Difference in dental lateral arch length between 9-year-olds born in the 1960s and the 1980s

This study was carried out in two cohorts of 9-year-olds, born in the 1960s and the 1980s in Sweden and Norway, to test the hypothesis that there has been a change in the lateral arch space conditions of the dentition during the last decades. In Norway, 61 children born in 1963 and 58 children born in 1983 were examined. In Sweden, 66 children born in 1961 and 67 children born in 1984 were examined. Children with a prolonged sucking habit, major dentofacial anomalies, history of orthodontic treatment, and ancestors of foreign origin were excluded to avoid influence of these factors on the development of the dentition. Linear measurements were performed between the mesial surface of the first permanent molars and the distal surface of the permanent lateral incisors in the maxillary and mandibular dental arches with use of a sliding caliper. The results showed that the children born in the 1980s had significantly larger lateral arch spaces in the maxillary dental arch (P <.05) and in the mandibular dental arch (P <.01) than did the children born in the 1960s. The amount of tissue loss in the second deciduous molars (the teeth having caries lesions or having been extracted) was greater in the 1960s groups than in the 1980s groups (P <.001). Thus, the hypothesis, that there has been a change in the lateral arch space conditions during the last decades, was confirmed. The most obvious reason is the decline in caries prevalence that has occurred in the same period; thus, there has been less loss of proximal tooth material of posterior teeth.