EFFECT OF THERMOCYCLING ON THE MICROLEAKAGE OF CONVENTIONAL AND RESIN-MODIFIED GLASS IONOMERS

Purpose: To compare the effect of thermocycling on the microleakage of conventional and resin modified glass ionomer restorative materials. Materials and Methods: Class V preparations, centered on the CEJ, were prepared on the lingual and facial surfaces of 30 extracted human thi rd molar teeth. Preparations were conditioned and restored randomly on one surface with Ketac-Fil and on the other surface with Photac-Fil. Restorations were protected during curing, finishing, and storage with Ketac-Glaze. Specimens were aged in room temperature distilled water for 7 days. Half of the specimens were thermocycled for 2,500 cycles i n 5 degrees-55 degrees water baths with 5-second dwell times. All spec imen apices were sealed with red compound, occlusal fissures sealed wi th pit/fissure sealant, and surfaces painted to within 1.5 mm of resto ration margins with red nail polish. Specimens were stained with 5% me thylene blue, invested in orthodontic resin, and sectioned faciolingua lly. The percentage of dye penetration along the tooth restoration int erface was measured with a digital imaging system. Results: Statistica l analysis showed that neither thermocycling or type of material had a significant effect on dye penetration (P>0.5).