Residual mercury content and leaching of mercury and silver from used amalgam capsules.

OBJECTIVE: The objective of this investigation was to carry out residual mercury (Hg) determinations and toxicity characteristic leaching procedure (TCLP) analysis of used amalgam capsules. METHODS: For residual Hg analysis, 25 capsules (20 capsules for one brand) from each of 10 different brands of amalgam were analyzed. Total residual Hg levels per capsule were determined using United States Environmental Protection Agency (USEPA) Method 7471. For TCLP analysis, 25 amalgam capsules for each of 10 brands were extracted using a modification of USEPA Method 1311. Hg analysis of the TCLP extracts was done with USEPA Method 7470A. Analysis of silver (Ag) concentrations in the TCLP extract was done with USEPA Method 6010B. RESULTS: Analysis of the residual Hg data resulted in the segregation of brands into three groups: Dispersalloy capsules, Group A, retained the most Hg (1.225 mg/capsule). These capsules were the only ones to include a pestle. Group B capsules, Valliant PhD, Optaloy II, Megalloy and Valliant Snap Set, retained the next highest amount of Hg (0.534-0.770 mg/capsule), and were characterized by a groove in the inside of the capsule. Group C, Tytin regular set double-spill, Tytin FC, Contour, Sybraloy regular set, and Tytin regular set single-spill retained the least amount of Hg (0.125-0.266 mg/capsule). TCLP analysis of the triturated capsules showed Sybraloy and Contour leached Hg at greater than the 0.2 mg/l Resource Conservation and Recovery Act (RCRA) limit. SIGNIFICANCE: This study demonstrated that residual mercury may be related to capsule design features and that TCLP extracts from these capsules could, in some brands, exceed RCRA Hg limits, making their disposal problematic. At current RCRA limits, the leaching of Ag is not a problem.

The removal of mercury from dental-operatory wastewater by polymer treatment.

The mercury (Hg) content of dental-operatory wastewater has become an issue in many localities, and Hg removal is rapidly becoming a matter of concern for all dental clinics. This preliminary study tested the efficacy of polymers for the removal of Hg contaminants from the dental-unit wastewater stream. Two commercially available polymers were used to treat dental-operatory wastewater. Used separately, each polymer removed from 74.9% to 88.4% of the Hg from dental-wastewater supernatant. The polymers used in combination, within the recommended pH range, removed up to 99.9% of the total Hg from dental-wastewater supernatant. The estimated optimal concentration of the two polymers is approximately 2.33 ml of each per liter of waste, and more than 90% of the Hg may be removed with 0.13 ml/l. Results indicate that a combination of the two polymers may sufficiently reduce Hg levels to allow discharge of clarified supernatants into public sewer systems.

Reducing medium for the cultivation of Porphyromonas gingivalis.

Porphyromonas gingivalis, a micro-organism frequently associated with human periodontal diseases, is commonly cultured under a reducing atmosphere in enclosed cabinets or glove boxes. This paper reports a modified Wilkins-Chalgren (MWC) medium for the culture of P. gingivalis under atmospheric conditions at 37 degrees C. On the basis of preliminary tests, WC broth was supplemented as follows: 500 mg/l cysteine hydrochloride; 250 mg/l sodium thioglycolate; and 1,000 mg/l sodium bicarbonate. Three P. gingivalis isolates (JKG-I, 33277 and A7436) showed very similar growth over 24 and 48 h periods when cultured both in WC medium in an anaerobic chamber and in the MWC medium. Culture of these isolates both in the anaerobic chamber and in the MWC medium yielded very similar data with respect to trypsin-like activity, total protease activity, and reactivity to monoclonal antibodies specific for P. gingivalis. Growth in the MWC medium varied over a 3- to 4-fold range for seven additional isolates (JKG-7, D86B6, D13B11, D84D2, JKG9, D67D9, D82F5) over 24 and 48 h periods.

Salivary levels of alpha 2-macroglobulin, alpha 1-antitrypsin, C-reactive protein, cathepsin G and elastase in humans with or without destructive periodontal disease.

Five host-response indicators were measured by enzyme-linked immunosorbent assays on unstimulated whole saliva samples from 45 adults (19 male, 26 female). The participants were distributed among four dentate groups representing oral health (I), gingivitis (II), moderate periodontitis (III), and severe periodontitis (IV), and one group of edentulous volunteers (V). Levels of the host-response indicators varied widely, from zero, primarily with groups I and V, to relatively high values with groups II, III and IV. The levels ranged as follows: alpha 2-macroglobulin, 0-4941 ng/ml; alpha 1-antitrypsin, 2-2271 ng/ml; C-reactive protein, 0-472 pg/ml; cathepsin G, 0-6035 ng/ml; elastase, 0-164 ng/ml (free), 0-732 ng/ml (bound to alpha 1-antitrypsin), and 0-318 ng/ml (bound to alpha 2-macroglobulin). Statistical evaluation by planned contrasts showed that levels of host-response indicators for group I were significantly lower (except for alpha 1-antitrypsin) than for groups II, III, and IV. A trend analysis of groups I-IV showed that mean scores (again, except for alpha 1-antitrypsin) increased significantly in a positive, monotonic manner. Group V showed significantly lower values for elastase than in the other groups. The findings demonstrate that these factors can be detected in whole saliva and suggest that, except for alpha 1-antitrypsin, their levels are directly related to an individual's periodontal status.

