Low levels of relatedness on black grouse leks despite male philopatry.

In lekking species, males cluster on specific areas for display (the leks) and females generally prefer to copulate with males on large aggregations. The maintenance of leks in which only a few males reproduce might be explained if subordinate males gain indirect fitness benefits. By joining a lek on which relatives are displaying, subordinates might attract more females to the lek thereby increasing the mating opportunities of their kin. In black grouse, a genetic structure among leks has previously been found suggesting that relatives could display together. Using 11 microsatellite loci, we extended this result by testing for the presence of kin structures in nine black grouse leks (101 males). The genetic differentiation among flocks was higher in males than in females, suggesting female-biased dispersal and male philopatry. Because of this genetic structure, males were more related within than among leks. However, the mean relatedness within each lek hardly differed from zero. The lekking males were not more related than random assortments of males from the winter flocks and there were no kin clusters within leks. Thus, black grouse males do not choose to display with and close to relatives. Male philopatry alone was not sufficient to induce elevated levels of relatedness on the leks either because of male partial dispersal or a rapid turnover of the successful males. The indirect fitness benefits associated with males' settlement decision are probably limited compared to the direct benefits of joining large aggregations such as increased current and future mating opportunities.

Radiographic assessment of dental health in middle-aged men following sudden cardiac death.

Poor oral health has been suggested to be a risk factor for myocardial infarction. To study if dental pathology might predispose to pre-hospital sudden cardiac death, and using a sum index of panoramic tomography findings, we compared the oral health of middle-aged (33-69 yrs) male victims (Helsinki Sudden Death Study) of sudden cardiac death (n = 117) with that of controls, who died of non-cardiac diseases (n = 63) or suffered unnatural sudden death (n = 120). The mean number of teeth was 15.2, and 17.4% of the men were edentulous. Frequent age-associated findings in dentate victims were fillings (79.9%), horizontal bone loss (72.1%), periapical lesions (45.6%), residual roots (38.2%), and vertical pockets (30.9%). In multivariate analysis with coronary heart disease risk factors and number of teeth as covariates, poor oral health was associated (p = 0.053) with the risk of sudden cardiac death along with age, smoking, and body mass index. This association was especially strong (p = 0.009) among victims < 50 yrs.

Amalgam and composite use in UK general dental practice in 2001.

OBJECTIVE: This study determined the reasons for dentists' choice of materials, in particular amalgam and resin composite, in Great Britain. METHOD: A questionnaire was developed to elicit this information. The names and addresses of 1,000 UK-based dentists were selected at random. The questionnaire was mailed to these dentists with an explanatory letter and reply-paid envelope. RESULTS: Six hundred and fifty four replies were received. Regarding choice of material, 100% of respondents cited clinical indication as the most influential factor, although patients' aesthetic demands (99%), patients' choice (95%) and patients' financial situation (92%) were also reported to influence respondents' choice. Thirty-five per cent of respondents used composite 'sometimes', 15% 'often', and 1% 'always' in extensive load-bearing cavities in molar teeth. For composite restorations in posterior teeth, 92% 'always', 'often' or 'sometimes' used the total etch technique and 53% never used rubber dam. Seventy per cent of respondents agreed with the statement 'discontinuation of amalgam restricts a dentist's ability to adequately treat patients'. Eighty-one per cent considered that the growth in the use of composites increased the total cost of oral healthcare. CONCLUSIONS: Forty nine per cent of the respondents from England and Wales seldom or never place large composite restorations in molar teeth. Their choice of material is influenced greatly by clinical indications, and patients' aesthetic demands.

The post-amalgam era: a selection of materials and their longevity in the primary and young permanent dentitions.

