Ameloblastoma of the mandible treated by resection, preservation of the inferior alveolar nerve, and bone grafting

Template based segmental mandibulectomy with nerve preservation and patient-specific PEEK plate reconstruction in a dog

A 7-year-old French Bulldog presented with an acanthomatous ameloblastoma affecting approximately 30% of the right mandibular body. We utilized a patient-specific 3D-printed surgical template to perform lateral fenestration of the mandible and elevation of the inferior alveolar nerve (IAN), facilitating nerve preservation during subsequent segmental mandibulectomy. The resulting critical-sized bone defect was anatomically stabilized using a patient-specific polyetheretherketone (PEEK) bridging plate. The recovery process was uneventful, with maintained occlusion and orofacial sensitivity.Similar to cases in humans with ameloblastoma, preserving orofacial sensitivity through the preservation of the inferior alveolar nerve seems feasible in dogs. Consequently, potential negative consequences of permanent regional denervation, which are unavoidable in traditional mandibulectomy, can be avoided. Bridging the ostectomy with a PEEK plate, offering advantages such as radiolucency, absence of imaging artifacts, and a modulus of elasticity similar to bone, proved to be functional in this canine patient, with no signs of complications observed up to the latest follow-up at 6 months.

A novel loop neurorrhaphy technique to preserve lower lip sensate in mandibular reconstruction using an innervated vascularized iliac bone flap

BACKGROUND

This study aimed to introduce a novel loop neurorrhaphy technique using an innervated vascularized iliac bone flap (VIBF) with vascularized ilioinguinal nerve (IIN) to reconstruct the inferior alveolar nerve (IAN) and preserve lower lip sensation simultaneously with mandibular reconstruction.

METHODS

This study prospectively included patients who underwent mandibular reconstruction using VIBF from May 2018 to April 2020. Subjects were allocated into two groups: (1) Group I; innervated VIBF with loop neurorrhaphy (IIN doubly anastomosed with IAN and mental nerve), (2) Group II (control); conventional VIBF. Evaluation was done with operative time, intraoperative indocyanine green (ICG), lower lip sensory assessment (two-point discrimination [TPD] test and current perception threshold [CPT]), and drooling.

RESULTS

Twelve patients were included; 6 in each group, (7 males and 5 females), age ranging from 18 to 57 years (average: 36.75 years). In all cases, intraoperative perfusion of IIN was confirmed by ICG. Group I showed a statistically significant more flap harvesting time compared with group II (mean difference, 5.67 min; P = 0.0091). There was a significant difference in sensory recovery favoring group I (P < 0.05). The TPD results in group I showed an average of 9.8 ± 6.9 mm and 6.2 ± 5.7 mm on operated and non-operated sides, while Group II showed a poor sensory recovery, and the TPD showed an average of 24.6 ± 6.7 mm and 8.4 ± 2.3 mm on operated and non-operated sides. The CPT results showed a significant difference between both groups. In Group I, the extent of drooling was 3.16 ± 0.75, while in Group II, the score was 1.6 ± 0.81, revealing a significant difference favoring Group I.

CONCLUSIONS

Concurrent mandibular reconstruction using VIBF and loop neurorrhaphy with vascularized IIN to reconstruct IAN successfully restore lower jaw form and preserve lip sensation.

A Novel Treatment Concept for Advanced Stage Mandibular Osteoradionecrosis Combining Isodose Curve Visualization and Nerve Preservation: A Prospective Pilot Study

Background

Osteoradionecrosis (ORN) of the mandible is a severe complication of radiation therapy in head and neck cancer patients. Treatment of advanced stage mandibular osteoradionecrosis may consist of segmental resection and osseous reconstruction, often sacrificing the inferior alveolar nerve (IAN). New computer-assisted surgery (CAS) techniques can be used for guided IAN preservation and 3D radiotherapy isodose curve visualization for patient specific mandibular resection margins. This study introduces a novel treatment concept combining these CAS techniques for treatment of advanced stage ORN.

Methods

Our advanced stage ORN treatment concept includes consecutively: 1) determination of the mandibular resection margins using a 3D 50 Gy isodose curve visualization, 2) segmental mandibular resection with preservation of the IAN with a two-step cutting guide, and 3) 3D planned mandibular reconstruction using a hand-bent patient specific reconstruction plate. Postoperative accuracy of the mandibular reconstruction was evaluated using a guideline. Objective and subjective IAN sensory function was tested for a period of 12 months postoperatively.

