The mucosal dental sinus tract or parulis is a fairly common condition that results from an abscess of odontogenic origin that drains through the bone into the oral cavity. The odontogenic infection may be of endodontic or periodontal origin.

This is usually a condition of adults. However, some developmental tooth malformations (such as dentinal dysplasia) predispose to necrosis of the pulp, apical abscesses and subsequent sinus tracts.

The condition is usually painless since pressure from the abscess within bone is released by drainage of pus through the tract.

Patients who are at risk for recurrent infections (e.g., patients with diabetes mellitus) are prone to develop this because of recurrent odontogenic infections. After a periapical lesion has developed from devitalization of the pulp and depending on host immune factors, the apical infection may erode through bone and break through onto the mucosal surface. Generally, the thinnest portion of the jawbone is involved and therefore the presentation is usually on the buccal aspect/facial aspect of the gingival. The same process is true for periodontal abscesses.