The prevalence of dental caries and fissure sealants in 12 year old children by disadvantaged status in Dublin (Ireland).

OBJECTIVE: The aim was to record dental caries levels and the presence of fissure sealants in 12-year-old schoolchildren whose domestic water supply had been fluoridated since birth in Dublin (Ireland). RESEARCH DESIGN: Cross-sectional study. Participants A representative, random sample of 12-year-old schoolchildren in north-west Dublin. OUTCOME MEASURES: Dental caries levels were recorded using WHO criteria and fissure sealant was recorded when sealant was detectable on a permanent molar tooth. Medical card ownership, as a surrogate for disadvantage, was recorded by use of a questionnaire. RESULTS: Three-hundred and thirty-two (332) children were examined. The mean DMFT was 0.80 (SD 1.24). Analysis (Mann-Whitney U test) based on stratification of the sample according to medical-card status revealed no statistically significant difference between DMFT median scores of children of medical-card holders (i.e., social disadvantage background) and non medical-card holders (p-value = 0.23). However, the data revealed a social gradient in the presence of at least one fissure sealant. Approximately 10% more children in the group of medical-card holders had no fissure sealants present. Fisher's exact test was used to examine the association between the absence of fissure sealants and at least one fissure sealant between the two groups and was considered to be statistically significant (p-value = 0.04). CONCLUSION: This study demonstrated a social gradient in the presence of fissure sealants, but no such gradient in dental caries levels. This demonstrates the importance of population-based measures in the prevention of dental caries, such as water fluoridation, in reducing oral health inequalities.

The ups and downs of genome size evolution in polyploid species of Nicotiana (Solanaceae).

BACKGROUND: In studies looking at individual polyploid species, the most common patterns of genomic change are that either genome size in the polyploid is additive (i.e. the sum of parental genome donors) or there is evidence of genome downsizing. Reports showing an increase in genome size are rare. In a large-scale analysis of 3008 species, genome downsizing was shown to be a widespread biological response to polyploidy. Polyploidy in the genus Nicotiana (Solanaceae) is common with approx. 40 % of the approx. 75 species being allotetraploid. Recent advances in understanding phylogenetic relationships of Nicotiana species and dating polyploid formation enable a temporal dimension to be added to the analysis of genome size evolution in these polyploids. METHODS: Genome sizes were measured in 18 species of Nicotiana (nine diploids and nine polyploids) ranging in age from <200,000 years to approx. 4.5 Myr old, to determine the direction and extent of genome size change following polyploidy. These data were combined with data from genomic in situ hybridization and increasing amounts of information on sequence composition in Nicotiana to provide insights into the molecular basis of genome size changes. KEY RESULTS AND CONCLUSIONS: By comparing the expected genome size of the polyploid (based on summing the genome size of species identified as either a parent or most closely related to the diploid progenitors) with the observed genome size, four polyploids showed genome downsizing and five showed increases. There was no discernable pattern in the direction of genome size change with age of polyploids, although with increasing age the amount of genome size change increased. In older polyploids (approx. 4.5 million years old) the increase in genome size was associated with loss of detectable genomic in situ hybridization signal, whereas some hybridization signal was still detected in species exhibiting genome downsizing. The possible significance of these results is discussed.

The prevalence of dental fluorosis in relation to water or salt fluoridation and reported use of fluoride toothpaste in school-age children.

AIM: To compare prevalence of dental fluorosis (DF) in permanent teeth in children whose domestic water supply was fluoridated since birth with that in a community where fluoridated salt was available. A second aim was to analyse the relationship between DF prevalence and reported use of fluoride toothpaste in early childhood. STUDY DESIGN: Cross-sectional study. METHODS: A representative, random sample of 12-year-old children was examined in water fluoridated Dublin (Ireland) and non-water fluoridated Freiburg (Germany), where fluoridated salt was available. DF was recorded using the Dean's Index. The child's early experience of toothpaste use was recorded using a questionnaire. RESULTS: 377 children in Dublin and 322 children in Freiburg were examined. In Dublin 11.7% of the whole sample had a 'Questionable' level of DF, 9.8% had 'Very Mild', 3.7% had 'Mild' and 0.3% had 'Moderate' fluorosis. The corresponding percentages in Freiburg for all children were 10.9%, 4.0%, 3.4% and 0%. The results suggest that children in Dublin started brushing their teeth at an older age than in Freiburg, but no difference in DF levels was found between 'early' and 'late' users. STATISTICS: Fisher's test revealed that the difference in DF levels between the two populations was statistically significant (p=0.03). CONCLUSIONS: The prevalence of aesthetically important DF ('Mild' and 'Moderate') was low and similar in both communities and considerably lower than the expected level at water fluoridation concentrations of 1 ppm. However, the prevalence of 'Very Mild' fluorosis was twice as frequent in Dublin than in Freiburg.

Role of fluoride in oral health promotion.

Fluoride has played a pivotal role in oral health promotion over the past 50 years. This paper reviews key issues currently impacting on the role of fluoride in preventing dental caries. The understanding of the process of dental caries and the mode of action of fluoride has changed in recent years. Dental caries is a continuous process of demineralisation and remineralization of the enamel and fluoride plays a key role in this process through its action at the plaque enamel interface. It is now accepted that the primary mode of action of fluoride is post-eruptive. The post-eruptive action of fluoride has resulted in new methods of delivering fluoride. The paper discusses the impact of these new methods of delivering fluoride on total fluoride intake in children and on the prevalence of dental fluorosis. The role of different methods of delivering fluoride both on a community and individual basis is presented and recommendations are outlined.

Prevalence of enamel defects/fluorosis in fluoridated and non-fluoridated areas in Ireland.

Water fluoridation was introduced in Ireland in 1964 and in recent years the availability of fluoride from other sources had increased. As part of a National Survey of Children's Health in Ireland Dean's and the DDE indices were used to determine the prevalence of enamel fluorosis/defects in 8- and 15-yr-old children in fluoridated and non-fluoridated areas. Over 94% of the children examined in all areas were regarded as having normal enamel, as defined by Dean's index, the remainder showing evidence of either questionable, very mild or mild fluorosis. Between 52% and 63% of the children had one or more teeth affected by enamel defects when measured by the DDE index. The prevalence of enamel fluorosis/defects was similar in children living in fluoridated and non-fluoridated areas but the prevalence of diffuse opacities (DDE) was higher in the fluoridated areas.

Edentulousness in the United Kingdom and Ireland.

Surveys of adult (16 yr and over) dental health were conducted in England/Wales and Scotland (n = 5967) and in Ireland (n = 1764) and Northern Ireland (n = 1176) in 1979. From the results of these surveys a comparison is made between levels of edentulousness, attendance patterns, attitude to loss of teeth and the wearing of full dentures. Scotland had the highest level of edentulousness (39%) and Ireland the lowest (26%). England/Wales had a level of 29% and Northern Ireland 33%. The percentage edentulous increased considerably ith age and females had a higher level of edentulousness than males. Regular attendance at the dentist was lowest in Ireland and in all countries there was a greater preference for filling rather than extraction of teeth. Levels of edentulousness do not appear to be directly related to any of the parameters investigated.