Microleakage of Bonded Amalgams Using Different Bonding Intermediates

Objective: To reduce the microleakage of high-copper amalgam the bonding of amalgam to tooth structure was introduced as a possible solution. The aim of this study was to determine and compare the microleakage of several bonding intermediates under thermal stress conditions. Methods: Class II butt joint cavities were prepared on the mesial aspects of 120 sound extracted human molar teeth. They were randomly divided into 3 groups of 40 each. The bonding intermediates Vitremer and Calibra were applied to two of these groups. The third group was left untreated. The 3 groups were then further divided into two groups of 20 each and restored with the high-copper amalgams Dispersalloy and Oralloy Magicap S respectively. Ten specimens of each group were thermocycled between 5 C and 55 C with a dwell time of 30 seconds for 400 cycles. All the teeth were stored in the dye Basic Fuchsin (0,5%), for 8 hours, sectioned and evaluated for dye penetration using a light microscope (40x magnification). The mean microleakage scores were analysed using the chi-squared test at a confidence level of 95%. Results: Microleakage of the non-bonded amalgams were significantly higher (p<0,0001) than for the bonded amalgams under both thermocycling and non-thermocycling conditions. In general, microleakage was not significantly increased by thermocycling. The sealing abilities of Vitremer and Calibra did not differ significantly. Conclusions: Within the limitations of this experiment it was concluded that the bonding of amalgam restorations to tooth structure would reduce the leakage of high-copper amalgam restorations. Furthermore, it was demonstrated that thermal stress would not affect the bond adversely.