An oral cutaneous sinus tract is a relatively uncommon condition that is generally associated with long-standing periapical inflammation. The traditional process of oral cutaneous sinus tract diagnosis is an invasive method based on the insertion of a lacrimal probe or wire. The present article describes the use of cone-beam computed tomographic imaging as a noninvasive assistant tool for the verification of the odontogenic origin.
Cone-beam computed tomographic imaging is a noninvasive assistant tool for verification of the odontogenic origin of oral cutaneous sinus tract.
A chronic apical abscess can be caused by root canal infection, resulting in an abscess draining from an enclosed area of inflammation, through oral communication, to the gingival or cutaneous surface1. This condition is known as an odontogenic sinus tract (ST)2. Drainage of the infected material (pus) through an intraoral opening in the gingival area (in the alveolar mucosa, free gingiva or periodontal ligament)3 is most common. Infrequently, drainage through the skin occurs, and an oral cutaneous sinus tract (OCST) opening appears4.
OCSTs, rather than intraoral STs, are likely to occur if the apices of the teeth are superior to the maxillary muscle attachments or inferior to the mandibular muscle attachments5.
Although OCSTs have been previously documented, they continue to represent a diagnostic challenge6. OCSTs are often misdiagnosed as lesions of nonodontogenic origin because the differential diagnosis of an OCST orifice may include a wide range of pathologies5, 7. An incorrect diagnosis leads to multiple inappropriate treatments that may result in temporary amelioration of symptoms5, 6, 7. After some time, recurrence of the OCST will occur, which might eventually lead the patient to seek dental therapy7. The principle of managing such lesions is to remove the source of dental infection6 because recurrence is likely unless the dental focal infection is treated4.
Unlike intraoral STs, OCSTs may heal with granulation tissue, and a residual scar may therefore occasionally persist8.
The traditional diagnostic approach for the origin of oral cutaneous lesions is an invasive method based on the insertion of a lacrimal probe or wire4, 6. This diagnostic procedure has several disadvantages, including possible damage to the tissues of odontogenic or nonodontogenic lesions, the discomfort of the patient, and stress of the operator9. Those disadvantages lead to the search for other noninvasive assistant diagnostic tools for OCSTs.
The use of cone-beam computed tomographic (CBCT) imaging is prevalent in the field of endodontics10. This technique allows visualization of the dentition, maxillofacial skeleton, and surrounding anatomic structures in 3 dimensions11.
The purpose of this case series was to present cases of OCST in which CBCT imaging is used as an assistant tool in the diagnostic process.
A 20-year-old woman with general good health was referred to the Department of Endodontics, Oral Maxillo-Facial Surgery at Tel Hashomer Medical Center, Israel Defense Forces Medical Corps, Tel Hashomer, Israel. The reason for this referral was nonpainful cutaneous ulceration that had existed for 8 months (Fig. 1A). During this period, the patient was examined by 2 dermatologists who recommended local treatment without resolution of the ulcer.
Figure 1. (A) An OCST in the left mandible. (B) A preoperative radiograph of tooth #19.
Two months before visiting our department, class II amalgam restoration was performed in the left mandibular first molar (tooth #19) because of secondary carries under a previous restoration.
Extraoral examination revealed an oral cutaneous ulcer opposite the left mandible in close proximity to the left molar area. Intraoral examination revealed extensive class II amalgam restoration with a composite component in tooth #19. The tooth did not respond to cold testing and was sensitive to palpation and percussion. The soft tissue was normal, without swelling or sinus tract; periodontal probing up to a 3-mm depth was performed, and physiological mobility was measured.
A diagnostic periapical radiograph of tooth #19 (Fig. 1B) revealed a high pulp horn in the mesial portion of the pulp chamber and an extensive radiolucent area surrounding the mesial and distal roots. The patient was referred for small field of view CBCT imaging (Carestream 9300; Carestream Health, Rochester, NY) in our department (Fig. 2A–C). CBCT imaging revealed a radiolucent area around the mesial and distal roots that advanced toward the buccal side and penetrated the cortical bone, supporting an odontogenic origin of the cutaneous ulceration (ie, an OCST).
Figure 2. (A) A CBCT sagittal image. (B) A CBCT axial image. (C) Three-dimensional reconstruction. Tooth #19: the radiolucent area advancing toward the buccal side and penetrating the cortical bone (arrows).
The diagnoses were pulp necrosis and chronic apical abscess. An unscheduled initial root canal treatment was initiated immediately, during which the tooth was anesthetized, and a rubber dam was placed. An access cavity was prepared, and 3 canal orifices were identified. Biomechanical preparation was performed using ProFile (Dentsply Maillefer, Ballaigues, Switzerland) instruments and a self-adjusting file (ReDent Nova, Ra’anana, Israel) with irrigation with 3% sodium hypochlorite. A dressing of creamy aqueous calcium hydroxide was placed as an intracanal medicament, and the tooth was temporized by double sealing with Cavit (ESPE, Seefeld, Germany) and IRM (DeTrey Dentsply, Saint-Quentin-en-Yvelines, France).
