Biological interpretation of the correlation of emergence times of permanent teeth.

The eruption mechanism is not fully understood. It is known that the dental follicle is essential and that experimentally provoked denervation influence the process of eruption. Accordingly, the purpose of this study was to elucidate the eruption pattern in a human population and relate this pattern to the pattern of jaw innervation. The eruption pattern was evaluated from the correlation between the emergence times of different teeth in the permanent dentition based on longitudinal data from a large national registry (12,642 boys and 12,095 girls). Correlations coefficients were generally high (>0.5) and higher between teeth within the same tooth groups (i.e. incisors, canines and premolars, and molars) than between teeth from different tooth groups. It was shown that the correlation in emergence of teeth closely followed the pattern of innervation of the jaws. Thus the study supported the hypothesis concerning a possible association between eruption and innervation.

A longitudinal study of time trends in the eruption of permanent teeth in Danish children.

The purpose was: (1) to estimate mean eruption times of permanent teeth in Danish schoolchildren for the birth cohorts from 1969 to 1982; and (2) to determine any time trends in eruption. For teeth with a low proportion of aplasia, the distribution of the eruption time was close to normal. For teeth with a higher proportion of aplasia there was a slight deviation from the normal distribution in the right-hand part of the distribution. For erupted teeth, the time to eruption was, however, again very close to the normal distribution. A small, but statistically significant, increase in mean eruption times was found for both sexes and almost all teeth. Averaged over all teeth the increase was 1.5 days per year (95% CI: 0.9--2.2) for boys and 2.6 days per year (95% CI: 2.2--2.9) for girls.

[Development of caries in a group of Danish school-age children after cessation of systematic fluoride rinsing]. / Kariesudvikling hos en gruppe danske skolebørn efter ophør af systematiske fluorskylninger.

In a municipality near Copenhagen, Denmark, where fortnightly fluoride rinses with 0.2% neutral sodium fluoride had been performed for more than a decade, 1306 children from kindergarten through sixth grade were stratified by school and grade and randomly distributed into two groups. One group continued with the fluoride rinses, the other group had the fluoride solution replaced with distilled water. Both solutions were slightly flavored. One thousand and eighty-three children completed the three-year trial. Caries was recorded clinically by the dentists in the municipal dental service using criteria common for the Child Dental Health Services, and on bitewing radiographs by one of the authors applying criteria developed by Gröndahl et al. Permanent molars and premolars were included in the study. Clinically, caries increment in the two groups was the same, with 94% of caries lesions and fillings situated in pits and fissures. According to the radiographs, caries progression in the water group was higher than in the fluoride group. This difference was statistically significant for the surfaces erupting during the study (p < 0.05).