Microleakage in Amalgam Restorations Using Three Groups of Dental Materials

Objective: The aim of this study was to compare microleakage, using radioactive Calcium 45 in bonded amalgam restorations using three different dental materials. Methods: Class V cavities were prepared at mesial and distal cemento-enamel junctions of 45 sound, extracted molar teeth. These teeth were divided into 3 groups of 15 each. Each group was treated according to manufacturers instructions with Polyvar Cavity Varnish (PV), Scotchbond Multi-Purpose Plus (SBMPP) and Panavia 21 (P) respectively, restored with Permite amalgam and stored at 37 degrees Celcius for 24hr in distilled water. Following thermocycling (500 cycles, 5 – 55 degrees Celcius, dwell time = 30s, transfer time = 10s) and storage (six weeks, 37 degrees Celcius, distilled water), teeth were sealed with clear nail varnish, excluding a 2mm border surrounding the restoration. Teeth were subsequently immersed in an aqueous solution of Calcium 45 (pH = 5.5; 0.1mCi/ml; 24hr; 37 degrees Celcius) before being embedded in clear resin and sectioned through the centre of restorations along the long axis of teeth. Samples were assembled on radiographic film and stored within light-proof containers (17 hr) before being irradiated (0.04s; 70kv; 10cm) after which the film was developed. Using magnification and evaluating leakage on a 1 to 4 scale, Calcium 45 penetration in enamel and cementum was scored by two independent examiners. Results: Frequency percentages demonstrated that PV performed worst (microleakage score = 4) in both enamel (43%) and cementum (100%). SBMPP completely eliminated microleakage (microleakage score =1) in 67% of enamel samples and 20% of cementum samples, and P demonstrated frequencies of 7% and 0% in enamel and cementum samples respectively. An excellent inter-reader agreement was demonstrated (Kappa = 0.9) Conclusion: Statistical analysis demonstrated that PV, SBMPP and P differ significantly (p=0.0) in their abilities to withstand microleakage in bonded amalgam restorations.