Thyroid cancer risk in Belarus among children and adolescents exposed to radioiodine after the Chornobyl accident.

BACKGROUND: Previous studies showed an increased risk of thyroid cancer among children and adolescents exposed to radioactive iodines released after the Chornobyl (Chernobyl) accident, but the effects of screening, iodine deficiency, age at exposure and other factors on the dose-response are poorly understood. METHODS: We screened 11 970 individuals in Belarus aged 18 years or younger at the time of the accident who had estimated (131)I thyroid doses based on individual thyroid activity measurements and dosimetric data from questionnaires. The excess odds ratio per gray (EOR/Gy) was modelled using linear and linear-exponential functions. RESULTS: For thyroid doses <5 Gy, the dose-response was linear (n=85; EOR/Gy=2.15, 95% confidence interval: 0.81-5.47), but at higher doses the excess risk fell. The EOR/Gy was significantly increased among those with prior or screening-detected diffuse goiter, and larger for men than women, and for persons exposed before age 5 than those exposed between 5 and 18 years, although not statistically significant. A somewhat higher EOR/Gy was estimated for validated pre-screening cases. CONCLUSION: 10-15 years after the Chornobyl accident, thyroid cancer risk was significantly increased among individuals exposed to fallout as children or adolescents, but the risk appeared to be lower than in other Chornobyl studies and studies of childhood external irradiation.

Duties and training of dental nurses: how do Irish practices conform to European standards?

AIM: The dental nurse is a key member of the dental team, having an important role in the delivery of oral healthcare. Despite this, there is considerable variation throughout Europe in relation to the level of training, permitted duties, and statutory registration of dental nurses. The purpose of this paper is to describe the opinions and attitudes of dental nurses to their roles and suitability of training in one European member state, Ireland, where statutory registration has recently been introduced. METHOD: A postal questionnaire was sent to 150 dental practitioners selected from the Irish Register of Dentists. The dentists were asked to distribute questionnaire to dental nurse(s) working in their practice. Information sought from the dental nurses included their employment setting, the nature of their employment, their level of training, additional qualifications held, their views on the key duties and responsibilities of a dental nurse, and the appropriate duration and content of a dental nurse training programme. RESULTS: Replies were received from 96 dental nurses (response rate = 64%). Fifty-five percent of respondents (n = 53) were employed in private practice, 39% (n = 37) were employed in the Health Board Dental Service, and 6% (n = 6) were employed in a dental hospital. Two thirds of respondents (n = 62) had been employed as dental nurses for more than five years. Eighty-six percent of respondents (n = 83) were in full-time employment. Seventy-three percent of respondents (n = 70) held a recognised dental nurse qualification. Sixty-five percent of respondents (n = 70) who held a dental nurse qualification felt that the appropriate duration of a dental nurse training programme was one year or less. Thirty-two percent of respondents (n = 30) had completed additional training in practice management, administration or computer skills. Ninety-five percent of respondents (n = 91) were interested in attending continuing education courses. Eighty-five percent of respondents (n = 82) felt that assistance at the administration of local anaesthetics was a key duty/responsibility for dental nurses, while only 20% of respondents (n = 19) felt that infection control procedures was a key duty. CONCLUSIONS: Within the group of dental nurses surveyed, there was a lack of clarity surrounding their perception of their key duties. This could present challenges to the effective delivery of oral healthcare regimens within Ireland. Further investigation of this situation in other European countries is indicated.

Posterior composites: Update on cavities and filling techniques.

OBJECTIVES: The aim of this paper is to examine cavity design for posterior resin composite restorations and to discuss various resin composite filling techniques. DATA: Literature with regard to cavity preparation for amalgam and resin composite restorations has been reviewed. An overview of available bulkfill resin composite systems is provided and a categorization of these systems according to their clinical application and their intended use is outlined. SOURCES: A literature search was carried out by the authors in Medline. STUDY SELECTION: Pre-defined inclusion criteria based on keywords were included and reviewed. CONCLUSIONS: Minimum cavity preparations are advised for posterior resin composite restorations, preserving the greatest amount of healthy tooth structure. For resin composite restorations only the lesion of caries needs to be removed with all remaining tooth structure protected for the bonding process. The anticipated outcome of this philosophy will result in increased survival of teeth. Newer bulkfill restorative resins offer many advantages such as reduces time for placement.

Autoimmune thyroiditis and exposure to iodine 131 in the Ukrainian cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: results from the first screening cycle (1998-2000).

