Pharmacokinetics of bisphenol A released from a dental sealant.

BACKGROUND: Limited information is available regarding potentially estrogenic bisphenol A, or BPA, released from dental sealants. This study determined the rate- and time-course of BPA released from a dental sealant (Delton Opaque Light-cure Pit and Fissure Sealant, Preventive Care/Dentsply) when applied at a dosage of 8 milligrams (one tooth) or 32 mg (8 mg on each of four teeth) to 40 healthy adults. METHODS: The authors recruited 40 healthy subjects (18 men and 22 women, 20-55 years of age) who did not have histories of pit and fissure sealant placement or composite resin restorations. The authors collected saliva (30 milliliters) and blood (7 mL) specimens from all subjects immediately before sealant placement (baseline) and at one hour, three hours, one day, three days and five days after sealant placement. They used high-pressure liquid chromatography to determine BPA (detection sensitivity 5 parts per billion, or ppb) in all specimens. RESULTS: The authors detected BPA in some saliva specimens (5.8-105.6 ppb) collected at one hour and three hours. The BPA, however, was not detectable beyond three hours or in any of the serum specimens. For the one- and three-hour saliva samples, the BPA concentration in the high-dose (32 mg) group was significantly greater than in the low-dose (8 mg) group (P < .05, Wilcoxon signed rank test). In the high-dose group, there was a significant decrease in saliva BPA concentrations from one hour to three hours (P < .01, Wilcoxon signed rank test). CONCLUSION: This study showed that BPA released orally from a dental sealant may not be absorbed or may be present in nondetectable amounts in systemic circulation. The concern about potential estrogenicity of sealant may be unfounded.

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.

Natural rubber latex hypersensitivity: incidence and prevalence of type I allergy in the dental professional.

The authors investigated the prevalence of immediate (Type I) hypersensitivity to gloves made from natural rubber latex, or NRL, by performing skin-prick tests on 2,166 dental workers over the course of a two-year period (with two one-year intervals). The investigator used two separate eluents made from different brands of natural rubber latex gloves. The study, conducted in 1994 and 1995 as part of the American Dental Association's Annual Health Screening Program, found that 6.2 percent of the participants (dentists, hygienists and assistants) tested positive for Type I hypersensitivity to NRL proteins.

Hepatitis B vaccination and infection among U.S. dentists, 1983-1992 .

The hepatitis B vaccine became commercially available in 1982. Since then, health care workers, including dentists, have been encouraged to be vaccinated. This study examines the prevalence of hepatitis B vaccination and infection among U.S. dentists from 1983 to 1992.

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.

Percutaneous injuries in practicing dentists. A prospective study using a 20-day diary.

A novel diary study of 2,304 practicing U.S. dentists examined the frequency and nature of percutaneous injuries over one dentist-month. Burs were responsible for most extraoral injuries (40 percent), and syringe needles accounted for most intraoral injuries (32 percent). The annualized mean injury rate was 3.35, which represents about a threefold decrease since 1987.

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 Association's 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.

Transamidase and collagenase activity in healthy and diseased human gingival tissues.

Transamidases are a class of calcium-dependent mammalian enzymes which cross-link proteins by catalyzing the formation of (gamma-glutamyl)-epsilon-lysine bonds. It is possible that these enzymes play an important anabolic role in tissue healing. This study was to quantitate transamidase activity in human gingival tissue and examine the relation between transmidase activity and degree of inflammation. Forty-four out of a total 120 collected human gingival specimens from healthy and diseased patients were selected based on histometric and microbiologic criteria. Specimens were minced and homogenized in 10 mM CaCl2 and then extracted for 30 min, in 50 mM tris-HCl buffer (pH 7.5) containing 100 mM CaCl2. Following low speed centrifugation at 4 degrees C, the supernatant solution was assayed for both transamidase and collagenase activities by radioactive amine incorporation, and digestion of tritiated collagen, respectively. Appreciable levels of transamidase and collagenase activities in healthy gingivae were found. These enzyme activities were significantly elevated in the diseased and healing tissues. Unlike other transamidases, calcium was required in the enzyme extraction process.

Human immunodeficiency virus type I. Infection among dentists.

The largest collection yet assembled of year-to-year data on the seroprevalence of antibody to HIV in practicing dentists confirms that dentists--along with other health care workers--remain at low risk for occupationally acquired HIV infection.

