Odontology Inn

Clinical Corner: Is it a Sinus Tract or a Fistula?
​At Odontology Inn, we often see patients presenting with cutaneous drainage. While the terms are often used interchangeably, the treatment outcome depends on a precise diagnosis.
​Are you looking at a simple Sinus Tract or a true Orofacial Fistula? Here is how we differentiate them chairside:
​1. The "Two-Opening" Test
​Sinus Tract: A "blind-ended" path. You’ll see a single exit point (punctum). It’s the path of least resistance for pus.
​Fistula: A "through-and-through" communication. You will find both an internal (oral) and external (skin) opening.
​Pro Tip: Use your air-water syringe! If air bubbles emerge from the skin when you spray the vestibule, you’re likely dealing with a patent fistula.
​2. GP Point Tracing (The Gold Standard)
​Never guess when you can trace. Insert a #20 or #25 Gutta-Percha point into the opening and take a radiograph.
​Sinus Tract: The GP point will track directly to the apex of the offending tooth.
​Fistula: The GP may pass entirely through or reveal a wide, epithelialized "tunnel" connecting the two environments.
​3. Palpation of the "Cord"
​The Cord: In a sinus tract, you can often feel a firm, string-like path of granulation tissue leading from the tooth to the skin.
​The Tether: A fistula often feels more "fixed" or tethered to the underlying bone, feeling more like a hollow, epithelialized tube than a solid cord.
​💡 The Treatment Takeaway
​A Sinus Tract usually heals spontaneously once the source of infection is cleared via Root Canal Treatment (RCT). However, because a Fistula is lined with epithelium, it may require surgical intervention to "close the tunnel" even after the infection is gone.