OBJECTIVES: During the last decade there has been a rapid change in the selection of dental restorative materials as the use of amalgam has decreased. The aim of this study was to obtain information on children's restorative dental care in Finland and to analyse the longevity of failed restorations. DESIGN: A random sample of public dental health care centres was drawn from the registers and the dentists working there were asked to record information for each restoration they placed during a three-day period. The survey data comprised a total of 2186 restorations in patients younger than 17 years. RESULTS: Of the children in need of restorative treatment, only a few had previous amalgam restorations. Primary caries was the main reason for restorative treatment in both primary and permanent dentitions (80% and 83%, respectively). In primary teeth, the most common restorative material was resin-modified glass ionomer cement (57.4%), whereas in permanent teeth, composite resin dominated (58.7%). Amalgam was not used at all in the primary dentition and in only 0.6% of permanent teeth. Eighteen per cent of treatments in primary and 12% in permanent teeth were replacements of previous fillings. The mean age of failed glass ionomer restorations was 2.8 years (n = 101) in the primary dentition, and 3.5 years (n = 54) in the permanent dentition. CONCLUSIONS: Until better restorative materials are developed, more attention should be paid to the prevention of dental caries as well as to the proper handling of alternative materials.

From amalgam to composite: selection of restorative materials and restoration longevity in Finland.

The aim of this study was to obtain information on restorative dental care in Finland and to analyze the changes in treatment over a 5-year period. A random sample of dentists was drawn from the registers of the health authorities and the dental association in Finland, and in the spring of 1997 a questionnaire was sent requesting the dentists to record information for each restoration placed during a given period. A total of 1,229 dentists were contacted, and 659 responded. The dentists treated 5,305 adults during the study period and placed 6,322 restorations. The most common restorative material was composite resin, which was used in 74.9% of the restorations, whereas amalgam was used in 4.8% and glass ionomers in 9.4% of the restorations. The median ages of failed restorations were nearly 12 years for amalgam, slightly less than 5 years for composite, and slightly more than 4 years for glass ionomer. The results indicate that clinical dentistry in Finland has made a definite step towards the post-amalgam era. However, the functional periods of the failed tooth-colored restorations were disappointingly short and warrant some serious consideration.

Release of fluoride from glass fiber-reinforced composite with multiphase polymer matrix.

This study investigated the suitability of a fluoride containing monomer resin system for use as a copolymer of dental fiber-reinforced composite (FRC) materials. The purpose of the study was to measure the release of fluoride from the test materials. The monomer resin system was either light-polymerized, or light-polymerized and post-cured with heat at 130 degrees C. The release of fluoride from FRC test specimens during 30 day storage periods was compared to the release of fluoride from unreinforced test specimens (n = 5). The fluoride release into distilled water was determined with an ionanalyzator. During the first week of water storage, the fluoride release was 0.31 wt % for the unreinforced specimens and 0.13 wt % for reinforced specimens. The post-curing had no influence on the fluoride release values. The results of this study suggest that fiber inclusion reduces fluoride release of reinforced specimens compared to unreinforced specimens because the amount of polymer was smaller in reinforced specimens. The results of this study showed that the fluoride containing monomer system could be incorporated into the polymer matrix of fiber-reinforced composites.

Increase in occupational skin diseases of dental personnel.

