Immediate Functional Loading of an Implant-Supported Fixed Prosthesis at the Time of Ablative Surgery and Mandibular Reconstruction for Squamous Cell Carcinoma

Today, mandible repair after tumor-related ablation is generally managed using a microanastomosed fibula free flap. The procedure is usually completed by postoperative external beam radiotherapy. Edentation is one of the most serious sequels of such surgery. Dental rehabilitation is complicated by the extremely unfavorable local conditions, which render appliances unstable and compromise patient tolerance. In this context, osseointegrated implants are often the only solution for stabilizing a prosthesis. However, dental implant placement after external beam radiotherapy increases the risk of mandibular osteonecrosis and justifies preventive hyperbaric oxygen therapy.

Implant placement can also be compromised by the side effects of radiotherapy, mycotic superinfections, and poor patient tolerance. Implant insertion during initial surgical repair carries an increased risk of trauma to the flap, but management using 2-step, submerged implant techniques with delayed prosthetic loading also has disadvantages. Patients often find it hard to deal with the postoperative response, and the esthetic and functional outcomes are not always predictable.

We describe a 1-step implant surgery protocol combined with immediate functional prosthetic loading that is illustrated by a clinical case report with a 24-month follow-up period.

A 65-year-old woman presented in 2006 with a T4 N1 M0 (TNM classification) squamous cell carcinoma of the floor of the mouth with extensive mandibular symphyseal bone involvement. The preoperative range of motion was severely limited owing to the invasive nature of the tumor, and the anterior teeth were extremely mobile. The maxilla had been edentulous for many years and was fitted with a complete removable denture. Physical examination revealed moderate denutrition.

The treatment plan included segmental mandibulectomy, resection of the floor of the mouth, and bilateral cervical node dissection completed by fibula free flap reconstruction, implant insertion, and immediate placement (48 hours later) of a fixed functional implant-supported prosthesis. Complementary radiochemotherapy was also scheduled. The maxillary prosthesis was initially conserved and relined, and then replaced by a new prosthesis.

Anterior tumor resection respected the right and left angles of the mandible (Figures 1 and 2). Reconstruction of the mandibular surgical defect justified a median osteotomy on the fibula (Figure 3). Osteosynthesis was performed using 3 screw-retained titanium mini-plates (2-mm thick plates, 5-mm long screws; Figure 4).

Seven mandibular implants were placed during initial surgery: 2 in each fragment of the remaining mandible and 3 in the fibula graft (Figure 5). The implants were inserted after completion of arteriovenous anastomoses and osteosynthesis. The implants were positioned so that they emerged through the skin paddle, and care was taken to respect the fascia and the perforating arteries. Of the 7 implants, 6 were screw-type Fractal implants (Victory, Nice, France), measuring 13 mm in length and 3.75 mm in diameter. The remaining implant was a plate-form Diskimplant (Victory, Nice, France) inserted in the ramus using a lateral osteotomy technique and screw-secured by 2 bone-anchored osteosynthesis screws (Figure 6).

An impression was taken immediately after implant installation, which permitted the fabrication of a highly rigid prosthesis (titanium/chromium-cobalt framework with resin teeth) that was screw-secured to the implants 48 hours later (Figure 7).

Complementary postoperative radiochemotherapy, instituted 6 weeks after surgery, consisted of 100 mg/m² cisplatin combined with external beam radiotherapy (64 Gy) delivered to the initial tumor site. External beam irradiation was delivered according to usual schedules without any particular problems. Six months after radiotherapy was completed, the prosthesis was modified to take into account the resorption of the postoperative edema (Figure 8).

Follow-up examination 2 years after radiotherapy was completed revealed the absence of any local or distant disease recurrence. The implants were tested after the retaining screws were unscrewed and the prosthesis was removed; all implants were osseointegrated, both clinically and radiologically (Figures 9 and 10). Osseous consolidation of the fibula flap was complete. The occlusion was correct. The patient had resumed nearly normal oral intake and had rapidly regained weight. The morphologic and cosmetic facial outcomes were also satisfactory (Figure 11).

Dental rehabilitation with a fixed prosthesis after osteocutaneous fibula free flap reconstruction is a major challenge that affects quality of life and the resumption of physiological oral intake, mastication, and normal speech. Implant techniques have been developed to manage these difficult situations. However, owing to the complex anatomic conditions and the commonly used complementary postoperative treatments (radiotherapy and chemotherapy), few patients actually benefit from complete dental rehabilitation.1 Implant placement after irradiation increases the risk of mandibular osteoradionecrosis and must be delayed until bony consolidation has occurred and the main side effects of irradiation have disappeared.

Numerous authors have underscored the need for hyperbaric oxygen therapy for the osseointegration of implants placed in irradiated bone.2 Prosthetic loading is usually delayed until osseointegration has occurred, which renders the protocols long and aleatory. In the study by Hundepool et al,1 70% of patients who received implants in these conditions were never really rehabilitated for reasons ranging from death to unfavorable local evolution of the site.

Implant insertion during initial surgical reconstruction eliminates many of these problems, but it also lengthens the operative time and can cause injury to the flap.3 The risks of implant failure are thus increased owing to the associated acts on the bone and cutaneous tissues. Moreover, the presence of osteosynthesis material can be a considerable hindrance to implant placement. Nevertheless, a small proportion of patients managed with a fibula free flap are successfully rehabilitated with a fixed dental appliance.

These difficulties can be overcome by installing implants and a functional screw-secured prosthesis that provides immediate, highly rigid contention and absolute initial stability of the bone fragment during opening and closing of the jaws. The numerous advantages of this approach include rapid resumption of a normal socioprofessional life. Rapid patient rehabilitation before radiotherapy reduces the risks of osteonecrosis and the difficulties encountered with delayed loading protocols, where postradiation edema prohibits denture placement. In addition, the prosthesis serves as a conformer for the flap skin paddle, thereby improving soft tissue positioning.

One of the goals of immediate functional loading is improvement of the initial bony stability of the flap. Improved stability promotes consolidation while minimizing the amount of osteosynthesis material required. This reduces the risks of injury to the pedicle and the periosteum during flap placement. The initial prosthesis must therefore be extremely rigid from the outset (titanium/chromium-cobalt framework) and perfectly stable, with a passive fit. The implant-supported prosthesis acts as an external fixator, thereby satisfying the requirements of basal implantology as routinely applied for full-arch dental rehabilitations.4–6 

Clinical evaluation of the patient 2 years after radiotherapy was completed revealed osseous consolidation. The appearance of the mucosa was satisfactory, and local and regional disease control had been achieved. The implants were tested individually after retrieving the prosthesis, and all were osseointegrated. Radiologic examinations confirmed the consolidation of the 3 osteosynthesized segments and integration of all of the implants.

The placement of dental implants during mandibular fibula free flap reconstruction reduces the risks of osteonecrosis linked to postradiation surgery and the need for hyperbaric oxygen therapy. Early functional dental rehabilitation with the one-step, immediate implant loading procedure described here is possible provided the concepts of basal implantology are respected. In particular, absolute primary implant stability and fabrication of a highly rigid prosthesis are essential from the outset. The initial prosthesis, which serves as an external fixator, reduces the amount of osteosynthesis material required and improves primary bony stability by limiting micromovements, thereby reducing the risks of postirradiation pseudarthrosis. This prosthesis must be screw-secured to allow easy retrieval during clinical follow-up.