To evaluate the effect of shef life on depth of cure of polyacid-modified composite - an in vitro study

ABSTRACT

The present study aimed to compare the curing depth of chemically similar Polyacid-modified composite resins [PAM-C] having different expiry periods. The curing depth of the PAM-C, Dyract Extra [Dentsply, U.K.] was determined for a near expiry and a long expiry material using a scraping method based on ISO 40492000. Samples were light-cured [800 mW/cm[2] at 40 seconds] in plastic mould. Immediately after light-curing the cylinder shaped material was removed from the mould, height of the cylinder of cured material was measured by using digital caliper and taken as the curing depth. The means of the curing depth of two materials were subjected to two sample independent t test using SPSS. The mean value of depth of cure for near expiry PAM-C [Group-A] was 6.389 mm [sd +/- .202] and that of long expiry material PAM-C [Group-B] was 7.087 mm [sd +/- .149]. The curing depth differed significantly between the materials of the two groups [P<0.001]. The curing depth greatly varies between the materials. It may be inferred that the curing depth of the two assigned groups of PAM-Cs depend on the period of expiry of the material: