The effect of acquired salivary pellicle on the surface free energy and wettability of different denture base materials

Objective: The objective of the present study was to evaluate the effect of salivary coating on the wettability and surface free energy of different denture base materials. Methods: Five acrylic resin and two metallic denture base materials were investigated. Ten specimens of each material (20 x 15 x 1.5 mm) were fabricated and a standardized method was used for polishing the test specimens. Whole unstimulated saliva was collected from a single healthy donor. The wettability properties of the materials were tested before and after organic layer formation. The wetting forces were determined according to the Wilhelmy Plate Technique. Diiodomethane, ethylene glycol and formamide were used as probe liquids. The contact angles, Lifshitz-van der Waals surface energy components, Lewis acid-base surface energy components and total surface energies were calculated using the equations described in the paper. The significance of the differences in the experimentally determined surface energies of different denture materials are calculated by statistical methods. Conclusions: Light-cured acrylic resin was the most wettable material with a significant basic character. Organic layers decreased the total surface free energies of all materials and at the same time imparted a more basic character. The coatings had a homogenizing effect in terms of the surface free energy components of the denture materials, nevertheless, their adhesive properties were still influenced by the substrate employed. (C) 2001 Elsevier Science Ltd. All rights reserved.