Effect of simulator design on in vitro profilometric assessment of toothpaste abrasivity

National and international standards detail in vitro methodologies for assessing toothpaste abrasivity using human enamel and dentine coupled with profilometric or radioisotope analysis. This profilometry-based study investigates the influence of brushing simulator design and choice of standard abrasive on enamel/dentine wear. Four simulators were evaluated including the flat-bed and V8 Grabenstetter designs described in the present BS EN ISO 11609: 1998 standard, together with the two abrasives prescribed therein. Vertical reciprocating-action and rotary-action simulators were also assessed. Mean abrasion depths for enamel and dentine specimen groups using the rotary-action simulator with either abrasive were ca. 0.9 μm and 4–5 μm respectively, significantly higher vs. comparators (p = 0.0001; CV ∼ 0.2). Mean abrasion depths determined using the flat-bed and V8 simulators were ≤0.1 μm (CV, 0.2–0.8) for enamel and ≤0.7 μm (CV, 0.2–0.6) for dentine. The vertical reciprocating-action simulator elicited intermediate levels of wear, but high design-driven variance (CV, 0.6–0.7). Mean enamel abrasion depths were independent of abrasive (p ≥ 0.534), however, mean dentine abrasion depths were significantly different for the vertical reciprocating and rotary-action simulators (p = 0.0026 and 0.0014 respectively). This study demonstrates the importance of simulator design in the assessment of dentifrice abrasivity, which is key to delivering the desired sensitivity and discriminatory power. Various limitations in design of the simulators studied highlight opportunities for improvements in simulator design.