Chakwan Siew

Occupational risk of hepatitis C infections among general dentists and oral surgeons in North America

PURPOSE To assess the occupational risk of hepatitis C virus (HCV) infection among dental personnel. METHODS Three hundred forty-three oral surgeons and 305 general dentists were recruited at national meetings of the American Dental Association and matched by gender, age, years of practice, and location of practice. Each participant completed a detailed questionnaire designated to measure occupational risk of blood-borne infections and supplied a sample of blood. Antibodies to HCV (anti-HCV) were assessed by second-generation enzyme immunoassay and recombinant immunoblot assay. As a marker of occupational exposure to blood-borne viruses, hepatitis B virus (HBV) surface antigen and antibodies to HBV surface and core antigens were measured by enzyme immunoassay. RESULTS Anti-HCV was found in 2.0% of oral surgeons and 0.7% of general dentists (odds ratio [OR] = 3.2, P = 0.133). Anti-HCV was more prevalent (P < 0.01) in dental personnel who were older, had more years of practice, and had serologic markers of HBV infection. Serologic markers of HBV infection were found in 7.8% of general dentists and 21.2% of oral surgeons (OR 3.1, P < 0.001). CONCLUSIONS These data confirm high rates of HBV infection among dental personnel, but suggest that the risk of HCV infection is considerably lower.

Factors Affecting Blood Mercury Concentrations in Practicing Dentists

It has been suggested that mercury vapor may be transformed into highly toxic organomercury compounds by micro-organisms in the oral cavity and gastrointestinal tract. If this hypothesis is correct, practicing dentists might be expected to have concentrations of organic mercury in their blood higher than that found in non-dentists. Blood mercury concentrations of practicing dentists and non-dentists were determined by means of cold-vapor atomic absorption spectrophotometry. Potential sources of mercury exposure were identified in both dentists and non-dentists through a questionnaire completed at the time of sampling. Concentrations of total and inorganic blood mercury were significantly higher in dentists than in non-dentists. The organomercury concentrations of the two groups were not statistically different (p ≥0.05). The high concentration of inorganic mercury in the blood of dentists was not related to the organomercury level, suggesting that biotransformation of inorganic mercury to organomercury does not occur in vivo. However, the concentration of blood organomercury was positively correlated with the frequency of fish consumption. There was no correlation between the number of amalgam restorations and the concentration of inorganic blood mercury for both groups. Accidental mercury spills in the dental operatory may contribute most to the concentration of inorganic blood mercury in the blood of dentists.

Occupational blood exposure and HIV infection among oral and maxillofacial surgeons

OBJECTIVE The purpose of this study was to examine occupational blood exposure and the seroprevalence of HIV infection among oral and maxillofacial surgeons. STUDY DESIGN Three hundred twenty-one oral and maxillofacial surgeons attending an annual meeting voluntarily and anonymously participated in an HIV serosurvey and completed a questionnaire assessing practice and demographic factors. Statistical tests included the Wilcoxon rank-sum test and the chi-squared test. RESULTS Eighty percent of those who completed the survey reported one or more blood-skin contacts within the previous month. The mean number of percutaneous injuries within the previous year was 2.36 +/- 0.2. Wire was most commonly associated with percutaneous injuries. Oral maxillofacial surgeons who reported three or more percutaneous injuries performed more fracture reductions than oral and maxillofacial surgeons reporting no percutaneous injuries (p < 0.01). No participant was HIV-positive; the upper limit of the 95% confidence interval was 1.15%. CONCLUSION The findings suggest that the occupational risk for HIV infection in oral surgery is very low even though most oral and maxillofacial surgeons experienced blood contact. Associations of percutaneous injuries with fracture reductions and wire may assist in the development of new techniques and equipment to minimize blood exposures.

Factors Associated with Hepatitis B Vaccine Response Among Dentists

The objective of this study was to evaluate personal and immunization factors associated with serologic evidence of hepatitis B virus (HBV) vaccine response. A study was conducted using data from United States dentists participating from 1987 to 1991 in the Health Screening Program of the American Dental Associations annual session. This study included dentists (n = 507) who (1) received their most recent dose of HBV vaccine within the previous 10 months, (2) completed a core questionnaire, and (3) were tested for HBV markers (HBsAg, anti-HBs, and anti-HBc) and were found not to have evidence of past or present infection. Non-responders were defined as dentists testing negative for all three markers (n = 100). Responders were defined as dentists having serological evidence of anti-HBs alone (n = 407). Logistic regression models were used to assess the relationship of vaccine response to the variables sex, age, number of vaccine doses, site of vaccination, type of vaccine, and history of hepatitis. Vaccine response was most strongly associated with sex, age, and number of doses. Factors unrelated to vaccine response included type of vaccine and history of hepatitis. Adherence to the recommended number of doses and early vaccination are critical to adequate protection against hepatitis B infection of dentists, who are often exposed to blood and other body fluids.

Environmental hazard evaluation of amalgam scrap

Amalgam scrap was subjected to two different Environmental Protection Agency (EPA) extraction procedures to determine if it presents an environmental hazard. The results indicate that concentrations of mercury and silver in the extracts do not exceed the EPAs maximum allowable concentrations. It was concluded that amalgam scrap is not a hazardous solid waste. Proper handling of amalgam scrap disposal by recycling is, however, highly recommended.