Cell cultures are a potentially useful model to predict in vivo oral mucosa irritation. To this end, oral mucosa organ equivalent cultures (OMOEC) and skin equivalent cultures (SEC), both derived from human tissue, were evaluated for their responsiveness to test dentifrices with graded degrees of irritation potential. OMOEC and SEC were treated with test dentifrices and responses were evaluated by histopathology, cell viability (MTT incorporation), and cytotoxicity [release of aspartate aminotransferase (AST)]. Cell viability in OMOEC and SEC was reduced in a dose- and time-dependent manner in response to the test dentifrices. Correspondingly, AST release was increased in a dose- and time-dependent manner in response to the test dentifrices. These results demonstrate that OMOEC and SEC systems respond linearly to graded degrees of irritation potential as represented by generic dentifrices. Such results in an in vitro model of oral mucosa irritation allow direct comparison of in vitro responses with those obtained in an in vivo model, thus providing the groundwork for a tiered approach to assessment of irritation potential of oral care products.