This manual is conceived as an aid to AO course participants both in grasping theoretical principles and in performing practical exercises, as well as a practical guide for clinicians in the application of AO principles. These principles are discussed in Part I and related to notions of stability, biomechanics, and technique. In addition to interfragmentary fixation and load bearing, the technique of external fixation is explained. The use of rigid external fixators with the mandible is proposed as a replacement for pin fixation, which has been obsolete for over two decades. Part II is a practical guide to the theoretical principles set forth in the first section of the volume, with the focus on case studies classified according to fracture type. This section provides a solid empirical basis of particular value in establishing indications and selecting appropriate techniques. Equally important is the anatomy of surgical points of access. In Part III, the increasing variety of indications for rigid internal fixation is confirmed. Three areas take on particular relevance here: the surgical treatment of pseudarthrosis, the by-pass of primary defects as an integral part of mandibular tumor surgery, and sagittal splinting and condylar replacement for orthopedic interventions involving the locomotor system of the mandible. A foldout entitled "AO Classification of Mandibular Fractures" is inserted at the back of the book. Its purpose is to help the clinician confronted by an acute case to determine its classification.