Methods: Forty patients (14 F, 26 M) aged 47.5 ± 5 years with severe tooth wear (3 or 4 according to Smith and Knight Index) were compared with 20 controls ( 8 F, 12 M) aged 46 ± 7 yrs (0 or 1 based on Smith and Knight Index). To determine the calcium, magnesium, zinc and copper content in enamel the acid biopsy technique was developed. Non stimulated and stimulated saliva were collected to assess the mineral content and acid-base balance. Spectrophotometry with air/acetylene flame was used for calcium, zinc and magnesium analyses. Graphite furnace atomic absorption spectrometry was used for cooper analysis.
Results: Patients with tooth wear had lower Ca concentration in their biopsy samples than controls (1.78 mg/l ± 1.48 vs 2.27 mg/l ±1.16 NS). Mg content among study patients was lower compared with controls (0.31 mg/l ± 0.15 vs 0.42 mg/l ± 0.09, p < 0.05), an increased Zn content was found in patients with tooth wear (0.14 mg/l ± 0.16 vs 0.08 mg/l ±0.07 NS), Cu content was lower in these patients than in controls (19.59 µg/l ± 16.40 vs 36.86 µg/l ± 26.10, p<0.01). The two groups differed by enamel Zn/Cu ratio (p < 0.02).
No differences were found in the salivary mineral contents. In patients with tooth wear, correlation between Ca and Zn in enamel was observed (r=0.438, p<0.01), whereas in controls, a correlation was found between Ca and Cu (r=-0.537, p<0.05).
Conclusion: Magnesium content and quantitative Zn/Cu ratio in enamel may be partly responsible for the mechanism of tooth wear.