Comparison of human polymorphonuclear neutrophil elastase, polymorphonuclear neutrophil cathepsin-G, and alpha 2-macroglobulin levels in healthy and inflamed dental pulps.

Polymorphonuclear neutrophils (PMNs) are found in dental pulp secondary to carious exposures, periodontal disease, or trauma. Lysosomal degranulation of these cells liberates cellular proteases, including elastase (PMN-E) and cathepsin-G (PMN-CG), which produce connective tissue degradation. However, nonspecific pulpal tissue destruction can be modified by a naturally occurring serum protease inhibitor alpha 2-macroglobulin (A2-M). This study relates the concentrations of human PMN-E, PMN-CG, and A2-M in healthy and inflamed pulpal samples. Evaluation of 21 specimens yielded statistically significant differences between healthy and moderate to severely inflamed pulps for all groups (p < 0.05). No significant correlation was detected among human PMN-E, PMN-CG, and A2-M in the healthy tissues (P > 0.05). However, in the moderate to severely inflamed pulps, there was a significant correlation between PMN-CG and A2-M (p < 0.05).

Trypsin-like activity levels of Treponema denticola and Porphyromonas gingivalis in adults with periodontitis.

Treponema denticola (Td) and Porphyromonas gingivalis (Pg) are associated with human moderate and severe adult periodontal diseases. This study quantifies these two anaerobes and their trypsin-like (TL) activities in subgingival plaque collected from both clinically healthy and periodontally diseased sites of human periodontitis patients. Antigen levels of the microorganisms were determined by monoclonal antibodies and TL activities were measured by the fluorescent substrate Z-gly-gly-arg-AFC in a disc format. Significant positive correlations were observed between the antigen levels and the TL activities when the data were subjected to statistical analyses both on a site-specific and on a patient basis. Anaerobe synergism was found between Td and Pg in a continental US population, and positive correlations were found between anaerobe levels (individually and total) and clinical indicators of adult periodontitis.

Measurements of interleukin-6 in gingival crevicular fluid from adults with destructive periodontal disease.

This paper describes a study of whether or not the amounts of interleukin-6 (IL-6) in gingival crevicular fluid (GCF) are correlated with periodontal clinical measures. A sensitive ELISA was developed to measure IL-6 in GCF. Two male and 3 female adult subjects with periodontal disease were examined at their first appointments, after 3 months, and after 6 months. Data were obtained on plaque index (PI), bleeding index (BI), probing depth (PD), and on the IL-6 content of GCF samples from 16 sites per subject for a total of 240 measurements. Significant correlations were found between BI and IL-6 (P < 0.005) and between PD and IL-6 (P < 0.05), but not between PI and IL-6. Only 6 out of the 80 sites (in 3 of the 5 subjects) showed PD increases of at least 2 mm. However, for each of these 3 subjects, the amounts of IL-6 in the GCF samples from these sites were markedly higher than the mean amounts of IL-6 in the GCF samples from the remaining sites. These findings suggest that IL-6 may be a useful indicator of periodontal disease, although more extensive longitudinal studies are needed to determine the real clinical value of this GCF component.

A sensitive method for the detection of immune complexes in human gingival crevicular fluid.

An assay for immune complexes [ICs] in gingival crevicular fluid [GCF] could be potentially useful to ascertain the risk of periodontal disease activity at specific oral sites. This paper describes and ELISA-based method sufficiently sensitive to measure ICs in GCF samples at levels below 1 microgram/ml. Static GCF samples taken from 5 adults showed IC levels ranging from 5 to 166 micrograms/ml. Additional tests of 10 GCF samples from 1 adult were conducted with complement components and indicated that either C1q or rabbit anti-human C3d was suitable as a capture agent in the assay procedure. Further application of this assay may help to assess the usefulness of IC levels in GCF samples as possible diagnostic indicators of periodontal disease activity.

Detection of microbial trypsin-like enzymes by use of an agar gel.

