Abstract
Aim
To review the management and reconstruction of ameloblastoma of mandible in different age groups over a period of 11 years.
Methodology
This retrospective study includes 51 cases operated in the Maxillofacial Unit, Bhagwan Mahaveer Jain Hospital, Bangalore, from the year 2007 to 2017. The data of these patients were collected to record demographic data such as age, gender with site of tumour and type of reconstruction after resection, follow-up period and incidence of complications. This study evaluated the outcome in terms of aesthetics, function and choice of reconstruction in different age groups.
Results
Most patients were of 21–40 age group. 37 (72.5%) were found to be unicystic ameloblastoma. 41 (80.3%) patients underwent reconstruction following the resection. There was a change in trend seen over a period of time with free grafts and reconstruction plate being historical, except in special situations like old age and unfit patients. According to one-way ANOVA and Tukey’s post hoc analysis, free flaps were known to take a longer duration (mean = 503 min) compared to other modes of reconstruction. However, free grafts and free flaps were demonstrated to have a good facial contour and speech with most cases dentally rehabilitated with implants. Among the complications, 1 (16%) case with reconstruction plate showed screw loosening, 2 (28%) cases with free grafts showed graft exposure, and 1 (3.5%) case with free flap had venous congestion, making free flaps the most reliable option.
Conclusion
Free fibula is the gold standard of mandible reconstruction, but depending on age, medical condition, economic status and size of the defect other modes of reconstruction can be chosen with the acceptance of suboptimal results.
Keywords: Ameloblastoma, Reconstruction plate, Free grafts, Fibula flap
Introduction
Ameloblastoma is the most common benign odontogenic neoplasm accounting for 1% of tumours of jaws and 9–11% of odontogenic tumours [1]. It occurs in all age groups with the peak incidence in third and fourth decades. Among the Indian population, it accounts for 60.3% of odontogenic tumours with a mean age group of 30.2 years [2]. It usually presents as slow-growing painless intraosseous swelling, more commonly involving the posterior mandible (80%) involving the posterior mandible. It is locally aggressive and has a potential to cause tooth displacement, mobility and root resorption with inadequate clearance. This tumour is considered a rarity in young children and accounts for approximately 10–15% of all reported cases of ameloblastoma [3, 4]. A review of literature revealed that numerous large case series of ameloblastoma have been reported, while only a few articles discussed this tumour in terms of reconstruction especially in different age groups and sites. The purpose of this study is to review the management and reconstruction of ameloblastoma of mandible in 51 patients of all age groups over a period of 11 years.
Materials and Methods
This retrospective study was done from 51 patients operated in the Department of Oral and Maxillofacial Surgery at Bhagwan Mahaveer Jain Hospital from 2007 to 2017. The inclusion criteria included the patients of all age groups with histologically proven ameloblastoma and supported with radiographic data. Cases with unilocular/multilocular lesions other than ameloblastoma were excluded.
All the data regarding age, sex, site, radiographic presentation, type of reconstruction following resection, follow-up period and incidence of recurrence were collected. The study variables were based on the reconstructive modality in different age groups which were as follows: with reconstruction versus without reconstruction, young age versus old age, free grafts versus free flaps, grafts and flaps versus reconstruction plate. The most common site for free grafts was iliac crest and for free flaps was the fibula. Fibula reconstructions were precisely planned and implemented using stereolithographic models (OSTEO 3D). The primary outcome of interest studied was aesthetics (contour, prosthetics), function (speech, mouth opening) and favourable choice of reconstruction. Follow-up period was from a maximum of 10 years to a minimum of 0.5 years.
Results
Out of 51 patients, 30 (58.8%) were male and 21 (41.1%) were female with age group range of 11–85 years (mean—38 years). Data regarding age, gender and site of distribution were collected (Table 1).
Table 1.
