
Publication title -
journal of evolution of medical and dental sciences
Language(s) - English
Resource type - Journals
eISSN - 2278-4802
pISSN - 2278-4748
DOI - 10.14260/jemds/2021/427
Subject(s) - sintering , cubic zirconia , materials science , metallurgy , ceramic
BACKGROUND This in-vitro study was conducted to compare the effect of different sintering cycles on the surface hardness of full contour monolithic Zirconia. METHODS In this in-vitro study, a total of 28 bar shaped Zirconia samples of final dimensions 20 x 4 x 2 mm were fabricated using Amann Girrbach CAD - CAM unit. These samples were randomly allocated into four groups with 7 samples in each group namely, Group 1, 2, 3 and 4 (Group 1: Long sintering cycle, Group 2: Intermediate sintering cycle, Group 3: Short sintering cycle, Group 4: Ultra-short sintering cycle) and sintered under the respective sintering cycles. The Ceramill® Therm sintering furnace provided 3 sintering cycles ranging from the longest Group - 1 (19 hours), to the short sintering cycle Group - 3 (8 hours), with an intermediate sintering cycle Group - 2 (15hours). The Zircom sintering furnace provided an ultra-short sintering cycle Group - 4 (2 hours). The testing of surface hardness was performed using TECSOL hardness tester. Statistical analysis of the collected data was performed by one - way ANOVA using SPSS software. Multiple comparison was done using post-hoc Tukey’s test. RESULTS One - way ANOVA showed statistically significant difference in the surface hardness of different samples (P < 0.05). The highest mean hardness was observed in Group 3 with 2713.757 + 233.89 VHN, followed by Group 2 with 2595.714 + 62.35 VHN, followed by Group 4 with 2518.600 + 103.65 VHN and Group 1 with the least, 1734.300 + 460.20 VHN. CONCLUSIONS The surface hardness of full contour monolithic Zirconia was influenced to some extent by various sintering cycles. The longest sintering cycle showed the least surface hardness whereas, the short sintering cycle showed the highest surface hardness. Also the ultra-short sintering cycle of 2 hours exhibited surface hardness comparable to the other sintering cycles with longer duration, making it a viable alternative to the conventional sintering cycles. KEY WORDS Monolithic Zirconia, CAD - CAM, Sintering, Hardness