Bond strength and interfacial micromorphology of four adhesive systems in primary and permanent molars.

The purpose of this study was to assess the dentin bond strength of four adhesives and the interfacial micromorphology in primary and permanent teeth. Thirty-two for each primary and permanent molar were divided into four groups. Buccal and lingual dentin surfaces were wet ground up to 600 grit. The teeth were bonded following the manufacturers' instructions, thermocycled (500x), mounted on plaster and sheared with instron machine. Some teeth were sectioned for SEM evaluation. The mean bond strengths (in MPa) for primary and permanent teeth respectively were: Scotchbond Multipurpose 19.4 +/- 4.0, 18.9 +/- 4.8; One Step 30.6 +/- 3.6, 35.6 +/- 1.9, Prime and Bond 2.1 28.3 +/- 4.8, 31.8 +/- 4.0, EBS Bond 31.5 +/- 4.6, 33.6 +/- 4.8. There was no significant difference between the last three adhesives nor between primary and permanent teeth except with One Step. All the adhesives formed a hybrid layer which was wider in permanent teeth. It was concluded that the products tested produced a strong bond strength to dentin and may function well clinically. The bond strength was not totally dependent on hybrid layer formation.