Anatomical considerations relevant to implant procedures in the mandible

The authors review anatomical facts significant for preoperative planning of implant procedures in the mandible. This planning includes the precise evaluation of distinct anatomical factors, such as the position of the mandibular canal, the width of the mandibular cortical plates and the degree of involutive changes of the inferior dental artery. The mandibular canal is usually situated centrally in the mandibular corpus, slightly closer to the lingual cortex in its distal parts; towards the front, it approaches the vestibular cortical layer. Mesially from the mental foramen, a clearly defined incisive canal is present in only one third of the edentate mandibles. Mandibular corpus of the edentate mandibles consists of cancellous bone enclosed by a shell of compact cortical bone. Cortical layers demonstrate significant variations in width; nevertheless, the widths of lateral cortical layers, generally, enable safe placement of endosseous implants. Finally, in patient's preoperative assessment, involutive changes of the inferior dental artery should also be considered. During the involution of the mandibular alveolar process, it shows changes of direction and calibre, changes in arborization and, sometimes, complete occlusion of the main trunk. The degree of these involutive changes points out the mandibular vascular supply and the regenerative capacity of the tissues needed for the success of the implant procedure.