evaluation of factors influencing urine mercury levels of general dentists and restorative specialists in mashhad in a one-year period

introduction: dentists are exposed to mercury vapor from dental amalgam in their routine occupational practice; excess exposure to mercury is harmful. the aim of this study was to assess the influence of some possible related factors on the urine mercury levels of general dentists and restorative specialists in mashhad in 2010. materials and methods: this cross-sectional study was performed randomly on 45 general dentists and 10 restorative specialists in all the regions of mashhad. a sample of the subjects’ urine was taken before routine daily occupational practice and they were provided with a questionnaire about their working conditions and demographics. the levels of urinary mercury were analyzed by atomic absorption spectrophotometry using 485-nm wavelength. data were analyzed by anova , pearson’s correlation coefficient and linear multiple regression ( α  = 0.05). results: the mean urine mercury levels for general dentists and restorative specialists were 9.26 ± 2.70 and 9.13 ± 1.79 µg/l, respectively. there were no significant relationships between urine mercury levels and working hours per day, type of amalgam used, number of amalgam restorations per week and different regions. however, there was significant relationship between type of office ventilation and urine mercury level (p value = 0.001) and amalgam waste disposal technique and urine mercury level (p value = 0.000). conclusion: the level of urinary mercury in general dentists and restorative specialists did not exceed toxic levels. there was a significant relationship between the urine mercury level and type of office ventilation and the method of amalgam waste disposal.   key words: dental amalgam, dentist, mercury toxicity, urine analysis