Salivary film and residual saliva

The salivary film and residual saliva represent the physiological liquid environment of the oral cavity, serving as a critical interface for oral health and function (Humphrey & Williamson, 2001). The salivary film is a thin layer, approximately 70 to 100 micrometers thick, that coats the oral mucosa and teeth, while residual saliva is the volume of fluid remaining in the mouth after swallowing, typically ranging from 0.5 to 1.0 milliliters (Dawes, 2008). This system is not a discrete molecular target like a receptor or enzyme; rather, it is a complex biological matrix composed of water, electrolytes, and proteins such as mucins and lysozyme that provide lubrication, buffering, and antimicrobial protection (Nieuw Amerongen et al., 2007). In conditions like xerostomia or Sjogren's syndrome, the reduction or alteration of this film leads to significant morbidity, including dental caries and oral infections (NIH, 2023). Drugs such as pilocarpine and cevimeline target the production of this fluid by acting as cholinergic agonists, while various saliva substitutes are designed to physically replenish the film to alleviate symptoms (StatPearls, 2023). Understanding the dynamics of the salivary film is also vital for optimizing transmucosal drug delivery, as the film's thickness and turnover rate directly influence drug dissolution and absorption (Journal of Controlled Release, 2011).

Other names

Salivary pellicleResidual salivary volumeOral fluid filmMucosal pellicleSalivary film thickness

Pharmacological agents interact with this system by either stimulating the autonomic nervous system to increase endogenous secretion or by providing exogenous polymers that mimic the viscoelastic and lubricating properties of the natural salivary film.