Transmucosal fixation is a new strategy for the treatment of edentulous mandibular fractures using external fixation principles within the oral cavity. The component parts of this technique are not new. External fixation, locking plates and transmucosal implants represent the foundations of this technique; the authors’ development has been to bring these established methods together as a transmucosal intra oral locking plate fixation technique. The first eight patients treated with this technique have achieved bony union, they have no long-term sensory deficit and all patients were able to eat a soft diet with minimal discomfort the day after surgery. The first five of eight patients on long-term review showed bony union confirmed radiographically. For the remainder and subsequent patients, radiographs have not been scheduled at review, in the absence of symptoms.
Treatment of the edentulous fractured mandible presents special difficulties . Many methods of immobilisation have been suggested over the years, most of historic interest given the modern acceptance of rigid plate fixation. Patients are often elderly with acute and chronic co-morbidities frequently complicating management and adding to anaesthetic risks . The specific problems of edentulous mandibular fractures relate to the remaining mandibular bone height. The difficulty of achieving bony union is well known. Fractures amenable to mini-plate fixation often leave a plate near the denture bearing area and/or place a screw near the inferior alveolar neurovascular bundle risking anaesthesia or paraesthesia in the distribution of the nerve . Since the screws are angled laterally in the posterior area, the benefit of bi-cortical fixation may be achieved and there is less risk to the neurovascular bundle. Anteriorly, the screws are medial to the inferior dental canal. In the authors’ experience, stability is sufficient with fixation through one cortical plate as S toelinga et al. described in the fixation of mandibular osteotomies 10 . Bi-cortical fixation would increase the firmness of fixation and can be achieved with this technique.
The aim of this study was to establish whether rigid fixation could be achieved transmucosally using existing locking plates and established external fixation concepts. The first eight cases are reported.
Materials and method
Patients with an edentulous fractured mandible that required fixation were selected. If they were unfit for a general anaesthetic the procedure could be carried out under local anaesthetic with or without sedation. An impression taken before surgery can facilitate plate contouring prior to plate placement, alternatively the plate can be contoured intra-operatively.
The fracture site(s) were palpated and if there was any problem with the accuracy of reduction a small incision was made to visualize the fracture line. A suitably long mini-locking plate straddling the fracture site was placed and fixed ( Fig. 1 ). Postoperative and 6-month review radiographs were taken. There was a buried premolar in the area of this fracture, the authors avoided extracting the tooth at the time of fixation, as this would have increased the risk of non-union. Bony union was confirmed by radiography and the tooth remained buried and asymptomatic. In later cases, longer plates were used, which ideally extended from retro-molar to retro-molar region where screws were grouped in three specific regions, both retro-molar regions and the bone anterior to the mental foramina. In the retro-molar region the screws are angled from a lingual entry directed downwards and slightly buccally and may engage the lateral cortex but mono-cortical engagement is adequate ( Fig. 2 ) . The authors now avoid the mandibular body for screw placement.
To avoid mucosal compression a periosteal elevator was used ( Fig. 1 ). The locking screw could then be engaged fully without compressing the mucosa. Although initially two screws were used on either side of the fracture line, the authors considered that a minimum of three mono-cortical screws in the ramus regions and in the anterior mandible would be better.
Postoperatively, orthopantomograms were carried out to confirm satisfactory reduction. At review, following fixation removal, patients were assessed for mobility or pain at the fracture site. If patients remained symptom free 2 weeks after fixation removal they were discharged. The first three patients returned for follow-up and radiography to confirm bony union.
All patients were able to eat a soft breakfast on the first postoperative day, seemed untroubled by the procedure and did not complain of any significant pain.
After fixation removal, carried out under local anaesthesia, all patients had clinical bony union so radiography was not considered appropriate at this stage on clinical grounds and no patient required further follow-up beyond 3 months. The first three patients were recalled at 6 months and agreed to assist the study by allowing clinical examination and a review radiograph, all had achieved bony union (Figs 1 c and 3 b ).