الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
The objective of this study was to evaluate the alveolar bone changes after en masse retraction of the anterior teeth using cone-beam computed tomography (CBCT). The study sample comprised ten patients (eight females and two males with mean age of 16.4 years) with Class I dentoalveolar bimaxillary protrusion. Patients were treated by extraction of the four first premolars. One-step en masse retraction of the anterior teeth was performed with absolute anchorage mechanics. Pattern and magnitude of retraction were evaluated by pre-retraction and post-retraction lateral cephalograms. Thickness of the labial and palatal/lingual alveolar bone was assessed for each of the maxillary and mandibular anterior teeth by using CBCT before and after completion of the en masse retraction. Changes were evaluated at the bone sites adjacent to the greatest width of the root labiopalatally/labiolingually, in three levels perpendicular to the tooth long axis and separated by 3 mm (crestal, midroot and apical). The mean time of the en masse retraction was 8.7 months. Retraction of anterior teeth was performed by controlled tipping. In the maxillary arch, labial alveolar bone thickness showed significant increase in the apical level. Palatal alveolar bone thickness showed significant decrease at the crestal level and the midroot level. In the mandibular arch, labial alveolar bone thickness showed significant increase in all levels. Lingual alveolar bone thickness showed significant decrease in all levels. For patients with bimaxillary protrusion, mechanobiological response of anterior alveolus should be taken into account during en masse retraction. CBCT has proved to be a reliable and diagnostic tool over conventional two-dimensional radiography to identify and quantify alveolar bone changes especially in cases of compromised periodontium support as bimaxillary protrusion.