Vandewalle Kraig S, Ferracane Jack L, Hilton Thomas J, Erickson Robert L, Sakaguchi Ronald L
USAF Dental Investigation Service, 310C B St., Great Lakes, IL 60088, USA.
Dent Mater. 2004 Jan;20(1):96-106. doi: 10.1016/s0109-5641(03)00124-6.
The purpose of this study was to determine the minimal extent of cure required by the base of a Class 2 resin composite restoration (Z250, 3M ESPE, St Paul, MN, USA) that allows it to support the rest of the restoration and maintain its marginal seal under simulated clinical conditions.
Resin composite (Z250, 3M ESPE, St Paul, MN, USA) was placed incrementally or in bulk into Class 2 preparations in extracted human molar teeth and exposed to various light-curing energy densities. The restorations were subjected to 1000 thermal cycles (5-55 degrees C) and 500,000 fatigue cycles from 18 to 85 N using a stainless-steel sphere. Marginal integrity was evaluated using visual rating (ridit analysis) and microleakage. Degree of conversion (DC) and Knoop hardness (KHN) were determined at the occlusal and gingival surfaces using a reusable tooth template with identical preparation dimensions. Percentage of maximum DC and KHN were determined. Mechanical properties were tested in resin composite bars having similar KHN values as the resin composite at the gingival margins.
Energy density had a significant effect on gingival marginal defects as determined by ridit analysis but not on microleakage. Water had a significant dissolving effect on gingival margin integrity at very low degrees of conversion and energy densities (4000 mJ/cm2). There was no overall significant effect of thermal-mechanical stressing on gingival marginal defects or microleakage.
Based on ridit analysis, a recommended lower limit of gingival margin acceptability in the bulk-filled Z250 resin composite restoration was created by 80% of maximum conversion, 73% of maximum hardness and approximately 70% of maximum flexural strength and modulus in the gingival marginal area.
本研究的目的是确定美国明尼苏达州圣保罗市3M ESPE公司的Z250类树脂复合材料修复体底部所需的最小固化程度，使其能够支撑修复体的其余部分，并在模拟临床条件下保持其边缘封闭性。
将树脂复合材料（Z250，3M ESPE，美国明尼苏达州圣保罗市）逐层或整体填入拔除的人类磨牙的二类洞型中，并暴露于各种光固化能量密度下。修复体经受1000次热循环（5-55摄氏度）和使用不锈钢球从18至85 N的500,000次疲劳循环。使用视觉评级（ridit分析）和微渗漏评估边缘完整性。使用具有相同制备尺寸的可重复使用的牙齿模板在咬合面和牙龈表面测定转化率（DC）和努氏硬度（KHN）。确定最大DC和KHN的百分比。在牙龈边缘处具有与树脂复合材料相似KHN值的树脂复合材料棒中测试机械性能。
如ridit分析所确定，能量密度对牙龈边缘缺陷有显著影响，但对微渗漏没有影响。在非常低的转化率和能量密度（4000 mJ/cm2）下，水对牙龈边缘完整性有显著的溶解作用。热机械应力对牙龈边缘缺陷或微渗漏没有总体显著影响。
基于ridit分析，在整体填充的Z250树脂复合材料修复体中，牙龈边缘可接受性的推荐下限是牙龈边缘区域最大转化率的80%、最大硬度的73%以及最大弯曲强度和模量的约70%。
