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So far Richardson GM. has created 996 blog entries.

Evidence that bisphenol a exposure is not associated with composite resin dental fillings.

In their recent article, Maserejian et al.(1) propose bisphenol-a (BPA) exposure as a hypothesis to explain apparent psychosocial effects in children of the New England Children’s Amalgam Trial (NECAT) who received composite resin fillings. The authors rightly point out that a “thorough investigation considering exposure levels is important to substantiate these findings”. Within the NECAT, no direct measure of BPA exposure, such as BPA concentration in urine, was reported. Data from Cycle 1 of the Canadian Health Measures Survey (2,3) (CHMS, 2007-2009) suggests that exposure to BPA is not associated with the presence of composite resin fillings.

By |2018-07-30T18:48:01+00:00January 1st, 2012|Other|

Release of metal ions from orthodontic appliances: an in vitro study.

In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15 μg/l in the controls) and chromium (101 vs. 8 μg/l in the controls). Three ion release coefficients were defined: α, a dimensionless multiplication factor; β, the difference in concentrations (in micrograms per liter); and γ, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be interrelated.

By |2018-07-26T18:32:49+00:00January 1st, 2012|Other|

Blood cadmium, mercury, and lead in children: an international comparison of cities in six European countries, and China, Ecuador, and Morocco.

Children’s blood-lead concentration (B-Pb) is well studied, but little is known about cadmium (B-Cd) and mercury (B-Hg), in particular for central Europe. Such information is necessary for risk assessment and management. Therefore, we here describe and compare B-Pb, B-Cd and B-Hg in children in six European, and three non-European cities, and identify determinants of these exposures. About 50 school children (7-14 years) from each city were recruited (totally 433) in 2007-2008. Interview and questionnaire data were obtained. A blood sample was analyzed: only two laboratories with strict quality control were used. The European cities showed only minor differences for B-Cd (geometric means 0.11-0.17 μg/L) and B-Pb (14-20 μg/L), but larger for B-Hg (0.12-0.94 μg/L). Corresponding means for the non-European countries were 0.21-0.26, 32-71, and 0.3-3.2 μg/L, respectively. For B-Cd in European samples, traffic intensity close to home was a statistically significant determinant, for B-Hg fish consumption and amalgam fillings, and for B-Pb sex (boys higher). This study shows that European city children’s B-Cd and B-Pb vary only little between countries; B-Hg differs considerably, due to varying tooth restoration practices and fish intake. Traffic intensity seemed to be a determinant for B-Cd. The metal concentrations were low from a risk perspective but the chosen non-European cities showed higher concentrations than the cities in Europe.

Perception of patients with amalgam fillings about toxicity of mercury in dental amalgam.

OBJECTIVE:
The objective of this study is to evaluate the awareness of patients with dental fillings about the toxicity of mercury in dental amalgam.

MATERIALS AND METHODS:
Adult patients having at least one amalgam filling in their mouth were recruited in the Oral Diagnosis Department of OAUTHC, Ile-Ife Dental Hospital. Participants were recruited consecutively as they report in the clinic. Data were collected using a structured questionnaire developed based on standard questions from relevant publications. They were asked to indicate the type of filling material in their mouth, ingredients of the material, previous knowledge of mercury in dental amalgam and ailments due to mercury. They were to indicate their level of agreement with filling their cavities with dental amalgam despite prior information about its mercury content.

RESULTS:
There were about 446 respondents analyzed; male, 194 (43.5%); female 252 (56.5%). Six (1.4%) and 21 (4.7%) respondents were primary and secondary schools students respectively; 15(3.4%) had no formal education while about 410 (91.9%) were either undergraduate or graduate. All of them had at least one amalgam filling. 249 (55%) participants know the type of filling on their teeth; 156 (34.5%) had the knowledge of the presence of mercury in dental amalgam while 26.1% believed mercury can cause problems in human beings. About 90 (19.9%) participants claimed to have heard about adverse reactions to dental amalgams and 34 (7.5%) of them have heard about people recovering from an illness after removal of their filling. The level of agreement with filling their cavities with amalgam despite prior knowledge of its mercury content was 74% while 60% was observed for allowing just any material to be placed on their teeth.

CONCLUSION:
Awareness of toxicity of mercury in dental amalgam was slightly low among the respondents studied. This may be suggested to be a reflection of nonexistent of global amalgam controversy in Nigeria.

By |2018-07-18T19:31:57+00:00January 1st, 2012|Mercury|

Practical issues for purchasing, installing and maintaining dental amalgam separators.

OVERVIEW:
The authors review factors related to office infrastructure and operation that dentists should consider when investing in an amalgam separator. They also provide a cost-analysis worksheet and checklist that may be useful to dentists who are considering purchasing a separator.

CONCLUSIONS AND CLINICAL IMPLICATIONS:
Before purchasing or installing an amalgam separator, dentists should consider factors specific to the available models, including size and maintenance requirements. In addition, office-specific actors should be considered (such as the plumbing configuration, available space for installation and subsequent access to that space for equipment replacement and maintenance). Dentists also should research whether any local or state regulations exist that might influence product selection or installation. Dentists should consider the effect an amalgam separator could have on existing suction equipment. Finally, dentists will want to consider the short- and long-term costs (including maintenance and parts replacement) of the available options.

By |2018-07-26T16:34:55+00:00January 1st, 2012|Mercury|

An unusual allergy to platinum embolization coils

Treating varicoceles with percutaneous embolization of the gonadal vein is a widely favored method of treatment. The procedure is minimally invasive, can be performed on an outpatient basis under local anesthetic, and has extremely high success rates with low incidence of complication
[1]. It has been shown to be of benefit in fertility treatment[2] and avoids the development of posttreatment hydroceles, because lymphatic channels are not affected [3]. We present a case of a patient who developed an allergy to metallic components of the embolization coils used during varicocele treatment.

