[Layer thickness of dental adhesives. Relation between layer thickness and viscosity].

Objective: To investigate the viscosity of two dental adhesives in relation to the adhesive layer thickness.

Design: In vitro study.

Methods: The viscosity of several dental adhesives has been determined with a reogoneometer. Both a high and a low viscous adhesive was used to restore class II preparations. These restorations were sectioned and the thickness of the adhesive layer was measured on several defined locations. A statistical analysis was performed.

Results: The high viscous adhesive resulted in a thinner layer along the cervical outline of the restoration. With both materials pooling occurred at the line angles of the preparation. On the flat surfaces of the preparations there was a layer of even thickness.

Conclusion: The differences in thickness of the adhesive layer as often seen on radiographs cannot be explained solely by the use of adhesives with a different viscosity.