| Abstract |
Background: sintering parameters were influenced to mechanical characteristics of dental restoration. This study investigated the effect of different sintering protocol on flexural strength of four multilayer monolithic zirconia materials.
Material and Methods: 360 bar specimens (width x length x thickness = 2 x 25 x 12 mm) were prepared from 3Y-TZP (super translucent multilayer zirconia, Boomden, China), 4Y-PSZ (super translucent plus multilayer zirconia, Boomden, China), 5 Y-PSZ (ultra-translucent multilayer zirconia, Boomden, China) and combined 3Y+4Y+5Y PSZ (3D pro multilayer zirconia, Boomden, China). Each material was randomly divided into three groups of sintering protocols (n = 30/group): regular (R = manufacturing temperature and time), speed (S = temperature R + 50°C, time R – 40 minutes), high speed (H = temperature R + 100°C, time R – 80 minutes). After the sintering, 180 specimens were aged by a thermocycling device (CWB332R, MERL, KMIT’L, Thailand) for 50,000 cycles in a coffee solution between 5°C and 55°C. Induced pre-cracks on the tension side and mechanical characteristics were defined by a four-point bending test for flexural strength ().
Statistical Analysis: Three-way ANOVA and Bonferroni multiple comparisons were applied to determine the significant differences of at p < 0.05. SEM was used for evaluating the grain size, and X-ray diffraction (XRD) was used to determine the number of tetragonal and monoclinic phases.
Result: The mean standard deviation of and 0 was highest in the STAH group (887.34 ± 30.15 and 939.03), whereas the lowest was the UTNR group (253.1 ± 11.58 and 271.47). There was a significant difference in the flexural strength value of the different materials, sintering protocol, interaction between the material and sintering protocol and interaction of materials and ageing (p < 0.05).
Conclusion: The sintering protocol of zirconia at a speed and super-speed sintering protocol can increase flexural strength, while the ageing process does not significantly affect flexural strength.
Keywords: multilayer zirconia, monolithic zirconia, sintering temperature, sintering time, flexural strength
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Publication
Journal Publication
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