光功率密度对光固化复合树脂耐老化性能的影响

摘要

目的:比较不同引发光功率密度对光周化复合树脂耐老化性能的影响.方法:选择光功率密度不同的3种引发固化光模式:(1)模式A,低光功率密度500 mW/cm2,22 s;(2)模式B,高光功率密度1100 mW/cm2,10 s;(3)模式C,渐强式光功率密度,0～650 mW/cm2,5 s,1 100 mW/cm2,8.5 s.3种模式总能量密度均为11 J/cm2.用不同光引发模式同化复合树脂样本,随机分为4绀(n=15),其中3组进行老化,分别浸泡于乙醇中24 h、7 d和30 d.对照组为纯水浸泡24 h.使用显微硬度仪测量样本表面维氏(VHN)硬度.同时使用Acuvol聚合收缩仪测定不同光功率密度引发光固化复合树脂的聚合收缩率(n=7).结果:不同引发光功率密度同化复合树脂的表面硬度为模式A 44.26±6.16,模式B 42.31±2.33,模式C 45.60±2.76.乙醇老化24 h后,树脂表面硬度均有明显下降(P<0.05).模式A(31.83 ±2.90)和模式C(32.13±2.77)固化后树脂表面硬度明显低于模式B(36.14±2.65)(P<0.05).乙醇继续老化7 d后,所有样本表面硬度继续降低(P<0.05),模式A降低为28.36 ±2.35,模式B降低为27.80 ±1.19,模式C降低为28.20±0.97,但三者之间差异无统计学意义(P>0.05).乙醇老化30 d后,样本表面硬度不再继续降低,与7 d组相比差异无统计学意义(P>0.05),表面硬度值为模式A 28.53±0.86,模式B 28.55±1.53,模式C 29.08±1.60.不同光功率密度模式固化复合树脂的聚合收缩率分别为模式A2.67%±0.28%,模式B 2.76%±0.29%,模式C2.73%±0.06%,差异无统计学意义(P>0.05).结论:光能量密度一致时,引发光功率密度对光固化复合树脂聚合收缩无显著影响,对树脂耐老化性能的影响与老化作用时间相关.%Objective:The purpose of this study was to investigate the effect of light power density on anti-aging property of composite resins. Methods: Three light curing modes with different power density (1. Mode A: low power density, 500 mW/cm2 for 22 s; 2. Mode B: high power density, 1 100 mW/ cm2 for 10 s; 3. Mode C: gradually enhanced power density, 0 ～650 mW/cm2 for 5 s + 1 100 mW/cm2 for 8.5 s) were used. The total energy density of these modes was all 11 J/cm2. Composite resin specimens were cured with three light curing modes respectively and divided into 4 groups randomly ( n= 15 ).Three groups were reserved in absolute ethanol for 24 h, 7 d and 30 d respectively for aging and one group was stored in water for 24 h as control. Vicker hardness (VHN) was measured with microhardness tester. Volumetric shrinkage was measured with Acuvol (n= 7 ). Results: The hardness of three light curing modes was: Mode A 44.26 ±6.16, Mode B 42.31 ±2.33 and Mode C 45.60 ±2.76. After aging in ethanol for 24 h, the hardness of all composites specimen decreased (P ＜ 0.05). Samples cured by Mode A (31.83 ±2.90) and Mode C (32.13 ±2.77) showed significantly lower hardness than Mode B (36.14 ± 2.65) (P ＜ 0.05 ). After aging in ethanol for 7 d, the hardness of composites continuously decreased (P ＜ 0.05) and was: Mode A 28.36 ± 2.35, Mode B 27.80 ± 1.19 and Mode C 28.20 ± 0.97. There was no significant difference among three curing modes ( P ＞ 0.05 ). The hardness of samples stored in ethanol for 30 d was no longer decreased and was: Mode A 28.53 ± 0.86, Mode B 28.55 ± 1.53 and Mode C 29.08 ± 1.60. There was no significant difference between composite specimen stored for 7 d and 30 d (P ＞0.05). The polymerization shrinkage of composite resin was: Mode A 2.67％ ± 0.28％, Mode B 2.76％ ± 0.29％ and Mode C 2.73％ ± 0.06％. No significant difference existed among polymerization shrinkage of composites cured by the three light curing modes with different power density (P ＞ 0.05 ). Conclusion: The power density of curing light affected the anti-aging property of composite resin which was aging time dependent. The polymerization shrinkage was not affected by light power density with same energy density.