University of Sheffield, Adult Dental Care, School of Clinical Dentistry, Claremont Crescent, Sheffield, United Kingdom.
Oper Dent. 2009 Nov-Dec;34(6):741-5. doi: 10.2341/09-024-L.
This study investigated the influence of a disposable light cure sheath on both the surface hardness and hardness at varying thicknesses of resin composite.
A series of resin composite discs (Spectrum) were fabricated with varying depths up to 6 mm. The light curing units used were a standard halogen unit (Elipar Trilight) and an LED unit (Elipar Freelight 2). Recommended curing times from the manufacturer were followed. The disposable light-curing sheath (Cure Sleeve) was used with both light-curing units. Two additional groups without the sheath were employed as controls. Each specimen (n = 4) was subjected to hardness testing to evaluate hardness from 0 mm to 5 mm thick. A 200g load was applied for 10 seconds using a Vickers diamond indenter and six indentations were obtained from each specimen. Statistical analysis was performed using two-way ANOVA.
The LED without a sheath achieved the highest surface hardness value (47.2 VHN +/- 5.5). There was no significant difference between the groups regarding surface hardness (p > 0.05). As the thicknesses of the resin composite increased, the hardness values decreased in all groups. The LED light curing unit, in combination with a sheath, demonstrated the lowest hardness values at a 5 mm thickness of resin composite (p < 0.05).
All four different methods of light curing resulted in a significant reduction in hardness values with increasing resin composite thickness, which could compromise the mechanical properties of the resin composite. However, the use of the light cure sheaths still provided an acceptable depth of cure when used following the 2 mm increment rule. It was not until 3 mm that the use of the light cure sheaths compromised the hardness results. It is recommended that the curing depth should not exceed 2 mm, regardless of light curing method.
本研究旨在探讨一次性光固化护套对树脂复合材料表面硬度和不同厚度硬度的影响。
制备了一系列深度达 6mm 的树脂复合材料圆盘（Spectrum）。使用的光固化单元为标准卤素单元（Elipar Trilight）和 LED 单元（Elipar Freelight 2）。按照制造商的建议固化时间进行操作。使用一次性光固化护套（Cure Sleeve）与两种光固化单元配合使用。另外两个没有护套的组作为对照组。每个样本（n=4）均进行硬度测试，以评估从 0mm 到 5mm 厚的硬度。使用维氏金刚石压头施加 200g 载荷 10 秒，从每个样本中获得六个压痕。使用双因素方差分析进行统计分析。
无护套的 LED 达到最高的表面硬度值（47.2VHN +/- 5.5）。各组之间的表面硬度无显著差异（p > 0.05）。随着树脂复合材料厚度的增加，所有组的硬度值均降低。LED 光固化单元与护套结合使用时，在树脂复合材料 5mm 厚度时显示出最低的硬度值（p < 0.05）。
四种不同的光固化方法均导致树脂复合材料厚度增加时硬度值显著降低，这可能会影响树脂复合材料的机械性能。然而，使用光固化护套仍能在遵循 2mm 增量规则的情况下提供可接受的固化深度。只有当使用 3mm 护套时，才会影响硬度结果。建议无论使用何种光固化方法，固化深度均不应超过 2mm。
