Cehreli Murat C, Canay Senay
Faculty of Dentistry, Hacettepe University, Gazi Mustafa Kenal Bulvari, 61/11, TR 06570 Maltepe, Ankara, Turkey.
J Prosthet Dent. 2002 Nov;88(5):461-6. doi: 10.1067/mpr.2002.129080.
Polymerization shrinkage is associated with light-polymerized and polyacid-modified composites.
This in vitro study compared the polymerization shrinkage of a light-polymerized hybrid composite, a posterior composite, and a polyacid-modified composite.
Five disk-shaped specimens (1 cm in diameter and 2 mm in thickness) were prepared in a mold from each of the following test materials: a light-polymerized hybrid composite (3M Valux Plus), a posterior composite (Filtek P60), and a polyacid-modified composite (Dyract AP). The hybrid composite served as the control material. A linear strain gauge was placed at the center of each specimen. After the specimens were light-polymerized for 60 seconds under 400-mW/cm(2) light intensity, microstrains were recorded with the strain indicator continuously every 4 seconds for 120 seconds. The data were evaluated with 1-way analysis of variance (P<.05) followed by a post hoc least significant difference test.
During the first 20 seconds of light polymerization, all materials exhibited tensile strains between 6 and 55 mu epsilon that quickly converted into compressive strains and continued rising after the light source was removed. The strains for all materials increased at a declining rate until they reached a constant level between 148 and 180 seconds. The polymerization shrinkage recorded for Filtek P60 was the lowest (-190.56 mu epsilon), followed by 3M Valux Plus (-303.94 mu epsilon) and Dyract AP (-345.64 mu epsilon) (P<.05). The dimensional change between Filtek P60 and Dyract AP and between Filtek P60 and 3M Valux Plus was significant (P=.001). However, the difference between Dyract AP and 3M Valux Plus specimens was not significant (P=.208).
Within the limitations of this study, the light-polymerized posterior composite tested demonstrated less polymerization shrinkage than the polyacid-modified and hybrid composites tested. Polymerization shrinkage velocity significantly affected the magnitude of strains.
聚合收缩与光固化复合树脂及含氟复合树脂有关。
本体外研究比较了光固化混合型复合树脂、后牙复合树脂和含氟复合树脂的聚合收缩。
从以下每种测试材料中在模具中制备五个圆盘形试件（直径1cm，厚度2mm）：光固化混合型复合树脂（3M Valux Plus）、后牙复合树脂（Filtek P60）和含氟复合树脂（Dyract AP）。混合型复合树脂作为对照材料。在每个试件中心放置一个线性应变仪。试件在400mW/cm(2)光强下光固化60秒后，用应变指示器每4秒连续记录微应变，共记录120秒。数据采用单因素方差分析（P<.05）进行评估，随后进行事后最小显著差检验。
在光固化的前20秒内，所有材料均表现出6至55με的拉伸应变，这些应变迅速转变为压缩应变，并在光源移除后继续上升。所有材料的应变以递减速率增加，直到在148至180秒之间达到恒定水平。Filtek P60记录的聚合收缩最低（-190.56με），其次是3M Valux Plus（-303.94με）和Dyract AP（-345.64με）（P<.05）。Filtek P60与Dyract AP之间以及Filtek P60与3M Valux Plus之间的尺寸变化具有显著性（P=.001）。然而，Dyract AP与3M Valux Plus试件之间的差异不显著（P=.208）。
在本研究的局限性内，所测试的光固化后牙复合树脂表现出比所测试的含氟复合树脂和混合型复合树脂更小的聚合收缩。聚合收缩速度显著影响应变的大小。
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