2024 Volume 66 Issue 1 Pages 88-90
Mandibular deviation and rotation following mandibulectomy can significantly impact oral function and quality of life. The postoperative course of a 57-year-old patient who underwent mandibulectomy for oral cancer and findings over 11 years of follow-up observation to monitor changes in the mandibular position are described here. Based on the observations, it is important to raise awareness regarding the necessity of continued monitoring of mandible position and regular adjustments of prostheses for patients who have undergone mandibulectomy.
Squamous cell carcinoma is one of the most common cancers of the oral cavity [1]. When it occurs in the mandible, mandibulectomy is performed to resect bone and other tissues [2]. The most common prognosis for mandibulectomy is mandibular deviation and rotation as well as masticatory dysfunction, which is especially common in patients who lose mandibular continuity [3].
The position of the mandible is determined by the muscles and ligaments that attach to it. For patients who undergo segmental mandibulectomy, there may be few muscles remaining even after reconstruction. This will force the surgical side lacking muscles or ligaments to compensate for the movement of the healthy side [4], causing the position of the mandible to change. The mandible might also change position as a result of the healing process. After mandibulectomy, the bone and surrounding tissue may experience swelling and inflammation. As the tissues heal, they may contract, changing the position of the mandible [3].
Options for correcting mandibular deviation include occlusal ramps, guiding flanges, and maxillary fixation [4,5]. Of these, occlusal ramps are the most widely used. They can be easily adjusted and are effective in rehabilitating masticatory function [5].
Although previous studies have investigated mandibular deviation and rotation [3,4,5], few have followed up patients long enough to observe changes in the position of the mandible. In one study, Awadalkreem et al. observed an implant-supported fixed prosthesis for a period of 2 years and did not find any complications [6]. In another long-term study with follow-up ranging from 11 months to 20 years, Mariani et al. found that reconstruction plates were ineffective in bridging large defects of the resected mandible [7]. The lack of information about changes in mandibular position may have negative implications for the long-term care and treatment of mandibulectomy patients. Therefore, further research in this area is needed to improve prognosis for these patients.
In this case report, a patient who underwent mandibulectomy due to oral cancer is presented. The postoperative course of the patient is described, with a focus on the significance of 11 years of follow-up observation to monitor changes in the mandible position. The report also highlights the challenges associated with managing changes in mandible positions. This case is useful for raising awareness of the need to continue monitoring mandibular position and regular adjustments of prostheses in patients who have undergone mandibulectomy.
The patient was a 57-year-old man who was diagnosed with squamous cell carcinoma (T2N0M0) of the right mandible in 2006 (Fig. 1). After radiotherapy (total 38 Gy in 19 fractions over 25 days), he underwent right-sided segmental mandibulectomy, partial maxillectomy, and right neck dissection in 2007. The resected mandible was reconstructed using a rectus abdominis myocutaneous flap and an AO (Arbeitsgemeinschaft für Osteosynthesefragen) plate (Fig. 2). He was referred to the Department of Maxillofacial Prosthodontics at Tokyo Medical and Dental University Hospital in 2011 for the fabrication of prostheses.
Intra-oral photographs capturing the mandibular position were taken periodically during the prosthodontic treatment and subsequent follow-up observation. In 2011, slight mandibular deviation, rotation, and retrusion were observed in the frontal (Fig. 3A) and lateral view (Fig. 4A), and a small maxillary occlusal ramp was fabricated to achieve occlusion (Fig. 5A). The maxillary prosthesis effectively sealed the communication between the oral and nasal cavities (Fig. 6). Additional support for occlusion was provided by the mandibular occlusal ramp (Fig. 7). During subsequent visits, in 2012, the prostheses were noted to be broken and minor repairs were needed twice. The maxillary prosthesis included an occlusal ramp (Fig. 8A) and an obturator (Fig. 8B), the mandibular prosthesis contained an occlusal ramp (Fig. 9). In 2014, hardly any differences in mandibular deviation (Fig. 3B) and retrusion (Fig. 4B) were observed compared with 2011, but a slight change in the frontal view was evident, the space between the right anterior teeth became larger (Fig. 3B), so the maxillary occlusal ramp needed to be extended slightly (Fig. 5B). The prostheses were noted to be more seriously broken early in 2016, requiring the fabrication of new ones. Later in 2016, mandibular deviation and rotation were still present (Fig. 3C) and retrusion was evident in the lateral view (Fig. 4C), so the occlusal ramp was expanded to both sides to achieve occlusion (Fig. 5C). In 2022, severe mandibular deviation and rotation were evident in the frontal view (Fig. 3D) and severe mandibular retrognathia was noted in the lateral view (Fig. 4D), the maxillary occlusal ramp was adjusted so that it was larger and wider (Fig. 5D). Furthermore, an evaluation of mastication function using gummy jelly (Glucorumn, GC corp., Tokyo, Japan) revealed an average glucose concentration of 150.0 mg/dL. As of May 2023, the patient is able to use the prostheses in daily life and has been asked to attend regular appointments every four months for oral care and prothesis adjustments.
During long-term observation, it was noted that the position of the mandible was continually changing. From the frontal view, the mandibular deviation and rotation towards the surgical side became increasingly severe (Fig. 3). From the lateral view, the mandibular retrognathia became increasingly apparent (Fig. 4). This meant that the patient’s prostheses needed to be regularly adjusted, especially the maxillary occlusal ramp, to prevent the gradual loss of occlusion. The maxillary occlusal ramp was adjusted based on the changes in mandibular position (Fig. 5), with additional materials added to the occlusal ramp to enable the patient to achieve occlusion and restore masticatory function. This case highlights the importance of careful monitoring of the mandibular position, even after reconstruction, and highlights the role of prosthodontists in ensuring the success of prosthetic rehabilitation. Compared with normal patients, the changing mandibular position would continue to create stress in some parts of the prosthesis, and the prosthesis would be more likely to fracture. Thus, the patient should be asked to visit the clinic every four months, which can help prosthodontists to detect any fractures in advance and prepare for fabricating new prostheses.
An interesting point to note is the use of the mandibular ramp, which is rare in mandibular prostheses. The case showed not only deviation but also rotation (Fig. 3), as a result, an occlusal ramp for the mandible was required. From Fig. 7A, it was hard to form occlusal contacts only with the help of a maxillary occlusal ramp, thus the mandibular ramp played an important role in restoring the occlusion of the surgical side (Fig. 7B). In addition, severe bone absorption was observed around the mandibular right canine by radiography (Fig. 2). However, the ramp part effectively reduced the occlusal force on this abutment tooth, which continues to function successfully even after more than 10 years. Despite the flap reconstruction limiting the mandibular denture space and rebuilding only a few occlusal units, the patient is still able to enjoy eating and is satisfied with his improved appearance.
One of the limitations of this case report is that there are no specific values of three-dimensional (3D) changes in the mandibular position, and it is important to record these values of patients in the future, which will provide more accurate and comprehensible results to understand changes in the occlusal condition. For example, the 3D data that was taken by intra oral scanner can be a good option and can help to detect changes in occlusion. Additionally, it is not clear whether the presence of maxillectomy increases the deviation level or not. Thus, in a further study, it is necessary to compare the deviation level differences between cases of mandibulectomy only and those that include maxillectomy and mandibulectomy.
Mandibular deviation, rotation, and retrusion are expected to continue to deteriorate in the years after mandibulectomy, so careful follow-up observation and regular adjustment of prostheses are indispensable to the prognosis of mandibulectomy patients.
None
This work was partially supported by the Japanese Dental Science Federation (JDSF-DSP1-2017-210-1).