Occupational diseases of dentists and dental nurses were compiled from the Finnish Register of Occupational Diseases. The cases were recorded during 3 3-year observation periods, namely 1982-1984, 1986-1988, and 1992-1994 (i.e., 9 observation years). The relative risk of developing occupational allergic contact dermatitis in different occupations was calculated from the statistics of the years 1986-1991, and was expressed as the age-standardized rate ratio (SRR). During the 9 observation years, the majority of registered occupational diseases of dentists and dental nurses were skin diseases (221/312; 70.8%), followed by occupational repetitive strain injuries (61/312; 19.6%) and occupational respiratory diseases (20/312; 6.4%). The incidence rate (IR) for allergic contact dermatoses/10,000 workers (contact urticaria included) increased from 26 (95% confidence interval (CI) 16-40) in 1982-1984 to 79 (95%, CI 64-97) in 1992-1994. The IR/10,000 of allergic contact dermatoses increased especially for dentists, from 5.4 (95% CI 0.7-19) in 1982 to 67 (95% CI 45-95) in 1992-1994. The increase of the IR/10,000 dental nurses was smaller: from 43 (95%, CI 26-66) in 1982-1984 to 87 (95% CI 67-111) in 1992-1994. There was no increase in the IR/10,000 cases of irritant dermatoses. The most common causes of allergic contact dermatitis were plastics, disinfectants and antimicrobials, rubber chemicals, and mercury/mercury salts. The most common causes of irritant contact dermatitis were detergents, wet and dirty work, plastic chemicals and antimicrobials. Currently, Finnish dentists have the highest risk and dental nurses have the 4th highest risk of any occupation for developing occupational allergic contact dermatitis: the risk was 6.4-fold (SRR 6.4) in dentists and 6.1-fold in dental nurses, as compared to the general working population. It is evident that safer acrylics and protective gloves, better product declarations and material safety data sheets, as well as more information about protective measures, including non-touch working techniques, are needed.

Efficiency of fluoride programs in the light of reduced caries levels in young populations.

Since the late 1930s, when the efficacy of fluoride in caries prevention was first detected, various efficient methods for fluoride delivery have been developed. Nowadays, fluoride is used for caries prevention on a global scale, the most widely used methods being fluoridated toothpaste and water fluoridation. The latter is a typical community-based prevention method, whereas the former method relies on individual motivation. The goal of an efficient community-based fluoride program is to maintain a constant low level of fluoride in as many mouths as possible at as low a cost as possible. Initially, water fluoridation and other community-based programs were highly efficient, but nowadays in societies in which the major part of the population is using fluoride toothpaste and caries levels are low, population-based programs show a low efficiency. As an example, even though water fluoridation was withdrawn in Kuopio, there have been no dramatic effects on the dental health of children and youths. In societies with well-attended, community-based, free dental health care for children and youths, the dental motivation of individuals is, in general, very high and the use of fluoride for caries prevention may be taken care of at the individual level.

Retention of a glass ionomer cement and a resin-based fissure sealant and effect on carious outcome after 7 years.

The aim of this study was to compare the retention and caries preventive efficacy of glass ionomer (Fuji III; GIC) and light-cured resin-based (Delton; LCR) fissure sealants. One hundred and sixty-six 5-14-year-old schoolchildren received sealants on their newly erupted first or second molars; a split mouth design was used. Previously reported 2-year results showed low retention rates for GIC sealants, but no difference in the caries increment between the groups. The same persons were invited to a dental check-up 6.1 to 7.8 (mean 7.1) years after the application of sealants; 111 persons (66.8% of the original group) participated in the study. The retention of sealants, and the caries status of occlusal surfaces and adjacent proximal surfaces was recorded. On the sealed occlusal surfaces, 10% of GIC and 45% of LCR sealants were totally and 9% of GIC and 20% of LCR sealants partially present. Twenty-three (23.5%) of the occlusal surfaces sealed with GIC and 16 (16.5%) of those sealed with LCR were carious or filled. Compared to LCR sealants, the effectiveness of GIC sealants was -44% (95% CI -71%, -16%) and net gain -7% (95% CI -18%, 4%). The relative risk of caries occurring was 1.44 (95% CI 0.96, 2.14).

Dental practitioners' experiences on the usefulness of restorative materials in Finland 1992-1996.

OBJECTIVE: To analyse general dentists' choice of restorative materials in Finland, where the use of amalgam has significantly decreased and the use of composites increased during the past 10 years. DESIGN AND SETTING: Postal survey in 1997 to a random sample of general dental practitioners mainly working with adult patients. MAIN OUTCOME MEASURES: Percentage distribution of dentists' opinions. RESULTS: The response rate was 82%. Tooth-coloured restorations were considered to be more time consuming, technically complicated and to have shorter life spans. Most dentists were not willing to return to the wide-scale use of amalgam restorations. CONCLUSIONS: The rapid changes in the restorative material selection have not resulted in serious problems in restorative therapy.

