Introduction

Sinus tracts (or fistulas) are a common manifestation of pulpal necrosis that requires conventional endodontic treatment in order to heal. They are mainly identified intra orally and sometimes they manifest as an extra oral opening, depending on the causative tooth, root location, bone thickness and muscle inserts. Such conditions may be misdiagnosed and confused with other non-pulpal pathologies. Patients with these lesions often present to the general practitioner rather than the dentist as they may not associate these with teeth and often may not have symptoms of dental origin. Facial fistulas of endodontic origin should be considered in differential diagnosis. It is important that interaction occurs between physicians and dentists to avoid exposing patients to insufficient treatment schemes.

Case Report

A nine year old boy presented to the pediatrician’s office with a draining skin opening under the chin, later was consulted with the plastic surgeon. It was treated apparently for caries about a month before by a dentist. Physical examination revealed a sinus opening under the chin (Figure 1). On oral examination, only related tooth identified was lower first permanent molar (#36) with composite occlusal filling. In the examination of the panoramic radiograph taken during the first visit (Figure 2), radiolucencies were observed both in the mezial and distal root apicies of the tooth #36, hovewer these radiolucencies were not found to be related to the cutaneous sinus tract. This radiological finding suggested that the root canal treatment had not been done efficiently. Therefore a computed tomography was necessary for the differential diagnosis. Computed tomography revealed a tubular linear cortical and medullary bone defect of 10 mm in length in the mandible at the first molar root level (Figure 3). There was also increased density of the soft  tissues at this level extending caudally and laterally to the skin suggesting cutaneous fistula tract. The root canal was explored by the dentist at our institution. Purulent material was aspirated from the cavity and a sample was sent for bacteriologic examination. The patient was given amoxicillin 50 mg/kg/day, for ten days as oral antibiotic treatment. Parvimonas micra was identified during culturing of the specimen. The patient responded to the antibiotic therapy uneventfully; during follow up visits irrigation and enlargement of both roots of no 36 tooth had been continued untill the endodontic treatment has been completed (Figure 4).

Discussion

Patients with cutaneos lesions from dental origin often present to the general practitioner rather than the dentist as they may not associate these with teeth and often may not have dental complainsts (1).

Dental caries is the most common cause of pulp necrosis (2). Restorable tooth is usually treated by endodontist. Some cases may undergo crown restoration. Other causes of pulp necrosis include trauma and periodontal infections. Depending on being acute or chronic pulp necrosis, the lesion may remain in the alveolar bone or drain intra-orally or extra-orally through cutaneous structures. In acute cases, patients may seek and get proper treatment. In chronic cases, however, alveolar and even cortical bone may be involved through sub-periosteal involvement. The most common sites of extra-oral sinus tract of odontogenic origin are the jaws and chin with the angle of the jaw being the most common site (2-4).

Diagnosis of cutaneous sinus tract of dental origin was straight  forward since the patient had been treated for caries a month prior to presentation. The interesting fact about this case was the CT evidence for iatrogenic perforation of mandibular bone during endodontic treatment. There was a tubular linear defect in the bone between the pulp of the involved tooth and cutaneous sinus tract.

Iatrogenic injury may be produced by an inadvertent or erroneous treatment or a result of act of omission by the dentist (5). Several examples of dental iatrogenic case report have been published in the literature. Various iatrogenic dental trauma induced as a result of dental treatment have been identified (6). Traumatically introduced dental materials and instruments have been one of the causes of iatrogenesis. There have been an increase in the occurrence of broken instruments especially after the advent of rotary nickel-titanium (NiTi) files (6). The separated instrument may cause nerve compression and if left in the canal, may lead foreign body reaction and even infection. Root canal perforations has been also cited as being the subject of improper handling of dental instruments  (7). There have not any reported mandibular perforation and consequent sinus tract formation in the literature in children. In our case a linear and tubular defect beginning at the tip of the root canal was evident by CT confirmation. Acute nature of the sinus tract formation, the unique shape of the bone defect, the timing of the caries treatment panoramic radiographic evidence pointed to the assumption that this was a case of iatrogenic dental manipulation. The defect created by the inadvertent use of dental bur apparently punctured adjacent mandibular bone and the  endodontic treatment. This resulted in void space in the root canal and the bone for bacterial seeding and abscess formation, eventually leading to development of the sinus tract.

In conclusion the skill, experience and up-to-date knowledge in dentistry are critical elements to prevent possible iatrogenic dental traumas. Proper treatment is necessary especially in children where maintenance of tooth for a longer period of time is of paramount importance. Although panoramic roentgenographic examination  is the first step diagnostic method for the diagnosis of such cases, CT examination have been proven to be superior to plain radiographs in detecting bone defects.