Materials and Methods: Mesio-occlusal and disto-occlusal preparations were made in 50 extracted molars. Teeth were randomly assigned to receive 1 of 5 treatments followed by restoration with Z100 composite resin: acid etch (control); Clearfi l SE Bond; Prompt-L-Pop; Vitrebond/Scotchbond Multipurpose Plus (closed-sandwich technique); or Geristore/Tenure (open-sandwich technique). After 48 hours of water storage followed by sectioning buccolingually, 1 restoration from each tooth was randomly assigned to either 2- or 4-hour immersion in 50% by weight silver nitrate solution. Restorations were removed and gingival fl oors analyzed to determine the percentage of surface area stained in each of 3 0.5-mm wide zones.

Results: Repeated measures ANOVA did not reveal statistically signifi cant differences in staining for 2 and 4 hours. Compared with the control group, Clearfi l SE bond produced statistically signifi cant reductions in leakage in all 3 zones. Prompt-L-Pop did not reduce leakage signifi cantly except in zone 3 (closest to the pulp). Vitrebond and Geristore both reduced microleakage in zones 2 and 3, but the reduction was greater with the use of Vitrebond.

Conclusion: Both Clearfi l SE Bond and Vitrebond in a closed-sandwich technique were effective methods for reducing microleakage within dentin.