D enture retention has been defined as the resistance of a denture to vertical and torsional stresses, or the resistance to removal of a denture in a direction opposite that of its insertion.‘,’ Retention of a complete denture may be influenced by a number of variables classified as physical, physiologic, mechanical, and surgical in nature.3 The physical forces operate in the salivary film between the denture and the surrounding tissues and involve factors such as adhesion, cohesion, capillarity, atmospheric pressure, surface tension, and viscosity.4-8 To produce adequate adhesion of a denture to the supporting tissues, saliva must flow easily over the entire surface to ensure wetting of the adherend surface. The fundamental requirement for good adhesive performance is intimate molecular contact between the adhesive and the adherend.’ The extent to which an adhesive will wet a surface depends on the viscosity of the adhesive, the shape of the irregularities on the surface of the adherend, and on the contact angle (e) at which the adhesive meets the adherend surface.“,” Since the tendency for the liquid to spread increases as 8 decreases, the contact angle is a useful inverse measure of spreadability or wettability.” The contact angle observed when a liquid boundary advances for the first time over a dry smooth surface is called the advancing contact angle (e,), while the contact angle observed when a liquid boundary recedes from a previously wetted surface is called the receding contact angle (0,). Contact angles are characteristic constants of liquid/solid systems.‘2 When contact angles are determined, the liquid and solid surfaces