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ORIGINAL ARTICLE
Year : 2017  |  Volume : 9  |  Issue : 2  |  Page : 106-110

Prevention of collapse of the contralateral half of the mandible after hemimandibulectomy: Our experience in a low-resource center


1 Department of Dental Surgery, University of Calabar/University of Calabar Teaching Hospital, Calabar, Nigeria
2 Department of Oral and Maxillofacial Surgery, University of Benin Teaching Hospital, Nigeria

Date of Web Publication8-Jan-2018

Correspondence Address:
Dr. Charles E Anyanechi
FWACS, Consultant/Senior Lecturer/Head of Department, Oral and Maxillofacial Unit, Department of Dental Surgery, University of Calabar/University of Calabar Teaching Hospital Calabar, Eastern Highway, 540001 Calabar
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jofs.jofs_92_16

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  Abstract 


Background: The management of pathologic lesions of the mandible includes plans for the reconstruction of the resultant defect to give the patients optimal surgical reconstructive and prosthetic results. Objective: To evaluate the degree of deviation of the contralateral half of the mandible toward the surgical defect after hemimandibulectomy and intermaxillary fixation (IMF). Patients and Methods: This is a 9-year prospective single-blinded clinical study conducted at the Dental and Maxillofacial Surgery Clinic of our institution. Information obtained from the patients included age, gender, type of mandibular lesion, method of wound closure, duration of IMF, temporo-mandibular joint (TMJ) symptom(s), and the deviation toward the surgical defect of the remnant contralateral half of the mandible, measured in centimeter at maximum mouth opening. Results: Ninety-six patients, unevenly distributed according to their duration of tolerance of IMF, were studied. The age of the patients ranged from 29 to 57 years with an overall mean age of 42.6 ± 5.1 years. There were 72 males and 24 females with a male-to-female ratio of 3:1 (P = 0.001). The lesions that were extirpated were all benign, and ameloblastoma was the most common tumor (P = 0.001). The shorter the duration of IMF, the greater the deviation of the mandibular mid-line toward the surgical defect (P = 0.001). Conclusion: This study shows that there is a deviation of mid-line of the residual mandible toward the surgical defect after hemimandibulectomy, even after its immobilization with IMF for 4–12 weeks. IMF is still useful in the prevention of mandibular collapse after hemimandibulectomy.

Keywords: Benign, deviation, hemi-mandibulectomy, lesion, mandible


How to cite this article:
Anyanechi CE, Saheeb BD. Prevention of collapse of the contralateral half of the mandible after hemimandibulectomy: Our experience in a low-resource center. J Orofac Sci 2017;9:106-10

How to cite this URL:
Anyanechi CE, Saheeb BD. Prevention of collapse of the contralateral half of the mandible after hemimandibulectomy: Our experience in a low-resource center. J Orofac Sci [serial online] 2017 [cited 2019 Jun 18];9:106-10. Available from: http://www.jofs.in/text.asp?2017/9/2/106/222392




  Introduction Top


The extirpation of the pathologic lesions of the mandible almost always leaves composite defects.[1] As the remaining mandibular fragments become freely mobile after segmental resection, the reconstruction of the defects can be performed immediately after surgery or may be delayed until a later date.[2],[3] The existing literature suggests that immediate reconstruction is a viable option and has the benefits of requiring a single surgical procedure and an early return to function with a minimal compromise to facial esthetics.[4],[5] However, the reasons given for the delay in reconstruction include the loss of the grafted composite tissues due to infection when an immediate reconstruction is performed, recurrence of the extirpated lesion, adjunctive use of radiation for the eradication of the lesion after the initial surgery if malignant, soft tissue deficits, lack of facilities or manpower, and economic reasons among others.[6],[7],[8] In delayed reconstruction, intermaxillary fixation (IMF), splints, internal fixation, external pin fixation, or a combination of these modalities can be used to maintain the residual mandibular fragment in their normal anatomic relationship.[9],[10],[11] In contemporary practice, to ensure optimal mandibular alignment with the maxilla, preplating with reconstruction plate, which acts as a space maintainer, is commonly performed before resection is performed.[12]

In our center, delayed reconstruction for 1 year post hemimandibulectomy is the management protocol, and because of lack of reconstruction plates, IMF is used to protect and maintain mandibulo-maxillary relationship for a minimum period of 4 weeks before the reconstruction of the defect and prosthetic rehabilitation. In addition, no specific time frame has been agreed upon for the duration of IMF when it is used to prevent the collapse of the contralateral half of the mandible after surgery. We share our experience after hemimandibulectomy for the benign lesions of the mandible over a period of 9 years.