Data regarding age, gender and site of distribution
| Distribution of study patients’ characteristics | |||
|---|---|---|---|
| Variables | Category | N | % |
| Age group | < 20 years | 6 | 11.8% |
| 21–40 years | 25 | 49.0% | |
| 41–60 years | 16 | 31.4% | |
| > 60 years | 4 | 7.8% | |
| Mean and SD | 38.3 | 17.9 | |
| Range | 11–85 | ||
| Gender | Male | 30 | 58.8% |
| Female | 21 | 41.1% | |
| Site | Ant. mandible | 7 | 13.7% |
| Rt. mandible | 23 | 45% | |
| Lt. mandible | 21 | 41.1% | |
| Ameloblastoma | Unicystic | 37 | 72.5% |
| Multicystic | 13 | 25.5% | |
| Ameloblastic CA | 1 | 2.0% | |
Of these 51 patients, 37 (72.5%) presented with unicystic ameloblastoma, 13 (25.5%) with multicystic/solid variants and 1 (2%) with ameloblastic carcinoma (Table 1). Four patients presented with recurrent ameloblastoma of mandible. These recurrent tumours were all of multicystic variant.
Among 37 cases of unicystic type, 21 (56.8%) showed intraluminal type and 16 (43.2%) showed mural variant. Out of 13 multicystic cases, 5 (38.46%) presented with follicular type, 4 (30.76%) presented with plexiform type, acanthomatous and granular variants were seen in 1 (7.69%) case each, and desmoplastic type was seen in 2 (15.38%) cases (Table 2).
Table 2.
Histologic variants of unicystic and multicystic ameloblastoma
| Clinical types | Histologic types | ||||
|---|---|---|---|---|---|
| Unicystic type | Intraluminal | Mural | |||
| 21 (56.8%) | 16 (43.2%) | ||||
| Multicystic type | Follicular | Plexiform | Acanthomatous | Desmoplastic | Granular |
| 5 (38.46%) | 4 (30.76%) | 1 (7.69%) | 2 (15.38%) | 1 (7.69%) | |
Forty-one (80.3%) patients underwent different types of reconstruction after resection of involved mandible, whereas 10 (19.6%) patients were treated with primary closure (Table 3).
Table 3.
Number of patients with different types of reconstruction
| Type of reconstruction/no reconstruction | Number of patients | |
|---|---|---|
| Primary closure (without reconstruction) | – | 10 (19%) |
| Reconstruction plate | – | 05 (9%) |
| Free graft (costochondral graft) | – | 07 (13%) |
| Free flap (fibula) | – | 29 (56%) |
One-way ANOVA and Tukey’s post hoc analysis were performed to assess the mean duration of surgery for different types of reconstruction modality. Free flaps have taken highest duration time of mean 503 min in comparison with reconstruction plate (mean—164 min) and free graft (mean—324.3 min). These results were found to be statistically significant (p < 0.001) (Table 4).
Table 4.
Comparison of mean duration of surgery time (in mins) taken for different types of reconstructive surgeries using one-way ANOVA followed by Tukey’s HSD post hoc analysis
| Type of reconstruction | N | Mean | SD | Min | Max | p value | Tukey’s post hoc | |
|---|---|---|---|---|---|---|---|---|
| Sig. diff. | p value | |||||||
| Recons. plate (RP) | 5 | 164.0 | 15.2 | 150 | 180 | < 0.001* | RP versus FG | < 0.001* |
| Free graft (FG) | 7 | 324.3 | 25.7 | 300 | 360 | RP versus FF | < 0.001* | |
| Free flap (FF) | 29 | 503.0 | 31.0 | 426 | 540 | FG versus FF | < 0.001* | |
p value < 0.05 indicates it is statistically significant
* indicates p value is statistically significant
The complication rates for each treatment modality are tabulated in Table 5.
Table 5.
Complication rates in different types of reconstruction
| Type of reconstruction | Complication rate | |
|---|---|---|
| Primary closure (without reconstruction) | – | – |
| Reconstruction plate | – | 01 (16%) |
| Free graft (costochondral graft) | – | 02 (28%) |
| Free flap (fibula) | – | 1 (3.5%) |
Free grafts were found to be associated with maximum complications (28%), the commonest being graft exposure and infection.
Free flaps were found to have minimal complications (3.5%) although there was a small percentage of patients with long-term donor site morbidity.
