Experimental Study On Marginal Microleakage Of Bonded Amalgam Restorations

Objective: The aim of this in vitro study was to compare the marginal microleakage of the amalgam restoration with bonding agent and the traditional amalgam restoration and the resin composite restoration as well,so as to investigate and analysis the principal of the amalgam bonding restoration. Method : Sixty premolar teeth without dental carries which were extracted because of orthodontics were assigned into two groups randomly. Each of the two groups were prepared class V restorations at the buccal and lingual neck of these teeth. In one of the two groups , for each tooth ,amalgam restoration were applied at the lingual side and the amalgam restoration with adhensives were done at the buccal side. In other group, the teeth were restored with resin composite at the buccal side, which teeth had been dipped into artificial salivary for thirty days and then stained into 2% basic fuchsin fluid for 24 hours, then washed and dried. After the previous steps, the teeth were cut vertically along buccolingual axis of the restoration, then observed under the anatomical microscope and SME to know the bonding strength between the material and the tooth. Result: For the microleakage in the dentinal and enamel margins, the amalgam restoration with bonding agent group is less than the amalgam restoration group (p<0. 01): there is no significance between the amalgam restoration withadhensives group and the resin composite restoration group (p>0.05); the resin composite restoration group is less than the amalgam restoration group (p<0.05). In each group, there issignificant difference between the dentinal margins and enamel ones (p<0.05). Observed under the SME, it is found that there is strong bonding between the bonding agent and the tooth or between the bonding agent and the amalgam in the amalgam restoration with adhensives group, meanwhile the amalgam inlayed into the bonding agent; it is also found that there is no obvious space between the resin composite and bonding agent or between the bonding agent and the tooth in the resin composite restoration group; however, the apparent space can be found between the amalgam and the tooth with different distance in the amalgam restoration group. Conclusion: The resin bonding agent can enhance the bonding strength between the amalgam and the tooth, and reduce the microleakage and strengthen the retention, and decrease the detachment rate and increase the success rate as well.