Effect of pathological tooth wear on the content of calcium, magnesium, zinc and phosphate in human dentin

To compare the mineral content of the dentin of worn versus unworn teeth. Coronal dentin samples were collected from twenty one premolar teeth extracted for prosthetic or periodontal indications, including 11 intact teeth and 10 teeth with a significant occlusal wear. Samples were placed in concentrated nitric acid and diluted 500 times for the analysis of calcium and magnesium content and 11 times for the analysis of zinc. Contents of calcium, magnesium and zinc ions were established by means of atomic absorption spectrometry in an oxygen acetylene flame. The content of phosphorus was established by means of spectrophotometry using a test basing on a reaction of colour phosphoric-molybdenic complex formation. Data normality was assessed with Shapiro-Wilk test. Student's t-test was used for all comparisons. A statistically significantly higher content of magnesium and a lower Ca/Mg ratio were found in worn teeth at the 5% level. The concentrations of the other minerals analysed were not significantly different between the worn and intact teeth at the 5% level. Higher magnesium content in the dentin of human worn teeth may constitute a defence reaction to dentin exposure.