ABSTRACT

Unicystic ameloblastomas and dentigerous cysts have similar clinical and radiographic appearance. Unicys-tic ameloblastomas generally have a better prognosis than multicystic ameloblastoma because of the grea-ter likehood of complete resection. The present case report provides the 11 year follow-up of a patient with unicystic ameloblastoma who was treated by enucle-ation. Conservative surgical enucleation with suffi-cient bone curettage and the use of osseointegrated implants for prosthetic rehabilitation could be useful as predictable treatment of unicystic ameloblastoma. This result extends the indication for conservative treatment of unicystic ameloblastoma and prosthetic planning with osseointegrated implants.

Unikistik ameloblastoma ve dentigeröz kistin klinik ve

radyolojik bulguları benzerdir. Unikistik ameloblasto-

maların prognozu radikal rezeksiyon gerektirmedik-

leri için multikistik ameloblastomalara oranla daha

iyidir. Bu makalede enükleasyon ile tedavi edilen ve

postoperative 11 yıl takip edilen bir unikistik amelob-

lastoma olgusu sunulmaktadır. Yeterli kemik küretajı

ile enükle edilen unikistik ameloblastoma olguların-

da protetik rehabilitasyonda osseointegre implantlar

kullanılmaktadır. Bu olgu sunumu ve uzun takip so-

nuçları unikistik ameloblastomanın konservatif tedavi

endikasyonunu ve ossointegre implantlarla protetik

rehabilitasyonunu vugulamaktadır.

Hacettepe Dişhekimliği Fakültesi DergisiCilt: 31, Sayı: 2, Sayfa: 49-53, 2007

Unicystic Ameloblastoma:Implant- supported Reconstruction and

Long-Term Follow-up

Unikistik Ameloblastoma: İmplant Destekli Rekonstrüksiyon ve Uzun Dönem Takip

*Celal Tümer DDS, PhD, *Gokce Meral DDS, PhD

*Hacettepe University Faculty of Dentistry Department of Oral Surgery

OLGU RAPORU (Case Report)

KEYWORDS

Unicystic ameloblastoma, Dental implant, Treatment, Recurrence

ANAHTAR KELİMELER

Unikistik ameloblastoma, Dental implant, Tedavi, Rekürrens

ÖZET

50

IntrODUctIOn

Ameloblastoma is an odontogenic epithelial neoplasm of tissue characteristic of the enam-el organ but not differentiated to the point of enamel formation; it usually originates in the mandibular molar-ramus area and is usually be-nign but locally invasive1. Ameloblastomas are often classified on the basis of histologic appear-ance, the most common subtypes being follicular, cystic, acanthomatous, plexiform, basal cell and granular cell; they are also sometimes classified as multicystic versus unicystic1,2. Multicystic am-eloblastoma, contains multiple cystic spaces; it may exhibit any or all of the histologic patterns described as subtypes of the lesion and is more aggressive and recurs more frequently than does unicystic ameloblastoma2.

The term Unicystic Ameloblastoma(UA) was adopted in the second edition of the interna-tional histologic classifications of odontogenic tumors3,4. UA’s account for 10% to 15% of all in-tra-osseous ameloblastomas in various studies2. It has a recurrence rate of 6.7-35.7% and the average interval to recurrence is approximately 7 years5,6,7.

UA’s and dentigerous cysts have an simi-lar clinical and radiologic appearance. In most cases UA’s are associated with tooth impaction, the mandibular third molar being most often in-volved4,6. Eversole et al found that the average age for unilocular impaction associated UA was 22 years, whereas multilocular lesion without im-paction occurred at an average age of 33 years8.

UA’s are usually treated as cysts by enucle-ation. The diagnosis of UA is made only after microscopic examination of the presumed cyst. If the ameloblastic elements are confined to the lumen of the cyst with or without intraluminal tumor extension, the cyst enucleation has prob-ably been adequate treatment. The patient, how-ever, should be kept under long-term follow-up. If the specimen shows extension of the tumor into the fibrous cyst wall for any appreciable distance, subsequent management of the patient is more

controversial. Some surgeons believe that local resection of the area is indicated as a prophylactic measure, others prefer to keep the patient under close radiographic observation and delay further treatment until there is evidence of recurrence2.

After removal of the large tumors, prosthetic reconstruction may be difficult because of the extensive tissue lost. Mandibular reconstruction with bone grafts and careful prosthetic plan-ning with placement of osseointegrated implants could achieve the successful rehabilitation of pa-tients with unicystic ameloblastoma who under-went large tumor enucleation9.

