El-Mowafy Omar, El-Badrawy Wafa, Wasef Mira, Omar Hanan, Kermanshahi Sanaz
Department of Clinical Sciences, Faculty of Dentistry, University of Toronto, 124 Edward St., Toronto, ON M5G 1G6.
J Can Dent Assoc. 2007 Apr;73(3):253.
The aim of this study was to determine the efficacy of new light-emitting diode (LED) curing units in the hardening of Class II composite restorations.
Disk specimens 2 mm in diameter and 2.5 mm thick were prepared from 2 composites (Vit-l-escence, shade A3, Ultradent; Herculite XRV, shade A2, Kerr) in the following manner. An extracted permanent molar tooth was prepared to receive a Class II restoration with proximal slot only. The tooth was sectioned horizontally on a plane above the gingival floor level such that the remaining depth of the proximal box was 4 mm. A Tofflemire matrix band and retainer were secured around the tooth. Composite specimens were placed below the tooth to coincide with the location of the slot opening at the bottom of the gingival floor. The specimens were subjected to light polymerization with various combinations of curing cycle and light unit: 1 of 3 continuous curing cycles (20 seconds, 40 seconds or 60 seconds) and 1 of 2 LED units (Utralume-5, Ultradent; IQ Smartlite, Dentsply) or a control quartz-tungsten-halogen (QTH) unit (Optilux 501, Kerr). Specimens were stored at 37 degrees C for 24 hours. A hardness tester was used to obtain 4 measurements of Knoop hardness number (KHN) for each surface (upper and lower) of each specimen. Relative hardness (RH) was calculated as the KHN of the lower surface divided by the KHN of the upper surface. Data were analyzed with analysis of variance (ANOVA) and Tukey"s test.
ANOVA indicated significant differences in mean RH among the groups (p < 0.001). RH increased with increasing curing time. For the 60-second cycle with Vit-l-escence composite, mean RH was 0.47, 0.25 and 0.39 for the Ultralume-5, IQ Smartlite and Optilux 501 curing units, respectively. For the 60-second cycle with Herculite XRV composite, mean RH was 0.71, 0.81 and 0.56 for the Ultralume-5, IQ Smartlite and Optilux 501 curing units, respectively.
In general, the 2 LED units performed as well as the QTH unit; however, brand of composite and curing cycle had significant effects on RH values.
本研究的目的是确定新型发光二极管（LED）固化灯对Ⅱ类复合树脂修复体固化的效果。
用两种复合树脂（Vit-l-escence，A3色，Ultradent公司；Herculite XRV，A2色，Kerr公司）按以下方式制备直径2mm、厚2.5mm的圆盘状试件。选取一颗拔除的恒牙，仅制备近中Ⅱ类洞形。在龈缘上方水平切割该牙，使近中盒剩余深度为4mm。在牙周围固定一个托菲米尔成形片夹。将复合树脂试件置于牙下方，与龈缘底部的洞开口位置对齐。对试件采用不同固化周期和固化灯的组合进行光聚合：3种连续固化周期（20秒、40秒或60秒）中的1种，以及2种LED固化灯（Utralume-5，Ultradent公司；IQ Smartlite，登士柏公司）中的1种或对照石英钨卤素（QTH）固化灯（Optilux 501，Kerr公司）。试件在37℃下储存24小时。使用硬度测试仪对每个试件的每个表面（上表面和下表面）进行4次努氏硬度值（KHN）测量。相对硬度（RH）计算为下表面的KHN除以上表面的KHN。数据采用方差分析（ANOVA）和Tukey检验进行分析。
方差分析表明各组间平均RH存在显著差异（p<0.001）。RH随固化时间的增加而增加。对于Vit-l-escence复合树脂的60秒固化周期，Ultralume-5、IQ Smartlite和Optilux 501固化灯的平均RH分别为0.47、0.25和0.39。对于Herculite XRV复合树脂的60秒固化周期，Ultralume-5、IQ Smartlite和Optilux 501固化灯的平均RH分别为0.71、0.81和0.56。
总体而言，两种LED固化灯的效果与QTH固化灯相当；然而，复合树脂品牌和固化周期对RH值有显著影响。
