Öztürk Caner, Çelik Ersan
Department of Prosthodontics, Faculty of Dentistry, Hatay Mustafa Kemal University, Hatay, Turkey.
Department of Prosthodontics, Faculty of Dentistry, Ordu University, Ordu, Turkey.
J Adv Prosthodont. 2019 Aug;11(4):202-208. doi: 10.4047/jap.2019.11.4.202. Epub 2019 Aug 27.
Fabrication of zirconia restorations with ideal mechanical properties in a short period is a great challenge for clinicians. The purpose of the study was to investigate the effect of heating rate on the mechanical and microstructural properties of monolithic zirconia.
Forty monolithic zirconia specimens were prepared from presintered monolithic zirconia blanks. All specimens were then assigned to 4 groups according to heating rate as Control, Group 15℃, Group 20℃, and Group 40℃. All groups were sintered according to heating rates with the sintering temperature of 1500℃, a holding time of 90 minutes and natural cooling. The phase composition was examined by XRD analysis, three-point bending test was conducted to examine the flexural strength, and Weibull analysis was conducted to determine weibull modulus and characteristic strength. Average grain sizes were determined by SEM analysis. One-way ANOVA test was performed at a significance level of 0.05.
Only tetragonal phase characteristic peaks were determined on the surface of analyzed specimens. Differences among the average grain sizes of the groups were not statistically significant. The results of the three-point bending test revealed no significant differences among the flexural strength of the groups (>.05). Weibull modulus of groups was ranging from 3.50 to 4.74. The highest and the lowest characteristic strength values were obtained in Group 20℃ and Control Group, respectively.
Heating rate has no significant effect on the flexural strength of monolithic zirconia. Monolithic zirconia restorations can be produced in shorter sintering periods without affecting the flexural strength by modifying the heating rate.
在短时间内制造出具有理想机械性能的氧化锆修复体对临床医生来说是一项巨大挑战。本研究的目的是探究加热速率对整体式氧化锆机械性能和微观结构性能的影响。
从预烧结的整体式氧化锆坯体制备40个整体式氧化锆试样。然后根据加热速率将所有试样分为4组，即对照组、15℃组、20℃组和40℃组。所有组均按照加热速率进行烧结，烧结温度为1500℃，保温时间为90分钟，然后自然冷却。通过XRD分析检测相组成，进行三点弯曲试验检测弯曲强度，并进行威布尔分析以确定威布尔模量和特征强度。通过SEM分析确定平均晶粒尺寸。以0.05的显著性水平进行单因素方差分析。
在分析的试样表面仅检测到四方相特征峰。各组平均晶粒尺寸之间的差异无统计学意义。三点弯曲试验结果显示各组弯曲强度之间无显著差异（>0.05）。各组的威布尔模量在3.50至4.74之间。分别在20℃组和对照组中获得最高和最低的特征强度值。
加热速率对整体式氧化锆的弯曲强度无显著影响。通过改变加热速率，可以在较短的烧结时间内生产出整体式氧化锆修复体，而不影响其弯曲强度。
