ABSTRACT
Tooth eruption is complex process that involves different mechanisms. Low birth weight [LBW] infants are prone to many serious medical problems during the neonatal period which may affect the development of oral tissues. The aim of this study was to evaluate the relationship between the birth weight and eruption time of the first primary tooth. We have conducted a cohort study on70 full term infants [35 low BW, 35 Normal BW]. This study was conducted in Al-Zahra hospital of Rasht-Iran in 2007.The infants observed periodically since 3rd month of birth until the first tooth eruption. X2 test has been used for comparison of the two groups and since month 8th the regression logistic test to determine the effect of relative birth weights risks and other variables in tooth eruption. The first erupted tooth was mandibular central incisor with [8.26 +/- 2.72] month in case group and [7.76 +/- 3.18] month in control group and there was no statistical difference between two groups, The first deciduous tooth had erupted in 51.4% of LBW and 42.9% of NBW infants until 8 months Relative risk of delay eruption after 8 months in LBW infants was 1.2.[RR=1.2]. Birth weight in full term infant wasn't influence on the first deciduous tooth eruption time