A Case of Ameloblastic Fibrodentinoma of the Mandible

Ai Enomoto DDS, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Takafumi Satomi DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Mitsumasa Yamashina DDS,PhD, Anatomic Pathology, Tokyo Medical University, tokyo, Japan
Harutsugi Abukawa DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Michihide Kohno DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Ko Fujikawa DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Toshiyuki Koizumi DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, Tokyo, Japan
Akira Matsuo DDS, PhD, Oral and Maxillofacial Surgery, Tokyo Medical University, tokyo, Japan
Toshitaka Nagao MD, PhD, Anatomic Pathology, Tokyo Medical University, tokyo, Japan
Daichi Chikazu DDS, PhD, Department of Oral and Maxillofacial Surgery, Tokyo Medical University, Tokyo, Japan
Ameloblastic fibrodentinoma (AFD) is a benign mixed odontogenic tumor which occurs predominantly in children and young adults. In the World Health Organization classification of odontogenic tumors, these tumors are defined as being composed of odontogenic epithelium with odontogenic ectomesenchyme with or without hard tissue formation. AFD is an exceedingly rare histological variant of ameloblastic fibroma (AF) in which dentin or dentinoid tissue is formed. It is believed to be an intermediate stage between AF and ameloblastic fibro-odontoma. An incidence of 0.1% is reported for this odontogenic benign tumor, and 49 cases have thus far been reported following a search in the literature after 1936[1] [2]. We encountered a case of AFD which occurred in the lower molar of an 11-year-old boy. We present the case and add discussion based on reports in the literature.

We describe the case of an 11-year-old boy. On a panoramic radiograph in a previous dental clinic, part of the lower right second molar showed radiability. Therefore, the patient was introduced by the dental clinic to our hospital for us to perform oral surgery, and thus we initially conducted a detailed examination. Clinical examination showed no sign of pain or swelling in his left mandible. The boy had no history of local trauma or infection. Computed tomography (CT) revealed cyst-shaped radiolucency between the lower right second molar tooth germ and the third molar tooth germ in the well-circumscribed lesion. A small calcification was present in the inner lesion. The CT level of the calcification was low. Based on these findings, a clinical diagnosis of benign mandibular tumor was made. We suspected odontogenic myxoma, a calcifying epithelial odontogenic tumor, a calcifying cystic odontogenic tumor, or an adenomatoid odontogenic tumor. We performed tumor excision and lower third molar exodontia under general anesthesia. At the time of removal, no hard tissue was clinically evident within the specimen. For histopathology findings, the odontogenic epithelium was arranged in the form of cords with an islet structure that lay scattered in the immature ectomesenchyme similar to the dental papilla. An acidophilic matrix intermingled with cells is partially formed. As this matrix had no regular canaliculi structure, it was considered an osteodentin. Enamel formation could not be identified on any sections. The final definitive diagnosis was AFD. The patient remained recurrence-free for 6 months postoperatively.

We also studied 49 reported cases of AFD in addition to the present case. The male to female ratio was 27:19, indicating a moderately high tendency for occurrence in male patients. The average age of the 49 patients reported in the literature was 20.2 years (range: 1.5 – 63 years). Of the 49 AFD cases reported, 61% occurred in a lower jaw molar tooth, ramus of the mandible, or body of the mandible when observed by site distinction.

The prognosis of the boy was good, and there was no recurrence for 6 months postexcision. We will examine the course of eruption of the second molar in the future. We report this case to add knowledge to the rare AFD with a review of the literature.

1.           Ulmansky M, Bodner L, Praetorius F, Lustmann J: Ameloblastic fibrodentinoma: report on two new cases. J Oral Maxillofac Surg 52:980, 1994

2.           Philipsen HP, Reichart PA, Praetorius F: Mixed odontogenic tumours and odontomas. Considerations on interrelationship. Review of the literature and presentation of 134 new cases of odontomas. Oral Oncol 33:86, 1997

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