Results

Five patients with advanced stage ORN were treated with our ORN treatment concept using the fibula free flap. A total of seven IANs were salvaged in two men and three women. No complications occurred and all reconstructions healed properly. Neither non-union nor recurrence of ORN was observed. Sensory function of all IANs recovered after resection up to 100 percent, including the patients with a pathologic fracture due to ORN. The accuracy evaluation showed angle deviations limited to 3.78 degrees. Two deviations of 6.42° and 7.47° were found. After an average of 11,6 months all patients received dental implants to complete oral rehabilitation.

Conclusions

Our novel ORN treatment concept shows promising results for implementation of 3D radiotherapy isodose curve visualization and IAN preservation. Sensory function of all IANs recovered after segmental mandibular resection.

Wide Excision with Immediate Reconstruction of the Mandible Using Free Fibular Flap in Ameloblastoma of the Mandible-A Need of Time: Our Experience of 37 Cases

Background  Ameloblastoma is a benign yet locally aggressive odontogenic tumor of the jaw with high recurrence rates. Despite many studies, the search is still on for the treatment approach which can render the acceptable recurrence rates with good functional and esthetic results.

Methods  In this prospective study, we operated on 37 patients of mandibular ameloblastoma between 2009 and 2018. Two patients were treated with curettage and chemical sterilization of the cavity. Resection of a tumor with a 2-cm margin was performed in the rest of 35 patients. The mandibular defect was primarily reconstructed with the microvascular free fibular flap in 29 patients.

Results  The follow-up ranged from 6 months to 7.7 years with a mean of 5.1 years. A tumor recurred within a year in all two patients (100%) treated with curettage. Out of 35 radical excisions, only one patient (2.85%) developed recurrence 3 years after the disease-free interval. Good mouth opening, intelligible speech, satisfactory lower jaw shape, and facial profiles were achieved in all 29 patients who were treated with primary free fibular flap.

Conclusion  We prefer wide excision with 2-cm margins on each side of a tumor with the primary reconstruction of the mandible in all cases of mandibular ameloblastoma. The free fibular microvascular flap is our treatment of choice as all defects of the mandible can be reconstructed with the free fibular flap. Wide excision is the key to prevent a recurrence.

Ameloblastoma Management: "Horses for Courses" Protocol

Purpose

The purpose of the article is to review 45 cases of ameloblastoma treated in a tertiary care centre depending on the extent of the pathology, in terms of recurrence and morbidity of the patients.

Materials and method

This was a retrospective study of patients who underwent treatment for ameloblastoma between 2009 and 2018 at Vydehi Institute of Dental Sciences, Bangalore. During the first phase of 4 years, the focus of the treatment was on avoiding any recurrence, and therefore, resection followed by reconstruction with reconstruction plates was the only modality used in ten patients. However, from 2014, it was decided to treat each patient based on the extent of the lesion and decide on either conservative management in the form of enucleation followed by peripheral ostectomy and chemical cauterisation or resection with safe margins and reconstruction with reconstruction plates.

Results

The study sample consisted of 45 patients, and the ages ranged from 12 to 65 years with an average of 36. There were 30 males and 15 females. In the first phase of treatment protocol adopted, ten patients underwent resection. In the later period, 18 patients were treated by conservative methods and 16 patients were treated by radical management. There were only three recurrences over a period of 3-year follow-up in the group treated conservatively.

Conclusion

Considering the benign nature of the tumour and the morbidity after resection, patients, most of whom are in the younger age group, can still be subjected to conservative treatment provided they are followed up for a long period thus assuring them of a better quality of life.

Modified technique for preservation of inferior alveolar nerve during mandibulectomy

BACKGROUND

The purpose of this article is to introduce the modified technique of preservation of the inferior alveolar nerve (IAN) during mandibulectomy for a benign lesion.

METHODS

Five cases of osteofibrous hyperplasia and 3 cases of centricity osteomyelitis were included. During surgery, the IAN was marked using a planned cutting guide. Using an oscillating saw, the depth of the osteotomy along the IAN was controlled until the bone cortex was cut through. After splitting, the bony section was removed, leaving the neurovascular bundle intact. The sensation of the lower lip was evaluated using current perceptive threshold testing during follow-up.

RESULTS

After follow-up for 6-27 months, no recurrence or secondary deformity was found. One patient had severe sensory disturbance.

CONCLUSION

With the use of a cutting guide and osteotomy tricks, mandibulectomy with preservation of the IAN can be accurately performed.

