the associated factors of permanent first molar caries in 7-9 years old children

introduction: permanent first molar is the most important unit in the chewing system. ear-ly loss of first molars can significantly reduce chewing efficiency, increase overbite, lead to premature eruption of the permanent second and third molars, and displacement of adjacent teeth. the purpose of this study was to determine the associated factors of permanent first molar caries in 7-9 years old children in rasht, in 2014. materials and methods: this cross-sectional comparative study was performed on 190 child-ren 7 to 9 years old. examination was carried out by one examiner in the pediatric depart-ment, with disposable mirror and explorer and under the light of dental unit. a self-adminis-tered questionnaire was completed by parents before the examination, containing an informed consent, demographic data and information about tooth brushing and dietary habits. data were statistically analyzed using independent t-test and chi-square tests. results: there was a significant relationship between the permanent first molar caries and dmft index (p = 0.001), mean plaque index (p = 0.001), consumption of between meal snacks three times a day (p = 0.046), using of sugar-containing drinks before bedtime (p = 0.048) and the age tooth brushing had started (p=0.027). there was no significant association between socio-demographic factors, frequency and method of tooth brushing and the perma-nent first molar caries. conclusion: high dmft and plaque index, con-sumption of between meal snacks and using sugary drinks before sleep increases the risk of permanent first molar caries.