Reconstrucción mandibular a medida con prótesis HTR-PMI con esqueleto de titanio / Patient matched mandibular reconstruction with HTR-PMI prosthesis with titanium framework

La prótesis HTR-PMI (hard tissue replacement - patient matched implant) es una prótesis reconstructiva compuesta por una combinación de materiales: un polímero de polimetilmetacrilato y polihidroxietilmetacrilato, no reabsorbible, biocompatible, aloplástico, indicado para la reparación de defectos esqueletales. El objetivo de este trabajo es presentar un caso clínico de reconstrucción mandibular post-osteomielitis de injerto libre de cresta ilíaca, por resección de un ameloblastoma invasivo, con un seguimiento de 7 años. El uso de este tipo de prótesis ofrece una alternativa más para la reconstrucción de grandes defectos.

Reconstrucción mandibular a medida con prótesis HTR-PMI con esqueleto de titanio / Patient matched mandibular reconstruction with HTR-PMI prosthesis with titanium framework

La prótesis HTR-PMI (hard tissue replacement - patient matched implant) es una prótesis reconstructiva compuesta por una combinación de materiales: un polímero de polimetilmetacrilato y polihidroxietilmetacrilato, no reabsorbible, biocompatible, aloplástico, indicado para la reparación de defectos esqueletales. El objetivo de este trabajo es presentar un caso clínico de reconstrucción mandibular post-osteomielitis de injerto libre de cresta ilíaca, por resección de un ameloblastoma invasivo, con un seguimiento de 7 años. El uso de este tipo de prótesis ofrece una alternativa más para la reconstrucción de grandes defectos.(AU)

Irradiation autogenous mandibular grafts in primary reconstructions.

The procedure, irradiated mandibular autografts, for primary reconstruction, is presented with an immediate success rate of 88%. Eight cases have undergone primary mandibular reconstruction with the tumorous mandible irradiated to 10,000 rads in a single dose. The longest follow-up is 2 3/4 years. The autograft has proven to be an ideal implant. Major resections of the mandible in conjunction with large myocutaneous flaps have been reconstructed utilizing this implant.

Particulate cancellous marrow crib graft reconstruction of mandibular defects.

Between 1969 and 1978 more than 1000 mandible fractures were treated by the otolaryngology services at the University of Minnesota and affiliated hospitals. Most were successfully treated but 17 patients had significant loss of mandibular bone resulting in a much more difficult management problem. The loss of bone was usually due either to the initial injury such as a gunshot wound or was secondary to the complications of non-union or osteomyelitis. Particulate cancellous marrow grafts within a Vitallium or titanium mesh crib (PCM crib graft) were used to reconstruct the mandibular defects. One patient had bilateral defects requiring 2 PCM crib grafts. Thus, 18 grafts spanning defects 2 to 12 cm were performed. Success was measured by a stable mandible with satisfactory occlusion and he ability to chew, swallow and articulate satisfactorally. Of 18 grafts, 15 met these requirements. Several factors important to successful mandibular reconstruction included adequate immobilization, intraoral soft tissue coverage, external skin cover and tension-free closure and optimal intraoral hygiene. The crib used to hold the particulate cancellous marrow in position during the healing phase has been removed in three otherwise successful cases because of intraoral mucosal tenting or dehiscence or to allow adequate fitting of dentures. In our experience, the use of autogenous cancellous bone and marrow in metallic mesh has been a successful means of restoring function and stability to mandibular defects.

Primary reconstruction of the mandible with a wire mesh prosthesis.

A stainless steel wire mesh prosthesis was used as a primary mandibular replacement in 102 patients following resection of malignant neoplasms arising in the head and neck. In 67 patients the prosthesis was considered successful. Failure of the host to tolerate the prostheses was associated with history of previous irradiation, extensive resections, and the loss of distant skin flaps used for coverage of the prosthesis. But the prosthesis is tolerated by the host in 90% of the cases if it is inserted in a non-irradiated bed, covered with local tissues, and the resection is limited to the maxillo-oral complex only.

Experience with 220 cases of mandibular reconstruction.

Extensive resections of the mandible are usually carried out for malignat tumours or non-malignant tumours with a tendency to reccur, such as ameloblastomas. These hemi-resections include the ascending and horizontal ramus of the mandible. Such mutilations have serious functional and aesthetic consequences. In order to avoid these drawbacks we use two sorts of implants. The first are made from metallic and plastic materials. They are used when patients are too weak to support a bone graft, when there is insufficient soft tissue coverage, or when a recurrence of the tumour is feared. In order to be well tolerated they must be made of materials which are fully accepted by the tissues. For the plastic part we use methyl-methacrylate and, for the metal part, "durallium". The second type is used to maintain a bone graft in good position. It is completely metallic. The pattern is made in wax and reproduced in durallium. They are made and adjusted in the same way as plastic implants. The results are analysed separately covering two periods. In the first (1955-1967), the failures have been relatively large (25%). During the second period (1967-1974), a better choice of operative indications and a more precise technique gave better results (failure: 13%).

[Subcutaneous silicone gel prosthese (author's transl)]. / Prothèses sous-cutanées en gel de silicone.

The use of silicone implants to correct an acquired or congenital abnormality of the face involves the use of:--blocks of foam, though these retract and the volume implanted must therefore be overestimated.--compact blocks of elastomer, which tend to migrate and to produce inaesthetic bumps with disturbances in the vascularisation of the skin. The authors therefore had the idea of making "to measure" implants similar to breast implants: envelope of silicone elastomer enclosing a gel of chosen viscosity, absorbing forces applied to the envelope and therefore tending to prevent migration of the implant. The latter has dacron patches to facilitate its adherence to deep layers. This description of manufacturing methods and operative techniques, despite a short follow-up, reports encouraging results from which it is possible to determine the indications of this type of procedure.

[Use of formalinized homologous bone in reconstructive operations on the mandible]. / Ispolzovanie formalinizirovannoi gomokosti pri vosstanovitel'nykh operatsiiakh na nizhnei cheliusti

An experience with 69 osteoplastic operations with formalinized homografts in 66 patients having various affections and injuries of the lower jaw is summarized. The grafts were preserved in 0.5% formalin solution or gel containing 0.25% formalin and 0.25% betapropiolactone as sterilizing agents. Positive issues during the follow-up from 4 months to 4 years 7 months were noted in 60 operative procedures, negative--in 9. It is concluded that the formalinized homobone shows good osteoplastic properties and may be used as a plastic material in reparative operations on the lower jaw bone.