Due to its numerous advantages, such as excellent drug accessibility, rapid absorption, and bypass of first-pass metabolism, the route of drug administration that involves crossing the oral mucosa is highly favored. As a result, there is significant interest in investigating the permeability of drugs through this region. The purpose of this review is to describe the various ex vivo and in vitro models used to study the permeability of conveyed and non-conveyed drugs through the oral mucosa, with a focus on the most effective models. Currently, there is a growing need for standardized models of this mucosa that can be used for developing new drug delivery systems. Oral Mucosa Equivalents (OMEs) may provide a promising future perspective as they are capable of overcoming limitations present in many existing models.

Background: Oral lichen planus (OLP) is a chronic autoimmune disease of the oral mucosa, classified among potentially malignant oral disorders (OPMDs). It is characterized by keratinocyte apoptosis and persistent inflammation. Standard treatments involve topical corticosteroids administered via mouthwashes, gels, or ointments, but these require frequent application, have limited retention, and may cause side effects. To address these limitations, this study aimed to develop an innovative dexamethasone delivery system targeting the oral cavity, based on poly(lactic acid) (PLA) fibers coated with chitosan (CS) and poly(lactic-co-glycolic acid) (PLGA) nanoparticles. Methods: CS-coated PLA fibers were characterized for their mucoadhesive and cytocompatibility properties, while PLGA nanoparticles were analyzed for size, shape, encapsulation efficiency, cellular uptake, drug release efficiency, and cytocompatibility. Results: Both polymers demonstrated cytocompatibility, and chitosan-coated PLA fibers exhibited mucoadhesive properties. PLGA nanoparticles were effectively internalized by the cells and successfully released the drug into the cytoplasm. The combination of CS-coated PLA fibers and PLGA nanoparticles provided dual benefits: mucoadhesion and efficient cellular uptake, even under conditions simulating salivation. Conclusions: These findings highlight the potential of the proposed system to improve mucoadhesive drug delivery. Further optimization is needed to enhance patient compliance and therapeutic efficacy.