EARLY VERSUS LATE TREATMENT OF CROWDED FIRST PREMOLAR EXTRACTION CASES - POSTRETENTION EVALUATION OF STABILITY AND RELAPSE

The purpose of this study was to evaluate the differences in the long- term stability of orthodontically induced changes in arch form between patients who receive early orthodontic treatment (Hellman's dental ag e III B, mixed dentition, n=36) and those who are treated later (Hellm an's dental age III C or after, permanent dentition, n=47). Dental cas ts were evaluated before treatment, after treatment, and at a minimum of 10 years after retention. All patients had received routine edgewis e orthodontic treatment that included maxillary and mandibular first p remolar extraction. There were no significant differences between thes e groups at pretreatment and posttreatment. In the majority of cases, some degree of mandibular crowding occurred during the postretention p eriod. There was a significant difference in the mandibular irregulari ty index at postretention between these groups. Regarding the deviatio n of the midline of the central incisors, there were no significant di fferences between these groups at pretreatment and posttreatment, but there was a significant difference at postretention. At the postretent ion stage, the late treatment group had greater mandibular anterior ir regularity and deviation of the midline.