ABSTRACT
The aim of this study was to evaluate the effect of a school-based intervention project conducted in a mid-sized Finnish city, Laukaa on schoolchildren's oral health behavior. Material and Methods. In the intervention, all children received dental education and some of the 7-12-year-old schoolchildren received individual tooth brushing instructions by a dental nurse in 2009-2010. Parents were present at the instruction sessions. In 2009 and 2010, all the children answered a questionnaire or an oral hygienist on their oral health behavior without identification. Results. Tooth brushing frequency increased significantly among the schoolchildren between the years 2009 (61.2%) and 2010 (65%) (P < 0.05); more so among younger children (7-10-year-olds) compared to the older ones (11-12-year-olds). The 2010 results showed a slight trend of decreasing tooth brushing frequency by age both among girls and boys. Younger children got significantly more often parental help or reminding. The girls brushed their teeth significantly more frequently (71.9%) than boys (57.0%). Conclusions. Our findings indicate that oral health intervention can be beneficial on health behavior especially for children at low grades. All children, 11 to 12 years of age, especially boys, need continuous health promotion.
ABSTRACT
Previous studies show that the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), interferes with mineralization of the dental matrices in developing mouse and rat teeth. Culture of mouse embryonic molar teeth with TCDD leads to the failure of enamel to be deposited and dentin to undergo mineralization. Lactationally exposed rats show defectively matured enamel and retardation of dentin mineralization. To see if the impaired mineralization is associated with changes in the expression of dentin sialophosphoprotein (Dspp), Bono1 and/or matrix metalloproteinase-20 (MMP-20), thought to be involved in mineralization of the dental hard tissues, we cultured mouse (NMRI) E18 mandibular molars for 3, 5 or 7 days and exposed them to 1 microM TCDD after 2 days of culture. As detected by in situ hybridization of tissue sections, localization and intensity of Bono1 and MMP-20 expression showed no definite difference between the control and exposed tooth explants, suggesting that TCDD does not affect their expression. On the contrary, TCDD reduced or prevented the expression of Dspp in secretory odontoblasts and decreased it in presecretory ameloblasts. The results suggest that the retardation of dentin mineralization by TCDD in mouse molar teeth involves specific interference with Dspp expression.
Subject(s)
Dentin/metabolism , Environmental Pollutants/toxicity , Molar/metabolism , Polychlorinated Dibenzodioxins/toxicity , Protein Precursors/metabolism , RNA, Messenger/antagonists & inhibitors , Animals , Cells, Cultured , Dimethyl Sulfoxide/toxicity , Extracellular Matrix Proteins , In Situ Hybridization , Insulin-Like Growth Factor Binding Proteins/metabolism , Matrix Metalloproteinase 20/metabolism , Mice , Odontoblasts/drug effects , Odontoblasts/metabolism , Organ Culture Techniques , Phosphoproteins , SialoglycoproteinsABSTRACT
Clinical studies suggest that maternal smoking during pregnancy can reduce the crown size of the child's teeth. Delayed dental age compared with chronological age has also been reported in children whose parents smoke. Among the main components of tobacco smoke are nonhalogenated polycyclic aromatic hydrocarbons (PAHs), many of which are highly toxic. Humans are exposed to PAH compounds mainly via tobacco smoke and diet. The aim of our study was to investigate the effect of PAHs on tooth formation and the function of tooth-forming cells. We exposed mouse (NMRI) E18 mandibular first and second molar explants to 7,12-dimethylbenz[a]anthracene (DMBA), a toxic PAH compound, in organ culture for 7 or 12 days. DMBA concentrations used were 0.1, 0.5, 1, and 2 microM. The mesiodistal width of each first molar (12-day culture) was measured in stereomicroscopic images, and the teeth were analysed histologically. DMBA exposure significantly reduced the mesiodistal width of the first molars. DMBA impaired or delayed amelogenesis and dentinogenesis in both molars at the lowest concentration of 0.1 microM. DMBA affected enamel formation more severely than dentin formation and occasionally prevented amelogenesis completely. Elongation and polarization of ameloblasts were impaired, and blood vessel architecture of the dental papilla (future pulp) was altered. Cusps were thin and sharp. In line with the finding that maternal smoking during pregnancy has an adverse effect on child's tooth development, this study shows the toxic influence of PAHs on tooth development in vitro.