Out of 5 cases of reconstruction plate, 1 (16%) case with screw loosening was seen.
Post-operative outcomes regarding facial contour, dental rehabilitation, speech, mouth opening and donor site morbidity without and with different types of reconstruction are tabulated in Table 6.
Table 6.
Post-operative outcomes without and with different types of reconstruction
| Parameter | Without reconstruction (primary closure) | Reconstruction plate | Free graft | Free flap | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Facial contour | Shape outline maintained without fullness | Shape outline maintained without fullness | Shape with fullness | Shape with fullness | ||||||||
| N | % | N | % | N | % | N | % | ||||||
| 10 | 100 | 5 | 100 | 7 | 100 | 29 | 100 | ||||||
| 2 | Dental rehabilitation | No | No | Yes | Yes | ||||||||
| 3 | Speech | Grading | N | % | Grading | N | % | Grading | N | % | Grading | N | % |
| Understood with effort | 2 | 20 | Understood with difficulty | 2 | 40 | Easily understood | 7 | 100 | Easily understood | 29 | 100 | ||
| Easily understood | 8 | 80 | Understood with effort | 3 | 60 | ||||||||
| 4 | Mouth opening | Inadequate | Inadequate | Adequate | Adequate | ||||||||
| 5 | Donor site morbidity | Not applicable | Not applicable | Donor site pain | Donor site pain | 6 | 20% | ||||||
| N | % | Transient peroneal sensory loss | 3 | 10% | |||||||||
| 1 | 14% | Wound dehiscence | 1 | 3.4% | |||||||||
Discussion
Ameloblastoma is one of the most common aggressive benign odontogenic neoplasms which have a recurrence rate of 8% in solid/multicystic variant and 4% in unicystic variant with radical resection [5]. Current evidence suggests that the management of this tumour should be radical in order to minimize the recurrence. This results in large bony defects requiring reconstruction in order to restore form and function. Various modes of reconstruction of mandible have been recommended in the literature. The purpose of this study was to evaluate the different modes of reconstruction in different age groups and present our experience in treating these patients.
In the present study, 37 (72.5%) patients showed unicystic variant, 13 (25.5%) patients presented with multicystic/solid variants, and 1 (2%) presented with ameloblastic carcinoma. Unicystic ameloblastoma is subclassified into (1) luminal, (2) intraluminal and (3) mural types among which the third type is found to be the most aggressive [6, 7]. Preoperatively, accurate diagnosis of unicystic subtype is difficult even with incisional biopsy, as it provides limited tissue for examination which may not record the subtype [8]. There is still controversy in management of unicystic ameloblastoma. Recurrence following conservative management of unicystic variant was about 60%, and it was similar to conservatively treated multicystic type [9]. Pogrel et al. [10] recommended application of physicochemical methods such as Carnoy’s solution or liquid nitrogen along with enucleation and curettage in order to reduce recurrence rate. In the present study, 21 (56.8%) patients showed intraluminal subtype and 16 (43.2%) patients showed mural type of unicystic variants.
Multicystic/solid type presented 5 (38.4%) follicular type, 4 (30.76%) plexiform type, 1 (7.69%) acanthomatous type, 2 (15.38%) desmoplastic and 1 (7.69%) granular variety. Literature suggested that the different histologic variants including follicular, plexiform, granular, basal and desmoplastic of solid/multicystic variant do not affect the prognosis or treatment [11]. Although some articles stated that granular cell [12] and desmoplastic [13] might be more aggressive, current literature does not support that case [14]. In our institution, radical treatment is standard option for the treatment of ameloblastoma. Tumour-free bony margins determine the success of the treatment. The bony margin is defined as the distance away from the radiographic margin predicted to be disease-free and oncologically safe to perform osteotomies [15]. It was documented from 82 ameloblastoma specimens that microscopic tumour extension will be 2–8 mm (mean of 4.5 mm) beyond the radiographic boundaries of the tumour [16]. In the present study, the resected bone margins were 1 cm for unicystic and 1.5 cm for solid/multicystic, which was in accordance with the existing literature [17]. One case with ameloblastic carcinoma had resected margins of about 3 cm similar to the study by Ndukwe et al. [18]. In cases with bony perforation, overlying mucoperiosteum was excised along with the bone. Histologically, all the resected bony margins were negative.
