|Year : 2016 | Volume
| Issue : 4 | Page : 228-232
Spontaneous regeneration of a wide mandibular defect following segmental mandibulectomy for ameloblastoma: A case report and review of the literature
Davis S Adeola, Ekene P Onyebuchi, Rowland Agbara, Albert U Okeke
Maxillofacial Surgery Unit, Ahmadu Bello University Teaching Hospital, Samaru, Zaria, Kaduna State, Nigeria
|Date of Web Publication||8-Dec-2017|
Dr. Ekene P Onyebuchi
Maxillofacial Surgery Unit, Ahmadu Bello University Teaching Hospital, PMB 06, Samaru, Zaria, Kaduna State
Source of Support: None, Conflict of Interest: None
Mandibular defects may be congenital or arise from a number of causes including surgery, infections, and trauma. Sporadic cases of spontaneous regeneration of jaw defects have been reported in the literature, however, the exact mechanism of this occurrence has not been fully understood. Some of the suggested factors that have been advanced for this phenomenon include age, periosteum, and genetics. Further studies are needed to elucidate the molecular basis of this phenomenon. We report a case of spontaneous regeneration of the mandible in a 14-year-old Nigerian boy following segmental mandibulectomy for ameloblastoma.
Keywords: Ameloblastoma, mandibulectomy, spontaneous regeneration
|How to cite this article:|
Adeola DS, Onyebuchi EP, Agbara R, Okeke AU. Spontaneous regeneration of a wide mandibular defect following segmental mandibulectomy for ameloblastoma: A case report and review of the literature. Arch Int Surg 2016;6:228-32
|How to cite this URL:|
Adeola DS, Onyebuchi EP, Agbara R, Okeke AU. Spontaneous regeneration of a wide mandibular defect following segmental mandibulectomy for ameloblastoma: A case report and review of the literature. Arch Int Surg [serial online] 2016 [cited 2020 Jul 10];6:228-32. Available from: http://www.archintsurg.org/text.asp?2016/6/4/228/220329
| Introduction|| |
Spontaneous regeneration of bone defects is a rare phenomenon which has been likened to an exuberant process of normal bone healing occurring in long bones as well as the jaws including the mandible., Although this phenomenon is unexpected, it has been observed to account for the regeneration of small mandibular defects, and in some cases, even the whole of the mandible including the condyles.,, The exact mechanism of spontaneous bone regeneration is unknown, however, some of the factors which have been suggested include age, periosteum, presence of bone fragments, infections, and genetics.,, We hereby present a case report of a 14-year-old Nigerian boy with spontaneous regeneration of the mandible following segmental resection for ameloblastoma.
| Case Report|| |
A 14-year-old male patient presented at the outpatient clinic of the Maxillofacial Surgery Unit on account of an anterior mandibular swelling of 2 years duration. Swelling was said to have been observed 3 months following trauma and was associated with occasional episodes of mild pain, however, there was no associated constitutional symptom, and the systemic review was essentially normal.
Examination of the swelling showed a minimally expansile mass extending from tooth 36 to 46, with lingual displacement of tooth 42 [Figure 1]a-c]; the swelling was firm with fluctuant areas. Aspiration of the swelling yielded a serosanguineous aspirate. Other systemic examination was essentially normal. Plain radiographs of the jaws revealed multilocular radiolucency extending from tooth 36 to 46 with a very thin lower border of the mandible. The histopathological report of the incisional biopsy revealed ameloblastoma and the patient was scheduled for resection of the mandible.
|Figure 1: (a) Preoperative view. (b) Preoperative intra-oral picture. (c) Preoperative plain radiograph|
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Intraoperatively, a mucosal defect from preoperative biopsy site was noted and via an intraoral approach with subperiosteal dissection, segmental resection of the mandible was done through the sockets of #37 and # 47, while incorporating the mucosal defect. The developing tooth buds of # 38 and #48 were exposed and mobile, which were extracted. Passive drains were inserted on both the sides and residual soft tissues were closed in layers. Antibiotics and analgesics were prescribed for 5 days. Postoperative recovery was uneventful and he was discharged 10 days postsurgery.
