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DENTOCUTANEOUS FISTULA

Cutaneous fistulas arising from chronic dental infections are uncommon, but periapical dental abscesses are the most common cause of suppurative cutaneous lesions of the face and neck.  The fistulous pathway develops as the chronic inflammation erodes through the cancellous alveolar bone, perforates the cortical plate and periosteum, and spreads into the surrounding soft tissues in dentocutaneous fistula and dental fistula. F1 The diagnosis is often obscured because there is generally a chronic asymptomatic dental infection and the skin lesion is mistakenly thought to arise locally or from subjacent soft tissues. If the dental infection is overlooked, a significant delay in diagnosis may occur, leading to unnecessary cutaneous surgery and prolonged antibiotic therapy. The mean age of occurrence is 31 years, and 80% of cutaneous tracts originate from mandibular dental infections.

The diagnosis is made by finding a cordlike sinus tract on intraoral palpation, along with a dental radiograph demonstrating the abscess. F4F5 A panorex radiograph is also useful in establishing the diagnosis. Referral to an endodontist is recommended, because elimination of the dental abscess invariably leads to healing of the sinus tract and its cutaneous opening.

Osteomyelitis of the jaws was relatively common before the era of antibiotic therapy and preventive and restorative dentistry. Today, osteomyelitis of the facial bones is a rare condition. Osteomyelitis represents an inflammation of the medullary cavity, Haversian system.

In a review of 141 cases of jaw osteomyelitis in Nigeria, Adekeye and Cornah found odontogenic infections to be the cause of 38% of mandibular and 25% of maxillary involvement. Similarly, Balm et al found odontogenic sources to be the most common cause.

Clinically, patients present with facial swelling, localized pain and tenderness, low-grade fever, draining sinus tracts, suppuration, dental loss, and sequestrum (ie, necrotic bone fragment) formation. New bone and oral mucosa will occasionally regenerate beneath the sequestra, probably because of activation of periosteal osteoblasts by the infectious process.

On radiographs, osteomyelitis appears as radiolucent (``moth-eaten'') regions representing bony destruction and avascular necrosis,F6 with evidence of sequestrum formation.

Predisposing factors found to contribute to the development of osteomyelitis include viral fevers (eg, measles), malnutrition, malaria, anemia, and tobacco and alcohol use. Treatment goals include reversal of any predisposing conditions, long-term antibiotic therapy, and various surgical procedures. Since most of the infections are polymicrobial oral flora.

Of all the dural venous sinuses, the cavernous sinuses are most often affected by thrombosis. The two cavernous sinuses are situated on either side of the sella turcica and are connected by the intercavernous sinuses. Within the lateral wall of the sinuses run cranial nerves (CN) III, IV, V1, and V2. The internal carotid artery and CN VI course through the center of the sinuses. Septa within the sinuses are believed to increase the likelihood of embolic entrapment or thrombus formation.

Septic thrombi of the cavernous sinuses most often result from infections of the midface, with Staphylococcus aureus being the predominant pathogen. Other primary foci of infection include paranasal sinusitis (primarily sphenoid) and otitis media. In approximately 10% of patients with cavernous sinus thrombosis (CST), the source appears to be odontogenic.  The incidence of CST secondary to dental infections is now rare, but was common in the pre-antibiotic era.

Sterile CST has been associated with polycythemia, sickle cell disease, paroxysmal nocturnal hemoglobinuria, contraceptive use, dehydration, compressive brain tumors or aneurysms, and pregnancy. Occasionally, no predisposing condition is evident.