CONTEXT: Due to the Chornobyl accident, millions were exposed to radioactive isotopes of iodine and some received appreciable iodine 131 (131I) doses. A subsequent increase in thyroid cancer has been largely attributed to this exposure, but evidence concerning autoimmune thyroiditis (AIT) remains inconclusive. OBJECTIVE: The objective of the study was to quantify risk of AIT after 131I exposure. DESIGN/SETTING/PARTICIPANTS: Baseline data were collected from the first screening cycle (1998-2000) of a large cohort of radiation-exposed individuals (n = 12,240), residents of contaminated, iodine-deficient territories of Ukraine. Study individuals were under the age of 18 yr on April 26, 1986, and had thyroid radioactivity measurements made shortly after the accident. OUTCOMES: AIT was defined a priori based on various combinations of elevated antibodies to thyroid peroxidase (ATPO), TSH, and clinical findings; elevated ATPO were considered to be an indicator of thyroid autoimmunity. RESULTS: No significant association was found between 131I thyroid dose estimates and AIT, but prevalence of elevated ATPO demonstrated a modest, significant association with 131I that was well described by several concave models. This relationship was apparent in individuals with moderately elevated ATPO and euthyroid, thyroid disease-free individuals. CONCLUSIONS: Twelve to 14 yr after the Chornobyl accident, no radiation-related increase in prevalence of AIT was found in a large cohort study, the first in which 131I thyroid doses were estimated using individual radioactivity measurements. However, a dose-response relationship with ATPO prevalence raises the possibility that clinically important changes may occur over time. Thus, further follow-up and analysis of prospective data in this cohort are necessary.

Fluoride-containing restorative materials.

Dental practitioners are exposed to an increasing number of dental materials, which claim the benefits of fluoride release. The purpose of this paper is to critically review the literature of these materials. Glass ionomers, resin modified glass ionomers, compomers, resin composites, fissure sealants and amalgam are discussed. It is clear that a long-term measurable release of fluoride can be observed from certain restorative materials, in vitro, particularly glass ionomer cement, resin modified glass ionomer cement, fluoridated cements, fluoridated dental amalgam and certain fissure sealants. In general, the rate of fluoride release is not constant but exhibits a relatively rapid initial rate, which decreases with time. However, the fluoride release profiles may be dependent on specific formulation and on experimental design and sampling methods. These materials may feature greater longevity, a reduced incidence of marginal failure, an elevated concentration of fluoride in contingent plaque, together with an antibacterial action when compared with non-fluoride releasing materials. In addition, fluoride-releasing materials may perform better in caries inhibition in artificial caries model studies than non-fluoridated materials. While any, or all, of these anti-cariogenic effects may be associated with fluoride release, a direct relationship between fluoride release profiles and such effects has not been determined in vivo.

Pituitary lymphoma presenting as fever of unknown origin.

An 86-yr-old woman presented with fever of unknown origin. When laboratory evaluation revealed partial hypopituitarism, a magnetic resonance imaging scan of the head was performed and revealed a sellar mass consistent with a pituitary adenoma. Only after other possible etiologies for fever were excluded did she undergo transsphenoidal resection of the sellar mass, which proved to be a B-cell lymphoma. Primary central nervous system lymphoma of the pituitary region is a rare cause of a sellar mass, and this is the first reported case of pituitary lymphoma whose presenting manifestation was fever of unknown origin. Several disease processes can manifest themselves as fever and a sellar mass, including lymphomas. In our case, only surgical biopsy could make a diagnosis and distinguish this process from the more common pituitary adenoma.

Defects of taste and smell in patients with hypothyroidism.

Taste and smell functions were measured in 18 unselected patients with untreated primary hypothyroidism, and in 15 of the 18 patients after treatment with thyroid hormones. Before treatment, 9 of the 18 patients (50 per cent) were aware of some alteration in their sense of taste, and 7 of the 18 patients (39 per cent) were aware of some alteration in their sense of smell. Distoritions of tase (dysgeusia) and smell (dysosmia) were frequent complaints among the untreated patients; dysgeusia was observed by 7 patients (39 per cent) and dysosmia by 3 patients (17 per cent). Median detection and recognition thresholds for four taste stimuli salt (sodium chloride), sweet (sucrose), sour (hydrochloric acid) and bitter (urea), and for two smell stimuli (pyridine and nitrobenzene), were determined in each patient before and after treatment with thyroid hormones. Before treatment, decreased taste acuity (hypogeusia) for at least one stimulus was observed in 14 of the patients (83 per cent); the most common abnormalities were in the detection and recognition of bitter stimuli. Median detection thresholds for both smell stimuli were also markedly elevated (hyposmia) before therapy. Treatment with throid hormones largely reversed both the taste and smell defects. In one patient, taste and smell abnormalities were completely corrected after 16 days of treatment with thyroxine. This study indicates that taste and smell defects are common clinical abnormalities in primary hypothyroidism, and suggests that these defects may contribute to the anorexia and lack of interest in eating which are frequently observed.

Changes in thyroid function tests during short-term salsalate use.

