Influence of different dentinal substrates on the tensile bond strength of three adhesive systems

To evaluate the influence of the method and duration of storage for different types of teeth prior to their use in dentin bonding tests with three adhesive systems.

Recently extracted sound human molars, bovine incisors, and human caries-free molars obtained from exhumed bones 5 years postmortem were used. The latter group of teeth was kept dry for 6 months, and then rehydrated in distilled water over a period of 30 days. The adhesive systems used were Prime&Bond 2.1. Single Bond, and Etch&Prime 3.0. Human teeth were embedded longitudinally in PVC cylinders; bovine incisors were embedded leaving the buccal surface exposed. Flat dentin surfaces were cut with a diamond disk and ground with up to 600-grit SiC paper. Adhesives were applied following manufacturers' instructions. A silicone mold with a cone-shaped perforation (4.5 mm high and 2 mm diameter at the smallest) was fixed on the dentin surface and filled with TPH composite resin. The specimens were stored in distilled water for two weeks before testing.

ANOVA did not detect statistical differences either in the main factors (substrate and adhesive system) or in their interaction (p > 0.05). Tensile bond strength averages ranged from 11.6 to 14.2 MPa. The dentinal substrates showed similar performances, regardless of the adhesives tested.

The differences among the three dentin substrates do not appear to be critical for the tensile bond strength test for the three adhesive systems. The adhesive systems presented similar bond strengths.