Ernst Claus-Peter, Brand Nicole, Frommator Ulrike, Rippin Gerd, Willershausen Brita
Department of Operative Dentistry, Johannes Gutenberg University, Mainz, Germany.
J Esthet Restor Dent. 2003;15(2):93-103; discussion 104. doi: 10.1111/j.1708-8240.2003.tb00323.x.
This study evaluated the influence of a soft-start light-curing exposure on polymerization shrinkage stress and marginal integrity of adhesive restorations.
Six resin-based composites (Pertac II, Tetric Ceram, Definite, Surefil, Solitaire, and Visio-Molar) were adhesively bonded to a cylindrical cavity (n = 9 per material/light) in a photoelastic material. Visible light-curing was applied using either the standard polymerization mode (800 mW/cm2 exposure duration 40 s) of the curing light (Elipar TriLight, 3M ESPE) or the exponential mode from the same device (ramp-curing: 150 mW/cm2 to 800 mW/cm2 within the first 15 s of a total curing time of 40 s). Polymerization stress was calculated at 5 minutes, 1 hour, and 24 hours postexposure from the second-order isochromatic curves obtained from photoelastic images (Matrox-Inspector). Two standardized Class V preparations were made each on the facial and lingual surfaces of 80 extracted human molars and premolars. Resin restorative systems (Pertac II/EBS Multi, Tetric Ceram/Syntac, Definite/Etch&Prime 3.0, and Surefil/Prime & Bond 2.1) were exposed using both light exposure modes (n = 20). Marginal dye penetration (2% methylene blue) was investigated separately for enamel and cementum margins after thermocycling. To obtain information on equivalent depth of cure, relative surface hardness measurements were performed on resin samples of the same material at the top surface and at 1.5 mm and 3.0 mm thickness (Zwick 3212, 10 N).
A significant (p < .01) reduction in polymerization stress of 7.1% for Pertac II, 4.1% for Tetric Ceram, 3.6% for Definite, 3.7% for Surefil, and 6.2% for Solitaire was observed when using the exponential mode as opposed to the standard. A significant (p = .04) reduction of marginal dye penetration was found only for Pertac II/EBS Multi at the cementum margins when the soft-start polymerization was used. For the sample thickness of 3 mm, a significant higher relative bottom to top surface ratio in favor of the standard exposure mode was found (p = .001).
Depending on the restorative material, soft-start polymerization may lead to a significant reduction in marginal microleakage of adhesive Class V restorations. This effect might be attributable to a significantly lower polymerization stress, as seen from photoelastic analysis, and/or a decrease in the degree of conversion, as deducted from surface hardness ratios. However, the effect of soft-start curing mode depends on the material itself, with the most effective response from hybrid resin-based composites.
本研究评估了软启动光固化照射对粘结修复体聚合收缩应力和边缘完整性的影响。
将六种树脂基复合材料（Pertac II、Tetric Ceram、Definite、Surefil、Solitaire和Visio-Molar）粘结到光弹性材料中的圆柱形窝洞（每种材料/光照条件下n = 9）。使用固化灯（3M ESPE公司的Elipar TriLight）的标准聚合模式（800 mW/cm²，照射持续时间40 s）或同一设备的指数模式（斜坡固化：在40 s总固化时间的前15 s内从150 mW/cm²升至800 mW/cm²）进行可见光固化。从光弹性图像（Matrox-Inspector）获得的二阶等色曲线计算曝光后5分钟、1小时和24小时的聚合应力。在80颗拔除的人类磨牙和前磨牙的颊面和舌面各制作两个标准化的V类洞型。使用两种光照模式（n = 20）对树脂修复系统（Pertac II/EBS Multi、Tetric Ceram/Syntac、Definite/Etch&Prime 3.0和Surefil/Prime & Bond 2.1）进行照射。热循环后分别研究釉质和牙骨质边缘的边缘染料渗透情况（2%亚甲蓝）。为了获得固化等效深度的信息，对相同材料的树脂样品在顶面、1.5 mm和3.0 mm厚度处进行相对表面硬度测量（Zwick 3212，10 N）。
与标准模式相比，使用指数模式时，Pertac II的聚合应力显著降低（p <.01）7.1%，Tetric Ceram降低4.1%，Definite降低3.6%，Surefil降低3.7%，Solitaire降低6.2%。当使用软启动聚合时，仅在牙骨质边缘的Pertac II/EBS Multi发现边缘染料渗透显著降低（p =.04）。对于3 mm的样品厚度，发现标准照射模式下相对底面与顶面的比率显著更高（p =.001）。
根据修复材料的不同，软启动聚合可能会显著降低粘结V类修复体的边缘微渗漏。这种效果可能归因于光弹性分析显示的显著较低的聚合应力，和/或从表面硬度比率推断的转化率降低。然而，软启动固化模式的效果取决于材料本身，混合树脂基复合材料的反应最为显著。