Although long-term administration of salsalate depresses blood levels of both total thyroxine (T4) and total triiodothyronine (T3) and at least transiently decreases serum thyrotropin (TSH), changes in thyroid function tests have not been fully characterized during its short-term use. It is also unclear if the observed changes are solely the result of decreased hormone binding to carrier proteins or if reduced hepatic 5'-monodeiodinase activity is important. Blood was sampled at baseline (day 0) and after 24 hours (day 1) and 72 hours (day 3) in eight subjects taking a therapeutic dose of salsalate 1,500 mg twice daily. Total T4 decreased from 90.1+/-7.7 nmol/L (mean+/-SD) on day 0 to 82.9+/-8.6 nmol/L on day 1 (P=.1 v baseline) and 68.6+/-8.7 nmol/L on day 3 (P=.0001). Total T3 decreased from 1.76+/-0.20 nmol/L to 1.61+/-0.16 nmol/L on day 1 (P<.05) and 1.31+/-0.27 nmol/L on day 3 (P=.002). The T4/T3 ratio was 51.7+/-7.7 at baseline and remained unchanged after 3 days. Levels of reverse T3 (rT3) were reduced from 0.24+/-0.05 nmol/L to 0.18+/-0.02 nmol/L on day 3 (P<.05). While the free T4 index (FTI) declined in parallel with total T4, the free T4 level by direct equilibrium dialysis (FTD) was unchanged after 3 days. Serum TSH decreased from 1.47+/-0.47 mU/L to 0.91+/-0.27 mU/L after 1 day (P<.05) and remained suppressed after 3 days (0.95+/-0.49 mU/L, P<.05). In conclusion, (1) therapeutic doses of salsalate significantly decrease serum concentrations of total T4, total T3, and rT3 to about 75% of baseline levels after 3 days without altering the T4/T3 ratio; (2) although the FTD does not change, serum TSH concentrations remain suppressed; and (3) the proportionate decrease in total thyroid hormone levels suggests that inhibition of hormone binding to serum proteins is more important in producing these changes than reduced hepatic 5'-monodeiodinase activity.

Bacterial adhesion to dental amalgam and three resin composites.

OBJECTIVES: The ability of three oral bacteria to adhere to hydrophobic amalgam (water contact angle 60 degrees) and hydrophobic resin composites (Prisma-AP.H 56 degrees. Herculite XRV 82 degrees and Z100 89 degrees) was compared using an in vitro assay. METHODS AND RESULTS: Following preincubation of the materials with human saliva, X-ray photoelectron spectroscopy showed the surfaces to adsorb carbon and nitrogen-containing compounds in a conditioning film that appeared to block the detection of Na and others in 2100 resin. Hg and Ag in amalgam, Si and Zn in Prisma AP.H resin and Ag and Na in Herculite resin. The precoating of the substrata by a proteinaceous conditioning film led to decreased binding of viable cells of Streptococcus sanguis CH3, Streptococcus salivarius HB and Actinomyces viscosus WG as compared with the adhesion to bare composites. With and without salivary coating, there was a correlation between increased bacterial hydrophobicity and increased retention on the substrata. However, there was no statistical difference in binding to the amalgam compared with the resin composites. In vitro studies showed that the bacteria autoaggregated in the presence of saliva. CONCLUSION: The results indicate the potential ability of normal oral flora to colonize resin composite.

A 2-year clinical evaluation of two pit and fissure sealants placed with and without the use of a bonding agent.

The purpose of the study was to evaluate whether the clinical effectiveness of pit and fissure sealant was increased (as demonstrated by an increased retention rate) when a bonding agent was used prior to the placement of the sealant. Two pit and fissure sealants, Concise Light Cured White Sealant and Prisma Shield Light Cured Sealant, were placed in vivo with and without the use of the bonding agents, Scotchbond 2 and Prisma Universal Bond. After 2 years, 55% of the sample was available for recall. The retention rates for the sealants were 77% for Concise with Scotchbond 2, 84% for Concise with no bonding agent, 77% for Prisma Shield with Universal Bond, and 77% for Prisma Shield with no bonding agent. Results of this study indicated that the use of a bonding agent prior to the application of a pit and fissure sealant does not increase the retention rate.

Orthodontic bonding to Adlloy-treated type IV gold.

Adlloy surface treatment of noble alloys has been shown to increase the bond strength of composite to gold alloys. The purpose of this study was to test the bond strength of Adlloy-treated type IV gold surfaces and orthodontic brackets bonded with self-curing composite resin, and compare it with sandblasted gold and etched enamel. Data were derived from a control sample of 40 human premolars and two experimental groups of Adlloy-treated and sandblasted gold surfaces. "A"-Company premolar brackets were bonded with Concise self-curing composite resin. The specimens were submerged in water for 30 days and thermocycled 1500 times before being subjected to shear bond tests. Statistically significant differences were found in the mean values of the three groups (F = 124.04; df = 2,117; P < .001). Bonds on the adlloy-treated gold were twice as strong as those found on microetched gold. Adlloy surface treatment of type IV gold will permit adequate bond strength; however, FDA approval is required for intraoral use.

