Intraoral sinus tracts (Dental fistulous tracts. | Recurring / persistent gum boils.)
What is a sinus tract?
In dentistry, the term “sinus tract” is used to refer to the situation where:
- Pus from a chronic endodontic infection (meaning a long-standing infection associated with the interior of a tooth) …
- … has established a drain pathway from a start point located in the area of the tooth’s root …
- … that then travels through the jawbone (via a small tunnel called a “sinus tract” that has formed in response to the presence of the pus) …
- … to an exit terminus in the person’s mouth.
(An opening that usually takes the form of a small persistent or recurring pimple-like lesion on the surface of the jawbone’s gum tissue, typically in a location immediately adjacent to the tooth.)
The anatomy of a sinus tract.
Despite the word “sinus” being a part of the term, a person’s nasal sinuses typically have no involvement with the lesion.
Signs and symptoms.
a) There’s usually no tooth pain.
While the formation of a tract is a sign of infection, the tooth in which it’s located typically remains asymptomatic. (Although there may be a history of pain or swelling associated with the tooth prior to the tract’s formation.) (Hargreaves)
That’s because the pain associated with pus formation is usually due to the effect of pressure buildup. Since with sinus tract formation the pus is free to vent off, no pressure buildup occurs and therefore no discomfort is experienced.
Because pain typically isn’t felt, these lesions may go unnoticed, possibly for years. Many times they’re only first discovered through the thoroughness of a dentist’s routine examination. (Tronstad)
b) Gum boil location.
Proximity to the tooth.
Making a diagnosis.
As a means of discovery, a dentist will often insert a slender cone of gutta percha What’s this? directly into the tract and then take an x-ray.
The flexible nature of the cone (which is radiopaque, meaning it will show up on the x-ray) will follow the tract’s path to its source (the infected tooth), thus making the diagnosis obvious.
Location on the jawbone.
c) Gum boil size.
The size of the tract’s orifice (the pimple-like lesion that forms on the patient’s gums) may enlarge or deflate over time. This may involve a daily, weekly or even monthly time frame.
As compared to the picture above, you can see the pimple is fuller (retains some pus).
Why this occurs.
▲ Section references – Tronstad
d) Foul taste.
Since a sinus tract is simply a drain for pus, the discharge coming from one may have a noticeably bad taste. Sometimes this is the only tip-off to a person that their lesion exists.
How and why do sinus tracts form?
What takes place.
The response of a person’s body to the presence of infection is a process termed inflammation. And some of the chemical mediators involved with this process trigger bone resorption (bone tissue breakdown). As a result, a tract begins to form.
- The bone resorption that takes place tends to follow the path of least resistance, which is often also the shortest route possible. This explains why the orifice of a sinus tract often lies directly opposite the position of the tooth’s root.
- The direction the tract takes isn’t always so predictable. In some cases, it will confusingly terminate some distance from the tooth. It’s even possible for a tract to vent pus into a person’s sinus space.
▲ Section references – Tronstad
What treatment is needed?
As an example of other possible factors, the continued source of infection may be due to a periodontal (gum disease) condition.
Page references sources:
Hargreaves KM, et al. Cohen’s Pathway of the pulp. Chapter: Instruments, materials, and devices.
Tronstad L. Clinical Endodontics. Chapter: Reaction patterns.
All reference sources for topic Root Canals.