When adequate bone supply is available, the replacement of missing molars with implants is considered a relatively easy and simple task in terms of the difficulty and complexity of the surgical procedure. However, the opposite is true in the case of increasing local atrophy of the alveolar process. Problems and difficulties will either be of a general nature due to local defects or atrophic changes of a posterior edentulous alveolar ridge segment, or they will specifically be due to pneumatization of the maxillary sinus in the maxilla or involve a subcrestal path of the inferior alveolar nerve in the mandible. To place implants without any augmentation measures, either immediate placement or ultrashort implants or implants with selective para-antral or paranerval positioning may be employed. This augmentation-free treatment option must be combined with appropriate prosthetic measures, such as implant-borne cantilevers with distal extension. If augmentation measures in the maxilla appear to be unavoidable, either internal augmentation in the form of sinus elevation surgery with percrestal or lateral access, external augmentation, or possibly a combination of both strategies will be indicated depending on the individual situation. In rare cases, distraction osteogenesis may also be indicated. If augmentation measures are needed in the mandibular molar region, horizontal or vertical ridge-splitting procedures and distraction osteogenesis may be used in addition to external alveolar ridge augmentation. Generally, autologous material, osteoconductive substances, or osteoinductive substances such as rhBMP-2 may be employed as augmentation materials. All of these treatment options will be discussed, and data from the literature will be compared to results and experiences from our own patient population. The various therapeutic approaches as well as the associated risks will then be explained in detail based on patient examples and documented by actual patient cases.
Georg Watzek, MD, DDS, PhD, is head of the Dental School at the University of Vienna. He is president of the Austrian Society of Oral Surgery and Implantology and a former president of the European Association for Osseointegration. Dr Watzek is the author of more than 200 publications, including 7 textbooks. He is the author of Implants in Qualitatively Compromised Bone (Quintessence, 2007) and The Percrestal Sinus Lift (Quintessence, 2012).
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