Procedure for the study of acidic calcium phosphate precursor phases in enamel mineral formation.

Considerable evidence suggests that an acidic calcium phosphate, such as octacalcium phosphate (OCP) or brushite, is involved as a precursor in enamel and other hard tissue formation. Additionally, there is in vitro evidence suggesting that fluoride accelerates and magnesium inhibits the hydrolysis of OCP to hydroxyapatite (OHAp). As the amount of OCP or brushite in enamel cannot be measured directly in the presence of an excess of hydroxyapatite, a procedure was developed that allows for their indirect in vivo quantification as pyrophosphate. This permits study of the effects of fluoride and magnesium ions on enamel mineral synthesis. Rat incisor calcium phosphate was labeled by intraperitoneal injection of NaH2(32)PO4. The rats were then subjected to various fluoride and magnesium treatments with subcutaneous implanted osmotic pumps. They were then killed at predetermined intervals; the nascent sections of the incisors were collected, cleaned, and pyrolyzed at 500 degrees C for 48 hours to convert acidic calcium phosphates to calcium pyrophosphate; the pyrophosphate was separated from orthophosphate by anion-exchange chromatography; and the resulting fractions were counted by liquid scintillation spectrometry. The activities of the pyro- and orthophosphate fractions were used to calculate the amount of acidic calcium phosphate present in the nascent mineral. The results demonstrated that the percentage of radioactive pyrophosphate in nascent incisors decreased with time, with increasing serum F- concentration, and with decreasing serum magnesium content. The technique described here should prove to be a powerful new tool for studying the effects of various agents on biological mineral formation.

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 greater than or equal to 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.

Antibiotic interference with oral contraceptive steroid efficacy.

PIP: Dentists prescribing antibiotics to women of childbearing age should be aware that current lower dosage oral contraceptives may fail and cause pregnancy, putting the practitioner at risk for damage claims. The most common antibiotics used in dental practice that may compromise oral contraceptive efficacy are penicillins, such as penicillin V, penicillin G, ampicillin, flucloxacillin, tolampicillin, amoxycillin and cloxacillin, and tetracyclines, such as tetracycline, oxytetracycline, doxycycline and chlortetracycline. Other common antibiotics include sulfonamides, erythromycin, metronidazole, griseofulvin and cephalosporins. The physiological basis for failure of the combined pill is loss of gut bacteria, and decreased enteric recycling of estrogen metabolites. The reason why progesterone-only pills may fail is unknown, and probably not related to drug interaction. Studies on blood levels of estrogens are conflicting; furthermore, it is impossible to predict which woman is at risk. Dentists should inform all women of childbearing age of possible failure of oral contraceptives. They should attempt to get an accurate drug history from female patients, and insert a signed copy in patients' record. It would be helpful to remind the pharmacist to label oral contraceptive prescription bottles with warnings about concurrent antibiotic usage.^ieng

Examination of blood levels of mercurials in practicing dentists using cold-vapor atomic absorption spectrometry.

The toxicity of mercury compounds in dentistry has been an issue of increasing concern. Relatively few data are available concerning the possible in vivo biotransformation of elemental mercury from dental amalgam into more toxic organic mercurials. The present study was designed to evaluate the existence of this in vivo pathway in dentists who work in a confined environment where metallic mercury vapor is constantly present. Two hundred five practicing dentists and 24 nondental controls were asked to participate in this study. The total, inorganic, and organic mercury contents of blood were determined by syringe-injection cold-vapor atomic absorption spectrometry. The student t-test indicates that the total and inorganic mercury levels in blood are significantly different between dentists and nondental controls at the significant level of p less than or equal to 0.05. The organomercurial levels are, however, insignificant at the same test level. This implies that high total and inorganic mercury levels are not correlated with high organomercurial levels in the blood of practicing dentists. Therefore, significant enzymatic conversion of inorganic to organic mercury compounds does not occur in vivo.

Survey of hepatitis B exposure and vaccination in volunteer dentists.

Hepatitis B virus (HBV) serum markers were surveyed at the 1983, 1984, and 1985 ADA annual sessions, beginning the first year after the hepatitis B vaccine became available to the dental profession. Results from serum samples from 2,776 dentists in regard to increase in vaccination against HBV and the incidence of natural exposure to HBV during the 2-year study are discussed; data addressing the development of surface antibody after administration of the three-inoculation vaccine are presented.