Change in proportion of extraction and non-extraction in orthodontic patients.

The purpose of this study was to determine whether there has been an increase in the number of non-extraction cases over recent years and investigate the selection of treatment devices. Patients attending the Department of Orthodontics at Tokyo Dental College Chiba Hospital in whom orthodontic treatment was commenced between July 1989 and July 1990 (Group A) or between June 1998 and May 2003 (Group B) were included in the study. The orthodontic diagnostic records of the patients were examined. Patients requiring orthognathic surgery, those with congenital diseases or cleft palate, and those with an uncertain diagnostic record were excluded. The characteristics, initial age, and classification of malocclusion in the two groups were almost the same. The patients in both groups were further divided into two subgroups: one in which treatment was commenced in mixed dentition and another in which it was begun in permanent dentition. The final therapeutic strategy, that is to say, non-extraction or extraction, was investigated in all groups. The final observation date in the mixed dentition group in Group B was September 2011. No major differences were observed in pattern or type of malocclusion between the two groups. Group B, however, showed an increased rate of non-extraction treatment. A policy of non-extraction was pursued in a higher proportion of patients in whom treatment was commenced in mixed dentition than in those in which it was begun in permanent dentition.