Validation of a Dental Erosion Model I–Chemical Analysis In-Vitro

An in-vivo experimental model for dental erosion has been utilised to assess the effects of treating dental enamel with fluorides as a preventive and/or treatment measure. Objective: To validate the in-vivo experimental model results in-vitro using chemical analysis. Methods: Crowns of intact, surgically extracted human third molar teeth were cut into 2-4 pieces, washed (deionised water, 50% ethanol, 96% ethanol), embedded in acrylic resin and polished (grit 4000). Specimens were exposed to 5 ml of 10 mmol/L citric acid for 1 min before (etch I) and after (etch II) fluoride treatment. Aqueous solutions of TiF₄, SnF₂, HF and NaF (all 0.1 M F-) and deionised water (negative control) were tested (n = 6 tooth specimens/test solution). The citric acid and test solutions were applied using a peristaltic pump (flow: 6 ml/min, Gilson model Minipuls 3). Etch and fluoride solutions were collected in coded tubes and analysed blind for calcium content using atomic absorption spectrometry (Model 3300, Perkin Elmer Analytical Instruments, USA) using air-acetylene flame and λ = 422.7 nm. D ppm calcium (etch I minus etch II) was calculated for each tooth and mean percentage reduction in calcium loss was determined for each test solution. Results were analysed using one way ANOVA and the Bonferroni t-test for multiple comparisons. Results: The HF- and SnF₂-treatments were significantly more effective in reducing calcium dissolution than the TiF₄- and NaF-treatments (p≤0.004). There was no statistical difference between TiF₄ and NaF- treatments (p=0.138). The water control resulted in an increase in calcium dissolution. Conclusion: These results correlate well with results from the in vivo model and help validate the use of calcium analysis in the in-vivo dental erosion model.