Jan Magne Birkeland

ALTITUDE AS A RISK INDICATOR OF DENTAL FLUOROSIS IN CHILDREN RESIDING IN AREAS WITH 0.5 AND 2.5 MG FLUORIDE PER LITRE IN DRINKING WATER

The purpose of this study was to assess the association between altitude and dental fluorisis among Ugandan children in two fluoride (F) districts while controlling for other factors related to fluorosis. A random sample of 481 children aged 10–14 years was examined for fluorosis using the Thylstrup and Fejerskov (TF) index. The prevalence and severity of dental fluorosis increased significantly with increase in altitude (900 vs. 2,200 m in the low– and 1,750 vs. 2,800 m in the high–F district) and in F concentration in the drinking water. In bivariate correlation analyses, F exposure from liquid (FEL), altitude, infant formula, vegetarianism and storing of drinking water in earthenware pots were significantly associated with the tooth prevalence of fluorosis (TPF), i.e. at a severity of TF score ≥1 (p<0.05); age and gender were not. The stepwise multiple linear regression explained 35 and 55% of the variance in TPF within the low– and high–F districts, respectively. The change in R2 due to FEL was 28 and 51% points compared with 5 and 4% points due to altitude. The significant effect of FEL and altitude was confirmed by multiple logistic regression analyses. Thus, although most of the variation in the prevalence and severity of dental fluorosis was explained by the F intake from liquid, altitude was a significant risk indicator after controlling for potential confounders.

Analyses of the caries decline and incidence among Norwegian adolescents 1985-2000.

Since most studies of caries decline are descriptive time-trend analyses, the purpose of this article was to identify factors statistically associated with the caries decline among Norwegian adolescents after 1985. The DMFT scores for the age groups 12 and 18 years reported annually by 19 counties were analysed. The average caries-free proportions of 18-year-olds increased from 2% to 15% between 1985 and 2000, while the DMFT declined by 49%; 10.2 - 0.75 to 5.2 - 0.78. The decline for the 12-year-olds was 53%. The mean DT at the dentinal level remained at about 0.8 for 12-year-olds and 1.5 for 18-year-olds throughout the observation period. There was no significant difference in DMFT increment from age 12 to 18 between the birth cohorts 1973 (3.8 - 0.46) and 1982 (3.0 - 0.52) when controlling for counties. The variables migration and children per dentist were significantly associated with the DMFT decline in multivariate analyses. The caries decline for 18-year-olds was significantly steeper before than after 1990. The decline among the 18-year-olds may be attributed to fluoride and more restrictive criteria for placement of fillings in teenagers in the 1980s and fewer filled teeth before the age of 12 years in the 1990s.

Some Factors Associated with the Caries Decline among Norwegian Children and Adolescents: Age–Specific and Cohort Analyses

The purpose of this study was to evaluate factors related to the caries decline in children between 1966 and 1983. The decline started in the late sixties for the 8– to 11– and the 17–year–olds, and after 1971 for the remaining age groups. Regression analyses confirmed a significantly different start of the decline. Fluorides in school–based programmes, lozenges, and toothpaste, as well as education and sale of antibiotics were significantly (p≤0.01) related to the caries decline in partial correlation analyses. Fluoride toothpaste was only significantly related to the decline in the last part of the period of observation. Supervised fluoride rinsing and brushing programmes at school may explain most of the decline before 1971. The later decline may be related to all fluoride agents and to education. Use of fluorides and other preventive efforts aimed at pre–school children may have contributed to the continual decline in the number of fillings in the permanent teeth of the youngest cohorts.

