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Potentiometric stipping analysis (PSA) was applied for the determination of lead and cadmium leaching from dental prosthetic materials and teeth. The soluble lead content in finished dental implants was found to be much lower than that of the individual compo-nents used for their preparation. Cadmium was not detected in dental implants and materials under the defined conditions. The soluble lead and cadmium content of teeth was slightly lower than the lead and cadmium content in whole teeth (w/w) reported by other research-ers, except in the case of a tooth with removed amalgam filling. The results of this work sug-gest that PSA may be a good method for lead and cadmium leaching studies for investiga-tion of the biocompatibility of dental prosthetic materials.

AIM:

The prevalence of apical periodontitis (AP) and the quality of root fillings and restorations were determined in two Canadian populations differing in avail-ability of endodontists.

METHODOLOGY:

Radiographs of first-time university patients aged 25-40 years in Toronto and Saskatoon were examined for missing teeth, presence and standard of root fillings, standard of restoration, and AP according to the Periapical Index. Patients with root-filled teeth were invited for clinical examination and interview to inspect the restorations, and to reveal the providers of endodontic treatment and reasons for extractions of missing teeth. Chi-square and independent t-tests interpreted at the 5% significance level were used to examine associations between the prevalence of AP in root-filled teeth and the standard of the root filling, restoration, and providers of treatment.

RESULTS:

Proportion of patients with root-filled teeth was significantly higher (P < 0.001) in Toronto than in Saskatoon (39 and 26%, respectively). Presence of AP about root-filled teeth (44% in Toronto, 51% in Saskatoon) was significantly associated with poor density (OR = 2.7) short (OR = 2.4) and long (OR = 2.8) root fillings, and with poor radiographic quality of the restoration (OR = 1.7) Prevalence of AP did not differ significantly between teeth treated by generalists and endodontists.

CONCLUSIONS:

The prevalence of AP in root-filled and untreated teeth was comparable to that reported in previous methodologically compatible studies. The quality of both the root filling and the restoration were found to impact on the periapical health of root-filled teeth, with the impact of the restoration being most critical when the quality of the root filling was adequate.

In this retrospective study the survival rate of 190 root-canal-treated teeth of 144 patients after 10-yr minimum was evaluated. Students during their training in 1987 and 1988 had performed the treatments. Age, gender, jaw, or quantity of root canals had no influence to the success of a root-canal treatment. Teeth with an apical lesion before the endodontic treatment showed a significantly shorter likelihood of survival. The best results could be found in root-canal fillings ending 0 to 1 mm and 1 to 2 mm before the apex. Comparing types of restoration, prosthetic-treated teeth with retention post and crown seem to be favorable. The study showed that root-canal treatment even conducted by students has a survival rate of 85.1% (Kaplan-Meier) after 10 yr and is a long-lasting, conservative therapy.

Symptoms, and especially those without clear underlying medical explanations, account for a large percentage of clinical encounters. Many unexplained symptoms have been organized by patients and practitioners into syndromes such as chronic fatigue syndrome, multiple chemical sensitivity, sick building syndrome, Gulf War syndrome, and the like. All these syndromes are defined solely on the basis of symptoms rather than by medical signs. Some of the above-described conditions overlap strongly with explained conditions such as asthma. The relationship of such symptoms and syndromes to environmental exposure is often sharply debated, as is the distinction between the various syndromes. This leads to problems of what type of research should be conducted and who should conduct it. It is time to develop a comprehensive research agenda to sort out nomenclature, epidemiology, and environmental causation for these conditions, moving toward comprehensive and effective public health and clinical approaches.

“The association between blood lead level and dental caries was evaluated in cross-sectional analyses of baseline data for 543 children 6-10 years old screened for enrollment in the Children’s Amalgam Trial, a study designed to assess potential health effects of mercury in silver fillings. Approximately half of the children were recruited from an urban setting (Boston/Cambridge, MA, USA) and approximately half from a rural setting (Farmington, ME, USA). Mean blood lead level was significantly greater among the urban subgroup, as was the mean number of carious tooth surfaces. Blood lead level was positively associated with number of caries among urban children, even with adjustment for demographic and maternal factors and child dental practices. This association was stronger in primary than in permanent dentition and stronger for occlusal, lingual, and buccal tooth surfaces than for mesial or distal surfaces. In general, blood lead was not associated with caries in the rural subgroup. The difference between the strength of the associations in the urban and rural settings might reflect the presence of residual confounding in the former setting, the presence of greater variability in the latter setting in terms of important caries risk factors (e.g., fluoride exposure), or greater exposure misclassification in the rural setting. These findings add to the evidence supporting a weak association between children’s lead exposure and caries prevalence. A biologic mechanism for lead cariogenicity has not been identified, however. Our data are also consistent with residual confounding by factors associated with both elevated lead exposure and dental caries.”

BACKGROUND:

We aimed to determine the prevalence of contact sensitization in the general population and to investigate associations with important sociodemographic and medical characteristics.

METHODS:

Within a population-based nested, case-control study in Germany, we performed patch tests with 25 standard allergens in 1141 adults (50.4% female, age median 50 years). Additional information was obtained by a dermatologic examination, a standardized interview, and blood analysis.

