Sinus Tract
Pronunciation: SY-nus trakt
An epithelialised or non-epithelialised channel through bone and soft tissue that drains suppuration from a periapical or periradicular abscess to a surface opening.
Full Definition
A sinus tract (formerly and still colloquially called a 'fistula' or 'fistulous tract') is a pathological channel that provides drainage from a chronic periapical abscess through cortical bone and mucosa or skin to an intraoral or extraoral orifice. In endodontics, sinus tracts are an important diagnostic indicator of chronic periapical infection, typically appearing as a small papule ('parulis') on the buccal mucosa. Gutta-percha tracing through the sinus tract to the radiographic apex is a classic diagnostic manoeuvre. Editors should note that 'sinus tract' is the preferred contemporary term; 'fistula' implies an epithelialised passage between two epithelialised surfaces and is technically less accurate in most endodontic contexts, though it persists in older literature.
Usage
Usage note: 'Fistula' should be flagged and queried when encountered in manuscripts; 'sinus tract' is the AAE-preferred term. 'Parulis' refers specifically to the soft tissue swelling at the tract's orifice, not the tract itself.
In Context
- "A sinus tract was present on the labial mucosa adjacent to the maxillary right central incisor; tracing confirmed its origin at the apex." — Clinical case report — diagnosis
- "Authors should use 'sinus tract' rather than 'fistula' in accordance with current AAE terminology guidelines." — Editorial note