Comparative evaluation of the microleakage of metal crowns cemented with two different luting agents : IN VITRO STUDY

Microleakage and marginal opening are related to most of the fixed restoration failures. The luting cements irrespective of their contents show some amount of dissolution when they come in contact with oral environment. Marginal opening between cemented crowns and their tooth margins mainly related to cement dissolution. This in vitro study investigated the effect of two different luting agent namely resin cement and resin modified glass ionomer cement on microleakage under metal crown. Twenty intact human premolars were randomized to two groups of ten teeth each. They were prepared in a standardized manner for receiving full metal crowns. Crowns were made following a standard laboratory technique and cemented on their respective abutments. The specimens were subjected to thermocycling for 500 cycle, placed in methylene blue solutions for 24hrs and vertically cut in the buccolingual direction. The microleakage in the area of tooth-cement interface was defined as linear penetration of methylene blue and was determined with a stereomicroscope to assign microleakage scores using a five-point scale. A significant association was found between a cement type and degree of microleakage. The smallest degree of microleakage was observed in specimens luted with resin cement, followed by modified resin glass-ionomer cement. The importance of gap formation and microleakage has been clearly established but the exact amount that becomes clinically significant remains undefined.