A study of bonding glass polyalkenoate cement to the surface of dental ceramic material.

The aim of this study was to compare the bonding of chemically-cured glass ionomer (polyalkenoate) cement (CGIC) and resin-modified glass ionomer cement (RGIC) to a ground ceramic surface (n = 6 per group). The ceramic surface was left untreated or treated with either commercial dental porcelain primer or with heat-cured gammamethacryloxypropyltrimethoxysilane solution (MPS), which was used as a reference treatment for good adhesion. Bonding was measured using a modified three-point loading test for the test specimen loaded at the interface of the cement and the ceramic. The adhesive fracture surfaces were examined by scanning electron microscopy (SEM). The most effective adhesion of the CGIC and RGIC specimens was found when the ceramic specimens had been treated with heat-cured MPS, whereas slightly lower adhesion was found by the treatment of ceramic specimens with a commercial porcelain primer. Poorest adhesion was found between CGIC and untreated ceramic. The number of adhesive failures was high in all CGIC groups, while no adhesive failures were observed between MPS treated ceramic and RGIC. This study encourages the of use porcelain primers when good bonding between glass ionomer cement and dental ceramic material is required.

Adhesion of glass ionomer cement to a ceramometal alloy.

STATEMENT OF PROBLEM: Glass ionomer cements can be used for restoring minor caries lesions, sealing an endodontic access, and repairing defective margins of inlay-onlay restorations. Little information is available on the adhesion between ceramometal alloys and various types of glass ionomer cements. PURPOSE: The aim of this study was to determine whether the adhesion of glass ionomer cement to the surface of a ceramometal alloy could be enhanced with pretreatment of the alloy surface. MATERIAL AND METHODS: Six groups of five specimens were either ground with a diamond bur, sandblasted with aluminum oxide, or ground with a silicon-carbide stone before bonding to either conventional glass ionomer or resin-glass ionomer cements. Resistance to bond failure was tested with a three-point loading test. RESULTS: The results revealed that the greatest resistance to bond failure was obtained by the resin-glass ionomer cement to the sandblasted alloy surface and the least resistance by the glass ionomer cement to the diamond ground alloy surface (p < 0.001). Both the type of glass ionomer cement (p = 0.002) and the type of mechanical treatment (p = 0.001) affected the resistance to bond failure. CONCLUSIONS: This study suggests that pretreatment of alloy surfaces with a sandblasting device may be recommended when repairing marginal defects of alloy restorations with glass ionomers. Resin-glass ionomer cements seem to give better adhesion than conventional glass ionomer cements do.

Factors influencing the selection of restorative materials in dental care in Finland.

OBJECTIVE: The aim of this study was to identify factors influencing the selection of restorative materials. METHODS: In 1992, a random sample of Finnish dentists working in the public and private health care sectors were asked to provide information on restorative treatments during a given period. The study material consisted of 9886 restorations placed by 855 dentists. RESULTS: The results indicate that private practitioners sought the opinions of their adult patients regarding the selection of restorative material more frequently (26% of restorative treatments) than their colleagues working in the public sector (11%; P < 0.001). The frequency of resin composite restorations increased and that of amalgam and glass ionomer restorations decreased when the patients' opinions were sought. Forty percent of restorations provided by public dentists and 69% of those completed by private practitioners were replacement restorations (P > 0.001). Secondary caries was the main reason for the replacement of amalgam restorations, whereas fractures of the teeth and restorations were the main reasons for the replacement of resin composite restorations. CONCLUSION: The results indicate that patients' opinions have a strong influence on the selection of restorative materials. A large proportion of the restorative treatment studied comprised replacement restorations.

Fluoride concentration, mutans streptococci and lactobacilli in plaque from old glass ionomer fillings.

