In vitro examination of dental erosion by a new model

Objectives: Examination of dental erosion runs into difficulties. Therefore, in vitro experiments carried out on human samples play a crucial role in the description of erosion processes. The aim of our experiment was to explore the dynamics of erosion on intact enamel surfaces and to compare the acid resistance of different tooth types. Methods: Surgically removed impacted teeth were used in our tests. Out of a total of 30 samples 17 were lower, 12 were upper third molars and 1 was an upper canine. A standard examination surface was prepared on the largest crown convexity. The remaining surface was covered with acid-proof varnish. The prepared samples were incubated in 20 ml of 10 mM (pH 2) hydrochloric acid solution. The samples were replaced into a fresh solution every 6 hours in the first 24 hours, then the incubation period was changed to 12 hours. The quantity of dissolved Ca2+ in the incubation solution was measured by a Radelkis OP-274 pH-ionometer using a OP-Ca-0711P-S-Ca2+ selective electrode. Results: The kinetics of Ca2+ dissolution was not uniform. In the first incubation period the Ca2+ dissolution rate was 0.39 mmol/l/hour, in the second 1.29 mmol/l/hour, in the third 0.26 mmol/l/hour, in the fourth 0.14 mmol/l/hour and in the fifth 0.2 mmol/l/hour (SEM=0.003; 0.09; 0.04; 0.01;0.15 respectively). The dissolution curves of different samples ran parallel, which suggests that the solubility difference present between samples doesn't change in the course of time. The difference between lower and upper molars proved to be significant (p<0.05) by the Mann–Whitney U test in each incubation period. Conclusion: Our study shows that Ca2+ dissolution rate changes with different enamel depths and different types of teeth have significantly different dissolution rates. These results suggest that in the course of similar tests the above variables can influence the final results. Support: TÁMOP-4.2.1/B-09/1/KMR-2010-0001