By |2020-01-10T03:17:45+00:00January 1st, 2012|Other|

Mercury toxicity in beluga whale lymphocytes: limited effects of selenium protection

Increasing emissions of anthropogenic mercury represents a growing concern to the health of high trophic level marine mammals. In its organic form, this metal bioaccumulates, and can be toxic to several physiological endpoints, including the immune system. In this study, we (1) evaluated the effects of inorganic mercury (mercuric chloride, HgCl2) and organic mercury (methylmercuric chloride, MeHgCl) on the in vitro function of lymphocytes isolated from the peripheral blood of beluga whales (Delphinapterus leucas); (2) characterized the potential protective effects of sodium selenite (Na2SeO3) on cell proliferation of HgCl2 or MeHgCl-treated beluga whale lymphocytes; and (3) compared these dose-dependent effects to measurements of blood Hg in samples collected from traditionally harvested beluga whales in the western Canadian Arctic. Lymphocyte proliferative responses were reduced following exposure to 1 μM of HgCl2 and 0.33 μM of MeHgCl. Decreased intracellular thiol levels were observed at 10 μM of HgCl2 and 0.33 μM of MeHgCl. Metallothionein induction was noted at 0.33 μM of MeHgCl. Concurrent exposure of Se provided a degree of protection against the highest concentrations of inorganic Hg (3.33 and 10 μM) or organic Hg (10 μM) for T-lymphocytes. This in vitro protection of Se against Hg toxicity to lymphocytes may contribute to the in vivo protection in beluga whales exposed to high Hg concentrations. Current Hg levels in free-ranging beluga whales from the Arctic fall into the range of exposures which elicited effects on lymphocytes in our study, highlighting the potential for effects on host resistance to disease. The implications of a changing Arctic climate on Hg fate in beluga food webs and the consequences for the health of beluga whales remain pressing research need

By |2020-12-23T03:04:11+00:00January 1st, 2012|Mercury|

Evaluation of the spatter-reduction effectiveness of two dry-field isolation techniques.

Background: The authors conducted a study to compare the effectiveness of two dry-field isolation techniques with that of a control technique (no isolation) in reducing spatter from a dental operative site.

Methods: The authors designed a benchtop experiment to evaluate spatter patterns after performing simulated occlusal surface preparations on three typodont teeth in a dental manikin. Fluorescein dye served as the marker to enable visualization of the spatter distribution. The authors compared the effectiveness of a nonisolated control consisting of high-volume evacuation (HVE) alone with that of two dry-field isolation techniques: a dental dam with HVE and the Isolite system (Isolite Systems, Santa Barbara, Calif).

Results: The authors performed a two-way analysis of variance. Both the Isolite device and the dental dam with HVE exhibited a significant decrease in the number of contaminated squares (P < .001) compared with that for the nonisolated control. In addition, overall, the results showed no statistically significant difference between the Isolite system and the dental dam with HVE (P = .126).

Conclusions: The study results showed that use of a dental dam with HVE or the Isolite system significantly reduced spatter overall compared with use of HVE alone.

Clinical implications: Isolation with a dental dam and HVE or with the Isolite system appears to aid in the reduction of spatter during operative dental procedures, potentially reducing exposure to oral pathogens.

Clinical effectiveness of direct class II restorations-a meta-analysis.

PURPOSE:

More than five hundred million direct dental restorations are placed each year worldwide. In about 55% of the cases, resin composites or compomers are used, and in 45% amalgam. The longevity of posterior resin restorations is well documented. However, data on resin composites that are placed without enamel/dentin conditioning and resin composites placed with self-etching adhesive systems are missing.

MATERIAL AND METHODS:

The database SCOPUS was searched for clinical trials on posterior resin composites without restricting the search to the year of publication. The inclusion criteria were: (1) prospective clinical trial with at least 2 years of observation; (2) minimum number of restorations at last recall = 20; (3) report on dropout rate; (4) report of operative technique and materials used; (5) utilization of Ryge or modified Ryge evaluation criteria. For amalgam, only those studies were included that directly compared composite resin restorations with amalgam. For the statistical analysis, a linear mixed model was used with random effects to account for the heterogeneity between the studies. P-values under 0.05 were considered significant.

RESULTS:

Of the 373 clinical trials, 59 studies met the inclusion criteria. In 70% of the studies, Class II and Class I restorations had been placed. The overall success rate of composite resin restorations was about 90% after 10 years, which was not different from that of amalgam. Restorations with compomers had a significantly lower longevity. The main reason for replacement were bulk fractures and caries adjacent to restorations. Both of these incidents were infrequent in most studies and accounted only for about 6% of all replaced restorations after 10 years. Restorations with macrofilled composites and compomer suffered significantly more loss of anatomical form than restorations with other types of material. Restorations that were placed without enamel acid etching and a dentin bonding agent showed significantly more marginal staining and detectable margins compared to those restorations placed using the enamel-etch or etch-and-rinse technique; restorations with self-etching systems were between the other groups. Restorations with compomer suffered significantly more chippings (repairable fracture) than restorations with other materials, which did not statistically differ among each other. Restorations that were placed with a rubber-dam showed significantly fewer material fractures that needed replacement, and this also had a significant effect on the overall longevity.

CONCLUSION:

Restorations with hybrid and microfilled composites that were placed with the enamel-etching technique and rubber-dam showed the best overall performance; the longevity of these restorations was similar to amalgam restorations. Compomer restorations, restorations placed with macrofilled composites, and resin restorations with no-etching or self-etching adhesives demonstrated significant shortcomings and shorter longevity.

By |2019-01-10T00:13:57+00:00January 1st, 2012|Other|
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