Previous studies have found that the fluoride concentration of plaque growing on or adjacent to glass ionomer cement (GIC) is increased and the proportion of mutans streptococci in plaque is reduced. So far, there are only a few studies of the long-term effect of glass ionomer fillings on plaque in vivo. The aim of this study was to determine whether old GIC fillings have effects on plaque fluoride and microflora and whether this effect can be increased by topical application of fluoride on GIC fillings in vivo. The participants were 27 adults with at least 3 GIC fillings about 3 years old. Plaque was collected from sites adjacent to the GIC fillings and from the contralateral teeth, after which a 1.2% fluoride gel was applied to all teeth. Three days later, plaque was collected from the same sites as before. Stimulated saliva was also collected at both appointments. The results show that none of the patients had elevated levels of fluoride in their saliva either before or 3 days after the fluoride treatment. The fluoride concentration was 0.51 microgram/mg protein in plaque on GICs and 0.35 microgram/mg protein in plaque on contralateral teeth (p = 0.028). After the fluoride treatment, the respective fluoride concentrations were 0.59 microgram/mg and 0.75 microgram/mg (p = 0.849). No significant differences in the proportion of mutans streptococci and lactobacilli in plaque from GIC and contralateral teeth were found. The results suggest that the fluoride concentration of plaque growing on old GIC fillings is slightly increased. In this study, however, this had no significant effect on the cariogenic microflora.(ABSTRACT TRUNCATED AT 250 WORDS)

Mineral status of skeleton and advanced periodontal disease.

Studies of the effect of general bone loss on periodontal condition and on development of periodontal pockets suggest that there is no clear correlation between periodontal health or number of teeth and the general mineral status of the skeleton. In some reports, however, deep periodontal pockets have been correlated with good mineral status in the jawbones and skeleton. The purpose of this study of 227 healthy postmenopausal women aged 48 to 56 years was to determine whether advanced alveolar bone loss, diagnosed by panoramic radiographs, and periodontal probing depths or number of remaining teeth were correlated with the bone mineral status of the skeleton and cortical bone in the mandible. The results suggest that individuals with high mineral values in the skeleton seem to retain their teeth with deep periodontal pockets more easily than those with osteoporosis. This finding may especially motivate treatment of persons suffering from advanced periodontal disease but having good mineral status.

Comparison of glass-ionomer and resin-based fissure sealants: a 2-year clinical trial.

In recent years, the interest in the use of glass-ionomer materials as fissure sealants has increased. The aim of this study was to compare the retention and caries-preventive effect of glass-ionomer (Fuji III) and resin-based light-cured (Delton) fissure sealants. Three health center dentists applied the sealants to 166 children; glass-ionomer sealants on one side and resin-based sealants on the contralateral side of the mouth. After 2 yr, one pair of molar teeth in the mouths of 151 children was compared. Twenty-six percent of glass-ionomer and 82% of resin-based sealants were totally present (P < 0.001). During the 2 yr, in both groups 4.6% of the sealed surfaces became carious. The results show that the retention of glass-ionomer sealants is markedly inferior to the resin-based sealants. In this study, however, no difference in caries increment on the sealed surfaces was observed. This may be due to the different mechanism of caries prevention for the sealant materials, or to the overall low caries activity of the participants.

Selection of restorative materials in dental treatment of children and adults in public and private dental care in Finland.

To obtain information on the present selection of dental restorative materials and factors related to it, questionnaires were sent to a random sample of public health centres (47) and private dental practitioners (716) in May 1992. The dentists were asked to collect information on all fillings they placed during 3 and 1 working days, respectively. The study material consisted of 9886 fillings placed by 855 dentists. Glass ionomer was the major filling material in children younger than 17 years, ninety-one per cent of the fillings in deciduous teeth and 47% of those in permanent teeth were inserted using that material. In adults, composite was the most frequently used material, fifty-two per cent of the fillings placed by private practitioners and 43% of those placed in health centres. In total, amalgam was used in 15% of fillings placed for patients 0-16 years old and in 29% of fillings in adults. The results show that in children, glass ionomer is the most frequently used filling material and the use of amalgam is very limited. In adults as well, amalgam seems to be increasingly replaced by other filling materials.