Certain oral micro-organisms associated with periodontal diseases elaborate trypsin-like enzymes. This study describes a single assay for these enzymes, based on the incorporation of the synthetic substrate N-alpha-benzoyl-DL-arginine-p-nitroanilide (BAPNA) into ion-agar gel. The system can provide quantitative or qualitative data within 24 h and is suitable for use in the dental clinic.

Fibronectin levels of unstimulated saliva from naval recruits with and without chronic inflammatory periodontal disease.

Past studies have suggested that gingival crevicular fluid is produced more readily in persons with severe periodontal diseases than in persons with healthy gingivae. In this study, salivary fibronectin was selected as an index of total gingival crevicular fluid flow. Our purpose was to determine whether a relationship could be found between salivary fibronectin level and periodontal disease status. Unstimulated saliva was collected from 20 healthy and 20 periodontally-diseased naval recruits. The periodontally-diseased subjects included 10 with localized juvenile periodontitis and 10 with moderate to severe periodontitis. Mean subject ages and salivary flow rates were similar for the 2 groups. Although 2 of the periodontally-diseased subjects showed unusually high fibronectin levels, the mean level for the remaining 18 subjects did not differ significantly from the mean of the healthy group, and no association of periodontal disease status with salivary fibronectin content was seen. Consequently, it was not evident from salivary fibronectin levels that the content of gingival crevicular fluid in unstimulated whole saliva differed significantly for persons with or without severe periodontal disease, except possibly for extreme cases of disease.

Susceptibility of fibronectin to degradation by various gram-negative and gram-positive oral micro-organisms.

The degradative effects on tritiated human plasma fibronectin (FN) of proteases associated with twenty five Gram-negative (GN) and fifteen Gram-positive (GP) oral microbial isolates were examined. Ninety-two per cent of the GN and 20% of the GP isolates degraded the FN. In the GN group, the degradative effects were greatest for Bacteroides gingivalis and Treponema denticola, while in the GP group Streptococcus faecalis produced appreciable, and the two Lactobacillus casei isolates moderate and low, levels of FN degradation.

The effects of basic and acidic synthetic polypeptides on the adherence of the oral bacteria, Streptococcus mutans and Streptococcus sanguis, to hydroxyapatite.

Two basic and two acidic synthetic polypeptides that bind strongly to hydroxyapatite at neutral pH were tested to determine their influence on adsorption of two Streptococcus mutans and two Streptococcus sanguis strains to hydroxyapatite. The adsorption of the strains was significantly enhanced or reduced by the basic and acidic agents, respectively. Study of acidic polypeptides provided evidence of competition between the polypeptides and the bacterial cells for hydroxyapatite adsorption sites.

Salivary pH-rise activities in caries-free and caries-active naval recruits.

Kleinberg (1967) (Archs oral Biol. 12, 1457-1473) has observed that the incubation of a salivary sediment/supernatant mixture with a low concentration of glucose produces a pH drop followed by a pH rise. As this pH-rise effect could elevate oral pH in vivo, the degree of such activity could be directly related to caries resistance. The pH-rise of paraffin-stimulated whole saliva samples from 54 caries-free and 54 caries-active male naval recruits was compared in two assays. The first, conducted with sediment/supernatant/2.8 mM glucose mixtures, showed no significant differences for mean pH versus time profiles for 26 caries-free and 26 caries-active subjects. Concomitant assays, in which 3.33 mM arginine and water replaced the supernatants in the assay mixtures, showed slightly higher mean pH/time profiles, with higher minima for the caries-free subjects. These profile differences were statistically significant for the arginine-containing mixtures, a result attributed to different microbial distributions for the caries-free and caries-active sediments. The second assays were conducted on saliva supernatants from 28 caries-free and 28 caries-active subjects, employing a strain of Lactobacillus casei in place of salivary sediment in the assay system. No statistically significant differences were evident between the mean pH/time profiles for the two groups of subjects, although a significant positive correlation was observed between pH minimum and bicarbonate content of the samples. Thus no relationship of salivary pH-rise activity and caries experience were found.

Relationship between dental caries experience and surface enamel fluoride concentration in young men from three optimally fluoridated cities.

An in vivo enamel biopsy technique was used to determine relationships between dental caries experience and surface enamel fluoride levels in a group of young men from three fluoridated cities on the east coat of the U.S. A significant inverse relationship between enamel thickness and fluoride concentration was observed, and a weak but statistically significant inverse relationship between caries scores and enamel fluoride concentration was noted. The effect was most pronounced in biopsies which did not exceed 5.9 micron in depth.

The hypermineralization of diseased root surfaces.

Root surfaces which have lost their attachment due to chronic inflammatory periodontal disease present significant increases in calcium, magnesium, phosphorus, and fluoride. The clinical significance of this effect is not known in regards to wound healing, but it may be helpful in control of cervical sensitivity.