Ecological time-trend analysis of caries experience at 12 years of age and caries incidence from age 12 to 18 years: Norway 1985–2004

Objectives. The purpose of the present investigation was to report on caries experience among Norwegian 12-year-olds from 1985 to 2004 and to assess caries incidence from 12 to 18 years of age for birth cohorts 1973 to 1986. Material and methods. Aggregated data from the Norwegian Public Dental Services and from official statistics were employed. Information was available about the number of subjects, the proportion receiving treatment, sales of fluoride tablets, socio-demographics, caries prevalence, and the number of decayed, missing, and filled teeth (DMFT). Results. An almost linear decline in caries prevalence and mean D3MFT (dentine level) occurred among 12-year-old children from 1985 until the year 2000, but from 2000 to 2004 an increasing trend was observed. The highest mean 6-year D3MFT increment (age 12–18 years) was 4.1 (cohort 1976), while the lowest was 3.2 (cohorts 1982 and 1983). In multiple linear regression analyses of trend, baseline D3MFT accounted for more than 91% of total explained variance in D3MFT increment (Models I and III). Without baseline D3MFT as predictor (Models II and IV), there was a significant association between education, social assistance, mobility, infant mortality, percentage examined, and the additive interaction terms year + income and year + education and D3MFT increment after controlling for confounding and multicollinearity. Conclusions. Four consecutive years of increase in caries experience among 12-year-old children after 15 years of decline and evidence of stability or increase of the caries increment from 12 to 18 years of age among Norwegian teenagers give cause for concern.

Continual highly significant decrease in caries prevalence among 14-year-old Norwegians.

The MFS of 14-year-old children in Lillehammer, Norway, were recorded in 1959, 1969, 1979, and 1984. The data were extracted from dental records of random samples of 76 children. The mean MFS was 34.1 in 1959 and 28.0, 13.8, and 7.5 the following years. The caries prevalence was reduced by 78% from 1959 to 1984. In 1959, 16.6 approximal surfaces were filled, but in 1984 only 1.3. Significantly fewer radiographically initial lesions were observed in 1984 than in 1979. The continual decrease in caries prevalence is related to various fluoride programs, fluoride dentifrices, decreased caries prevalence among preschool children, and an assumed decreased challenge.

Analysis of the ups and downs of caries experience among Norwegian children aged five years between 1997 and 2003

Objective. To study caries trends and investigate the possible reasons for changes among 5-year-old Norwegian children in the period 1997–2003. In this cross-sectional analytical time trend study at district, county, and national levels, aggregated data from the Public Dental Services (PDS) and official statistics were used, i.e. number of children and percentage receiving treatment, sale of fluoride tablets, socio-economic background, caries prevalence, and d3mft scores. Results. Caries prevalence increased from 30% in 1997 to just over 40% in 2001, but by 2003 it had dropped to 36%. The corresponding mean number of d3mft were 1.1, 1.6, and 1.4 at national level. Caries prevalence and experience varied considerably between counties and between dental districts throughout the observation period. Multivariate analyses at county level indicated a significant negative association (p<0.05) between caries prevalence, the sale of fluoride tablets, and net mobility. The impacts of the predictor variables education, income, infant mortality, proportion of immigrants, and the percentage of children treated varied but were rarely significant. Conclusions. The increasing trend in the prevalence of caries among 5-year-old Norwegian children in the period 1997 to 2001 has reversed. The deterioration in dental health of 5-year-olds after 1997 was associated with a reduction in the sale of fluoride tablets, whereas increased sales of fluoride tablets after 1998 reflect improved caries prevention among preschool children and may explain the improved caries status of these children in 2003.

Age as a determinant of severity of dental fluorosis in children residing in areas with 0.5 and 2.5 mg fluoride per liter in drinking water

Abstract The purpose of this study was to investigate the influence of age on the severity of dental fluorosis in children exposed to drinking water with either low or high fluoride concentrations. The children selected for this study were aged 10–14 years, with 28 permanent teeth and at least 1 tooth pair with fluorosis. The children were permanent residents of districts in western Uganda with either 0.5 mg (n=33) or 2.5 mg fluoride/l in drinking water (n=186). All vestibular tooth surfaces were examined for fluorosis using the modified Thylstrup and Fejerskov (TF) index. In the high fluoride community, the proportion of teeth per child with TF scores ≥4, and ≥5 was significantly higher among children aged 13–14 years compared to those aged 10–12 years. Children’s chronological age correlated positively and significantly with the median TF scores for all teeth, including early erupting (first molars and incisors) and late erupting teeth (canines, premolars and second molars). In linear regression analyses, the median TF score for all teeth, as well as for early erupting and late erupting teeth, increased significantly with age. On the other hand, in the low fluoride community there was no significant association between age and the severity of fluorosis. This study showed a significant increase in the severity of fluorosis with increasing age in a high fluoride community, whereas no change in severity with age was observed in a low fluoride community.