This case report presents the clinical man-agement of a patient with unicystic ameloblas-toma. Treatment is described over a period of 11 years.

caSe repOrt

A 24 year old female patient was referred to Hacettepe University, Dental Faculty, Depart-ment of Oral Surgery in September 1993 with a painless swelling in the right mandibular molar region. The patient described initial observation of the swelling approximately 6 months prior to presentation. Clinical examination revealed an expansile lesion in the right mandibular third mo-lar region. Panoramic radiograph demonstrated a unilocular radiolucent area including third mo-lar tooth (Figure 1). An antero-posterior radio-graph also showed the large radiolucent area on the right mandibular posterior region (Figure 2). Clinical and radiological features were sugges-tive of dentigerous cyst.

Under general anesthesia enucleation was performed. In addition the impacted teeth were extracted. The bone cavity was filled with allo-genic bone graft material (Tutoplast microchips) (Figure 3). The excised lesion was fixed in 10% neutralized buffered formalin and sent for histo-pathological examination.

The lesion was diagnosed as unicystic amelo-blastoma with intramural proliferations. Because this diagnosis carries a risk of recurrence, a long-

51

term follow-up period was planned. The patient called for panoramic radiographic controls every 6 months (Figure 4). After 5 years of mandibular reconstruction with allogenic bone graft mate-rial, appropriate bone healing was observed in the enucleation area and there were no sign of recurrence and one side free-end saddle remov-able partial denture was performed to achieve patient’s functions. At 8 years follow-up ap-pointment patient complaint about the difficul-ties of using partial denture and wanted to have a fixed reconstruction. A simple prosthetic ap-proach using with a solid secrew implant (ITI implant, Straumann) was planned. 3.3mm in diameter and 12mm in length implant inserted with one stage surgery in the mandibular second molar region to improve the patient’s functions and aesthetics. Following the 3 months ossoin-tegration process of the implant prosthetic reha-bilitation completed. The patient continues to be followed and now has been disease free for 11 years (Figure 5).

DIScUSSIOn

According to Neville et al, histopathologic variants of the UA described as luminal UA, in-traluminal UA, mural UA. In the luminal amelo-blastoma the tumor is confined to the luminal surface of the cyst. One or more nodules of am-eloblastoma project from the cystic lining into the lumen of the cyst in the intraluminal UA. In the mural UA the fibrous wall of the cyst is in-filtrated by typical follicular or plexiform amelo-blastoma2.

Enucleation has probably been adequate treatment for intralumenal or luminal UA’s2. Some authors believe that the local resection of the area is indicated as a prophylactic measure if the specimen identified as mural UA, others pre-fer the conservative enucleation and long-term follow-up to delay further radical treatment until the evidence of recurrence10,11,12.

Gardner discussed the treatment of amelo-blastoma on the basis of pathologic and anatomi-

FIGURE 1

Preoperative panoramic radiograph which shows unilocular radiolucency and impacted tooth on the right posterior

mandibular region

FIGURE 2

Preoperative antero-posterior radiograph

FIGURE 3

After the enucleation cavity filled with allogenic bone graft material

52

cal considerations and stated that recommended treatment for solid and multicystic ameloblas-toma was radical treatment and UA was usually cured by curettage13. Although Nakamura et al adopted more conservative treatment protocol

and compare the long-term results of different approaches to ameloblastoma and reported that the conservative approaches for ameloblastoma namely, marsupyalization and enucleation with sufficient bone curettage are useful as predict-able treatment methods that reduce the need for jaw resections14. Gardner et al reported that plexiform UA is less aggressive with a lower re-currence rate after conservative treatment15.

Implant supported prosthetic rehabilitations in the UA treatments are rarely reported in the literature. Becker and Wong reported an early functional loading case in the fully edentulous mandibular resection and reconstruction due to an ameloblastoma and inserted five implants two years after the removal of the tumor and they concluded that the implants are stable and the patient eating comfortably16.

The interval between bone grafting and im-plant placement in the patients with reconstruct-ed mandibles ranged from 8 to 34 months17. In the presented case one side free-end saddle re-movable partial denture was performed for pros-thetic rehabilitation 5 years after surgery because more than 50% of all recurrences of UA occur within 5 years of surgery. At the 8 year follow-up, not only for the patient’s complaints about partial denture but also achieve more suitable function and minimum bone lost at the region, an implant supported prosthesis was planned according to the complete bone healing and no sign of recurrence on clinical and radiological examinations.

This case presentation supports the conser-vative treatment of the unicystic ameloblastoma. The benign nature of UA often leads a surgeon to perform simple procedures to avoid the po-tential morbidity associated with larger resection. Radical surgery often means that the patients have serious complications including facial de-formity, masticatory dysfunction and abnormal jaw movement18. In many cases UA typically ap-pears as a dentigerous cyst so the biopsy should be taken before the surgery. In this case report preoperative diagnosis was made as a dentig-erous cyst and enucleation was performed for treatment without preoperative biopsy.

