Critical design errors in maxillary subperiosteal implants.

A maxillary full arch subperiosteal implant consists of a metallic framework that rests closely on the atrophied residual ridge beneath the mucoperiosteum and offers support for a dental prosthesis by means of posts or bars with O-ring protrusions or internal clip attachments. The maxillary subperiosteal implant is indicated for those patients presenting with advanced atrophy of the maxilla leaving the patient with three existing stable dense bony areas (the anterior nasal spine, the canine eminences, and the palatal surface of the existing crest) for its support. Over 300 cases with up to 12 years in function are presented. The importance of the basic anatomic and physiologic background required to optimize results are emphasized. The first 600+ subperiosteal implant cases that were placed prior to 1985 showed considerably lower success rates.