A novel methodology based on contact angle hysteresis approach for surface changes monitoring in model PMMA-Corega Tabs system

The aim of the paper is to propose a quantitative description of dental surface modifications, resulting from application of Corega and oral cavity liquids, with several surface parameters derived from liquid/solid contact angle measurements. In particular, to predict the long-term effectiveness of denture cleansers in prosthetics, it is necessary to determine surface wettability variations for model dental materials/probe liquid systems related to the contamination effect caused by substances found in the oral cavity. A novel simple low-cost methodology, based on liquid drop contact angle hysteresis CAH approach developed by Chibowski, was adopted to trace solid surface free energy changes in the model PMMA-Corega Tabs interfacial layer. Contact angle and its hysteresis were studied with a sessile drop-inclined plate method in contact with a cleanser (Corega Tabs) and model liquids found in the oral cavity. The apparent solid surface free energy, adsorptive film pressure, work of adhesion and spreading were derived from contact angle hysteresis data for both model solid surfaces (reference) and samples affected by different reactive liquids for a certain time. A time-dependent surface wettability changes of dentures were expressed quantitatively in terms of the corresponding variations of the surface energy parameters which turned out to be unequivocally related to the cleanser exposure time and polarity of the liquids applied to the dental material.The novel methodology appeared to be a useful tool for long term surface characterization of dental materials treated with surfactants-containing liquids capable of forming adhesive layers. The time of optimal use and effectiveness of cleansers are also reflected dynamically in the corresponding variations of the surface wettability parameters. Further studies on a large group of dental surface-probe liquid systems are required to specify the role played by other important factors (liquid polarity, pH and temperature).