Central odontogenic fibroma.

Central odontogenic fibroma (COF), which has been categorized under the subheading of odontogenic tumors of ectomesenchyme, is such an uncommon neoplasm that much of its nature is left uncharted. COF is a rare tumor that accounts for 0.1% of all odontogenic tumors. Clinically, the lesion grows slowly and leads to cortical expansion. Radiologically, the lesion may be unilocular or multilocular. In some cases, it may be associated with root resorption or displacement. Histopathologically, the lesion is characterized by mature collagen fibers and numerous fibroblasts. A case of COF of the mandible in a male patient aged 49 years is described in this report. The patient showed no symptoms, no history of swelling discomfort or pain, and was unaware of the presence of the lesion. Orthopantomogram (OPG) showed generalized bone loss along with a unilocular radiolucent area, with a clear sclerotic lining and angular bone loss. Surgical enucleation of the lesion along with placement of osseo-graft, which is a bioresorbable demineralized bone matrix (DMBM), and platelet-rich fibrin was carried out in the defect site. Following surgery, patient was recalled for revaluation of the lesion; the surgical site showed good healing and an increase in bone height was seen.

INTRODUCTION

Central odontogenic fibroma (COF) is a rare benign neoplasm that could appear very similar to the endodontic lesions and/or to the other odontogenic tumors.[12] This lesion is considered to be derived from the mesenchymal tissue of dental origin, such as periodontal ligament, dental papilla, or dental follicle. Connective tissue proliferation can have different localizations. It exists both as intraosseous (central) and gingival (peripheral) lesions and is designated as odontogenic fibroma. While peripheral odontogentic fibroma clearly represents a periodontal lesion, the COF usually resembles an endodontic lesion and has been reported in the literature.[34] It should be pointed out that the most usual site of presentation of COF in the mandible is the posterior area, while in the maxilla it is in the anterior region.[5] This neoplasm is a rare tumor and accounts for 0.1% of all odontogenic tumors. COF radiologically presents both as unilocular[67] and multilocular radiolucent lesion.[8] Root resorption and displacement have been reported in cases of severe lesions.

The purpose of this report is to present a case of COF in the mandibular left premolar and the mesial root of first mandibular molar in a male patient aged 49 years and to compare its clinical, radiographic, and histologic features with those cases previously reported.

CASE REPORT

A male patient aged 49 years reported to the Department of Periodontics, Sri Siddhartha Dental College and Hospital, Tumkur, with the chief complaint of deposits present on his teeth and he desired to get his teeth cleaned. Patient's medical history was not contributory. Patient had undergone extraction of upper right canine 2 years back, with uneventful healing.

On intraoral examination, stains and calculus were present along with generalized gingival inflammation and bleeding on probing [Figure 1]. Generalized periodontal pockets and attrition were present. Grade I mobility was present w.r.t. 12, 17, 25, 26, 35, and 36. Periodontal pocket measuring 7 mm was found w.r.t. 35 and 36, and no carious lesion was seen. The patient was advised orthopantomogram (OPG) which revealed presence of generalized bone loss along with a unilocular radiolucent area resembling a “tear drop shape” with a clear sclerotic lining, along with angular bone loss involving the mandibular left premolar and the mesial root of mandibular first molar [Figure 2].

Figure 1

Preoperative photograph

Figure 2

Orthopantomogram showing generalized bone loss along with unilocular radiolucent area resembling a “tear drop shape” involving mandibular left premolar and the mesial root of mandibular first molar

The vitality of the pulp was checked w.r.t. 35 and 36; it showed positive response as that of the contralateral side, and hence, endodontic involvement was ruled out. The patient was explained regarding the presence of lesion and a surgical excision of lesion was planned. The patient showed no symptoms, no history of swelling, discomfort, or pain, and was unaware of the presence of the lesion. Hematological investigation was done prior to surgery and was found to be normal. A comprehensive explanation was given to the patient regarding the intended surgical procedure to be done and an informed consent was taken before starting the procedure.

