Bacca, L.A., Jewell-Motz, E. A. Procter & Gamble Co., Mason, Ohio.

This study by researchers at The Procter & Gamble Co. demonstrated that MatTek’s EpiOral in vitro human buccal (inner cheek) tissue equivalent provided a quick, reproducible method for evaluating the irritation potential of oral care excipients and prototype formulations, the methodology correlated well to human irritation results, and that this EpiOral-based methodology proved to be a reliable alternative to animal testing. 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: Scientists at The Procter & Gamble Co. exposed in vitro tissue models of human oral keratinocytes (EpiOral™, MatTek Corp.) 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-â and IL1-á 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-á and IL1-â. 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 EpiOral 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.


3-dimensional model, Cell viability, Cytokine expression analyses, ELISA, EpiOral, Human buccal epithelium, Human oral keratinocytes, IL-1a, IL-1b, In vitro tissue model, MTT, MTT tissue viability assay kit, Mucosal corrosivity, NaF dentifrice, ORL-100, Oral irritation, Pyrophosphate (PPi)/NaF dentifrice, SLS, Tissue desquamation

Materials Tested

NaF dentifrice, Pyrophosphate(PPi)/NaF dentifrice, Sodium lauryl sulfate (SLS), Water

Request a copy of this paper, click here.