15. Treating the Atrophied Mandible

It is standard procedure in crestal implantology today to insert screws with a minimum length of 10–13 mm in the anterior mandibular region, provided there is enough vertical bone height. Depending on how many screw implants there ultimately is room for, the patients may receive ball abutments, bars, or – in favourable situations – cantilevered-pontic bridges according to Brånemark. When it comes to distributing forces into the interior of the bone, patients with minimal bone height at the outset are at a disadvantage. It is precisely in these patients that only a small fraction of the overall masticatory forces will be directly toward the implants when designing the superstructure. In most cases, the crestal implants in these cases will offer only rudimentary support for a removable denture that, for the most part, will be periodontally supported. While this initially seems to alleviate the problem of denture retention, the disabling loss of teeth and jaw substance is not actually addressed. We as dentists have been able and continue to be able to make money on this type of «therapy» only because this disability is relatively invisible and because patients are ashamed and unwilling to bring their problem out into the open. As the most recent publication by Godbout et al. (2002) shows, subperiosteal implants are sometimes used – despite the fact that they are difficult to produce and difficult to insert and that they require a two-stage surgical approach – to treat situations of extreme vertical atrophy of the distal mandible.