Erosion-like lesions progression in human and bovine enamel

Resumo

Although on dental erosion studies bovine enamel has been considered a feasible option to human enamel, time dependence related to the erosive challenge remains uncertain. Thus, in this study the following null hypothesis was tested: 1) independent of the number of erosive challenges, no microhardness (SMH) differences exist between human and bovine enamel and 2) the behavior of bovine substrate along the erosive challenges do not differ from the human substrate. Human and bovine enamel slabs were embedded in epoxy resin and serially polished and flattened. Initial SMH tests were measured. The erosive challenge consists of an immersion of the specimens in continuously stirred orange juice (20ml) for 5 minutes at room temperature twice a day, for 5 days. Between the immersions the specimens were washed with deionized water and stored in artificial saliva (20ml). SMH tests were daily measured at the end of 2,4,6,8 and 10 challenges. Data were analyzed by two-way ANOVA as a split-plot design in time and Tukey´s test. Regression analyses were used to model the SMH of human and bovine enamel over time. The first null hypothesis was rejected. Regression analysis exhibits a quadratic polynomial reduction of SMH in function of the number of erosive challenges for both substrates, revealing the admission of the second null hypothesis. Bovine substrate showed the most susceptible substrate to erosive challenge, but after several days of erosive challenge this difference disappears. Thus, the use of bovine tooth instead of human tooth in studies of erosive lesions formation seems to be feasible.