The effect of fluoride application on fluoride release and the antibacterial action of glass ionomers.

The aim of this study was to investigate whether the release of fluoride and the antimicrobial effect of freshly mixed glass ionomers could be prolonged by application of fluoride on aged material. Test slabs of freshly mixed and aged (14 d in water) conventional and silver glass ionomer (Ketac-Fil and Ketac-Silver, Espe, Seefeld, Germany) and composite (Silux Plus, 3M, St. Paul, MN) were fitted into the bottom of a test tube. A layer of S. mutans Ingbritt cells was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% sucrose solution. After the incubation, pH, F, and Ca contents of the fluid phase, and F, Mg, P, and K contents of the cells were determined. The aged glass-ionomer samples were then covered with toothpaste (0.1% F) or with fluoride gel (1.25% F), and the composite samples with fluoride gel. After being thoroughly rinsed, S. mutans cells were incubated on the samples as above. The pH fall was significantly inhibited by freshly mixed glass ionomers, and there were changes in cellular cation and phosphorus contents. Large amounts of fluoride were found in the fluid and cells. For old glass ionomers, no inhibitory effect on pH fall could be seen. Fluoride release had decreased to a low level.(ABSTRACT TRUNCATED AT 250 WORDS)

Release of fluoride and other elements from light-cured glass ionomers in neutral and acidic conditions.

The purpose of this study was to measure the release of fluoride, sodium, silicon, calcium, strontium, and aluminum from light-cured glass ionomers. The materials tested were: (1) Baseline VLC thick mix; (2) Baseline VLC thin mix; (3) Fuji Lining LC; (4) Vitrebond; and (5) XR-Ionomer. A conventional glass ionomer, Ketac-FilAplicap, and a silver-reinforced glass ionomer, Ketac-Silver, were used as controls. Each test specimen was first stored for 16 days in de-ionized water, followed by a further 16 days in 0.01 mol/L lactic acid (pH 4.0); both solutions were replaced at predetermined intervals. After that, the specimens were immersed for up to 122 days in de-ionized water. During the immersion, light-cured glass ionomers showed considerable variation in the release of fluoride and other elements. In lactic acid, all cements eluted the matrix-forming cations, aluminum and calcium or strontium. This suggests that light-cured materials are as equally susceptible to erosion as are chemically cured glass ionomers. During the immersion, some of the light-cured materials showed a considerable weight gain.

Enamel and plaque fluoride following glass ionomer application in vivo.

Glass ionomer fillings have been suggested to act as a fluoride-releasing system in the mouth. The aim of the present study was to evaluate whether a glass ionomer slab applied on the enamel can increase the fluoride content of the enamel and plaque of adjacent teeth in real-life conditions with frequent exposure to fluoride from other sources. Twenty-five adults living in a town with fluoridated drinking water participated in the study. The initial enamel fluoride content on the buccal surface of the contralateral premolars was determined using the acid etch biopsy technique. A round glass ionomer slab was placed buccally on the first molar on a randomly chosen side of the mouth (test side). After 2 weeks, the enamel fluoride content of premolars on the test and control sides was again determined whilst avoiding the site of the first biopsy. In addition, one biopsy was made on a previously etched area. After 2 and 4 weeks, plaque was collected from three approximal surfaces both on the test and control side, and the total fluoride content of the plaque was analysed. There were no significant differences in the fluoride content of sound or etched enamel before and after placement of glass ionomer. The fluoride content of approximal plaque of teeth close to glass ionomer was not higher than that of the control teeth, either after 2 or 4 weeks. Using the present method, no increase in the fluoride level of teeth adjacent to glass ionomer could be demonstrated. This may be due to the masking effect of fluoride from other sources.