Salivary films are (mostly) proteinaceous nm-thick films that form on any type of surface upon exposure to saliva. The role of the pellicle is manifold. Among its functions, hydration of the underlying tissues is often listed. Indeed, the hydration of salivary films was recently proved by a neutron reflectometry study by the applicants. This proposal focuses on the interaction between salivary films and surfactants used in oral health products. The use of these compounds has been related to the occurrence of mucosal damage in the oral cavity. Thus, it is of high interest to identify and use surfactants with the lower adverse effects. In this context, we intend to use neutron reflectometry to study how surfactants of different ionic character interact with salivary films and influence their hydration and, therefore, their protection of oral mucosa.