Salivary concentrations of nickel and chromium in patients with burning mouth syndrome

It has been documented in vitro and in vivo that metal dental appliances release metal ions due to corrosion. Dentists must choose among many dental casting alloys available, often without knowledge of their biological properties and effect on oral mucosa. The aim of this study was to measure metal content of nickel (Ni) and chromium (Cr) in whole saliva of 85 patients with and without metal dental appliances. Unstimulated whole saliva was collected and analyzed by using electrothermal atomic absorption spectrometry. History data, subjective complaints and objective findings on oral mucosa were recorded. The concentration of metal ions was investigated in correlation to burning mouth syndrome, erythema of oral mucosa, pH and smoking habit. Results showed a higher Ni concentration in patients with metal restorations, especially wearers of predominantly base metal appliances. The concentration of Cr showed no difference between patient groups. Although burning mouth syndrome was more frequent in the group with dental casting alloys, there was no correlation between higher Ni and Cr concentrations and burning mouth syndrome. Erythema of oral mucosa was a common finding in study patients, but did not correlate with salivary Ni and Cr ion concentrations. Salivary Ni and Cr concentrations were not related to either pH or smoking habit.