Surgical management of an odontogenic cutaneous fistula

Abstract

A patient presented to our unit with a long history of a discharging skin infection on his left cheek, which came and went. He had been seen by numerous healthcare practitioners including his general practitioner, general dental practitioner and dermatologist, with no resolution. He was eventually diagnosed with an odontogenic cutaneous fistula (OCF), for which he underwent surgical management. The purpose of the study is to describe the diagnosis and surgical management of an OCF, from initial assessment through to postoperative review and discharge. Following surgical management of the OCF and treatment of the source of infection by dental extraction, the patient is no longer experiencing purulent discharge through his left cheek. The extraoral skin site of drainage at his left cheek has resolved completely, with minimal residual scarring. OCF can be managed by a number of different treatment modalities. The treatment of an OCF by surgical excision is presented.

Background

Although chronic odontogenic infection can commonly present as an intraoral draining sinus, less commonly it can drain to the skin of the face via an odontogenic cutaneous fistula or sinus (OCF).¹ A fistula can be defined as a pathological, epithelial-lined communication between two epithelial-lined surfaces—in this case the oral mucosa and the skin of the face. OCF often presents a diagnostic challenge to the practitioner. Indeed, some 50% of these patients will have undergone dermatological surgical intervention or long-term antibiotic treatment before a diagnosis is achieved.²

When established, dental periapical infection, as a result of caries and pulpal necrosis, spreads into surrounding tissues by the path of least resistance.³ As infection progresses, resorption of bone and perforation of the cortical plate allow spread of infection into fascial spaces.⁴ Extraoral fistula formation can result from tracking of infection below mentalis, mylohyoid or buccinator muscle attachments in the mandible, with 80% of reported extraoral fistulae associated with a mandibular tooth.^{1 3} Similarly, an extraoral fistula can occur from a maxillary tooth via infection tracking above buccinator muscle attachment.¹ As with an intraoral sinus tract, chronic OCF infection may not be associated with a history of pain.⁴

Case presentation

A 54-year-old man attended our unit with a long-standing history of a discharging lump on his left cheek. He reported that this swelling had a several-year history of coming and going, with no evident precipitating factors. The patient had previously seen both a general practitioner (GP) and general dental practitioner (GDP) regarding the area. Furthermore, he had been referred by his GP to a dermatologist and subsequently underwent biopsy of the skin site which did not determine a definitive diagnosis.

On clinical examination, the presence of crusty, erythematous swelling at the left malar region was noted, of 2 cm width, with a greater dimension palpable underneath. The area had a well-defined apex, through which the tract could be traced with a point and resultant prominent facial asymmetry was noted as a result of this swelling (figure 1). On intraoral examination, there was a significant palpable tract, the buccal sulcus at the upper first premolar region. The patient had a moderately maintained, heavily restored dentition. The teeth were not tender on percussion. The upper left first premolar tooth was heavily restored with a large amalgam restoration, as were the majority of other teeth in the quadrant. Other than the palpable tract, there was no pain, swelling or evidence of odontogenic infection in the area.

Figure 1.

Clinical appearance of swelling at left malar region and tracing of the lump with a point.

Investigations

Radiographically, a well-defined periapical radiolucency was detected, associated with the upper left first premolar tooth. The periapical area could be seen to erode through the buccal cortex of the alveolus. Incidentally, retained roots of the upper left first molar were also seen on radiographic evaluation. A cone-beam CT (CBCT) scan allowed for a three-dimensional (3D) perspective to be gained, as well as 3D reconstruction (figures 2–4).

Figure 2.

Panoramic reformatting of cone-beam CT scan, with evident apical pathology of the upper left first premolar.

Figure 3.

Saggital views from cone-beam CT scan, with red denoting periapical area associated with upper left first premolar and retained roots of upper left first molar.

Figure 4.

Three-dimensional reformat of cone-beam CT scan, with periapical area of first premolar and erosion of buccal cortex evident.

Treatment

Treatment options were discussed with the patient, and it was ultimately decided to surgically excise the fistula tract and extract the culprit upper first premolar tooth, as well as the retained roots of the upper first molar. The fistula tract was identified by raising of an intraoral full-thickness mucoperiosteal flap, dissecting around the tract in the process. The fistula was confirmed to be associated with the first premolar tooth, and the minimal extraoral dimensions for excision were determined by pulling on the now exposed intraoral portion. The fistula was released extraorally by incision and dissection from skin and then excised intraorally, with curettage of the apical area at the upper left first premolar. The final excised tract measured 47 mm in length. The premolar and roots of the upper first molar were then extracted, prior to closure of both intraoral and extraoral sites (figures 5–7).

Figure 5.

Exposure of the intraoral component of the odontogenic cutaneous fistula.

Figure 6.

The site for extraoral excision is identified.

Figure 7.

Excision of odontogenic cutaneous fistula.

Outcome and follow-up

Postoperatively, the patient was discharged without complication. At review, he has recovered well and has not had any evidence of recurrence of swelling intraorally or extraorally. He subsequently was referred back to the care of his GP and GDP (figure 8).

Figure 8.

Postoperative photographs at follow-up.

