The aim of this epidemiological study was to evaluate the need for orthodontic treatment in a sample of adults living in France.The indicator selected was the dental component, IOTN (index of orthodontic treatment need).Among the 258 adults evaluated, 37% of patients had a strong need and 21% had a moderate need; 29% of those aged 35 and under were in strong need for treatment compared with 47% of those over 35 years, with the need for treatment increasing with age. The most frequent occlusal anomalies were dental migrations following an uncompensated tooth extraction (a situation that involved 22% of subjects). It was the only occlusal anomaly whose frequency increased significantly with age. Among patients with uncompensated tooth extraction, two thirds experienced dental migrations requiring orthodontic treatment.Although the IOTN indicator is widely used in the literature, it is controversial since all the characteristics evaluated are liable to impact longevity and the functioning and esthetics of the dentition, thus excluding any other consideration. The need for treatment in adults in France would therefore appear to be greater than in adolescents and would seem to increase with age, mainly due to uncompensated dental extractions.