AlShaafi Maan M
Associate Professor, Department of Restorative Dental Sciences, College of Dentistry King Saud University, Riyadh, Kingdom of Saudi Arabia, Phone: +966114677420, e-mail:
J Contemp Dent Pract. 2016 Mar 1;17(3):217-23. doi: 10.5005/jp-journals-10024-1830.
Dental materials are often made at room temperature, whereas clinically they are made in the mouth. This study evaluated the effects of temperature on the degree of conversion (DC) and Knoop microhardness (KHN).
Two types of resin-based composites (RBCs) were light-cured using a light-emitting diode (LED) light-curing unit. The resin specimens were centered on an Attenuated Total Reflectance Fourier transform infrared (FT-IR) plate heated to 23°C or 33°C. The DC of the resin was calculated after 120 seconds, the specimens were removed, and the KHN was tested at the bottom of the specimens both immediately, after 24 hours, and after 7 days storage in distilled water in complete darkness at 37°C. The effects of different temperatures on the DC and KHN with their storage time were compared by analysis of variance and Fisher's protected least significant difference post hoc multiple comparison tests (p < 0.05).
Increasing the temperature had a significant and positive effect on the DC and KHN for immediate values of the RBCs. Greater conversion and hardness occurred when the curing temperature was increased from 23°C to 33°C. The KHN increased significantly after 24 hours of storage. There was a linear relationship between DC and KHN (R(2) = 0.86) within the range of DC and KHN studied.
The physical properties of dental materials can be expected to be better when made in the mouth than when they are made in a laboratory at room temperature.
牙科材料通常在室温下制作，而在临床上是在口腔内制作。本研究评估了温度对转化率（DC）和努氏显微硬度（KHN）的影响。
使用发光二极管（LED）光固化机对两种树脂基复合材料（RBC）进行光固化。将树脂标本置于加热至23°C或33°C的衰减全反射傅里叶变换红外（FT-IR）板上。120秒后计算树脂的DC，取出标本，并在标本底部立即、24小时后以及在37°C完全黑暗中于蒸馏水中储存7天后测试KHN。通过方差分析和Fisher保护最小显著差异事后多重比较检验（p < 0.05）比较不同温度及其储存时间对DC和KHN的影响。
温度升高对RBC的即时DC和KHN有显著的正向影响。当固化温度从23°C升高到33°C时，转化率和硬度更高。储存24小时后KHN显著增加。在所研究的DC和KHN范围内，DC和KHN之间存在线性关系（R(2) = 0.86）。
牙科材料在口腔内制作时的物理性能预计比在室温下的实验室制作时更好。
