To determine the prevalence of nonfluoride enamel hypomineralization in the permanent first molars, we examined 488 7– to 13–year–old children. We further examined the impact of such defects on the treatment need by evaluating the number of caries lesions, restorations and extractions of the target teeth. Nonfluoride hypomineralization(s) were seen in 94 children (19.3%). The severity of defects varied from mild lesions with local color change to more severe ones where the hypomineralized tissue had been replaced by a restoration or the tooth had been extracted. Further examination of 65 children with nonfluoride hypomineralization showed that the defects had significantly increased the treatment need of the target teeth compared with the age– and sex–matched controls (p<0.001). Consequently, also the DMFT index of the whole dentition was higher in the children with hypomineralizations than in the controls (p<0.05). The results indicate that nonfluoride hypomineralizations have a significant impact on treatment need in the present child population with low caries activity.

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To characterize further the nature of calcifying odontogenic cyst (COC), we studied histologically and immunohistochemically an extraosseous and two intraosseous lesions. The extraosseous COC was in continuity with the stratified squamous epithelium of the alveolar mucosa. Immunostaining with monoclonal antibodies showed reactivity of both low- and high-molecular-weight cytokeratins, the degree of coexpression decreasing with the increasing morphological diversity of the cyst/tumour epithelium. Staining for the matrix glycoprotein tenascin-C was seen not only in the connective tissue, where its distribution patterns corresponded to the stage of hard tissue formation, but also in epithelial elements. The staining patterns were analogous to those described during normal tooth formation. Both the morphological characteristics and expression patterns of the various cytokeratin types and tenascin-C implied that COC represents a pathological counterpart of normal odontogenesis. In the case of the extraosseous COC, the correspondence could be traced back to early stages of tooth development.

The authors determined that demarcated hypomineralizations of developing teeth are a biological indicator of an early dioxin exposure in a healthy population of children. In the current study, the authors examined the prevalences of the demarcated hypomineralization lesions of teeth in 2 Finnish towns by the Kymijoki River--a river that is severely contaminated by dioxins and furans. The 4,120 permanent first molars of 1,030 children were studied. The prevailing levels of dioxins and furans in human milk were measured. The prevalences of the defects in children in Kotka and Anjalankoski were 14.2% and 5.6%, respectively, and the corresponding dioxins and furans in human milk were 13.4 pg/gm fat and 10.9 pg/gm fat (International Toxic Equivalents). In Anjalankoski, the duration of total breast-feeding was associated with the prevalence of the defects. Compared with the figures reported earlier in Finland, neither the prevalence of dental lesions nor the levels of dioxins and furans in human milk were increased in riverside residents.