Materials and methods. 307 subjects were examined at bimonthly intervals during the first and second years of life and then at six-month intervals until the eruption of first permanent tooth. Eruption times of primary and permanent tooth were recorded for each child. A modified form of Kuppuswamy’s scale was used to assess the SES. 

Results. Among 267 subjects completed all follow-ups, the eruption time for first primary and permanent teeth indicated a direct strong correlation in that one month delayed or early eruption of first primary tooth resulted in 4.21 months delayed or early eruption of first appearing permanent tooth (r = 0.91, n = 267, P <0.001). No significant correlation was observed between the eruption time of first primary and first permanent teeth and SES (P = 0.67, P = 0.75, respectively). 

Conclusion. The eruption timing for the first primary tooth had a correlation with the first permanent tooth eruption timing, while SES did not have any influence on eruption times.