Frameshift mutations in dentin phosphoprotein and dependence of dentin disease phenotype on mutation location.

We describe results from a mutational analysis of the region of the dentin sialophosphoprotein (DSPP) gene encoding dentin phosphoprotein (DPP) in 12 families with dominantly inherited dentin diseases. In eight families (five mutations in the N-terminal third of DPP), the clinical and radiologic features were uniform and compatible with dentin dysplasia type II (DD-II) with major clinical signs in the deciduous dentition. In the other families (four mutations in the more C-terminal part), the permanent teeth also were affected, and the diseases could be classified as variants of dentinogenesis imperfecta. Attrition was not prominent, but periapical infections were common. Discoloring with varying intensity was evident, and pulps and root canals were obliterated in the permanent dentition. All mutations caused a frameshift that replaced the Ser-Ser-Asx repeat by a code for a hydrophobic downstream sequence of approximately original length. We conclude that frameshift mutations in DSPP explain a significant part of dentin diseases. Furthermore, we propose that the location of the mutation is reflected in the phenotypic features as a gradient from DD-II to more severe disease that does not conform to the classic definitions of DI-II.

A seven-year survival analysis of caries onset in primary second molars and permanent first molars in different caries risk groups determined at age two years.

OBJECTIVE: To investigate in a group of children (n=183) the effect of possible risk factors registered at the age of 2 years on caries development in 7 years of follow-up, and to study associations between risk groups. MATERIAL AND METHODS: Consumption of candies, use of a nursing bottle at night, use of fluorides, toothbrushing, pacifier sucking, and prolonged breastfeeding (>or=12 months) were recorded at the age of 2 years. The timing of caries onset in different groups was compared by applying a survival analysis method--the survival curves produced separately for selected teeth in different risk groups. RESULTS: The survival curves of caries onset for both primary and permanent molars were consistently lower for children who consumed candies more than once a week, did not brush their teeth daily, were given a nursing bottle at night or a pacifier at age 2 years. The multivariate survival analysis confirmed that consumption of candies and lack of daily toothbrushing were the factors that had the major impact on caries onset in both primary and permanent molars. Prolonged pacifier sucking (>or=2 years) was related only with short duration of breastfeeding. Children with prolonged use of a nursing bottle at night also consumed candies more than once a week, did not brush their teeth regularly, and did not use fluoride tablets. CONCLUSIONS: Consumption of candies and inadequate oral hygiene at age 2 years are important long-term risk factors for caries development in both primary and permanent molars.