Modification of salivary multilayer for improved oral lubrication

Modification of saliva film effectively enhances lubrication for both dry-mouth patients and healthy individuals. This process focuses on altering the salivary multilayer in mouth by adjusting mucin interactions to alleviate oral dryness. The structure and properties of mucins, polymers, and physiological factors – such as lubricity, papillae height, and tongue density – are all related to the success of these modifications. In this review, we present three methods (physical, chemical, and physiological) with distinct lubrication effects. We discuss three modifications (electrostatic attraction, covalent grafting, and laser therapy) of the salivary multilayer that enhance lubrication at sliding interfaces in the oral cavity. This review provides insights into oral lubrication, addressing key questions: what lubrication is, why do we need oral lubrication, and how can we achieve optimal oral lubrication. Advanced techniques for elucidating interfacial adsorption and the applications of surface modifications are also emphasized. Modulating salivary multilayer is a promising approach to enhance lubrication and create a more comfortable eating experience. This strategy is vital for both food scientists and healthcare professionals, as it helps reduce oral friction and alleviate dry mouth symptoms. The interaction of mucins in salivary film is a key for effective modification. In this review, the effectiveness of chemical grafting outperforms electrostatic attraction on xerostomia, providing more durable lubrication. Low-level laser lightning is another therapy for salivary gland dysfunction. We aim to inspire innovative designs for artificial saliva and biomimetic devices through these modifications at oral bio-interfaces, ultimately improving salivary hypofunction and addressing mechanistic challenges in oral lubrication. •The molecular structure of multilayered salivary film is critical for oral lubrication behavior.•Surface modification of oral bio-interfaces is classified into three mechanisms and approaches.•Xerostomia can be revealed by food oral processing combined with clinical studies.