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To be presented at the International Association of Dental Research Annual Meeting, abstract #1189, Baltimore, MD (March 2005).
Title:
Novel in vitro Methodology Evaluating Potential Mucosal Irritation of Oral Care Formulations. L.A. Bacca*, Procter & Gamble Co., Mason, Ohio; E. A. Jewell-Motz, Procter & Gamble Co., Mason, Ohio
Abstract:
Background: Oral irritation/tissue desquamation can result from exposure of the soft tissue to some dentifrice/rinse formulations. The potentially corrosive effects of common excipients, such as SLS, are well documented. As manufacturers develop products utilizing new actives or combinations of excipients and actives, testing methodology is needed to evaluate the irritation potential of these formulations and ingredients prior to human exposure.
Objective: To develop in vitro methodology for the determination of potential oral irritation of oral care excipients/formulations.
Methods: in vitro tissue models (EpiOral, MatTek Corp.) of human oral keratinocytes were exposed to varying concentrations of common oral care excipients and dentifrice supernatants. These include SLS, poloxamer, NaF dentifrice, and pyrophosphate (PPi)/NaF dentifrices. As a measure of mucosal corrosivity, cell viability levels were monitored over time (up to 24 hrs) via the MTT assay. ET-50 values were calculated. IL1-β and IL1-α profiles were also monitored via ELISA. Correlations were made to in vivo human desquamation testing.
Results: SLS solutions (0.2% to 0.6%) provided a clear dose response in both cell viability and cytokine levels. ET-50 values ranged from 10.5 to < 2 hrs. A dose response was observed for expressed levels of IL1-α and IL1-β. Addition of poloxamer to SLS solutions increased cell viability levels to the range of >24 to 9 hrs, and decreased levels of expressed cytokines. Treatments of NaF and PPi/NaF dentifrices (10% supernatants) exhibited differences for both ET-50 values and cytokine expression levels. These results are consistent and correlate with in vivo oral desquamation testing. Additionally, cell viability results provide a strong correlation to cytokine expression levels.
Conclusions: The in vitro tissue models provide a quick, reproducible method for evaluating the irritation potential of oral care excipients and prototype formulations. The methodology correlates well to human irritation results, and can provide a reliable alternative to animal testing.
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