Lindberg Anders, Peutzfeldt Anne, van Dijken Jan W V
Public Dental Health Clinic, Seminariegatan, Skellefteå, Sweden.
Clin Oral Investig. 2005 Jun;9(2):71-6. doi: 10.1007/s00784-005-0312-9. Epub 2005 Apr 7.
This in vitro study compared the depth of cure obtained with six quartz tungsten halogen and light-emitting diode curing units at different exposure times and light tip-resin composite distances. Resin composite specimens (Tetric Ceram, A3; diameter 4 mm, height 6 mm) were exposed from 0-, 3-, and 6-mm distance. The curing units (200-700 mW/cm2) were used for standard (20 and 40 s), pulse-delay mode (initial exposure of 3 s at 200 mW/cm2, followed by a resting period of 3 min and a final exposure of 10 or 30 s at 600 mW/cm2), or soft-start curing (40 s; exponential ramping). Curing depth was determined by measurement of Wallace hardness for each half millimeter starting at 0.5 mm from the top surface. For each specimen, a mean H(W) value was calculated from the H(W) values determined at the depths of 2.0 mm and less (0.5, 1.0, 1.5, and 2.0 mm, respectively). The depth of cure for each specimen was found by determining the greatest depth before an H(W) value exceeding the minimal H(W) value by 25% occurred. For all curing units, an increase in exposure time led to significantly higher depth of cure. Increasing the light tip-resin composite distance significantly reduced the depth of cure. With a light tip-resin composite distance of 6 mm, median values of depth of cure varied between 2.0 and 3.5 mm following a 20-s (or 3+10 s) exposure and between 3.0 and 4.5 mm following a 40-s (or 3+30 s) exposure. The composite situated above the depth of cure value cured equally well with all curing units. At both exposure times, Luxomax resulted in the significantly lowest depth of cure, and Astralis 7 yielded significantly higher depth. At both exposure times, a significant linear correlation was found between the determined power densities of the curing units and the pooled depth of cure values obtained. It seems that for the resin composite tested, the recommended exposure time of 40 s per 2-mm increment may be reduced to 20 s, or that increments may be increased from 2 to 3.5 mm. It may be that the absolute values of depth of cure found are material specific, but we believe that the relationships found between curing units, between exposure times, and between light guide distances are universal.
这项体外研究比较了6种石英钨卤素灯和发光二极管固化设备在不同曝光时间及光尖端与树脂复合材料距离条件下的固化深度。树脂复合材料样本（Tetric Ceram，A3；直径4毫米，高6毫米）在距离为0毫米、3毫米和6毫米处接受照射。固化设备（功率200 - 700毫瓦/平方厘米）用于标准模式（20秒和40秒）、脉冲延迟模式（初始以200毫瓦/平方厘米照射3秒，接着3分钟的静置期，最后以600毫瓦/平方厘米照射10秒或30秒）或软启动固化（40秒；指数递增）。从距离顶面0.5毫米处开始，每隔半毫米测量华莱士硬度来确定固化深度。对于每个样本，从在2.0毫米及以下深度（分别为0.5毫米、1.0毫米、1.5毫米和2.0毫米）处测定的H(W)值计算出平均H(W)值。通过确定在H(W)值超过最小H(W)值25%之前的最大深度来找出每个样本的固化深度。对于所有固化设备，曝光时间增加会导致固化深度显著增加。光尖端与树脂复合材料距离增加会显著降低固化深度。在光尖端与树脂复合材料距离为6毫米时，20秒（或3 + 10秒）曝光后固化深度的中位数在2.0至3.5毫米之间，40秒（或3 + 30秒）曝光后在3.0至4.5毫米之间。位于固化深度值以上的复合材料用所有固化设备固化效果相同。在两个曝光时间下，Luxomax的固化深度显著最低，而Astralis 7的固化深度显著更高。在两个曝光时间下，所测定的固化设备功率密度与获得的合并固化深度值之间均发现显著的线性相关性。对于所测试的树脂复合材料，似乎每2毫米增量推荐的40秒曝光时间可减至20秒，或者增量可从2毫米增加到3.5毫米。所发现的固化深度绝对值可能因材料而异，但我们认为在固化设备之间以及曝光时间和光导距离之间所发现的关系具有普遍性。
