Posterior Implantations

Molars are commonly the first teeth lost from the maxillae, and the loss tends to progress anteriorly — tooth by tooth — accompanied by a reduction in ridge height and sinus enlargement unless the situation is stabilized and proper occlusal relationships re-established in both arches.

In the partially edentulous arch, a posterior implant not only provides support for a restoration, it also relieves stress on the anterior teeth used as abutments in a fixed partial prosthesis, pro-longing their lives. Sturdy posterior support can minimize the number of anterior teeth included in the restoration, if a full arch prosthesis is neither necessary nor desirable.

As in any implant situation, the type of implant to be employed depends upon the amount and character of the remaining bone. It would be misleading to anticipate that the presence of sturdy anterior teeth in good occlusion implies minimal bone re-sorption posteriorly. Radiographs and observations of the revealed site are the only reliable means of accurately evaluating the potential implant site.

The posterior regions of a totally edentulous maxillary arch present the most challenging problems in implantology. Bone loss and fragility and sinus enlargement are usually far more extensive when no teeth are present. However, current implant techniques provide several alternative implant approaches that are being used with increasing success in posterior maxillary situations. These include several bladevents specifically designed for sinus circumvention, the pterygoid extension implant and, to a more limited extent, the standard unilateral subperiosteal implant.

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