Timing of eruption of permanent teeth: standard Finnish patient documents.

Current standards for the eruption of teeth are constructed mostly on the basis of cross-sectional data. The aim here was to analyze the suitability of the standard patient documents created for health center dental care purposes for the collection of longitudinal data on tooth emergence. Copies of the oral health records of the 911 children born in 1970 and 1971 and in 1980 and 1981 living in three rural communities in Finland were re-examined and analyzed using a specially compiled computer program. The means and standard deviations are in line with previous results. The sex difference in emergence timing ranged from 0.1 to 1.0 years for the various teeth. The emergence of the teeth of the second phase of the mixed dentition was later in the children living in an endemic fluoride area, this difference being statistically greater for the boys than for the girls (95% Cl for differences between means was used to evaluate statistical significance). A secular trend in the eruption of permanent teeth was found between 1970 and 1980. Patient documents are shown to be suitable for the collection of longitudinal data on dental emergence.

Effect of early restorations of permanent molars on filling increments of individual teeth.

OBJECTIVES: The purpose of this work was to analyse longitudinally whether the placement of restorations on permanent molar teeth immediately after their eruption results in (a cohort with) higher filling increments in all individual teeth thereafter. The patient documents of 937 subjects born either in 1970-1971 or in 1980-1981 were analysed. METHODS: The methods of survival analysis were employed. If any of the first permanent molar teeth had been restored in the course of tooth emergence, the person was assigned to the experimental group, and all the others were placed in the control group. Those in whom all the first permanent molar teeth had been restored at the time of emergence were compared with all the others. RESULTS: Early restoration of any permanent molar indicated higher filling increments in all the other molar teeth. The differences between the groups with regard to the first and second molar teeth were statistically highly significant (e.g. D.17 for the girls: log-rank chi 2 = 32.8, p = 0.0001 and Wilcoxon chi 2 = 28.7, p = 0.0001). The differences were greater among the girls than among the boys. Early restoration of the first permanent molar teeth did not indicate high filling increments in the incisors, canines or the smooth surfaces of any tooth. CONCLUSION: Fissure caries and smooth surface caries are different entities. The present method can be of help as an additional tool to help the clinician identify "risk" patients, in that an early restoration in any first molar is a powerful indicator of a risk of restorations in the other first molar teeth and also the second molar teeth.

Effect of early or late eruption of permanent teeth on caries susceptibility.

OBJECTIVES: The aim of this study was to analyse the possible effect of early or late eruption of permanent teeth on the placement of first restorations on the different surfaces. The oral health records, of a total of 486 children born in 1970 and 1971 living in three rural communities in Finland, were analysed. METHODS: Caries susceptibility was determined indirectly by a new method. The study groups were defined as falling outside one standard deviation either side of the mean value for the timing of the eruption of first permanent molar teeth. RESULTS: No statistically significant differences in restoration increments between the early and late eruption cohorts were found at the end of the study period. For the occlusal surfaces of the first molar teeth, the restoration placement curves plateaued at about 60-70%, while for the second molar teeth, the plateaus occurred at 50-60% for both study cohorts. In girls with 'late eruption', the height of the post-eruptive step (i.e. the number of teeth filled on the year of their eruption) was higher (50-100%) compared to boys and girls with 'early eruption'. The difference was statistically significant. For example, for the occlusal surface of D. 36, the 95% confidence interval for the difference between proportions was 12-53%. CONCLUSION: No consistent effect of early or late eruption of permanent teeth was found on caries susceptibility measured post-eruptively by the placement rate of first restorations in a follow-up study of more than 10 years among Finnish children born in 1970-1971.

Timing of first restorations in permanent teeth: a new system for oral health determination.

OBJECTIVES: A system of oral health determination in which times between eruption of teeth and first restorations because of caries is measured is applied in a retrospective analysis of oral health data relating to rural health centres in Finland. METHOD: The retrospective analysis was carried out using data relating to three health centres in different parts of Finland. The times between eruption and the placement of the first restorations in subjects up to 18 years of age were investigated. RESULTS: Between 10% and 25% of all permanent molar teeth were filled in the year of tooth emergence--the 'immediate posteruptive step'. A steadily increasing restoration placement rate--the 'ascending growth phase'--was observed after the 'posteruptive step'. The restoration rate was found to plateau 5-8 years after eruption--the 'retardation phase'. CONCLUSIONS: Restoration increment curves with longitudinal measurements are believed to be a sensitive indication of oral health at both individual and population levels.

Timing of first restorations before, during, and after a preventive xylitol trial.

An independent longitudinal retrospective analysis of the timing, number, and cost of tooth restorations was conducted for all subjects (n = 313) in the age cohort of a municipal health center, in which two consecutive field trials of up to 3 years on the caries-preventive effect of the use of xylitol chewing gum were conducted (Ylivieska study, 1982-85). A computer program calculated the post-eruptive timing of the first restorations on each permanent tooth surface, and survival analysis methods were applied before, during, and after the trials. The cost of restorations was then calculated. The total number of new restored surfaces was 4.0 per child in the xylitol group and 9.3 in the controls during the decade after onset of the trial. The number of restorations on the occlusal surfaces of the first molars leveled off at 40-50% in the xylitol group and at about 60-70% in the control group. Plateaus for the second molars were at 30-40% and 60-70%, respectively. The time lag for the first restorations was longer in the xylitol group for the proximal and other smooth surfaces. A marked difference in favor of the xylitol group was observed in the proximal surfaces of the upper incisors (for example, the mesial surface of the upper mesial incisor for girls: log-rank chi-square = 11.1, p < 0.001). The preventive effect was most pronounced in teeth that had erupted during the trial. This analysis indicated that participation of subjects in the xylitol chewing gum trials resulted in a significant reduction in the number of first restorations and hence in costs during the decade after the onset of gum use.