Methods: Mesio-occlusal and disto-occlusal preparations were made in 50 recently extracted human molars. Teeth were randomly assigned to receive one of 5 treatments: (1) acid etching and Z100 (control); (2) Clearfil SE Bond and Z100; (3) Prompt-L-Pop and Z100; (4) Vitrebond, Scotchbond Multipurpose Plus and Z100 in a closed sandwich technique; (5) Geristore, Tenure and Z100 in an open sandwich technique. Specimens were stored in water for 48 hours, sectioned buccolingually and randomly assigned to either 2 hour immersion or 4 hour immersion in 50 wt % silver nitrate solution. Restorations were removed and gingival floors were photographed and analyzed to determine the percent surface area stained in each of three 0.5mm zones.
Results: With both the 2 and 4 hour immersion in silver nitrate solution, Groups 2 and 4 produced statistically significant improvements in microleakage in all zones, while Group 3 did not produce significant reductions until zone 3. Group 5 produced significant reductions in leakage in all zones with the 2 hour staining procedure, but did not produce significant improvements until zone 3 when stained for 4 hours. There is a general trend of greater microleakage occurring with the 4 hour staining, but the differences were not statistically different from the 2 hour staining.
Conclusions: The use of a resin-modified glass ionomer applied in a laminate technique or a self-etching primer adhesive system may be effective methods for reducing composite microleakage within dentin. In future microleakage studies, the use of longer staining times may provide a better indication of the extent of the existing gap in the tooth-restoration interface.