Standardized cylindrical Class V preparations, 3 mm in diameter and 1.5 mm deep, were made on the roots of 60 extracted human maxillary permanent canines. The teeth were restored with Scotchbond 2/Silux (S); Gluma/Lumifor (G); and Tenure/Perfection (T), respectively. The root apices were sealed with Copalite/amalgam and two coats of nail varnish applied to the teeth except for 1 mm around the restorations. For the qualitative microleakage evaluation the teeth were thermocycled x500 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C and for the quantitative microleakage evaluation in 2% methylene blue solution. The marginal gap dimensions were measured on cylindrical restorations placed on the facial surfaces of ground root surfaces of 30 teeth. Epoxy replicas were made of the restorations, coated with gold/palladium and examined with the SEM. The maximum marginal gap dimensions were measured. The data were analyzed by ANOVA, Duncan's and their nonparametric analogues. In the qualitative microleakage evaluation the total microleakage was: S: 16; G: 50; T: 18. The quantitative microleakage (micrograms) was: S: 3.1 +/- 2.9; G: 16.1 +/- 5.3; T: 4.4 +/- 4.1. The maximum marginal gap dimensions (microns) were: S: 4.1 +/- 3.6; G: 9.3 +/- 3.4; T: 16.4 +/- 7.0.