Physiologic drift of the mandibular dentition following the extraction of four first premolars

Chun, Youn Sic

Abstract

Retrostpective study of two groups of patients was conducted to evaluate the physiologic drift of the mandibular teeth following the extraction of four first premolars. The concept of physiologic drift, commonly referred to as "driftodontics", following first premolar extractions has been gaining acceptance in the orthodontic community, the exact nature and amount of drift has not been adequately documented. There were also no guide lines as to when drift should be allowed to occur. The purpose of this study was to quantify physiologic drift of the untreated mandibular dentition following extraction of the four first premolars during the early permanent and late permanent dentition stages. The early permanent dentition extraction sample(Group 1) included 26 patients and the mean age at pretreatment was approximately 13.5 years. The observation period following extraction was approximately 6.96 months. The late permanent dentition extraction sample(Group 2) included 31 patients. The mean age at pretreatment was 21.3 years, followed by a observation period of 7.26 months. During the observation period, except for the extractions, no other mandibular therapy was rendered. Pre-and post-treatment lateral cephalograms and dental casts were analyzed. The obtained results were as follows 1. Group 2 showed marked changes in movements of the mandibular incisors and canines but minimal changes in molars. 2. The amount of changes in movements of the mandibular incisors and canines were significantly greater in Group 1 than in Group 2. The results showed no differences in rates of molar movements between groups. 3. Physiologic drift of the dentition produced desirable changes such as decreased Incisor Irregularity.