*Perspective Chapter: Ameloblastoma – Present and Future Concepts of Managing DOI: http://dx.doi.org/10.5772/intechopen.107403*

and psychological effects affecting the quality of life are also important factors that should not be overlooked.

Relatively high recurrence rate of ameloblastoma presents a major challenge. The recurrence rate of aggressively treated ameloblastomas is approximately 12%, which is significantly lower than that for conservative treatment, with posttreatment recurrence of 30% [33]. In a retrospective review by Ooi et al. [31] patients with conventional and unicystic ameloblastoma treated with segmental mandibulectomy and free fibula flap reconstruction were observed. The treatment showed no recurrence in a 5-year follow-up period with overall patient satisfactory regarding esthetic and functional results. 40% of the patients did not receive any form of prosthodontic rehabilitation and only 3 patients underwent dental implant insertion, showing that low uptake of dental rehabilitation did not adversely affect outcome and patient satisfaction. Another retrospective study by Bianchi et al. [34] confirmed positive outcomes of radical therapy. The study comprised 34 patients with histologically confirmed mandibular ameloblastomas, treated with segmental mandibular resection, fibula or iliac crest free flap reconstruction, and immediate or delayed dental implant placement. The duration of follow-up was from 18 to 120 months and no patient showed radiological or clinical signs of recurrence. Furthermore, recurrence rates up to 80% were reported after enucleation of conventional ameloblastoma, indicating the necessity for segmental resection with at least 1 cm of margin to the bone, including an adjacent soft tissue margin [35]. Moreover, the importance of adequate treatment choice is evident in the study by Hertog et al. [36]. The experience with the treatment of recurrent ameloblastoma previously treated by enucleation over a 40-year period was reported. Of all patients who underwent radical surgery, not a single recurrence was found during 10.5 years follow-up period. The remaining patients treated with conservative approach all developed one or more new recurrences. Observing a localization of tumor alone, it is believed that the best treatment option for maxillary ameloblastoma is radical resection [37]. Maxillary tumors are believed to be more aggressive than those found in the mandible due to the bone histomorphology, which is spongier providing a weak wall of defense against local spread (**Figure 4**). Moreover, the proximity of important anatomical structures such as the orbit, infratemporal fossa, pterygopalatine fossa, nasal fossa and base of the skull makes the treatment more difficult

and mutilating [38]. These tumors can be resected via various midface approaches, resulting with defect that unifies oral cavity, nasal cavity and paranasal sinuses causing alterations in phonation, mastication and deglutition [32]. The remaining defects can be fitted with an obturator, allowing surgeons an easy access for clinical examination [2].

With the development of bone grafting and osteomyocutaneous free flaps, loss of function and esthetics can finally be considered relics of the past. Patients undergoing extensive tumor removals are now enabled to receive improved postoperative course with preserved essential functions such as mastication, deglutition and phonation together with a satisfactory esthetic outcome [39]. Nowadays, the emphasis is increasingly placed on the use of *computer-aided design/computer-aided manufacturing* (CAD/ CAM) technology in reconstructive surgery. Virtual surgical planning and 3D printing techniques are used to preoperatively shape free flap dimensions or individually fabricate titanium meshes and fixation plates [40]. In a recent study by Lv et al. [41], guiding plate system for precise mandibular reconstruction was introduced with thorough postoperative evaluation. Mandibular and fibular osteotomy guides for tumor resection and simultaneous donor site bone segment shaping were designed and fabricated using CAD/CAM technology. All patients underwent successful surgery with 100% overall survival rate of flaps. Postoperative esthetic assessment was rated as excellent and quantitative evaluation was performed by measuring different parameters such as discrepancy in osteotomy lines, mandibular resemblance and symmetry. The cohort included patients undergoing traditional resection and reconstruction. There was significant difference between cohort and test group in all the mentioned parameters.

Last but not least important step in surgical management of ameloblastoma is postoperative follow-up. Various examples of recurrences emphasize the inevitable need for prolonged follow-up visits after surgery [42]. Adebayo et al. [42] presented a case of soft tissue recurrence 21 years after radical surgery in the mandible which leads to conclusion that radiological follow-up should be carried out throughout life in ameloblastoma patients.

### *4.2.2 Conservative surgical approach*

Conservative treatment has found its purpose in treating less aggressive types of ameloblastoma [2]. It involves one or more of the following procedures: enucleation, curettage, physicochemical treatment (cryotherapy or Carnoy's solution), marsupialization and decompression (**Figure 5**) [43]. The main advantages of the conservative approach are: preservation of adjacent healthy tissues, avoidance of facial disfiguration and, consequentially, better postoperative quality of life. Pediatric patients are, for instance, very approach sensitive and radical surgery may affect the growth dynamics of the dentition, soft tissues and entire craniofacial skeleton [44]. Therefore, a conservative approach is often the treatment of choice in children. However, ameloblastoma type and histological pattern must be taken into account during the planning and selection of the adequate treatment. These are mandatory factors influencing the surgeon's decision with a primary goal of minimizing the possibility of recurrence and avoiding under- or overtreatment [16].