The occurrence of ameloblastoma in children below 10 years was found to be rare with an incidence rate of 8.14% [19]. In the present study, minimum age of incidence was 11 years. We report 9% occurrence of tumour in age group below 18 years, whereas in a study conducted by Bansal et al. [20] it was found to be 15.2%.
In the present study, 5 patients under 20 years of age underwent primary closure (Fig. 1) and one patient underwent reconstruction with reconstruction plate. The reconstruction option in children and adolescents is limited as they have a growing skeleton with the donor sites commonly (iliac, fibula) which may show unpredictable growth inhibition and incomplete ossification during surgery [21]. These patients were followed up for secondary reconstruction with free fibula flap once their skeletal growth was achieved.
Fig. 1.
Ameloblastoma of left ramus of mandible (primary closure)
Five patients underwent enucleation and primary closure due to their compromised medical condition and were kept under close follow-up. Four patients underwent reconstruction with reconstruction plate (Fig. 2) due to financial reasons. Seven (13%) patients underwent reconstruction with costochondral graft (Fig. 3) as the defect size was less than 6 cm. Among these 7 patients, 1 (14.3%) case presented with graft exposure and 1 (14.3%) case with infection in comparison with 24% of complications reported in the literature [22].
Fig. 2.
Ameloblastoma of left mandible (reconstruction plate)
Fig. 3.
Ameloblastoma of left mandible (costochondral graft)
Twenty-nine (56%) patients underwent free fibula reconstruction after resection (Fig. 4). Among these patients, 4 (13.7%) patients underwent double-barrel fibula flap and the remaining all had mono-fibula flap. Double-barreling of the fibula is a technique which involves osteotomies and folding over the fibula flap to create equal struts, while preserving the blood supply throughout the graft [23]. Double-barrel fibula flap is advantageous over mono-fibula as it increases bone height and thickness, which helps in wearing conventional denture or immediate placement of osseointegrated implants. In the present study, dental implant placement in mono-fibula and double-barrel fibula was planned at least 6 months after reconstruction. This time period facilitates integration of fibula bone with native bone. Regarding complications, there was failure of 1 (3.5%) flap due to venous congestion in comparison with a 5% failure rate reported in the literature [22]. This flap has become the gold standard for mandibular reconstruction due to its versatility and ability to dentally rehabilitate these patients. A few patients complained of preauricular pain post-reconstruction, it eventually resolved with adaptive mechanism of bone remodelling.
Fig. 4.
Ameloblastoma of anterior mandible (fibula flap)
Regarding quality of life, reconstruction plate only helped in achieving the lower border contour of mandible but lacked fullness and function in comparison with other methods of reconstruction. Facial contour and aesthetics were most favourable in patients with free graft and free fibula reconstruction. Ablative surgery of the oral cavity can notably change speech [24]. It was significantly affected in patients with reconstruction plate when compared to the other modes of reconstruction especially if tumour was involving the anterior mandible. Reconstruction plate could not provide stable platform for tongue movement while delivering the speech. Reconstruction of mandible with free graft and fibula flap enhanced the quality of speech by restoring the bony contour. The main disadvantage with free grafts and free flaps was donor site morbidity. One (14%) patient with costochondral graft reconstruction and 6 (20%) patients with fibula free flap complained of donor site pain which eventually subsided during the 2-month post-operative follow-up. One (3.4%) patient in free flap reconstruction showed wound dehiscence over the skin grafted area which was managed with regular dressings and antibiotic therapy. Three (10%) patients presented with numbness of donor site which recovered within 9 months of surgery. The maximum duration of surgery was found in the group who have undergone reconstruction with free fibula flap. Many geriatric patients with medically compromised conditions were not found to be good candidates for free fibula reconstruction.
Among all the types of reconstruction, free fibula is the gold standard of mandible reconstruction, but depending on age, medical condition, economic status and size of the defect other modes of reconstruction can be chosen with the acceptance of suboptimal results.
Footnotes
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