A longitudinal study of the condition of first permanent molars in a group of adolescents with special reference to elective orthodontic tooth extraction.

The aim of this study was to investigate changes in the condition of first permanent molars over the teenage years, with special reference to adolescents who lost premolar teeth for orthodontic purposes. A total of 453 South Wales schoolchildren (219 males and 234 females) were examined at the ages of 11-12 and 19-20 years. At 11-12 years, 89.6 per cent of the cohort had all four first permanent molars, while 3.3 per cent had already lost these teeth. Of those first permanent molars present, 61.7 per cent had some caries experience. At age 19-20, 80.6 per cent of subjects retained four first permanent molars while 4.4 per cent had none. Of the first permanent molars present, 80.6 per cent had been affected by caries. In 60 per cent of the 186 subjects (75 males and 111 females) who had lost premolar teeth in the course of orthodontic treatment, a sound premolar was extracted in preference to a first permanent molar which already had evidence of dental disease. At age 19-20 years, the majority of the first permanent molars were restored and otherwise sound, though a small number which had been restored at age 11-12 years had been lost due to caries.