An attempt to explain why Tanzanian children drinking water containing 0.2 or 3.6 mg fluoride per liter exhibit a similar level of dental fluorosis

Abstract The aim of this study was to identify factors that might explain the similar level of prevalence and severity of dental fluorosis in two neighboring areas in Tanzania: Kibosho; 0.2 mg fluoride/l, n=96 and Arusha; 3.6 mg fluoride/l in drinking water, n=80. Subjects aged 8–16 years were examined for dental fluorosis using the Thylstrup and Fejerskov Index (TFI). Based on the score on the upper left central incisor, the prevalence was not significantly different between the communities (TFI≥1). The severity, however, was significantly higher in Arusha.The areas had different food habits, e.g., type of weaning food used, and the use of magadi, a fluoride containing salt. In Arusha, 99% of the children had been given lishe, which is a magadi-free weaning food. Conversely in Kibosho, 61% used lishe while 39% used the magadi-containing weaning food kiborou. Magadi was used as food tenderizer in ’adult food’ by 98% in Kibosho and 45% in Arusha. Residencial area and use of magadi explained 5% of the variance in TFI scores in inter-area analyses. In intra-area analyses, weaning food in Kibosho and use of magadi in Arusha had a significant effect, but the total explained variance was only 5 and 4%, respectively.Apart from fluoride in the drinking water, other sources of fluoride such as use of magadi in weaning food (kiborou) and in the adult food may partly explain the high prevalence and severity of dental fluorosis in the community with 0.2 mg fluoride per liter in the drinking water.

An 11-year follow-up study of dental caries after discontinuation of school-based fluoride programs

The purpose of the present study was to determine whether the caries-preventive effect of school-based programs with fluoride (F) mouthrinsing or toothbrushing was evident at the end of a post-treatment follow-up period of 11 years. Two groups of subjects examined at 14 years of age (born in 1960), who had participated in fortnightly F rinsing (n = 52) or in F brushing 4-5 times a year at school (n = 50), were re-examined radiographically and completed a questionnaire at age 25 years. A comparison group of 25-year-olds (n = 51) was also included. Analyses of variance showed that the benefits of participation in school-based F programs seem to have been lost. It appears that these caries-preventive programs have delayed rather than prevented caries and that F toothpaste and other caries-preventive efforts have been insufficient to avert a substantial caries activity during the follow-up period.

Dental caries among 10- to 14-year-old children in Ugandan rural areas with 0.5 and 2.5 mg fluoride per liter in drinking water.

Abstract The purpose of this study was to report on dental caries among Ugandan children residing in rural areas with either a low or high fluoride concentration in the drinking water, and to assess factors associated with caries. A random sample of 481 children aged 10–14 years was selected from Mpondwe (n=81) and Kyabayenze (n=82) in the Kasese district with 0.5 mg and from Mutolere/Kagera (n=163) and Kabindi (n=155) in Kisoro with 2.5 mg fluoride/l in the drinking water. The children were examined for caries using the DMFT index as described by the World Health Organization in 1987. The mean DMFT was 0.34 in the whole material. In one low fluoride area, Kyabayenze, all children were caries-free compared to 75% to 86% in the other areas. In Kyabayenze, tea with sugar was taken significantly less frequently than in the other low-fluoride area. In the high-fluoride district, age and consumption of tea with sugar were positively and significantly correlated with caries. Multivariate analyses showed age to be the only significant risk indicator.