At the second visit 3 weeks later, the OCST was closed (Fig. 3A). Temporary filing and calcium hydroxide were removed, and root canals were obturated by lateral compaction with gutta-percha and AH Plus sealer (Dentsply, York, PA). The access cavity was temporized by a double seal with Cavit and IRM, and the patient was referred to her dentist for prosthodontic restoration (Fig. 3B).
Figure 3. (A) A closed OCST in the left mandible. (B) A postoperative periapical radiograph of tooth #19.
A 19-year-old man with general good health was referred to the department of endodontics because of drainage of pus and blood from his nose. Four years before attending our department, a class III composite restoration was performed in the patient’s right maxillary incisor (tooth #8). Five months before attending our department, root canal treatment was initiated because of acute apical abscess. Clinical examination revealed that tooth #8 was sensitive to palpation and percussion. The intraoral soft tissue was normal without swelling or sinus tract; periodontal probing up to a 3-mm depth was performed, and physiological mobility was measured. A diagnostic periapical and occlusal radiograph of tooth #8 revealed a 10-mm-diameter radiolucent area surrounding the apex of the roots of teeth #7 and #8 (Fig. 4A and B). The patient was referred for small field of view CBCT imaging (Carestream 9300) in our department. CBCT imaging revealed that a radiolucent area surrounding the apex of the roots of teeth #7 and #8 penetrated the cortical bone at the floor of the nose, extending to the area of a draining lesion (Fig. 4C) (ie, an extraoral ST).
Figure 4. (A) A preoperative periapical radiograph of tooth #8. (B) A preoperative occlusal radiograph. (C) Three-dimensional reconstruction. Tooth #8: a radiolucent area advancing toward the buccal side and penetrating the cortical bone (arrows). (D) A postoperative periapical radiograph of tooth #8.
The diagnoses were previously initiated therapy and chronic apical abscess. Two-visit root canal treatment was performed, as in the first case (Fig. 4D). The draining lesion disappeared after 2 weeks of treatment with a calcium hydroxide dressing.
A 34-year-old man with good general health was referred for a biopsy of a nonpainful cutaneous lesion that had existed for 3 months and was nonresponsive to local antibiotic treatment. The patient’s history revealed that the right mandibular first molar (tooth #30) had been extirpated approximately 1 year ago because of an episode of spontaneous pain.
An extraoral examination revealed a raised red lesion near the mandibular angle on the right side (Fig. 5A). An intraoral examination revealed a temporary restoration on the occlusal surface of tooth #30. The tooth did not respond to cold stimuli and was not sensitive to palpation or percussion. The probing depth in the midbuccal aspect was 12 mm. The probing depth at other sites around the tooth was 3–4 mm.
Figure 5. (A) An OCST in the right mandible. (B) A preoperative periapical radiography of tooth #30. (C) A CBCT axial image showing the radiolucent area between tooth #30 roots advancing toward the buccal side and penetrating the cortical bone (arrows). (D) A postoperative periapical radiograph of tooth #30. (E) A closed OCST in the right mandible.
A periapical radiograph of tooth #30 revealed a halo-shaped radiolucency around the distal root, extending to the mesial aspect of the root up to the furcal area, and a separate radiolucent area of 4–5 mm in size around the apex of the mesial root (Fig. 5B). The patient was referred for a small field of view CBCT scan, which revealed extensive bone loss around tooth #30 with destruction of the buccal plate (Fig. 5C), supporting the odontogenic origin of a cutaneous lesion (ie, an OCST).
The diagnoses were previously initiated therapy with a chronic apical abscess. Two-visit root canal treatment was performed as in the first and second cases (Fig. 5D).
The extraoral lesion was significantly reduced in size after 4 weeks of treatment with a calcium hydroxide dressing and ultimately disappeared, leaving a small recessed scar during follow-up (Fig. 5E).
STs are generally associated with long-standing inflammation. The inflammation spreads from the periradicular area of an infected tooth along the path of least resistance, through the alveolar bone and mucosa or skin5. Teeth with chronic apical abscesses show a complex infectious pattern in the apical root canal system, which may be accompanied by an extraradicular mineralized biofilm2, 12.
The prevalence of intraoral ST in teeth with apical periodontitis lesions ranges from 8.5%–18.1%, whereas an OCST of odontogenic origin is a relatively uncommon condition5, 13, 14.
The most common locations for OCSTs are the mandibular angles, chin, cheeks, and, occasionally, the floor of the nose7, 15. OCSTs, rather than intraoral STs, are likely to occur if the apices of the teeth are superior to the maxillary muscle attachments or inferior to the mandibular muscle attachments5. In 80%–87% of reported cases, the mandibular teeth are most frequently associated with OCSTs7, 16.
