Bouschlicher M R, Vargas M A, Boyer D B
Department of Operative Dentistry, College of Dentistry, University of Iowa, Iowa City 52242-1001, USA.
Am J Dent. 1997 Apr;10(2):88-96.
To investigate the effect of composite type, light intensity, configuration factor and laser polymerization on polymerization contraction force.
Glass rods (10 pairs/group) were etched with HF acid, silanated, unfilled resin applied and light cured for 20 s. Rods were held vertically in chucks on a Zwick machine. A cylindrical matrix was filled with Silar chemical cure, Silux Plus microfill or Z-100 hybrid composite and the crosshead of the UTM positioned at an inter-rod distance corresponding to a specific ratio of bound to unbound composite surface area (configuration factor or C). Exposure time with the Demetron 401 conventional visible light curing unit (D401) was 40 s/side (80 s total). Exposure times for the ILT Model D5500 air cooled laser (LAC) and Model 5500ABL water cooled laser (LWC) was 20 s/side (40 s total). Experimental groups, n = 10 with constant factors in parentheses, included: (1) Silar chemical-cured (C = 3); (2) Z-100 hybrid (C = 3, D401, 100% intensity); (3) Silux Plus microfill (C = 3, D401, 100% intensity); (4) D401 100% light intensity = 476 mW (Z-100, C = 3, D401); (5) D401 50% intensity = 238 mW (Z-100, C = 3, D401); (6) D401 25% intensity = 119 mW (Z-100, C = 3, D401); (7-9) C = 5, 3 & 1 respectively (Z-100, D401, 100% intensity); (10) D401 with 13 mm tip = 391 mW/cm2 (Z-100, C = 3; D401); (11) D401 with Turbo Tip = 811 mW/cm2 (Z-100, C = 3; D401); (12) LAC = 265 mW, 689 mW/cm2 (Z-100, C = 3); (13) LWC = 365 mW, 1100 mW/cm2 (Z-100, C = 3). One Way ANOVA and Duncan's Multiple Range Test (alpha = 0.05) were performed separately for each variable.
Homogeneous subsets by variable were: composite type Group 1 (25N) < Group 3 (65.8N) < Group 2 (90.4N); intensity Group 6 (73.9N) = Group 5 (77.7N) < Group 4 (90.4N); C-Factor Group 7 (81.8N) < Group 8 (90.4N) < Group 9 (103.4N); light source Group 12 (77.4N) = Group 13 (79.1N) < Group 10 (90.4N) = Group 11.(89.4N). The chemical-cured composite had the lowest maximum polymerization contraction force, the microfill was intermediate and the hybrid composite had the highest recorded force. Increases in light intensity increased the maximum force on the force/time curve. Maximum forces were inversely related to C-factor (C5 < C3 < C1) and directly related to composite volume in a non-rigid system which allowed compliance. Maximum force was not significantly different with the two tips tested on the conventional curing light. Forces obtained with laser polymerization were similar for the two laser groups, which were both statistically lower than the conventional light tested.
研究复合材料类型、光强度、形态因子和激光聚合对聚合收缩力的影响。
用氢氟酸蚀刻玻璃棒（每组10对），进行硅烷化处理，涂抹未填充树脂并光固化20秒。将棒垂直固定在Zwick机器的卡盘上。用Silar化学固化材料、Silux Plus微填料或Z - 100混合复合材料填充圆柱形模具，并将万能材料试验机的十字头定位在棒间距离处，该距离对应于结合与未结合复合材料表面积的特定比例（形态因子或C）。使用Demetron 401传统可见光固化装置（D401）的曝光时间为每侧40秒（共80秒）。ILT D5500风冷激光（LAC）和5500ABL水冷激光（LWC）的曝光时间为每侧20秒（共40秒）。实验组，n = 10，括号内为恒定因素，包括：（1）Silar化学固化（C = 3）；（2）Z - 100混合材料（C = 3，D401，100%强度）；（3）Silux Plus微填料（C = 3，D401，100%强度）；（4）D401 100%光强度 = 476 mW（Z - 100，C = 3，D401）；（5）D401 50%强度 = 238 mW（Z - 100，C = 3，D401）；（6）D401 25%强度 = 119 mW（Z - 100，C = 3，D401）；（7 - 9）C分别为5、3和1（Z - 100，D401，100%强度）；（10）带13毫米尖端的D401 = 391 mW/cm²（Z - 100，C = 3；D401）；（11）带Turbo尖端的D401 = 811 mW/cm²（Z - 100，C = 3；D401）；（12）LAC = 265 mW，689 mW/cm²（Z - 100，C = 3）；（13）LWC = 365 mW，1100 mW/cm²（Z - 100，C = 3）。对每个变量分别进行单因素方差分析和邓肯多重范围检验（α = 0.05）。
按变量划分的同质子集为：复合材料类型 第1组（25N）<第3组（65.8N）<第2组（90.4N）；强度 第6组（73.9N）=第5组（77.7N）<第4组（90.4N）；C因子 第7组（81.8N）<第8组（90.4N）<第9组（103.4N）；光源 第12组（77.4N）=第13组（79.1N）<第10组（90.4N）=第11组（89.4N）。化学固化复合材料的最大聚合收缩力最低，微填料居中，混合复合材料记录的力最高。光强度增加会使力/时间曲线上的最大力增加。最大力与C因子成反比（C5 < C3 < C1），并且在允许顺应性的非刚性系统中与复合材料体积成正比。在传统固化光上测试的两种尖端所获得的最大力没有显著差异。两个激光组通过激光聚合获得的力相似，且在统计学上均低于测试的传统光。
