# Development of an In Vitro Method for Assessing the Potential Irritation of Medical Devices and OTC Products Used in the Oral Cavity

## TL;DR

This study developed a lab-based method using human oral tissue to test how irritating common OTC and medical products are to the mouth.

## Contribution

The study introduces a validated in vitro method for assessing oral irritation potential with accurate potency classification.

## Key findings

- The EpiOralTM model showed a clear dose–response relationship for irritant chemicals.
- The method's classifications matched historical in vivo data in most cases.
- Multiple exposure times improved accuracy for identifying irritant potency.

## Abstract

The aim of this study was to evaluate an in vitro method using the EpiOralTM model, a three-dimensional cultured human buccal epithelium, for assessing the oral irritation potential of various products. We evaluated different concentrations of nine chemicals commonly found in over-the-counter (OTC) products and medical devices, including chlorhexidine digluconate, sodium hypochlorite, phosphoric acid, hydrogen peroxide, lactic acid, ethanol, sodium dodecyl sulfate, 1-decanol and methyl methacrylate. The method was able to identify the irritants with a clear dose–response relationship between cell viability and an increasing concentration of the chemicals in the tested solutions. Using three exposure times (1, 4 and 18 h) and calculating the ET-50 (time required to induce a 50% reduction in cell viability), the solutions were classified according to their irritant potency (strong, moderate, mild or non-irritant). The results showed excellent correlation with historical in vivo data by matching the potency classifications in most cases. This study highlighted the importance of multiple exposure times for accurate assessment, as some solutions with irritant chemicals require longer exposure to produce effects. By providing information on both the irritant potential and potency, this method proved useful for toxicologists in the risk assessment of OTC products and medical devices that come into contact with the oral cavity.