Clinically, the orifice of OCSTs may present different shapes, including nodules, boils, indurated areas, cystic areas, ulcers, draining lesions, or nodulocystic lesions with suppuration. The orifice might extend from 1–20 mm in diameter8, 17. In general, a periapical infection with an associated OCST is not painful although there is often a history of varying magnitudes of discomfort before ST development16. Only 50% of these patients experience dental pain, and the involved teeth are in most cases not tender to percussion5, 16, 17. The lack of specific intraoral symptoms and an unpleasant esthetic appearance might be the reason that patients usually do not relate the skin lesion to a dental origin. Thus, patients are likely to first seek help from physicians, instead of dentists18, 19.
The differential diagnosis of an OCST orifice may include a wide range of nonodontogenic pathologies, such as topical dermal infection, osteomyelitis, tuberculosis, actinomycosis, squamous cell carcinoma, traumatic lesions, salivary gland parulis, deep mycosis infections, reaction to a foreign body, congenital fistulas, pyogenic granuloma, and gamma of tertiary syphilis. All of these pathologies may have an appearance that is superficially similar to a draining OCST of dental origin7, 8, 14, 20, 21. An incorrect diagnosis usually leads to multiple inappropriate treatments by a physician, dermatologist, or general surgeon (eg, surgical excision, biopsy, radiotherapy, systemic or topical antibiotic, or steroid regimens). These unnecessary treatments may result in temporary amelioration of symptoms. However, after some time, recurrence of the OCST will occur. This might eventually lead the patient to seek dental therapy5, 6, 7, 18, 22.
The reverse situation is also possible in which a dentist initiates endodontictreatment of a suspected tooth with apical radiolucency, but the cutaneous draining or ulcer lesion does not react to the endodontic treatment. The possible reasons for such a situation are a nonodontogenic origin of a cutaneous lesion concomitant with endodontic pathology of a nearby tooth or inappropriate endodontic treatment. Misdiagnosis of the origin might lead to delayed treatment of a nonodontogenic pathology and may result in life-threatening situations.
When a patient with an extraoral lesion arrives at the dental clinic, the origin of the lesion should be identified8, 17. The recommendation in the literature is a tracing X-ray after insertion of a lacrimal probe or a sharp-tipped wire into the orifice opening, which will pass through the ST path until resistance is felt4, 6, 9, 20, 21, 22, 23. This diagnostic procedure has several disadvantages, including possible damage to the tissue of odontogenic or nonodontogenic lesions, discomfort of the patient, and stress of the operator9.
The use of CBCT imaging in endodontics is justified in specific cases when information from the patient's history, clinical examination, and periapical radiography does not provide an accurate diagnosis. In these cases, the benefits to the individual patient outweigh the potential radiation exposurerisk11.
In the case of extraoral lesions, CBCT images can confirm the odontogenic origin by showing periapical radiolucency and cortical plate perforation leading to the lesion. Moreover, CBCT imaging can in some cases reveal periapical radiolucency areas that are not visible upon panoramic and periapical radiography24. Therefore, CBCT imaging is an effective assistant diagnostic tool for the verification of odontogenic etiology.
An intact cortical plate on a CBCT scan means that there is no possible ST from the offending tooth. However, when the overlaying cortical plate is penetrated on a CBCT scan, intraoral or extraoral ST will appear. Intra- or extraoral location of the ST depends on the orientation of the root apex to the facial muscle attachments. When the tooth apices are superior to the maxillary attachment of the buccinator muscle or inferior to the mandibular attachments of the buccinator, mylohyoid, and mentalis muscles, an OCST appears19.
Thus, in this case series, a combination of clinical and radiologic examination, including CBCT imaging, verified the odontogenic origin of the extraoral lesion and avoided the stressful and invasive mapping procedure.
The appropriate treatment for chronic periapical abscess with intraoral or extraoral sinus tract is the elimination of infection (endodontic treatments or tooth extraction when the tooth is nonrestorable)8, 17. The use of calcium hydroxide as an intracanal medication is advocated for rapid and successful treatment of OCSTs, leading to a closure of the OCST within 5 to 14 days after proper treatment4, 9, 17, 22, 23. Unlike intraoral STs, OCSTs may heal with granulation tissue, and a residual scar may therefore occasionally persist8(Fig. 3A).
The clinician should perform a close follow-up shortly after the procedure to ensure that the lesion heals. In cases of nonhealing lesions, the differential diagnosis of nonodontogenic origin should be considered.
CBCT imaging is a noninvasive assistant diagnostic tool for the verification of the odontogenic origin of extraoral lesions. CBCT images enable demonstration of the exact spatial periapical radiolucency location and the cortical plate perforation in relation to the OCST. Data collected from clinical examinations and CBCT evaluations allow the stressful and invasive mapping of extraoral lesions to be avoided.