Bond strengths of two ceramic brackets using argon laser, light, and chemically cured resin systems.

The present study compared tooth-bracket bond strengths using two types of ceramic brackets and three methods of polymerization: argon laser, conventional light, and chemical. Ninety extracted human premolars were prepared for bonding with pumice and gel etchant. Using single crystal alumina brackets with silanated bases, three groups of 15 teeth were bonded with one of the three polymerization methods. Similarly, three groups of 15 teeth were bonded with polycrystal alumina brackets with nonsilanated bases. Each bonded bracket was tested on an Instron tensile testing machine in shear mode to determine shear debonding strength. Fracture sites were recorded. Results demonstrated that (1) all combinations produced shear bond strengths greater than those considered clinically acceptable, (2) the mean shear bond strengths of the single crystal alumina brackets with silanated bases were significantly higher than those of the polycrystal alumina brackets with nonsilanated bases, and (3) no enamel fractures were found on debonding the chemically cured brackets while the light and laser groups exhibited a 10% rate of enamel fracture on debonding.

Metal-resin bonding.

Achieving an effective and lasting bond of resin to dental alloys is an essential component in today's restorative dentistry. This paper reviews the history of metal/resin bonding, outlines different surface treatments of base and noble alloys and compares some of the resin luting materials used. The clinical application of metal/resin bonding to repair porcelain veneered fixed prostheses and the potential of bonded amalgams is discussed.

The performance of conventional, fixed bridgework, retained by partial coverage crowns.

A retrospective study was carried out on 248 partial coverage retained fixed bridges, in 211 patients. All were inserted at an undergraduate dental clinic and their length of service ranged from 1 to 19 years. In 211 prostheses, on which current information was available a total of 20 (9.5%) bridges had failed. The reasons for failure were loss of retention and, to a lesser extent, caries. Using a LIFE TABLE of survival, it was calculated that the percentage of short span, partial veneer retained prostheses that would survive TEN years was 76.5% +/- 5.99% (standard error). This figure is comparable to that quoted for resin-bonded bridges, and hence would militate against the use of conventional partial coverage fixed retainers on intact teeth. Where abutment teeth are heavily restored, full coverage retainers provide a more predictable, long term result.

State-of-the-art techniques in operative dentistry: contemporary teaching of posterior composites in UK and Irish dental schools.

AIM: Advances of composite systems and their application have revolutionised the management of posterior teeth affected by caries, facilitating a minimally invasive approach. Previous surveys have indicated that the teaching of posterior composites within dental schools was developing, albeit not keeping pace with clinical evidence and the development of increasingly predictable techniques and materials. Concurrently, surveys of dental practice indicate that dental amalgam still predominates as the 'material of choice' for the restoration of posterior teeth within UK general dental practice. In light of such considerations, the aim of this study was to investigate current teaching of posterior composites in Irish and UK dental schools. METHODS: An online questionnaire which sought information in relation to the current teaching of posterior composites was developed and distributed to the 17 established Irish and UK dental schools with undergraduate teaching programmes in late 2009. RESULTS: Completed responses were received from all 17 schools (response rate = 100%). All 17 schools taught the placement of occlusal and two-surface occlusoproximal composites in premolar and permanent molar teeth. Two schools did not teach placement of three-surface occlusoproximal composites in either premolars or molars. In their preclinical courses, ten schools taught posterior composites before teaching dental amalgams. Fifty-five percent of posterior restorations placed by dental students were of composite (range = 10-90%) and 44% amalgam (range = 10-90%), indicating an increase of 180% in the numbers of posterior composites placed over the past five years. Diversity was noted in the teaching of clinical techniques and students at different schools are trained with different composites and bonding systems. Some cause for concern was noted in the teaching of certain techniques that were not in keeping with existing best evidence, such as the teaching of transparent matrix bands and light-transmitting wedges for occluso-proximal composites (eight schools) and the teaching of bevels on the cavosurface enamel margins of both the occlusal and proximal box margins (three schools). CONCLUSION: The teaching of posterior composites in the Irish and UK dental schools has substantially increased over the last five years. Dental students in these schools often gain more experience in the placement of posterior composites than amalgam. However, practice trends indicate that a majority of GDPs continue to place amalgam in preference to composite, thereby suggesting a source of tension as current dental students emerge into the dental workforce over the coming years. There is, as a consequence, a challenge to the dental profession and its funding agencies in the UK to encourage more of a shift towards the minimally interventive use of composite systems in the restoration of posterior teeth, in particular among established practitioners.