A Confocal Microscopic Evaluation of the Dehydration Effect on Conventional, Resin Reinforced Powder/Liquid and Paste to Paste Glass Ionomer Luting Cements

BACKGROUND The purpose of this study was to evaluate the effect of dehydration of resin-modified glass ionomer powder/liquid system, resin-modified glass ionomer paste/paste luting cements in three different quantities and to compare them with a conventional glass ionomer luting cement using confocal laser scanning microscope. MATERIALS AND METHODS A conventional glass ionomer (Group I), a resin modified powder/liquid system (Group II), and a resin-modified paste/paste system (Group III) were selected for the study. In Group III, there were three subgroups based on the quantity of material dispensed. 50 premolar teeth were selected and randomly divided among the groups with 10 samples in each. The teeth were ground flat to expose a flat occlusal dentin. A device was made to standardize the thickness of cement placed on the teeth. The teeth were stored in distilled water for 24 h and then longitudinally sectioned to examine the tooth dentin interface under a confocal microscope. The specimens were allowed to dehydrate under the microscope for different time intervals. The width of the crack after dehydration near the dentinal interface was measured at definite intervals in all the groups and analyzed statistically using Student's t-test. RESULTS Conventional glass ionomer cement showed the maximum width of the crack followed by resin modified paste/paste system during the dehydration period. Resin modified powder/liquid system did not show cohesive failure. CONCLUSIONS Conventional glass ionomer luting cement is more susceptible to cohesive failure when subjected to dehydration compared to resin-modified glass ionomer paste/paste luting cement. Among the luting cements, resin-modified glass ionomer powder/liquid system showed the best results when subjected to dehydration.