z Khamverdi
N Ronaci

Statement of the problem: In recent years, amalgam has been considered a danger for dentistry personnel due to toxicity of mercury (Hg). Purpose: This study aimed at investigating the relationship between scientific indices and dentists’ urine Hg level through measuring its concentration rate among dentists with over four years of experience. Materials and methods: Thirty dentists with over four years of experience in clinic completed a questionnaire related to practical indices such as working time in clinic, the number of amalgam restorations, waste disposal methods, the number of amalgam repair finishes per day, and the number of amalgam-repaired teeth in dentists’ oral cavity. Thirty urine samples were collected from the participants and the urine specific weight was measured on the same day with a refractometer. After completion of preparation stages, Hg was extracted from the upper organic layers of the solution by potassium bromide and measured by a spectrophotometer at a wavelength of ۴۸ nanometer in µgHg/L. Urine creatinine of each sample was measured and the Hg concentration obtained was divided by creatinine concentration. The urine Hg values were reported in terms of µg Hg/gr.cr. Data were analyzed by t-test, Pearson’s correlation coefficient and linear multi-variate regression test. Results: The urine Hg level rate was ۳۱.۶۲–in average lower than admissible threshold level. Totally, ۱۱ samples were greater than threshold level. Among the practical indices in the study, the method of cleaning amalgam-contamionated instruments, the method of amalgam waste disposal and the number of restorations carried out showed a significant relationship with urine Hg level (P< ۰.۰۵). The number of restorations carried out plays an important role in determining urine Hg levels. Conclusion: The Hg concentrations were lower than the admissible level. The most influential factor was the number of restorations carried out.