The case for bone graft reconstruction including sinus grafting and distraction osteogenesis for the atrophic edentulous maxilla

The case for bone graft reconstruction including sinus grafting and distraction osteogenesis for the atrophic edentulous maxilla
November 2004
Ole T. Jensen, DDS, MS * *
Aldo Leopardi, DDS, MS ЗѓЬ
Louisa Gallegos, DDS, MSD Зѓ?
Journal of Oral and Maxillofacial Surgery Online
The 2 basic criteria for restoration of the edentulous maxilla are adequate bone mass and orthoalveolar form. These goals can be achieved by augmentation of the available substrate using prescribed techniques such as vertical and lateral augmentation of the alveolus, sinus floor bone grafting, and jaw bone repositioning.1ЗѓП4
When the available substrate is too deficient for implant placement, 1 or more of these options can be used to improve load-bearing capacity for implants. The use of vertical alveolar grafting for augmentation without the placement of dental implants remains suspect as a viable long-term strategy for bone mass maintenance.5,6
Optimal restoration of the edentulous alveolus suggests the concept of orthoalveolar form. Orthoalveolar form is defined as idealized alveolar bone positioned in Class I relation axially aligned with the opposing arch. When orthoalveolar form is achieved, implant prosthetic horizontal cantilever is minimized and crown/implant ratios are favorable. Restorations are short, Зѓ?gum set,Зѓ? and axially placed over implants.7
Resorption of the atrophic maxilla often results in a disparity of the arches mediolaterally and anterior-posteriorly. The resorbed maxilla decreases in bone mass in all directions. The basal maxilla presents up and back in its cephalometric projection and is often in Зѓ?cross-biteЗѓ? in its alveolar position as it relates to the lower arch. This means that despite vertical and lateral grafting, the interarch position of the maxilla, as it relates to a dentate mandible, is still Class III. Therefore, orthoalveolar form is largely unachievable in the resorbed retrodisplaced maxilla with bone graft reconstruction alone. Distraction osteogenesis is required to finalize the jaw into a more favorable position. This subjects the patient to a second surgical procedure, which may not be warranted given the ability for prosthetics to make up for surgical inadequacy.8,9
The problems with improper orthoalveolar form have largely been ignored in favor of concentrating on the task of increasing available bone stock.10,11 In the Cawood classification of edentulous atrophy, the Class IV maxilla requires augmentation bone grafting for implants to be performed. Specific sites within the maxilla vary. In the posterior, sinus grafting is needed when there is 4 mm or less of vertical bone or there will be insufficient support for implant osseointegration.12,13
In advanced maxillary atrophy, although there may be vertical height available anteriorly, a width deficiency will need to be addressed. Both vertical and horizontal bone deficiencies are usually present in the second bicuspid and first molar positions.14
When there is significant loss of vertical alveolar height, interocclusal space is usually increased, complicating the reconstruction. Despite this, there may not be enough interarch room in the posterior to vertically augment the crest without performing a sinus graft. The net effect is that vertical alveolar augmentation is often deferred or combined with sinus bone grafting to place implants in the posterior maxilla.15,16
Of the various augmentation procedures presently in use, certainly the most volumetrically stable bone graft in the jaws is the sinus bone graft. Sinus grafts, using a variety of materials and techniques, have shown an 80% to 90% success rate at integrating dental implants of at least 10 mm in length.17 The use of bone grafting to gain width for implants by various approaches is also 80% to 90% effective.18 In experienced hands, onlay block grafts or alveolar split grafts have been shown to be highly effective.19,20 Vertical augmentation by Le Fort I down graft has been reported to be stable enough for implant placement in a high percentage of cases.21 Finally, the orthopedic movement of the edentulous jaw or segments into prescribed locations by distraction osteogenesis has been found to be reliable.22,23
Two cases are presented here to illustrate the desired prosthetic restoration by first obtaining increased bone mass and improved orthoalveolar form.
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