  Materials and Methods Top


Ethical approval for this study (Ethical Committee UCTH/HREC/19/291) was provided by Health Research Ethics Committee of University of Calabar Teaching Hospital Calabar, Nigeria, on 25th October 2005. This prospective single-blinded clinical study was designed to evaluate the degree of deviation of the contralateral half of the mandible toward the defect created after hemimandibulectomy and IMF. The patients considered for this study presented at the Oral and Maxillofacial Surgery Clinic of our institution between January 2006 and December 2014. The Research and Ethics Committee of the institution approved the study, which was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2000 (all patients gave their signed, informed consent to take part). The participants who had hemimandibulectomy (all the procedures were performed through intraoral approach) within this period were included in the study. Excluded from the study were all the cases of hemimandibulectomy resulting from treatment of malignant neoplasm, epileptic and asthmatic patients, and those with neuromuscular disease or deficit after the surgery.

The IMF was performed in all the patients on the 5th postoperative day by the same surgeon and assistant in the same operating room, and left in place for a minimum period of 4 weeks or for a maximum duration of 12 weeks depending on the patient’s level of tolerance of the fixation. The patients were recalled fortnightly in the first 4 months, but subsequently every 2 months for 8 months. At the maximum mouth opening using the facial midline and mesial part of the maxillary central incisor on the unresected side as guide, the degree of deviation of the remnant half of the mandible toward the defect was measured in centimeters (cm) with a ruler after 1 year of hemimandibulectomy by the same clinician as follows: The ruler was placed vertically from the mesial side of the maxillary central incisor in a straight line to a point on a tooth (reference point) on the unresected half of the mandible. The deviation of the mandible was then measured from the reference point to where the midline was located in the defect [[Figure 1]a and [Figure 1]b].
Figure 1: (a) Patient wearing IMF shortly before it was removed at 6 weeks. (b) Same patient with deviation of the remnant mandible to the defect at maximum mouth opening after 1 year

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A proforma designed for the study was used to document age, gender, type of mandibular lesion, method of wound closure, duration of IMF, temporomandibular joint (TMJ) symptom(s) during the period of immobilization and after the release of the IMF, and the degree of deviation of the contralateral half of the mandible toward the defect at the maximal mouth opening. The data obtained were analyzed with EPI INFO 7, 0.2.0, 2012 version software (CDC, Atlanta, GA, USA). Statistical analysis included mean values and standard deviation. Comparative statistics were performed using Pearson’s chi-square test and Fisher’s exact test as was appropriate. A P-value of less than 0.05 was considered to be significant.


  Results Top


A total of 96 patients, unevenly distributed according to the duration of their tolerance of IMF were studied [Table 1]; [Figure 2]]. The age of the patients ranged from 29 to 57 years with a mean age of 42.6 ± 5.1 years. The difference between the mean ages of the patients in the 4 weeks duration of IMF 43.6 ± 2.1 years, 6 weeks duration of 44.0 ± 3.1 years, 8 weeks duration of 42.7 ± 4.8, and 12 weeks duration of 42.0 ± 5.7 years was not significant (P = 0.643). There were 72 males and 24 females with a male-to-female ratio of 3:1 (P = 0.001).
Table 1: Types of lesions compared to the duration of IMF after hemimandibulectomy (n = 96)

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Figure 2: Duration of IMF and demographic profile

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The lesions that were extirpated were all benign, and ameloblastoma was the most common type (P = 0.001, [Table 1]). After the extirpation of the lesions, the wounds were closed primarily by interrupted 3/0 vicryl sutures, and TMJ symptoms were not reported by any of the participants.

The demographic and clinical characteristics of the patients compared to the period of tolerance or duration of IMF are shown in [Table 1] and [Figure 2]; the longer the duration of IMF, the fewer the patients. The side of mandibular resection was not significant [P = 0.74, [Figure 2]]. The shorter the duration of IMF, the greater the deviation of the remnant half of the mandible toward the surgical defect [P = 0.001, [Figure 3]].
Figure 3: Mean deviation following IMF

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  Discussion Top


When delayed reconstruction is adopted as the management protocol of the surgical defect after hemimandibulectomy, consideration is usually given to maintaining the residual half of the mandible in its anatomic relationship, and this technique prevents or minimizes the cicatricial and muscular deformation and displacement of this segment that would result due to muscle imbalance. This method also simplifies the secondary reconstruction when it is eventually performed.[1],[2],[3] This study showed that there is a deviation of mid-line of the mandible toward the surgical defect after hemimandibulectomy, even after its immobilization with IMF for a period of 4–12 weeks; and that the shorter the duration of IMF, the greater was the deviation toward the surgical defect on the contralateral side of the fixation. This is similar to previous reports,[10],[13],[14],[15] although the method of postoperative prevention or reduction of this deviation toward the surgical defect was not by IMF in these earlier studies. It was shown that the use of reconstruction plates gives superior outcome result when compared with all other methods or materials used for this purpose.[11],[12] After hemimandibulectomy, there is an imbalance of muscles of mastication, altered and restricted mandibular movements and decreased forceful mandibular closure.[1],[6] The main objective in the rehabilitation of these patients is retraining the remaining mandibular muscles to provide an acceptable clinical maxilla-mandibular relationship of the remaining half of the mandible.[7] The IMF was, therefore, used to establish the correct occlusion and maintain the jaws in their normal relationship during the healing phase and prevent collapse of the remaining half of the mandible into the surgical defect. The outcome of the rehabilitation process is generally influenced by the site and extent of surgery, presence or absence of teeth, psychology of the patient, and effect of radiation therapy where applicable.[3],[7] The measurements obtained in this study were taken at the maximal mouth opening, because it was observed that the wider the mouth opens, the greater were the deviations. The deviation toward the surgical defect is due to the loss of muscle action on the resected side.[16] The tissues within the surgical defect are scarred and uneven and also those became not only unsupported by bone, but also movable to various degrees.[2] Consequently, the movements of the mandible in the functional range and occlusal proprioception will differ from those of movements and occlusion of the normal mandible, causing the remaining mandibular segment to retrude and deviate toward the surgical defect.[17],[18] Some other researchers[19],[20] also believed that the primary determinants of the abnormal positioning of the remnant half of the mandible after hemimandibulectomy were the action of the remaining suprahyoid muscles and the uncompensated influence of the contralateral muscles, particularly the internal pterygoid muscle.

