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Introduction & Objective: Based on the carried out studies, the prevalence of dental caries in preschool children is high and ranges from 31.64 to 83.7 percents in Iran. The dmft criterion is not able to compute the impact of neighboring teeth on caries status of a tooth in deciduous teeth. The purpose of this study was to investigate the above issue in a sample of 3-5 years old children in Tehran during 2008-2009. Materials & Methods: In this cross-sectional study, a group of 400, 3–5 years old children who lived in Tehran and referred to Pediatric Dentistry Department of the Dentistry Faculty of Tehran University of Medical Sciences, Iran, for treatment of their deciduous teeth were investigated The demographic variables and mouth health cares data were collected by a questionnaire and the caries status of deciduous teeth were diagnosed by standard methods. The caries statuses were considered as spatially correlated binary data. The auto logistic regression model was implemented for inspecting the association of a tooth and its neighboring teeth which consists of two adjacent teeth and the opponent tooth. The effects of factors were tested using z-score. Results: The fitted model and the computed criteria showed that there was a strong dependency between caries statuses of a tooth and its three neighbors (including the two adjacent and the vertically opponent teeth) (p=0.0001). Also the effect of spatial auto covariate which is equivalent to the sum of statuses of nearest neighbors of a tooth is highly significant. Furthermore, the effects of local variables such as jaw and posterior-anterior positions were also highly significant (p=0.0001). Conclusions: In deciduous teeth, the three nearest neighbors have a high effect on a tooth. As a result, the teeth in maxilla and posterior locations are decayed sooner than the other ones. These findings may be considered in preventive programs of health of mouth and tooth in children.

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Introduction and objective: Tooth caries is the most prevalent infectious disease in children. The purpose of this study was to assess carries experience indexes and related factors among 7-12 year-old school children in Yasuj, Iran, in 2014.

Materials and methods: In the present Cross-sectional and analytical study, using a two-stage random sampling, 460 students from primary schools of Yasuj city and surrounding villages were selected. The children were clinically examined at their school by a professional calibrated dentistry team. Their demographic and socioeconomic status, mouth health behaviors and teeth carries status and consumed nutritional materials were gathered by a questioner and a dental chart. The data were analyzed using inferential statistical methods. The SPSS software version 22 was used to extract the outputs and &alpha=0.05 was considered as the significant level.

Results: The dental caries prevalence of deciduous, permanent and total of  two type of dents were  75.2, 41.1 and  89.8 percent, respectively and the dmft, DMFT and dmft+DMFT indexes were 3.57, 0.87, and 4.44, respectively.. The caries prevalence of permanent teeth and DMFT in girls were significantly higher than boys (p=0.046), but the caries prevalence in total of dents in boys was significantly higher than girls ( p=0.32). Furthermore, the dental caries prevalence in permanent teeth and DMFT in children resident in rural areas were significantly higher than those in urban areas (p<0.0001). The DMFT had a direct association with the children’s age and the dmft + DMFT index had a significant adverse linear correlation with Body Mass Index (BMI) of children (p=0.004). Moreover, the output indicated that tooth caries experiences in children who used dental flossing was significantly lower (p=0.027). Correspondingly, in children who used tooth brushing, consumed dairy foods, whom their fathers being official employees and parents having higher education, dental caries prevalence was lower (p>0.1).

 Conclusions: Prevalence and severity score of dental caries among 7 - 12 year-old Yasuj students were higher than the WHO standards. The tooth caries experiences were more prevalent in boys and in children resident in rural areas, increased with age and decreased with BMI and less prevalent in children with higher family socioeconomic status. Tooth brushing and flossing and consuming dairy foods were protective agents in occurring tooth caries in primary school children in Yasuj, Iran.