PARTICIPANTS AND ELIGIBILITY CRITERIA
dentofacial anomalies, malocclusion, crowding or bimaxillary dentoalveolar protrusion, orthodontic
SYSTEMIC DISEASE, PERIODONTAL DISEASE, CLASS I MALOCCLUSION
Fifty consecutive patients attending the orthodontic outpatient clinic were screened. Thirty-eight patients (30 females) were recruited, with an age range between 15.5 and 23.5 years. Four premolars were extracted in 33 patients, three premolars in 3 patients and two premolars in 2 patients. The trial included 145 quadrants (74 maxillary and 71 mandibular). At the start, there were 36, 37, 36, and 36 quadrants in the two-week, four-week, six-week and eight-week groups, respectively. The inclusion criteria were: permanent dentition, malocclusion requiring at least two first premolar extractions, and Group A anchorage demand. The recruited patients had Class I malocclusion with severe crowding or bimaxillary dentoalveolar protrusion, Class II div. 1, or Class III. Patients were excluded if pregnant, smokers, or reported a systemic disease or medication that interfered with bone metabolism. Patients with a history of dentofacial anomalies, periodontal disease, or orthodontic treatment were not eligible.