The location of dental fistulas makes them relevant to several medical specialties, but it is the dental surgeon who is best placed to appreciate their nature. Long asymptomatic and often hidden in mucosal folds, dental fistulas are still quite common: errors in diagnosis and treatment are generally good.
Definition of Dental fistula
From the Latin fistula, which means “tube”, the dental fistula is a duct bringing into communication a lesion near the tooth with an outlet. This evacuation opening opens either at the level of the gingival mucosa, or in a natural cavity of the face (sinuses, orbits, floor of the nasal fossae), or at the level of the skin. These ducts deliver permanent or episodic passage to saliva or more frequently pus related to a more or less deep tooth injury.
Some fistulas exist from birth, but most appear at various times in life. The researchers noted that it was more prevalent in young populations, 10 to 30 years on average.
It is the relatively quiet testimony of a “blocked” infection at the chronic stage. So it can be months or years before the infection related fistula is diagnosed and then treated.
Symptoms of a fistula
Dental fistulas are not easy to spot: the generalists themselves often miss out on them. This can be explained by the lack of clinical signs that accompany them. Most people are unaware of having a dental problem and have equated fistula with a simple “pimple”.
It should be noted, however, that on average, one in six teeth with inflammatory status (caries for example) causes a fistula. The teeth most affected by the phenomenon are those that are necrotic and those that have already been treated “endodotoniquement”, that is to say, whose interior has been treated by a dentist.
Mucous fistulas are very much superior to those that pierce the skin. About 1 in 20 dental fistula is cutaneous. Nevertheless, in cases of cervico-facial fistula, it is the dental origin that must be suspected.
In general, the fistulas found on the nose, the upper lip and the infra-orbital region concern the incisors and canines, while the fistulas of the sub-maxillary, neck and cheek regions are more concerned with the molars and premolars.
The appearance will differ according to the age of the fistula.
If it is recent, the edges are detached or slightly edematous. If it is old, the orifice is at the bottom of a clear depression.
Most often, the orifice of the fistula is slightly brownish and is accompanied by a slight crust that falls regularly to allow passage to a tiny drop of pus. The nodule is between 2 mm and 1 cm in diameter. Sometimes it is difficult to see because hidden in a mucosal fold.
It uses the X-ray examination to diagnose successfully fistula and an understanding of sinus tracts of dental origin.
Mechanisms of fistulization
At the origin of a fistula, one often finds odontological infections caused by bacteria belonging to the oral flora. When they reach the deep tissues, they are likely to precipitate the appearance of the most common dental diseases, namely caries, gingivitis and periodontitis.
In the case of fistula, necrosis of the dental pulp resulting from a very advanced caries or dental trauma, which has gone unnoticed, is the most frequent cause.
When the pulp is invaded by bacteria, inflammation and edema quickly cause congestion and necrosis due to the closed and rigid space in which the tissues are held. This necrosis causes an infection that can take two paths:
1) Either it evolves in one piece in an acute mode, causing particularly fierce pain.
2) Either it cools quickly and becomes “chronic”: it goes unnoticed for months or even years but can “warm up” at any time and bring back to the previous case.
This deep tissue infection, which has become chronic, can cause fistulization.
What does the “chronicity” of an infection depend on?
Chronic or acute progression depends on many factors such as the virulence of the bacteria, their number, and the victim’s immune resistance, the anatomy of the affected areas and the possible flow of pus. As all these data may vary over time, the infection may change from chronic to acute at any time.
The place of infection, the position of the teeth involved and those of muscle insertions will determine whether the fistulous path will pierce the skin or mucosa.
Causes of Dental fistula
The tooth decay is undoubtedly the major cause of dental fistula. Typically, fistulas are asymptomatic, but when the fistula channel comes to be obstructed, pain can appear. The tooth concerned is often more or less mobile, a sign of the absence of pulpal vitality.
Bruises, subluxations, cracks and fractures can also cause fistulas, because of the lesions of the pulp they cause. The frequency of fistula occurrence for fractured teeth was approximately 35%.
Odontological therapeutic accidents and the consequences of tooth extraction are also possible causes of a dental fistula.
Finally, the included teeth, those teeth that have not totally erupted in the oral cavity (this is often the case with wisdom teeth), can cause pericoronitis and various infections of the gums, the chronicity of which may be accompany drainage to the oral cavity.
To eradicate the dental fistula, it is essential to treat the dental cause at the origin of the cutaneous lesion or mucous membrane. Antiseptic or antibiotic attempts will have no effect until the cause is treated. Once resolved, the fistula tends to disappear quickly, between 5 and 15 days, even if it can persist a slight scar, especially if the fistula is old. After a few months, it nevertheless goes unnoticed .