Consequently, the IMF was utilized to establish the correct occlusion and maintained the jaws in their normal relationship during the healing phase and also reduced the severity of deviation of the mandible. However, IMF, when used in combination with interdental eyelet wires or arch bars, does not ensure acceptable three-dimensional stability of the remnant mandibular segment, and the technique also cannot be used in an edentulous patient to achieve this purpose.[21] This is a part of the reason that it is not routinely used in well-equipped centers to prevent or minimize the deviation of the mandible toward the surgical defect after mandibulectomy. Furthermore, following the regressive changes that occur in joints, bones, ligaments, and muscles as a result of immobilization of fractured skeletal units by IMF, Glineburg et al.[22] suggested that immobilization of TMJ with IMF may not be an entirely benign procedure. This view is contrary to our report, because we recorded no adverse effect or symptoms of TMJ disease or disorder in all the patients during the period of immobilization and thereafter. The reasons for the variation in the duration of IMF in this study were due to the complaints of want of food, poor oral hygiene including foul breath, pain, and visible wires, which further impaired esthetics and general patients’ discomfort. These concerns of the patients have been reported by earlier researchers.[23],[24]

Mandibular deviation is a multifactorial defect, and its severity depends on the type of lesion extirpated, which invariably determines the extent of osseous and soft tissue involvement and the extent of surgery.[1],[2],[3] In addition, the type of wound closure, effect of radiation, degree of impairment of tongue function, loss of motor and sensory innervations as well as loss of proprioceptive sense of occlusion are determinant factors.[1],[2],[3],[4] Furthermore, the presence, absence, and the state of remaining natural teeth, the time when prosthetic treatment was initiated, and its psychological impact on the patients are also important.[3],[25] These factors guided the study design, and their conflicting negative influence may not have adversely affected the outcome of this study, because the lesions extirpated were all benign, and the mean age of patients in the different IMF groups and side of resection were insignificant coupled with the surgery and method of wound closure that were the same in all the patients. As it relates to the type of lesions that presented, the male-to-female gender was not significant. However, the predisposing factors that determine the severity of mandibular deviation includes scar tissue contracture, tight wound closure, and muscle imbalance secondary to primary resection.[2],[16] Furthermore, mandibular deviation is most severe after the primary closure of the base of the tongue lesion after excision and depends on the amount of soft tissue loss, fibrosis due to radiation therapy and cases that includes radical neck dissection.[20],[26] Apart from scar tissue contracture and muscle imbalance secondary to primary resection, other predisposing factors leading to adverse outcome or increased severity of deviation were not encountered in the present study.

The clinical significance of reduction and/or elimination of mandibular deviation cannot be overemphasized, because it partly determines the occlusal relationship that is finally obtained, which if favorable, aid surgical reconstruction and prosthetic rehabilitation, which improve the well-being of the patient.[2],[16] In this study, the IMF established the correct occlusion and maintained the jaws in their normal relationship during the healing phase and prevented collapse of the remaining half of the mandible. However, reconstruction plate was not used in this study, because the hardware was not available in this center during the study period. In addition, discrepancies might have been introduced by the method the mandibular deviations were measured, but this would not have altered the outcome of the study.

This study showed that there is a deviation of mid-line of the residual mandible toward the surgical defect after hemimandibulectomy, even after its immobilization with IMF for 4–12 weeks. The IMF established the correct occlusion and maintained the jaws in their normal relationship during the healing phase and prevented the collapse of the remaining half of the mandible. Although reconstruction plate was not used in this study and discrepancies might have been introduced by the method the mandibular deviations were measured, the outcome suggests that IMF is still relevant and useful in the prevention of mandibular collapse after hemimandibulectomy, particularly to oral and maxillofacial surgeons practicing in resource-limited hospitals/clinics.

Acknowledgements

The authors are grateful to the nurses and dental therapists, all the staff of the institution where the study was conducted for their clinical assistance during the management of the patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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