PARTICIPANTS, ELIGIBILITY CRITERIA, AND SETTINGS
orthodontic
Patients who required extraction of their maxillary and mandibular first premolars and orthodontic mini-implants for anterior The mini-implants used in the study were surface-treated, self-drilling, tapered titanium mini-implants of 2-mm diameter and 8-mm length (A1 orthodontic mini-implants, Bioray Enterprises, Taipei, Taiwan), which were sandblasted with large-grit alumina particles, followed by acid etching with hydrochloric acid and sulfuric acid. This surface treatment was customized by Bioray enterprises for evaluation in the present study. A total number of 18 surface-treated and 18 non-surface-treated mini-implants were placed in these patients following an intra-individual split-mouth design (
