EFFECT OF CO-CURING ON SEALING ABILITY AND SHEAR BOND STRENGTH OF RESIN COMPOSITE TO DENTIN

Abstract

This study was designed to compare between two curing techniques, conventional and co-curing, by evaluating the effect of each of them on the sealing ability and shear bond strength of resin composite to dentin after aging periods of 3 and 6 months. Two dentin bonding systems, SBMP and PL, representing the fourth and the sixth generation respectively were used. One type of resin composite, Z/100, was utilized in this study. 120 sound human molars were utilized, 60 for each bonding

system. Each group was further subdivided into 3 subgroups, 20 specimens each, relative to the test parameter used. Each subgroup was further classified into 2 classes, 10 specimens each, whether they were conventionally cured or co-cured. For the micro leakage and SEM testing, specimens of each class were further sub classified into 2 subclasses, 5 specimens each, relative to the test period either 3 months or 6 months. They were stored in distilled water. The specimens for the shear push-out test were subjected to thermo cycling and mechanical loading respective to each test interval. Three test parameters of micro­ leakage, ultra structure morphology and shear bond strength were performed.

For the sealing ability examination, buccal square class V cavities were prepared, restored and aged in distilled water. Teeth for micro­ leakage study were immersed in 1% methylene blue dye for 24 hours, rinsed and sectioned bucco-lingually into two halves. The dye penetration was measured according to a scoring system ranging from 0- 3. Scanning Electron Microscope was used to analyze the ultra-structure Morphology of tooth/restoration interface.