不同充填方式对复合树脂在盒形洞壁产生收缩应力的影响

Effect of filling techniques of composite resin on the shrinkage stress on the wall of box cavity

目的:观察不同充填固化方式对复合树脂在盒形洞壁产生收缩应力的影响。方法:在厚度为4 mm、边长4 cm的聚碳酸酯板上制备直径4 mm、深3 mm的窝洞,涂布粘结剂后分别以4种充填固化方式充填复合树脂(卡瑞斯玛):①整体充填,照射40 s;②水平2层充填,每层照射20 s;③水平3层充填,每层照射20 s;④斜向3层充填,每层照射20 s。分别于照射后3 min、24 h在显微光弹仪上观测窝洞周围应力等差条纹的直径,计算出洞壁承受的收缩应力。结果:所有充填方式组固化后24 h的收缩应力均显著大于其固化后3 min的应力(P<0.05);不同充填方式组间比较,无论是固化后3 min,还是24 h,均以斜向3层充填组的收缩应力最小,分别与其他各组相比差异均有统计学意义(P<0.05);其次是水平3层充填固化组,显著小于整体充填固化组和水平2层充填组(P<0.05);整体充填固化组收缩应力最大,但与水平2层充填组相比无统计学差异(P>0.05)。结论:分层充填能够降低盒形洞壁的收缩应力,其中斜向分层充填的效果最好。

AIM： To compare the effect of filling techniques of composite resin on the shrinkage stress on the wall of box cavity. METHODS： 40 box cavities of 4 mm in diameter and 3mm in depth were prepared in polycar bonate （PC） plates with the thickness of 4 mm. After application of an adhesive, composite resin was placed into the cavities by four techniques ： ①bulk filling and light-curing for 40 s ; ② two horizontal layers with light-curing for 20 s for each layer; ③ three horizontal layers with light-curing for 20 s for each layer; @ three oblique layers with light curing for 20 s for each layer. Photoelastic images were recorded at 3 rain and 24 h after curing in a photoelastic work station and the shrinkage stresses on the wall of box cavities were calculated. RESULTS ： The shrinkage stresses tested at 24 h were higher than that at 3 min for all cavities（ P 〈 0.05 ）. The three oblique layers produced the least shrinkage stresses, followed by three horizontal layers （P 〈 0. 05 ）. Bulk filling produced the greatest shrinkage stresses （ P 〈 0.05 ） , but showed no statistical difference with two horizontal layer filling. CONCLUSION ： Incremental filling technique can decrease the shrinkage stress on the wall of box cavity, which is affected by the thickness and shape of each increment. Oblique layering is a better incremental filling technique.