Considering the high recurrence rate of conservatively treated conventional type of ameloblastoma it is crucial to emphasize the right indication [33]. Firstly, histopathological analysis is necessary to confirm the type of ameloblastoma curable with conservative approach. Only less aggressive types such as unicystic or peripheral are

*Perspective Chapter: Ameloblastoma – Present and Future Concepts of Managing DOI: http://dx.doi.org/10.5772/intechopen.107403*

### **Figure 5.** *Preoperative decompression of the unicystic ameloblastoma in the mandible of young patient.*

suitable to be treated by this type of approach [35]. In a study by Seintou et al. [43], a thorough review of clinical, radiological, and histopathological characteristics of unicystic ameloblastoma in children was presented with findings that treatment is still controversial. However, it was concluded that conservative treatment was preferable due to better postoperative quality of life, despite a slightly higher recurrence rate. Huang et al. [45] also claim that radical treatment should be reserved for recurrent and more aggressive types of ameloblastoma, with important statement that recurrence is probably not a major consideration for pediatric patients and should not be considered as equivalent to failure. On the other hand, some authors [46, 47] believe that radical resection should still be a treatment of choice whenever follow-up examinations are limited. This applies usually to developing countries, but any other limiting factors are not excluded. Even though the radical treatment results with less recurrence, a majority of ameloblastoma cases in pediatric patients

### **Figure 6.**

*Postoperative healing after conservative surgical treatment of ameloblastoma in adolescent patient (a), and patient in the middle of 20's (b).*

are unicystic [43, 44]. Less aggressive behavior and lower recurrence rate are factors that furtherly support the conservative treatment of ameloblastoma in these patients (**Figure 6**). In addition, peripheral ameloblastoma is another entity successfully treatable with conservative therapy. It is most frequently present in the gingival tissues and the conservative approach with narrow margins of unaffected tissue is treatment of choice [48].

Altogether, opinions on the treatment of conventional ameloblastoma are still divergent with valid arguments regarding both radical and conservative approaches. It is of vital importance to know the differences between various types of conservative procedures. A simple enucleation is considered as inadequate with unacceptably high recurrence rate of up to 60% in unicystic ameloblastoma and up to 80% in conventional ameloblastoma [35]. Enucleation followed by curettage and/or physicochemical treatment has been suggested as standard conservative approach (**Figures 7** and **8**) [43].

It is necessary to eradicate intraosseous ameloblastoma cells that can be found up to 8 mm from the clinical and radiographic margin of the lesion (**Figure 9**).

### **Figure 7.**

*Conservative surgical treatment of ameloblastoma in an adolescent patient with CBCT image presented in*  **Figure 3***: (a) enucleation of tumor mass; (b) enucleated ameloblastoma; (c) status post-enucleation and curettage; and (d) primary wound closure.*

*Perspective Chapter: Ameloblastoma – Present and Future Concepts of Managing DOI: http://dx.doi.org/10.5772/intechopen.107403*

### **Figure 8.**

*Conservative surgical treatment of ameloblastoma in patient in the middle 20's with radiological status presented in* **Figure 2***: (a) status post enucleation and curettage; (b) enucleated tumor mass; and (c) primary wound closure.*

### **Figure 9.**

*Orthopantomographic image showing postoperative margins after conservative surgical treatment with decompression and subsequent enucleation and curettage. Preoperative radiological status is presented in* **Figure 2***.*

Physicochemical treatment of these cells can be performed with liquid nitrogen cryospray or with Carnoy's solution [30]. Carnoy's solution is a fixative initially proposed by Stoelinga and Bronkhorst [49]. It has ability to penetrate cancellous bone to a depth of 15 mm, so it is ideal for application after enucleation [35].

Decompression is a valuable method most commonly used to preoperatively reduce the size of cysts [50]. The size of the lesion is expected to be reduced by inserting a rubber tube or a stent through a previously created hole in the overlying bone and mucosa [51]. Huang et al. [45] have reported a significant reduction in ameloblastoma size using 6–12 months preoperative decompression. Furthermore, Park et al. [51] reported a 36.7% reduction in size of unicystic ameloblastoma after 13 months of decompression in 5 patients with mean age of 18.6 years (**Figures 10** and **11**). They also highlighted that the patient's age is inversely proportional to the relative velocity of shrinkage. Additionally, contemporary methods including active decompression and distraction osteogenesis have been developed for the treatment of odontogenic cystic entities [52]. Active decompression and distraction osteogenesis involve the use of active negative pressure inside a cyst to increase the velocity of cystic lesion shrinkage and to stimulate the regeneration of bone [52]. There is still no evidence of its clinical use in literature, thus the further research is required to verify the effect of active decompression on pathophysiology of ameloblastoma.

### **Figure 10.**

*Decompression in a pediatric patient with unicystic ameloblastoma of the mandible. Preoperative radiographic follow-up (surgical procedure is presented in* **Figure 7***: (a) initial situation of a large ameloblastoma; (b) 2 months after rubber tube insertion; (c) 4 months after tube insertion; and (d) 9 months after tube insertion.*
