Emergence of permanent teeth: secular trends and variance in a modern sample.

The purpose of this study was to update the most commonly used tables of dental eruption (emergence), which are more than 50 years old and do not distinguish between ethnic and socio-economic groups. Clinical emergence data was collected for a modern sample of 574 French children and adolescents, aged 5.5 years to 15 years (294 girls and 280 boys). With respect to the present sample, the commonly used eruption tables of Hurme were accurate for most aspects of mandibular emergence, but were seriously flawed for the maxillary arch. Emergence of all permanent maxillary teeth varied by at least 3 months from Hurme's means; lateral incisors, canines, and second molars erupted earlier, but both premolars emerged later. Compared to similar French data collected in 1958, there appears to be a secular trend for later eruption of the maxillary premolars and earlier emergence of permanent second molars. These changes may reflect an evolutionary reduction in the size of the maxilla, a progressive decrease in genetic control of permanent canines, as well as first and second premolars, and/or progress in dental preventive measures to conserve primary molars. From a clinical perspective, appropriate dental emergence data are essential for effectively intercepting developmental malocclusions in children and adolescents.