Discussion

The spread of infection in the head and neck is typically via the ‘path of least resistance,’ as a result of increased hydrostatic pressure.^{3 5} First described in detail by Grodinsky and Holyoke in 1938, the fascial planes of the head and neck provide a path of reduced resistance by which orofacial infection can easily spread.⁵ By the release of enzymes such as hyaluronidase and collagenase by pathogenic bacteria, such infections can gain access to these spaces and enable the continued spread of infection in the head and neck region. Perforation of the buccal cortical plate, as seen in this case, is a prerequisite for the spread of infection into fascial spaces.⁴ In this case, the extraoral drainage of infection related to the upper left first premolar was likely due to tracking of the infection above the level of attachment of the buccinator muscle. For maxillary teeth, extraoral drainage of a dental abscess becomes possible when infection tracks above the level of muscular attachments, specifically buccinator. Similarly, for mandibular teeth, extraoral drainage of a dental abscess becomes possible when infection tracks below the level of muscular attachments such as mylohyoid, mentalis or buccinator.¹

Diagnosis of an OCF can be a challenge, and often patients will have seen multiple practitioners prior to diagnosis.² In the case of our patient, he had attended his GP, GDP and a dermatologist prior to successful diagnosis, even having undergone skin biopsy in the process. In order to diagnose an OCF, a thorough history as well as clinical and radiographic evaluation should be undertaken (table 1). Many patients will have a history of toothache or trauma to the affected tooth, which should not be overlooked and may contribute to earlier diagnosis.^{3 4 6} Pulp sensibility testing, percussion and palpation will all yield further diagnostic value. The tracking of the extraoral fistula with a radio-opaque material prior to radiographic evaluation is particularly effective in ascertaining if the tract is of dental origin and in determination of the culprit tooth.2 3 7 8 A gutta percha point is typically readily available within dental practice for such purposes. Radiographic evaluation is essential for both diagnosis and treatment planning in cases where OCF is suspected or diagnosed. A periapical radiograph or orthopantomograph can be used to this end.^{3 7} In our case, a CBCT scan was particularly useful in determining the 3D extent of the OCF and in treatment planning for surgical management.

Table 1.

Investigations and their common findings in OCF

Investigation	Common findings
History Pain history Trauma history	Previous toothache, which resolved prior to onset Previous trauma to suspected tooth
Clinical examination Dental caries	Obvious dental caries with breakdown of tooth structure or pulpal involvement
Special tests Pulp sensibility tests (hot/cold/electric pulp test) Percussion Palpation	Negative, suggesting pulpal necrosis May cause increased pain May result in tenderness, sinus may be palpable at depth of buccal sulcus if large
Radiographic evaluation Periapical radiograph OPG CBCT scan	Established periapical radiolucency Established periapical radiolucency Shows 3D extent of apical infection

CBCT, cone-beam CT; 3D, three dimensional; OCF, odontogenic cutaneous fistula; OPG, orthopantomograph.

The treatment of OCF is typically centred on the removal of the source of the infection—by root canal treatment of the affected tooth or extraction of the affected tooth (table 2).⁴ Although antibiotic therapy will result in temporary resolution of the fistula, if the source of infection is not managed, the fistula will continue to recur.² Resolution of an OCF can occur spontaneously with management of the culprit tooth alone, typically healing by granulation within 5–14 days.^{9 10} However, it is worth noting that although spontaneous healing following odontogenic management does occur, this can result in scarring or hyperpigmentation of the extraoral site.¹⁰ In the case presented, due to the large dimensions of the OCF extraorally and the long-standing cutaneous irritation with a significant contour deformity, surgical excision was decided on in order to maximise the aesthetic result. Odontogenic management alone would not have resolved the significant extraoral contour deformity that was already present (figure 1). Ultimately, management of such cases should be discussed with the patient, taking their treatment wishes into consideration.

Table 2.

Treatment modalities for OCF and their advantages/disadvantages

Treatment modality	Advantages	Disadvantages
Root canal treatment	Allows tooth to be maintained, optimising dental function and aesthetics Will result in resolution of the fistula	Requires multiple appointments Not possible in unrestorable teeth Will require restoration of tooth on completion
Dental extraction	Will result in resolution of fistula Can be completed in one appointment No maintenance of restored tooth required Treatment of choice for unrestorable tooth	Tooth is lost, compromising dental function and aesthetics Will result in gap where tooth is lost, which may require replacement
Surgical excision of fistula in combination with root canal treatment or dental extraction	In cases of large fistulae, can improve aesthetic result Allows for histopathological evaluation of lining to confirm diagnosis Ensures swift resolution of fistula	Requirement for further surgery, with possible general anaesthetic May cause extraoral scarring Second site of treatment

OCF, odontogenic cutaneous fistula.

Learning points.

• Although an unusual manifestation of odontogenic infection and a diagnostic challenge, chronic periapical infection can present in the form of an odontogenic cutaneous fistula (OCF).

• Appropriate diagnosis and management of an OCF results in resolution of the fistula and associated chronic infection.

• For the general practitioner or dental practitioner, an odontogenic aetiology of lesions of the skin of the head and neck should always be considered and excluded.