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.
Two hundred and seventeen approximal spaces, initially caries free, in 58 patients were studied clinically and radiographically, at intervals of 6 months, for 3 years. Samples of approximal dental plaque were removed for culture of Streptococcus mutans, Streptococcus sobrinus, and lactobacilli. During the study approximal caries developed in 16 subjects (27.6%) at 30 sites (13.8%), involving 42 teeth. 56 of 58 (96.7%) subjects harboured S. mutans at some time during the study, 62.1% lactobacilli, and 29.3% had S. sobrinus. The counts of S. mutans were significantly higher in those subjects that also carried S. sobrinus than in the remaining subjects. A persisting high count of S. mutans > 10(5) colony-forming units per millilitre (CFU/ml) or a count that rose by > or = 1 x log10 CFU/ml during the study was seen in 25 of 30 sites that subsequently became carious (p 10(3) CFU/ml or rising by > or = 1 x log10 CFU/ml were seen in 17 of 30 sites that became carious (p
Caries prevalence and several caries-related factors were measured in 158 pre-school children in Reykjav?k, initially aged 4 years and followed longitudinally for 2 years. The mean dmfs at 4 years was 3.3 and rose to 5.8 at 6 years although 34% remained caries-free throughout the study. Caries was very unevenly distributed. Children with dmfs > or = 5 at 4 years were significantly more likely to have caries in their permanent dentition at 6 years than those with a lower caries score at 4 years. Almost all children carried Streptococcus mutans but only 58% carried lactobacilli at 4 years. Lactobacilli declined in numbers at 5 and 6 years as the number of open carious lesions decreased but the mean count of S. mutans remained fairly static (> 10(5) cfu/ml). There were strong associations between high counts of S. mutans or lactobacilli and caries. Salivary parameters were not as strongly associated with caries although a low salivary pH and low salivary flow rate were significantly associated with high caries scores. The misuse of sugar as determined by dietary questionnaire was strongly associated with a high caries score and low caries prevalence was found in those children that took fluoride tablets regularly.
Fifty 5-yr-old preschool children living in Akranes, a small community in West Iceland known to have a high caries prevalence, were investigated with respect to caries, salivary counts of mutans streptococci and lactobacilli, and consumption of cariogenic foods. Fifteen months later, after being in school for half a year, 43 of the 50 children were reexamined and investigated as before. Mean dmfs scores rose from 7.1 to 9.0, but the scores including initial caries rose from 9.7 to 15.3. Mutans streptococci were carried by 84% of children on both occasions with a mean count 2.1 and 3.6 x 10(5) cfu/ml. Lactobacillus carriage increased from 29 to 38% and the mean count from 5.1 to 13 x 10(3) cfu/ml at 6 yr. The frequency of consumption of sugar-containing foods increased from 4.2 to 5.2 intakes per day and between-meal snacks rose from 3.0 to 3.7 per day. Children classified as "misusing" sugar were 59% at 5 yr and 83% at 6 yr. The mean caries score at 6 yr for children "misusing" sugar was 10.7 but only 2.0 for those not misusing sugar. Thus the deterioration in dental health appears, in these children, to be associated with the increased consumption of sweets and other cariogenic between-meal snacks after starting school.
Data obtained in a longitudinal study of caries incidence and caries-related factors were analysed with a view to producing a model for the prediction of caries. In direct correlations, caries incidence was significantly associated with bacterial, dietary and salivary variables; but when the data were examined by stepwise regression the strongest variables were the baseline caries score and misuse of sugar. Counts of Streptococcus mutans entered into the analysis but only as a relatively minor component. Similar significant relationships were seen with the determination of odds ratios. A caries activity test was formulated combining the following caries-associated variables: high counts of S. mutans, or lactobacilli, or the misuse of sugar, or frequent consumption of paediatric medicines. Regular use of fluoride tablets could compensate for paediatric medicine use or misuse of sugar. Such a caries activity test if it had been applied to the children at baseline would have had a positive predictive value of 0.76, a negative predictive value of 0.82, a sensitivity of 0.8 and a specificity of 0.78. Combining tests made the prediction of caries more accurate and in the population for which it was intended gave a reliable means of detecting those children most in need of enhanced caries prevention.
The aim of this study was to investigate the presence of S. sobrinus and S. mutans in specimens of dental plaque and saliva of children five years of age in Reykjavik, Iceland (study 1) and in samples of dental plaque from children nine years of age in Amsterdam, The Netherlands (study 2). The immuneblotting technique (IBT) was a suitable method to evaluate the presence and numbers of S. mutans and S. sobrinus in human dental plaque and saliva. In study 1, eighty-four children were evaluated bacteriologically; of these, 73 percent harbored mutans streptococci in their plaque or saliva. S. sobrinus similarly was present in 29 percent of the children. In study 2 (seventy-two children), the corresponding percentages were 81 percent for S. mutans, and 35 percent for S. sobrinus. The latter was detected in 6 percent of the plaque samples exclusive of S. mutans.
Caries experience, oral hygiene and caries-related salivary parameters were recorded in a 20% representative sample of 12-year-old schoolchildren in Reykjavik, Iceland in 1991. The majority of the children was re-examined 3 years later in 1994. Trends in prevalence of caries and salivary bacteria were assessed by comparison with an analogous earlier longitudinal study (1984-87). Mean DFS values for 12-year-olds were 12.1 and 4.1, for 15-year-olds 23.3 and 11.3 in the earlier and later study, respectively. Reduction in DFS was 66% and 52% for the respective age groups. The decline was most pronounced in the group with low caries prevalence. Trends in caries experience were paralleled by salivary bacteria. The mean caries scores and frequency distributions of 15-year-olds in 1994 closely resembled those of 12-year-olds a decade earlier, suggesting a delay rather than a true fall in caries prevalence.