Method: As a measure of mucosal irritation, cell viability was monitored for up to 24 hours using the MTT assay. The expression of pro-inflammatory cytokines, IL-1β and IL-1α, were also monitored via ELISA. In addition, a novel oral sloughing assay was developed to quantitate the level of physical damage to the oral tissue when exposed to mouth rinses containing various levels of surfactant.
Result: Tissues treated with SLS solutions (0.2%-0.6%) provided a clear dose response with ET-50 values ranging from 10.5 to < 2 hrs. A dose response was also observed for IL-1α and IL-1β expression in SLS-treated tissues. The addition of poloxamer to SLS solutions increased tissue viability and decreased levels of pro-inflammatory cytokines. Treatment of tissues with NaF and PPi/NaF dentifrices (10% supernatants) exhibited differences in both ET-50 values and cytokine expression levels. In addition, the cell viability results strongly correleated to cytokine expression levels. Differences in the level of sloughed protein were observed following application of various oral rinse formulations to the organotypic oral epithelium. Findings from the oral sloughing assay correlated to changes in tissue thickness.
Conclusion: The oral tissue models represent highly reproducible, non-animal means to screen newly developed oral care products for oral irritation and should be useful to study the innate immunity, biology, and pathology of the oral mucosa.