RESULTS:

At least one positive reaction was exhibited by 40.0% of the subjects, with reactions most frequently observed to fragrance mix (15.9%), nickel (13.1%), thimerosal (4.7%), and balsam of Peru (3.8%). Women were sensitized more often than men (50.2% vs 29.9%, OR 2.36, CI 1.84-3.03), and this was also significant for fragrance mix, nickel, turpentine, cobalt chloride, and thimerosal. Contact sensitization was more frequent in subjects who reported adverse skin reactions (53.8% vs. 32.6%; OR 2.41, CI 1.85-3.14), and this was particularly true for sensitization to nickel (45.5% vs 8.8%, OR 8.64, CI 5.67-13.17) and fragrance mix (29.0% vs 14.0%, OR 2.51, CI 1.60-3.91) and the corresponding intolerance of fashion jewelry and fragrances. Contact sensitization decreased with increasing degree of occupational training (unskilled 45.9%, apprenticeship 40.1%, technical college 40.4%, and school of engineering 12.5%; P=0.023; trend test P=0.042). Significant associations of contact sensitization and presence of allergen-specific IgE antibodies, atopic eczema, or psoriasis were not observed. Frequency estimates for the general adult population based on these findings were 28.0% for overall contact sensitization and 11.4% for fragrance mix, 9.9% for nickel, and 3.2% for thimerosal.

CONCLUSIONS:

It is concluded that contact allergy is influenced by sociodemographic parameters and plays an important role in the general population.

AIM:

The aim of this study was to compare the effects of four preparation techniques on canal volume and surface area using three-dimensionally reconstructed root canals in extracted human maxillary molars. In addition, micro CT data was used to describe morphometric parameters related to the four preparation techniques.

METHODOLOGY:

A micro computed tomography scanner was used to analyse root canals in extracted maxillary molars. Specimens were scanned before and after canals were prepared using Ni-Ti – K-Files, Lightspeed instruments, ProFile.04 and GT rotary instruments. Differences in dentine volume removed, canal straightening, the proportion of unchanged area and canal transportation were calculated using specially developed software.

RESULTS:

Instrumentation of canals increased volume and surface area. Prepared canals were significantly more rounded, had greater diameters and were straighter than unprepared canals. However, all instrumentation techniques left 35% or more of the canals’ surface area unchanged. Whilst there were significant differences between the three canal types investigated, very few differences were found with respect to instrument types.

CONCLUSIONS:

Within the limitations of the micro CT system, there were few differences between the four canal instrumentation techniques used. By contrast, a strong impact of variations of canal anatomy was demonstrated. Further studies with 3D-techniques are required to fully understand the biomechanical aspects of root canal preparation.

“Selenium is of fundamental importance to human health. It is an essential component of several major metabolic pathways, including thyroid hormone metabolism, antioxidant defence systems, and immune function. The decline in blood selenium concentration in the UK and other European Union countries has therefore several potential public health implications, particularly in relation to the chronic disease prevalence of the Western world such as cancer and cardiovascular disease. Ten years have elapsed since recommended dietary intakes of selenium were introduced on the basis of blood glutathione peroxidase activity. Since then 30 new selenoproteins have been identified, of which 15 have been purified to allow characterisation of their biological function. The long term health implications in relation to declining selenium intakes have not yet been thoroughly examined, yet the implicit importance of selenium to human health is recognised universally. Selenium is incorporated as selenocysteine at the active site of a wide range of selenoproteins. The four glutathione peroxidase enzymes (classical GPx1, gastrointestinal GPx2, plasma GPx3, phospholipid hydroperoxide GPx4)) which represent a major class of functionally important selenoproteins, were the first to be characterised. Thioredoxin reductase (TR) is a recently identified seleno-cysteine containing enzyme which catalyzes the NADPH dependent reduction of thioredoxin and therefore plays a regulatory role in its metabolic activity. Approximately 60% of Se in plasma is incorporated in selenoprotein P which contains 10 Se atoms per molecule as selenocysteine, and may serve as a transport protein for Se. However, selenoprotein-P is also expressed in many tissues which suggests that although it may facilitate whole body Se distribution, this may not be its sole function. A second major class of selenoproteins are the iodothyronine deiodinase enzymes which catalyse the 5’5-mono-deiodination of the prohormone thyroxine (T4) to the active thyroid hormone 3,3’5-triiodothyronine (T3). Sperm capsule selenoprotein is localised in the mid-peice portion of spermatozoa where it stabilises the integrity of the sperm flagella. Se intake effects tissue concentrations of selenoprotein W which is reported to be necessary for muscle metabolism. It is of great concern that the health implications of the decline in Se status in the UK over the past two decades have not been systematically investigated. It is well recognised that dietary selenium is important for a healthy immune response. There is also evidence that Se has a protective effect against some forms of cancer; that it may enhance male fertility; decrease cardiovascular disease mortality, and regulate the inflammatory mediators in asthma. The potential influence of Se on these chronic diseases within the European population are important considerations when assessing Se requirement.”

“There are several proteins in mammalian cells that can metabolize hydrogen peroxide and lipid hydroperoxides. These proteins include four selenium-containing glutathione peroxidases that are found in different cell fractions and tissues of the body. This review considers the structure and distribution of the selenoperoxidases and how this relates to their biological function. The functions of the selenoperoxidases were originally studied in systems where their activity was manipulated by changing dietary selenium levels. More recently, molecular techniques have allowed overexpression of selenoperoxidases in cell lines and animals. Additionally, cellular glutathione peroxidase knockout mice have been used to investigate the functions of this protein. From this work it is clear that the selenoperoxidases are involved in cell antioxidant systems. However, they also have more subtle functions in ensuring the regulation and formation of arachadonic acid metabolites that are derived from hydroperoxide intermediates. The range of biological processes, which are potentially dependent on optimal selenoperoxidase activity in mammals, emphasises the importance of achieving adequate selenium intake in the diet.”