ABSTRACT
Ankylosis of a tooth is a pathologic condition commonly manifested by infraocclusion and vertical alveolar bone defect of the involved tooth. Extraction is often indicated in patients with severe tipping of adjacent teeth and serious infraocclusion, rather than attempting orthodontic repositioning. However, the residual alveolar bone defect after extraction must be restored adequately to establish sound dentition with a healthy periodontium. The bone-forming potential of sound periodontal ligament cells of the adjacent teeth can be used to restore the bone defect, through precisely controlled mesial movement of the root of the tilted molar. In this case report, a successful mesial root movement of the mandibular second molar is shown by the combined use of a conventional uprighting spring and orthodontic miniscrew implants in the mandibular premolar area. Adequate occlusion and periodontal health were restored in a 15-year-old girl with the typical sequela of an ankylosed molar.
Subject(s)
Alveolar Bone Loss/therapy , Bicuspid/pathology , Dental Implants , Molar/pathology , Orthodontic Anchorage Procedures/instrumentation , Tooth Ankylosis/therapy , Tooth Movement Techniques/methods , Tooth Root/pathology , Adolescent , Female , Humans , Orthodontic Appliance Design , Orthodontic Retainers , Orthodontic Space Closure/instrumentation , Orthodontic Space Closure/methods , Orthodontic Wires , Osteoblasts/pathology , Periodontal Ligament/pathology , Tooth Extraction , Tooth Movement Techniques/instrumentation , Tooth, Impacted/therapy , Tooth, Unerupted/therapyABSTRACT
INTRODUCTION: When monocortical orthodontic miniscrews are placed in interdental alveolar bone, the safe position of the miniscrew tip should be ensured. This study was designed to quantify the periradicular space in the tooth-bearing area to provide practical guidelines for miniscrew placement. METHODS: Computerized tomographs of 30 maxillae and mandibles were taken from nonorthodontic adults with normal occlusion. Both mesiodistal interradicular distance and bone thickness over the narrowest interradicular space (safety depth) were measured at 2, 4, 6, and 8 mm from the cementoenamel junction. RESULTS: Mesiodistal space greater than 3 mm was available at the 8-mm level in the maxillary anterior region, between the premolars, and between the second premolar and the first molar at 4 mm. In the mandible, sufficient mesiodistal space was found between the premolars, between the molars, and between the second premolar and the first molar at the 4-mm level. Safety depth greater than 4 mm was found in the maxillary and mandibular intermolar regions, and between the second premolar and the first molar in both arches. CONCLUSIONS: Subapical placement is advocated in the anterior segment. Premolar areas appear reliable in both arches. Angulated placement in the intermolar area is suggested to use the sufficient safety depth in this area.
