Background: Amalgam is the restorative material chosen by many dentists because of its easy manipulation, durability and low cost. It is well known that mercury is highly toxic to the human body. Dentists are exposed in their working environment to mercury vapor and this exposure constitutes a potential risk to them. American Dental Association (ADA) established the recommendations for appropriate mercury hygiene within the dental offices, but they are not practiced properly. Objective: the aim of this study is to evaluate mercury hygiene practice among dentists in Cairo University and
its reflection on urine mercury level and kidney function. Methods: This study was carried on 30 dentists working in the Operative Dental Clinics in Faculty of Oral and Dental Medicine, Cairo University. Using a specially designed questionnaire to evaluate the attitude of dentists in their following the ADA mercury hygiene recommendations. Urine sample was taken for analysis of mercury concentration and kidney functions from dentists and compared with urine taken from
25 nurses and employers working in Kasr El- Aini Hospital not exposed to mercury after taken their consent who served as control group. Results: Showed that 50% of dentists were aware about mercury hazards to them, while 46.66% of dentists believed that amalgam was hazardous to patients only.  Preventive measures taken by the dentists when working with amalgam showed that most of dentists were not following the ADA recommended guidelines. As regard asking the patient not to swallow the spilled mercury in maxillary cavity, there were 23.34% always asking the patient not to swallow the spilled mercury, where as 13.33% never asking the patient not to swallow the spilled mercury. As regard the disposal of mercury waste, dentists did not know the proper method to dispose the waste mercury, 100% of dentists use waste bag to discard excess amalgam. This study showed a highly significant difference between the level of mercury (ug/creatinine) in dentist's urine (19.73±1.5) and control (5.16±1.47). While as regards urea & creatinine level in urine our results showed a highly significant difference between dentists & control, urea level in dentist's urine (21.70±2.78) while in control (16.54±1.28) creatinine level in dentist's urine (1.40±0.59) & among control (0.88±0.34).
Conclusion: This study showed that most dentists do not strictly follow the mercury hygiene and ADA guidelines