An Improved In situ Model to Evaluate Erosive Protection

Methods: Three iterative clinical studies were conducted to investigate model robustness, reproducibility and sensitivity to discriminate positive and negative control agents. Studies were conducted at a single centre, employing a randomised, single blind (to specimen analysis), cross-over, in situ design in approximately 28 healthy adults. All studies used sodium fluoride (225 ppm F) solution (FS), deionized water (DI) as a negative control and a pit and fissure sealant (Delton®) (PFS) (Studies 1 and 2 only) as positive control. Subjects wore a palatal appliance containing two plastic holders carrying a total of six bovine enamel specimens. During each treatment period, specimens were exposed to three cycles of treatment consisting of 2 min of product, 15 min resting interval and 10 or 20 min erosive challenge. Specimen surface microhardness (SMH) was tested pre- and post–treatment. ANOVA between-treatment comparisons of the mean SMH change were completed to establish relative performance.

Results: Statistically significant treatment differences (p < 0.05) in SMH changes were consistently observed in all studies between FS and DI. Following Study 1, total dietary erosive challenge was extended from 30 min to 60 min to enhance demineralization and thus increase model sensitivity. The final design, as employed in Studies 2 and 3, indicated a statistically significant difference in mean %SMH change (confidence intervals) of 47.3% (-59.4, -35.2) and 50.5% (-64.2, -36.9), respectively between FS and DI. Furthermore in Study 2, a 13.6% (1.8, 25. 5) mean %SMH change (p<0.05) was observed between PFS and FS.

Conclusions: The results of these studies demonstrate the sensitivity and potential application of this in situ model design for the purpose of evaluating novel anti-erosion agents.