Evaluation of Mercury Vapour Levels Associated with Amalgam Usage at the Wits Oral Health Centre (WOHC)

Abstract

Background: Dental alloys contain 50% or more mercury by weight, raising concerns about their toxicity. Mercury is a hazardous heavy metal; in particular, its gaseous and organic forms contain nephrotoxic and neurotoxic chemicals. The danger of mercury poisoning may rise with prolonged exposure to mercury vapor. Understanding the safety precautions for amalgam can help prevent mercury poisoning in both the patient and the dentist. Aim: The purpose of this study was to evaluate the levels of mercury vapour released in the atmosphere during the use and disposal of dental amalgam at the Wits Oral Health Centre (WOHC). In addition, the perceptions and opinions of dental professionals towards mercury toxicity were evaluated with the use of a survey. Methods: A laboratory analysis was carried out to measure the mercury vapour levels released into the atmosphere from dental amalgam restorations. A questionnaire was administered to 117 dental professionals comprised of dental students, dental assistants and dentists to evaluate their perception and awareness towards mercury toxicity regulations. Results: The laboratory experiments conducted showed that mercury levels at WOHC were below the detection limit of the assay. The average number of amalgam capsules used by dental students per day for a single tooth cavity restoration was two capsules. About 115 dental professional participants completed the questionnaire resulting in a 98.3% response rate. The majority (84.3%) of participants were aware of mercury toxicity issues associated with amalgam use. However, about 70% of the participants suggested that stricter measures regarding the safe use and disposal of dental amalgam should be implemented, to prevent exposure to mercury vapor released from dental amalgam. Furthermore, more than 68 % of the participants were in support that dental amalgam restorations should be removed based on the patient’s request. In addition, about 70% of the participants suggested that mercury levels in the blood of health care professionals should be evaluated periodically. Conclusions: Mercury vapour levels released into the atmosphere at WOHC were below the recommended threshold described by the World Health Organisation (WHO), despite the average number of amalgam capsule usage per tooth restoration. Dental health care professionals at WOHC were aware of dental amalgam safety regulations. However, a larger number of dental students suggested that stricter safety V guidelines should be implemented. In addition, dental students also suggested that monitoring of mercury vapour levels in the atmosphere and evaluation of mercury levels in the blood of dental professionals handling amalgam restorations at WOHC should be done frequently. The dental students’ heightened awareness was due to their recent undergraduate education, serving as the major source of information on the safety concerns of using dental amalgam restorations.