A 33 year old male patient, who was referred from another hospital centre for presenting a large right hemimandibular tumour, 6 months old, which had experienced progressive growth, and which he reported after exodontia of a molar in the fourth quadrant, with no mention of significant pain at that level.
Physical examination and orthopantomography revealed a bone-dependent tumour 5-6 cm in diameter, with involvement of both bony cortices, extending from the region of the second premolar to the middle of the right mandibular ramus, with involvement of the ipsilateral internal pterygoid muscle.
A facial computed tomography (CT) scan showed a mandibular tumour lesion measuring 5.5 × 4.8 × 3 cm, destroying the internal mandibular cortex, displacing the musculature and structures of the base of the tongue, and involving most of the right mandibular body and ramus, with preservation of the condyle. A diagnostic biopsy was performed, with the result of a myxoid lesion with a reactive lymphoplasmacytic inflammatory component, with positivity for vimentin, CD138, Kappa, Lambda and partial positivity for actin. Immunohistochemistry showed negativity for S-100, CD31 and CD68. The diagnosis was mandibular odontogenic myxoma.
Under general anaesthesia and nasotracheal intubation, surgical excision of the lesion with margins was performed using a combined intraoral and extraoral approach, with segmental haemimandibulectomy from the canine region to the ipsilateral mandibular ramus and coronoid process, preserving the mandibular condyle. The patient had a serrated contralateral hemimandible. Primary reconstruction was performed using a microvascularised free fibula graft. The maximum thickness of the fibula was 14 mm. The flap was preformed in situ, with carving of the new hemimandible using a reconstruction bar modelled on the original mandible, and subsequent osteotomy of the peroneal bone and fixation with miniplates. Vascular anastomosis was performed between the right peroneal and facial arteries, and between the concomitant right peroneal veins and right thyrolinguofacial venous trunk. The histological study of the specimen was reported as a mandibular odontogenic myxoma without involvement of the surgical edges. The postoperative period was uneventful. One year after the operation, on observing a height discrepancy of 17 mm between the fibula and the alveolar ridge of the contralateral hemimandible, it was decided to perform vertical osteogenic distraction of the fibula by placing an intraoral alveolar distractor.
Distractor placement was performed under general anaesthesia. The fibula graft was exposed through an incision in the vestibular oral mucosa, after which a subperiosteal dissection was performed to adequately visualise the underlying bone, taking extreme care to preserve the periosteum of the lingual aspect of the fibula.
The intraoral alveolar distractor (MODUS ARS 1.5; Medartis®, Basel, Switzerland) was placed on the vestibular surface of the fibula to correctly design the osteotomies. The osteotomies were performed on the vestibular surface of the fibula, using an oscillating saw, with saline irrigation. A trapezoidal bone segment was obtained, with the lingual periosteum remaining intact. The alveolar distractor was fixed with screws on both sides of the horizontal osteotomy. Once the perfect functioning of the distractor had been checked, the distractor was placed in its starting position, so that both bone fragments were in perfect apposition. This is essential to initiate bone formation from the position of maximum contact between fragments and to achieve adequate post-osteotomy haemostasis. The vestibular incision was closed leaving part of the distractor through the incision to facilitate activation of the distractor.
Distractor activation was not performed during the latency period (10 days). After this, activation was performed at a rate of 0.5 mm per day. Serial orthopantomographic controls (obtained weekly) showed vertical distraction of the peroneal bone and the formation of bony trabeculae at the interface at the end of stabilisation. 17 mm of bone was obtained in 34 days, so that the fibula graft reached the same level as the contralateral alveolar ridge, with optimal correction of the initial height discrepancy between the two.
The consolidation period lasted three months, during which the distractor was maintained in its initial fixation site. Orthopantomography at three months confirmed excellent ossification between the basilar and the distracted fragment. Subsequently, in a second operation, the distractor was removed using the same intraoral approach. The quality of the newly formed bone, ascertained macroscopically, was excellent. In the same operation, three 3.75 × 15 mm threaded titanium implants (Mozo-Grau®) were placed in the distracted area. Good primary stability was achieved in all implants. The postoperative period was uneventful. Prosthetic rehabilitation, using an implant-supported prosthesis, was successfully completed after three months of osseointegration. The results obtained, both aesthetic and functional, were satisfactory for both the patient and the surgeon after 18 months of follow-up.
