Discussion

A clinical and radiographic evaluation of the alveolar distraction

Evaluación clínica y radiográfica de la distracción alveolar

The authors of this article present the results of the alveolar distraction technique, reporting 15 cases of alveolar distraction of the anterior region of the upper maxilla. The mean gain was 7.04 mm and the number of complications was high at 53.33%, although there was only a major complication in one patient. Most of the complications were due to dehiscence and infection and the case with the major failure consisted in it being impossible to activate the distractor, although we are not told if this was due to a defect of the device or to a badly designed transport segment and/or to a failure to check the activation of the distractor intraoperatively.

Recently, Chiapasco published in 2004 a multicenter study of 37 patients that underwent alveolar distraction. There was a 9.9 mm mean bone gain, 138 implants were placed and loaded with an average post-loading follow-up of 9.9 months and a success rate 4 years later of 94.2%. The complication rate was low at 13.5%, which was related to problems with the direction of the vector, and there was only one failure due to the faulty design of the transport disk.

In the article ‘A clinical and radiographic evaluation of the distraction osteogenesis technique for the reconstruction of atrophic alveolar ridges in the anterior region of the upper maxilla.’ the authors concentrate on evaluating bone gain radiologically, but we miss a better clinical analysis of these cases, with regards to how many implants were placed and if these were successful. The number of complications experienced was high, although there was only one failure. Most of the authors that publish articles on distraction center the complications more on the difficulties in directing the vector of distraction than on local infections, although they probably do not analyze lesser problems such as the dehiscence of sutures and scars.

Bone distraction is the production of a bone callus with osteogenic capacity in a bone in which an osteotomy has been carried out and its ends have been subjected to a process of progressive tension that is maintained. In order for the distraction to be effective, it has to be gradual and progressive and the vascular supply should not be interrupted. In the distraction area the same basic phenomena occur as in the healing of a fracture, from the initial fibrous callus phase to the final phase of bone remodeling and the production of mature bone. The stability of the callus is, according to the literature, mandatory. That is, the distractor should not allow any movement in the distracted fragment.

Alveolar distraction is indicated principally for the anterior portion of the maxilla and mandible, where simultaneous lengthening of soft tissue is achieved with very predictable results.

In the posterior portion of the maxilla, where the aesthetic requirements are not so high, the grafting and sinus elevation techniques may be more advisable at the present time, although those defending distraction indicate that this technique allows bone to be generated from below, returning to a more physiological state as the prosthetic space is reduced, in many cases increased by previous bone resorption, while the crown-implant relationship is improved and in specific cases a more aesthetic smile is achieved.

J.I. Salmerón Escobar
Servicio de Cirugía Oral y Maxilofacial
Hospital Universitario Gregorio Marañón. Madrid. España

Bibliografía

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