Impacted mandibular canine

Impacted mandibular canine

Question

Hi Doctor Chamberland,
We consulted an oral implantology and maxillofacial surgeon (Dr D.. L. A.) in P… Fr. He was recommended to us by the orthodontist (Dr Leco…) who we consulted for our daughter who is 12 years and 4 months of age. The mandibular panoramic X-ray indicates 2 impacted canines. We have an appointment at the end of the month for the extraction of an impacted canine in the lower jaw which presses on the roots of 3 front teeth (incisors). After reading your article, I wonder if this extraction is necessary and if there are other methods to correct her dentition. The orthodontist told us that it was necessary before any treatment.

The pictures are real X-rays, I will however try to scan them so you can see clearer. I am not a physician, but if it is possible to avoid surgery for my daughter, then I am ready to try.

I thank you for your response.

Response

I identified the teeth following the universal numbering system on the panoramic X-ray provided and indicated by a white arrow the position of the impacted lower canine crown with regard to the roots of the lower incisors (black arrow).

Teeth #43 (lower right canine) and #23 (upper left canine) are the impacted ones.

I confirm that I would not extract the lower right canine (#43) on the pretext that it is in front of the roots of the lower incisors. I was able to spare, more than once, this type of canine and I learned to be creative as much in the mechanics of treatment to use as in the finishing of such treatment. People have to accept that this kind of treatment can last 36 months, but efforts are worth it.

An additional reason not to extract the impacted canine is that the analysis of the picture of the lower dentition and the panoramic X-ray does not show a lack of space. If a lack of space had been noted (> 8 mm), it could have been justified to foresee the extraction of the impacted canine and of 3 other premolars, but it is not the case.

Here is what I would have done if I had treated this case:

1. Extract the residual primary canines (identified by a “c”) and the primary first molars (#54, #64, #74). These are the teeth that are aligned with the first premolars identified by a “4 “.
2. Request surgical exposure by using the exposition technique for vestibular canines recommended by Vanarsdall.
3. Use a removable appliance: Hawley retainer, Adams clasp on teeth #36 and #46, cantilever armspring with a hook with rounded end to pull using a short elastic connecting the hook and the metal ligature bonded to the canine. The cantilever could also be a spring with helices near the Adams clasp.
4. After some 4-6 months, control the evolution with a new panoramic X-ray.

Here is an example:

The lower canine #43 shows an impaction similar to your daughter’s. Its relative position to the roots of the lower incisors is identical to your daughter’s (black and white arrows). The canine crown was palpable in the oral vestibule where indicated by the circle.

After 6 months of traction with a removable appliance, the canine significantly straightened up, but we observed a side effect of a forward shift of the posterior teeth. The canine was almost vertical, but transposed between the central incisor and the lateral incisor. I decided to finish the treatment by keeping this canine-lateral incisor transposition.

This picture shows the evolution of the position of the canine after 7 months of traction (picture on the left, black circle) and after 11 months of treatment with fixed appliances (X-ray on the right). The teeth sequence is identified. The #43 is between the #42 and #41 instead of being between the #42 and #44. The treatment ended 15 months later.

The above pictures show the quality of the occlusion 9 years after the fixed appliances were removed. Notice the good gingival health. The mandibular arch midline does not fit with the maxillary midline, but does it matter since the impacted tooth is spared and that no implants were necessary to replace the tooth which would have been extracted?

Consult the Keynote called “Éruption ectopique-dystopie dentaire” slides 30 à 35 (in French).

Another more recent case:

Notice the traction initiated with an elastic on the left and the cantilever on the right. The cantilever spring on the left was not engaged at the beginning, because the canine must be posteriorly straightened up before making it erupt vertically. When the cleat was visible on the right, we continued the treatment with fixed appliances.

Notice how parallel the roots are and the absence of radicular resorption.

Mechanotherapy

Here is an example of a removable appliance used to apply traction to the canine. On the January 08 and April 08 pictures, a simple 3/16″ 3,5oz elastic connects the hook to the ligature wire. This ligature wire was shortened during the visit in April, because the visible part had become too long, which means that the impacted tooth had straightened up. At the visit in May 08, the appliance was modified and a cantilever spring with a .020 SS wire was used. Notice that exceptionally, the helices are distal to the Adams clasp to lengthen the lever arm. Generally, the helices are mesial to the hook where indicated by the white arrowhead.

Etiology

Among impaction causes, of course there are genetic causes, meaning hereditary. Like it is demonstrated that the impaction of upper canines can be explained genetically.

But there are at least 2 other causes to mandibular canine impaction.

Iatrogenic cause: pulpotomies on primary canines that cause a chronic apical lesion and constitute an obstacle to the resorption of the roots and consequently, the exfoliation of the primary canine does not occur.

Supernumerary tooth: An odontoma is a misshaped supernumerary tooth and constitutes an obstacle to the eruption of the permanent tooth. The extraction of this odontoma allows the auto-eruption of the canine.