A study on the chronology and sequence of eruption of primary teeth in Spanish children

The aim of this study is to determine the timing of primary teeth eruption in Spanish children, and to distinguish gender and arch differences.

A cross-sectional study was performed on primary teeth eruption in a sample of 1,250 children (623 girls and 627 boys) from the Region of Madrid aged between 3 and 42 months. The clinical emergence of teeth was taken to estimate the mean ages of primary teeth eruption. The t test was used to analyse gender and arch differences.

The process of primary dentition lasted 22.28 months, and statistically significant differences were found in the eruption of homologous contralateral teeth. The first molars and maxillary lateral incisors erupted earlier in girls than in boys, with no statistically significant chronological differences. The central incisors and second molars erupted first in the mandibular arch, while the lateral incisors, canines and first molars erupted first in the maxilla. A greater chronological difference was found between the lateral incisors, which erupted more than 8 months earlier in the maxilla than in the mandible.

In the overall sample, the first tooth to erupt was the lower right central incisor at 10.96 ± 1.88 months, and the last was the upper left second molar, at 33.24 ± 4.35 months, symmetry was found in the eruption of the deciduous teeth. The greatest chronological difference was observed in the lateral incisors, with the upper ones erupting more than 8 months before the lower ones. Although statistically significant gender differences were found, they were considered clinically irrelevant.