Postoperative follow-up is important in the management of UA19. In this case report a suc-cessful outcome of the treatment now has been observed for 11 years, with bone healing, os-seointegration of the implant, the provision of functional and aesthetically pleasing implant

FIGURE 4

Postoperative follow-up radiograph showed bone healing

FIGURE 5

Postoperative 11 year panoramic radiograph with implant rehabilitation

53

7. Isaacson G, Andersson L, Forsslund H, Bodin I, Thompson M. Diagnosis and treatment of the unicystic ameloblastoma. Int J Oral Maxillofac Surg 1986; 15: 759-64.

8. Eversole LR, Leider AS, Strub D. Radiographic characteristics of cystogenic ameloblastoma. Oral Surg Oral Med Oral Pathol 1984; 57: 572-577.

9. Turesky JD, Shepherd NJ, Morgan VJ, Muftu A. a simple prosthetic approach using cement-retained implant prosthesis after surgical treatment of ameloblastoma. Implant Dent 1999; 8: 407-12.

10. Ackermann GL, Altini M, Shear M. The unicystic ameloblastoma: a clinicopathological study of 57 cases. J Oral Pathol 1988; 17: 541-6.

11. Ueno S, Mushimoto K, Shirasu R. Prognostic evaluation of ameloblastoma based on histologic and radiolographic typing. J Oral Maxillofac Surg 1989; 47: 1115.

12. Nakamura N. Clinical and histopathological studies on the characteristics of growth of mandibular ameloblastoma. Jpn J Oral Maxillofac Surg 1991; 37: 1600-15.

13. Gardner DG. A pathologist’s approach to the treatment of ameloblastoma. J Oral Maxillofac Surg 1984; 42: 161-6.

14. Nakamura N, Higuchi Y, Tashiro H, Ohishi M. Marsupyalization of cystic ameloblastoma: a clinical and histopathologic study of the growth characteristics before and after marsupyalization. J Oral Maxillofac Surg 1995; 53: 748-54.

15. Gardner DG, Corio RL. Plexiform unicystic ameloblastoma: A variant of ameloblastoma with low-recurrence rate after enucleation. Cancer 1984; 53: 1730-5.

16. Becker W, Wong J. Early functional loading in the fully edentulous mandible after mandibular resection and reconstruction due to an ameloblastoma: case report. Clin Implant Dent Relat Res. 2003;5:47-51.

17. Papageorge MB, Karabetou SM, Norris LH. Rehabilitation of patients with reconstructed mandibles using osseointegrated implants: clinical report. Int J Oral Maxillofac Implants 1999; 14: 118-26.

18. Nakamura N, Higuchi Y, Mitsuyasu T, Sandra F, Ohishi M. Comparison of long-term results between different approaches to ameloblastoma. Oral Surg Oral Med Oral Pathol Oral Radiol Oral Endod 2002; 93: 13-20.

19. Kim SG, Jang HS. Ameloblastoma: A clinical, radiographic and histopathologic analysis of 71 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Oral Endod 2001; 91: 649-53.

supported prosthesis and the absence of clini-cal or radiographic evidence of recurrence of the unicystic ameloblastoma

As a conclusion more conservative surgical enucleation with sufficient bone curettage and the use of osseointegrated implants for pros-thetic rehabilitation could be useful as predict-able treatment of unicystic ameloblastoma after the proper follow-up period. Primary bone graft-ing and osseointegrated implants could be the best option for adequate reconstruction after the treatment of a pathologic lesion in the mandible with the long-term follow-up. More cases of UA with long term follow-up periods (10 year and more) are needed to be reported to give better understanding of all aspects of this lesion.

REFERENCES

1. Regezi J, Sciubba J, Richard CK. Oral pathology: Clinical pathologic correlations. 4th Edition Saunders Publishing: 2003;218-220.

2. Neville BW, Damm DD, Allen CM, Bouquot JE. Oral&Maxillofacial Pathology. Second Edition W.B. Saunders Company: 2002;617-618.

3. Philipsen HP, Reichart PA. Unicystic ameloblastoma: A review of 193 cases from the literature. Oral Oncology 1998; 34: 317-325.

4. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumors. Berlin: Springer, 1992; 11-4.

5. Dunsche A, Babendererde O, Lüttges J, Springer IN. Dentigerous cyst versus unicystic ameloblastoma- differential diagnosis in routine histology. J Oral Pathol Med 2003; 32: 486-91.

6. Reichart PA, Philipsen HP, Sonner S. Ameloblastoma: biological profile of 3677 cases. European J Of Cancer 1995; 31: 86-99.

CORRESPONDING ADDRESS

Gökçe MERAL DDS, PhDHacettepe University Faculty of Dentistry Department of Oral Surgery 06100 Sihhiye Ankara TURKEY

Tel: + 90 312 305 22 00 Fax: + 90 312 468 78 00 e-mail: dmeral@hacettepe.edu.tr