Surgical procedure

For surgical enucleation of the lesion, crevicular incision was given extending from canine till the first molar region [Figure 3], with two vertical releasing incisions given, one on the mesial aspect of 33 and the other on the distal aspect of 36. A subperiosteal flap was raised [Figure 4] and a surgical window was prepared [Figure 5] between 35 and 36 using a straight fissure surgical bur under copious irrigation and the lesion was enucleated in the Department of Oral and Maxillofacial Surgery [Figure 6]. The biopsy specimen was sent to the Department of Oral Pathology for histopathologic investigation. Ten millilitres of blood was drawn from the median cubital vein using a 5-ml syringe with 25-gauge needle [Figure 7] and it was centrifuged at 3000 rpm for 12 min for procuring platelet-rich fibrin [Figures 8–10]. Platelet-rich fibrin obtained was mixed with osseo-graft (DMBM) [Figure 11] which is a sterile bioresorbable demineralized bone matrix for bone void filling. The cavity was filled with the mixture of platelet-rich fibrin and DMBM, marketed by [Advanced Biotech Products (P) Ltd, Chennai, India]. The defect was closed using 3-O silk suture [Figure 12]. The patient was prescribed amoxicillin 500 mg, 3 times daily, for 5 days. The patient was advised to use chlorhexidine 0.12% (Periogard) as postoperative oral rinse for 30 days. Postoperative instructions were given to the patient to neither brush nor floss the surgical area for the first 4 weeks and to continue with the chlorhexidine (0.12%) oral rinse for 4 weeks. The patient was recalled after 7 days for suture removal at the surgical site and postoperative evaluation was done. The patient was recalled after 15 days and 3rd and 5th months for checkup and revaluation. After the 5th month, the surgical site showed good healing and an increase in bone height was seen [Figure 13].

Figure 3

Incision

Figure 4

Flap raised

Figure 5

Surgical window

Figure 6

Enucleation of lesion

Figure 7

Intravenous blood drawn

Figure 8

Centrifugation

Figure 10

Fibrin clot

Figure 11

Fibrin clot mixed with osseo-graft demineralized bone matrix

Figure 12

Sutures placed

Figure 13

Postoperative radiograph after 5 months

Platelet-rich fibrin

Histopathologic examination

Histological examination of the lesion was carried out as follows: The specimen was fixed in phosphate-buffered neutral formalin for 1 day. Later, 5-micron paraffin sections were obtained and stained with hematoxylin and eosin stain. Sections showed connective tissue stroma made up of bundles of thick, mature collagen fibers, resembling fibroma with plump fibroblast uniformly distributed. Also seen were many islands of odontogenic epithelium which appeared to be inactive [Figure 14]. The features were suggestive of COF (simple type).

Figure 14

Histopathology

DISCUSSION

According to the latest classification of the World Health Organization (WHO), COF is defined as a fibroblastic neoplasm that contains varying amounts of apparently inactive odontogenic epithelium. Although COF is a rare lesion, it should be considered by the general dentists and periodontists as it closely resembles endodontic lesions.[9] According to Neville and Damn, the lesion is reported to occur in patients whose age ranges from 4 to 80 years, with a 2.2:1 female: male ratio. According to the latest classification of odontogenic tumors reported by Gardner,[10] COF is classified as a benign lesion derived from “odontogenic ectomesenchyme with or without odontogenic epithelium”. The author reviewed the information, identifying lesions with two different histologic patterns. The first is classified as the simple type which consists of fibrous tissue along with varying amounts of collagen, while the second has been referred to as the WHO type or the complex type, which consists of fibrous tissue along with myxoid area associated with odontogenic epithelium.

COF responds well to surgical enucleation with no tendency to undergo malignant transformation[11] and recurrence is very uncommon.[12] Some lesions may contain varying amounts of hard tissue that resembles dysplastic cementum or bone. Finally, clinical, radiological, and histological aspects of the case reported here were consistent with the diagnosis of COF (simple type). The lesion was surgically removed and no recurrence of the lesion was observed until 1 year of follow-up.

CONCLUSION

Because of the scarce number of reported cases in the literature, diagnosis of this tumor cannot be based only on clinical and radiographic features. But like most of the lesions, only histological findings can confirm this particular entity.