Mandibular resection via mandibular-lip L flap for the treatment of extensive multicystic Ameloblastoma

Ameloblastoma is a benign odontogenic tumor accounting for 1% of all tumors of the maxilla and mandibula. The mandibula is committed in 85% of the cases. The tumor is locally invasive, able to infiltrate bone marrow spaces, without radiographic or macroscopic evidence. High recurrence rates are associated with different surgical techniques, which range from simple tumoral enucleation to extensive resections. The authors report a case of a 26-year old female patient with an 8-year history of progressive, non-tender, swelling of the left mandibular region. The intraoral examination showed that the floor of mouth was raised on the left side by a bulging along the bottom of the left mandibular vestibule as well as the lingual region. Over this area, there were ulcerated areas in the alveolar region of the molars and mucosal fenestration in the alveolar and lingual regions were present. A panoramic radiography revealed a multicystic lesion, resembling the soap-bubble shape endosseous lesion. The computed tomography revealed an expandable multicystic lesion compromising both mandibular cortices. The patient underwent a biopsy, which revealed the diagnosis of a multicystic variant of Ameloblastoma, with plexiform pattern, treated with left mandibular resection and immediate installation of a customized prosthesis. After a year of follow-up, no evidence of the tumor relapse was evidenced.

Perineural infiltration of the inferior alveolar nerve in mandibular ameloblastomas

Our aim was to evaluate the histological association of mandibular solid and multicystic ameloblastoma with the inferior alveolar nerve, both in situ and in segments of the nerve that had been removed separately, to assess the feasibility of preserving the nerve during resection of mandibular ameloblastomas. In this prospective histological examination of 13 resected hemimandibulectomy specimens, we studied the proximity of tumour cells to the inferior alveolar nerve. In group 1 (n=8) this association was examined with the nerve still within the mandibular segment after resection, while in group 2 (n=5) the nerve was removed from the resected tumour and examined separately. Perineural and intraneural involvement of the ameloblastoma with the nerve was confirmed in 5 cases in group 1 and 2 cases in group 2. Tumour cells abutted the nerve directly in group 1. In group 2 tumour was removed with, and found within, the nerve. On this evidence we cannot recommend preservation of the inferior alveolar nerve during operation for large, advanced, mandibular ameloblastomas.

A case of recurrent ameloblastoma developing in an autogenous iliac bone graft 20 years after the initial treatment

A case of recurrent ameloblastoma developing in an autogenous iliac bone graft 20 years after radical resection of primary mandibular ameloblastoma is presented. This case showed extensive bony resorption extending throughout the auto-grafted bone. Seeding to the graft bone was suspected as a cause of the recurrence in the iliac bone graft because wide destruction of the graft bone was observed without any prior signs and symptoms of intraoral mucosa. Consequently, extensive resection of bone as well as adjacent soft tissue was performed. Persistent follow-up examination is essential for management of ameloblastoma.

Segmental mandibulectomy and immediate free fibula osteoseptocutaneous flap reconstruction with endosteal implants: an ideal treatment method for mandibular ameloblastoma

Thirteen patients with large ameloblastomas of the mandible underwent segmental mandibulectomy and immediate reconstruction, with simultaneous placement of osseointegrated implants. All patients received palatal mucosal grafts around the dental implants 6 to 10 months after surgical treatment and received implant-supported prostheses another 1 to 2 months later. There were five female and eight male patients, with a mean age of 32 years (range, 17 to 50 years). The mean length of the mandibular defect was 8.8 cm (range, 5 to 13 cm). All free fibula flap procedures were successful, with no reexplorations or partial flap losses. There was no clinical or radiographic evidence of failure during the osseointegration process for any implant. With functional occlusal loading, the marginal bone loss around the implants was less than 1.5 mm in a mean follow-up period of 40 months (range, 18 to 70 months). There were no recurrences during that time. The technique described allows improved access to the bone at the time of reconstruction, immediate assessment of alveolar ridge relationships, and accurate fixation of the implant-fibula construct. The advantages of this procedure include a reduced risk of recurrence with segmental resection, reliable mandibular reconstruction, and reduction of the number of surgical procedures, allowing full oral rehabilitation in a shorter time. It is concluded that segmental mandibulectomy and immediate vascularized fibula osteoseptocutaneous flap reconstruction, with simultaneous placement of osseointegrated implants, represent an ideal treatment method for large ameloblastomas of the mandible.

Growth characteristics of ameloblastoma involving the inferior alveolar nerve: a clinical and histopathologic study

OBJECTIVE

Growth characteristics of ameloblastomas involving the inferior alveolar nerve were examined to determine the most appropriate surgical management of the nerve at the time of the surgical procedure.

STUDY DESIGN

Clinical and histopathologic examinations were performed on 22 resected mandibles in which the inferior alveolar nerve was lying adjacent to, or contained within, the tumor.

