To investigate attrition of subjects in a longitudinal study of caries.
A radiographic study of caries and caries-associated factors was carried out in subjects, initially aged 14 years, and followed-up for six years. Attrition of subjects occurred at the last stage of the study.
A nationwide survey of subjects living in fishing, rural farming, and urban communities in Iceland.
A sub-sample of the nationwide random sample comprising 150 subjects was investigated using bitewing radiographs and a structured questionnaire to determine caries-risk factors. Subjects were re-examined at 16 years and 20 years using the same methods.
Mean caries increment from 14-16 years was 3.0 lesions (1.5 lesions/subject/year) but reduced to 2.6 lesions (0.7 lesions/subject/ year) by 20y. The proportion of subjects found to be caries-free at 14 years, 16 years and 20 years, was 29%, 17% and 10%, respectively. "Dropouts" from this study occurred mostly after 16 years. Analysis of subjects dropping out showed that they were least likely to be from the rural farming community but most likely from the fishing community. Those dropping out attended their dentist less frequently, had a higher consumption of carbonated drinks and a higher prevalence and incidence of caries by 16 years.
Subjects with high-risk behaviours, or residents in a fishing community were more likely to drop out of the study. Recognised advantages of conducting longitudinal studies of caries may, therefore, be lost.
The aim of this study, conducted in 1994, was to examine the association between approximal caries and sugar consumption in teenagers residing in three fluoride-deficient areas in Iceland while controlling for a number of behavioral, residential and microbiological factors. One hundred and fifty subjects (mean age 14 years) selected from the Icelandic Nutritional Survey (INS) were examined radiographically and they completed questionnaires about sugar consumption frequency. Total grams of sugar intake were obtained from the INS for each subject. Caries experience on approximal surfaces, diagnosed from radiographs, was used as the dependent variable in the analyses. Altogether 45.2% of subjects were caries free on approximal surfaces. The overall sample was found to have a mean DFS on approximal surfaces of 2.73 (s=4.36) per subject. Average daily total sugar intake was 170 g per subject and the mean number of sugar-eating occasions between meals was 5.32 (s=6.29) per subject. The regression model indicated that the frequency of between-meal sugar consumption was associated with approximal caries, with frequency of candy consumption being the most important of the sugar variables. In multivariate analysis, no relationship was found between dental caries and total daily intake of sugar, although a significant relationship between total sugar consumption and presence of caries was seen in bivariate analysis. Between-meal consumption of sugar remains a risk factor for the occurrence of dental caries, especially in populations with moderate-to-high levels of dental caries experience.
In spite of having a high socioeconomic standing, in Iceland caries prevalence has remained stubbornly high. This study reports findings from a mixed fishing and farming community in East Iceland that has traditionally been associated with the highest prevalence of caries. A total of 188 children aged 3-16 yr (96.4% of residents of that age group) were examined. At 6 yr the mean dmfs score was 4.1, DMFS 0 and 48% were caries-free. The mean DMFS score at 12 yr was 4.7 and 22.6% remained caries-free but at 16 yr the DMFS score was 11.6 and no children were caries-free. Caries was unevenly distributed within each age group and was more prevalent among residents of the fishing town than the surrounding farming district. In a pilot study conducted in 1989 mean counts of Streptococcus mutans for children aged 4-7 yr were 2.6 x 10(5) cfu/ml and declined to 4.6 x 10(4) cfu/ml in 1990 after a program of chlorhexidine brushing had been added to the routine caries preventive measures adopted in this community. It may therefore be possible to screen Icelandic children for caries risk and apply preventive measures to those demonstrated to be most in need.
The prevalence of dental caries in Iceland has been high for many years and the improvements reported from the other Nordic countries in recent years has been slow to appear in Iceland. In this study the prevalence of dental caries among young children in VopnafjÃ¶rour, a small community in East Iceland, was investigated in the spring of 1989. Virtually all children in the community born between 1982 and 1985 were examined clinically and with bite-wing radiographs and caries scored as dmfs and DMFS according to standard criteria. The results indicated that children in this community did not have poor dental health, no worse than children from other parts of the country. Sixty-five per cent of four year old children were caries-free which is similar to the proportion reported from other Nordic countries. Children living in the country districts surrounding the town had significantly better dental health than those living in the fishing town itself. It was also apparent that four year old children attended the dentist less regularly than those aged 6 years and this was attributed to the failure of the State Health Insurance Scheme to reimburse the full cost of treatment for children younger than 6 years. Caries was unevenly distributed among the children with 78% of the total amount of caries being found in 21% of children. Clearly the best way to reduce further the prevalence of dental caries would be to concentrate effort on those children most at risk.