During follow-up review 2 weeks post discharge, his facial profile was observed to have improved with good saliva and lip control [Figure 2]a and [Figure 2]b. The bony outline of the mandible was palpated in the region of the previous mandibular defect. Further reviews at 3, 6, and 10 months postsurgery confirmed new bone formation, which was seen on plain radiograph [Figure 3].
|Figure 2: (a) Postoperative facial profile. (b) Six months postoperative intra-oral picture|
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| Discussion|| |
Spontaneous regeneration of the mandible following mandibulectomy is a rare event and in most cases unexpected regeneration of the mandible postsurgery was discovered after routine examination or following radiographic investigation.,,, [Table 1] gives a summary of cases of spontaneously regenerated mandibular defect. The period of onset of bone regeneration varies from a few weeks to several months.,, Budal, and Nagase et al. observed new bone formation as early as 2 weeks after resection, whereas spontaneous bone regeneration that occurred 10 months postresection was reported by Kisner. Osteoinduction, osteoconduction, and osteogenesis are the processes involved in bone formation, and these processes which are involved in new bone formation have been described as being similar to that of fracture healing., The exact mechanism of spontaneous bone regeneration is not known, however, some of the factors associated with this phenomenon include young age, preservation of a part of or the entire periosteum, infection, and genetics.,,,,
|Table 1: Summary of reported cases of spontaneous regeneration of the mandible|
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A literature search reveals that most reports of spontaneous regeneration of the mandible were observed in relatively young individuals with almost all cases occurring within the 5–16 year age range.,,,, However, few cases with higher age ranges have also been reported., Da villa et al. reported a rare case of mandibular regeneration in a 58-year-old woman with avulsion of part of the mandible following blast injury. The presence of abundant mesenchymal cells and thus a greater healing potential have been suggested to account for this observed higher incidence of spontaneous bone regeneration among the young., The patient in our case report is 14 years which is consistent with previous findings. However, the fact that not all young individuals who had mandibular resections experience spontaneous regeneration of the mandible highlights the fact that certain critical factors may be important for spontaneous bone regeneration.
The periosteum is considered a principal factor in spontaneous bone regeneration, which has been highlighted by most previous reports.,,,,,, The periosteum is rich in osteoprogenitor cells and consists of two layers – an outer densely fibrous layer with few blood vessels and an inner cellular part which contains the osteoprogenitor cells.,, Furthermore, the periosteum serves as a protective membrane to the newly deposited bone and plays a role in bone remodelling via its inner layer and together with the endosteum of the medullary cavity controls the inflow and outflow of ions. The periosteum in whole or fragments has the ability to induce osteogenesis, which persists even after irradiation although to a lesser extent. Preservation of the periosteum in the patient in our case report may have contributed to the spontaneous bone regeneration observed.
The role of infection in the induction of spontaneous bone regeneration has been suggested by Adekeye, and supported by recent studies by Elbeshir, and De Villa et al. Infection is believed to activate the dormant osteoblasts in the periosteum, thus inducing them to commence new bone formation. Furthermore, inflammatory bone conditions, such as osteomyelitis, result in new bone formation in response to a focus of infection., However, Azumi et al. argues that osteogenesis is inhibited by substance p released during inflammatory conditions. In our case report, the preoperative biopsy site was infected with the subsequent breakdown of mucosa, which may have contributed to the spontaneous bone regeneration that was observed.
Some authors have suggested stabilization of the resected bone margins using titanium reconstruction plates or kirshner wire., This serves both as a means of stabilizing the resected bone margins, and a temporary means of restoring the contour of the mandible to prevent collapse of the soft tissues into the residual surgery bed.
The use of a means of stabilization has been suggested to encourage osteogenesis.,,,,,, However, stabilization did not play any role in the bone regeneration observed in our case as no means of stabilization was employed.
Although most reported cases in the literature had mandibulectomy via an extraoral approach,,,,,, two case reports were found which had resection via an intraoral approach., Ogunlewe et al. reported a case of complete regeneration of the whole mandible and both condyles following total mandibulectomy via an intraoral approach. Our case report had mandibulectomy via an intraoral approach, and Khodayari et al. asserted that the intraoral approach preserves the periosteum better than the extraoral approach.
The presence of Runt-related transcription factor 2 which is strongly expressed by cells undergoing active osteogenic process has been highlighted by Devlin and Sloan. Runt-related transcription factor 2 (Runx 2) induces the differentiation of nonosteoblastic cells to express osteoblastic specific genes and its disruption in embryonic mice results in complex lack of bone formation in the skull and mandible., Although the role of genetics could not be ascertained in our patient, it may hold the key to a better understanding of the mechanism of spontaneous bone regeneration.
| Conclusion|| |
Spontaneous regeneration of the mandible provides a natural interventional means of restoring mandibular defect especially in a resource poor environment. Although the interaction of a host of factors have been implicated in cases of spontaneous bone regeneration. Further studies need to be conducted in the area of genetics as this may hold the key to a better understanding of spontaneous bone regeneration.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]