RESULTS

Patterns of tumor involvement of the nerve bundle were evaluated with respect to the presence of bone (11 patients) or connective tissue wall (7 patients) between the tumor and the nerve bundle, and tumor infiltration of perineural connective tissue (4 patients). Neither invasion into the nerve sheath nor invasion into the nerve itself by the ameloblastoma was detected. Tumor infiltration of the tissue surrounding the nerve was identified for the multicystic and solid types but not for the unicystic type. Presence of bone or connective tissue wall between the tumor and the nerve bundle was dominant in the unicystic and plexiform ameloblastomas, whereas tumor infiltration of the perineural tissue was frequently observed in ameloblastomas with the follicular pattern.

CONCLUSION

The preservation of the inferior alveolar nerve may be possible in the management of the unicystic type of ameloblastoma. However, a more radical approach is necessary for treatment of multicystic or solid tumors, especially those exhibiting a follicular pattern.

Ameloblastoma: the Zimbabwean experience over 10 years

OBJECTIVES

A review of 117 ameloblastomas treated over a 10-year period was carried out.

STUDY DESIGN

Clinical records of 117 patients treated for histologically diagnosed ameloblastoma were retrieved and analyzed for age, sex, anatomic distribution, duration of lesions, clinical features, and treatment methods with results and complications.

RESULTS

Men and women were equally affected. The average age at the time of presentation was 28 years; 95.7% of the ameloblastomas occurred in the mandible; and 59% occurred in the premolar/incisor/canine region.

CONCLUSION

Ameloblastoma occurs predominantly in the anterior mandible with equal frequency in men and women. Wide resection reduces recurrence.

Ameloblastoma: biological profile of 3677 cases

Available literature on ameloblastoma of the jaw was reviewed, including publications from 1960 to 1993, and compared to the latest larger review, published by Small and Waldron in 1955. The average age of patients with ameloblastoma is 36 years. In developing countries ameloblastomas occur in younger patients. Men and women are equally affected. Women are 4 years younger than men when ameloblastomas first occur, and the tumours appear to be larger in females. Dominant clinical symptoms such as painless swelling and slow growth are non-characteristic. The ratio of ameloblastoma of the mandible to maxilla is 5 to 1. Ameloblastomas of the mandible occur 12 years earlier than those of the maxilla. Ameloblastomas occur most frequently in the molar region of the mandible. In Blacks, ameloblastomas occur more frequently in the anterior region of the jaws. Radiologically, 50% of ameloblastomas appear as multilocular radiolucent lesions with sharp delineation. Histologically, one-third are plexiform, one-third follicular; other variants such as acanthomatous ameloblastoma occur in older patients. Two percent of ameloblastomas are peripheral tumours. Unicystic ameloblastomas occurring in younger patients have been found in 6%. Detailed data on 345 patients with ameloblastoma were evaluated for clarification of therapeutic approaches. Chemotherapy and radiation seem to be contraindicated. Ameloblastomas of the maxilla should be treated as radically as possible, ameloblastomas of the mandible should also be treated radically. However, ameloblastomas which radiologically appear as unilocular lesions may be treated conservatively (enucleation, curettage), whenever all areas of the cystic lumen are controllable intraoperatively. Unicystic ameloblastomas occurring in patients 15 years younger than those with multisystic ameloblastoma may be treated conservatively except in cases with invasion of epithelium into the cyst wall. Different recurrence rates have been found for histological variants of the ameloblastoma. Follicular ameloblastomas appear to recur more often than the plexiform type. Unicystic ameloblastomas reveal lower recurrence rates than "non-unicystic" ameloblastomas. The peripheral type of ameloblastoma may be excised, since conservative therapy results in low recurrence rates. Postoperative follow-up is most important in the therapy of ameloblastoma, because more than 50% of all recurrences occur within 5 years postoperatively.

Late loco-regional recurrences after radical resection for mandibular ameloblastoma

5 cases of mandibular ameloblastoma are described with multiple recurrences after a long period of time. 4 of them were primarily treated by radical resection. 1 was initially treated by enucleation and extensive resection was performed only after its recurrence. The invasive growth of the recurrent tumor into the soft tissues and the cranial base, necessitating extensive ablative and reconstructive surgery, reflects the potential aggressiveness of this tumor. It is therefore recommended, to plan an adequate resection in cases of multicystic ameloblastoma, which includes a margin of at least 1 cm, of apparently non-invaded bone. If the tumor has eroded through the cortical bone and invaded into the soft tissues, wider margins are necessary to eliminate possible tumor extensions that are left behind. Adequate follow-up on a regular basis should enable the clinician to detect early recurrence so as to avoid major surgery.