Impacted canines: So I’ve identified an impacted canine- what do I do?

We often get asked this question by dentists: When should I refer (to an orthodontist) for an impacted canine? 

Impacted canines are very difficult to treat orthodontically. They are very taxing on orthodontic anchorage and often can take a long time treat. Treatment times upwards of 2 to 4 years is not uncommon. There are also instances where the impacted canine may be ankylosed or develop ankylosis during its path down, all of which can be disappointing for patients.

A more important reason is as the canines erupt, they erupt into a narrower width of alveolar bone. There is therefore a greater risk of resorption of the roots of adjacent teeth if left in situ and observed, not to mention a greater risk of root resorption of the canine root or adjacent teeth during its orthodontic correction. 

It is therefore incumbent to identify early stages of impacted canines. Unerupted canines which are overlapping the lateral incisor radiographically are a concern, or if the canine tip appears to be angulated towards an adjacent teeth.

In rare cases, the canine long axis may be lying horizontal or transposed between the 1st and 2nd premolar. These are all early abnormal signs of canine eruption. 

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Our key orthodontic considerations would be whether an eyelet can be bonded safely to the canine tooth without damaging the adjacent developing adult teeth. As the canine tooth is usually one of the last permanent teeth to fully develop, this is a less significant consideration compared with an impacted central incisor tooth associated with a mesiodens supernumerary.

A principle that has worked well for us is where there is crowding present to regain space early (example below). This can be achieved usually through arch or orthopedic expansion, depending on the diagnosis. 

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Molar distalization works well if there are early signs of a developing transposed premolar tooth.  (see below of an impacted 15 & 23 in a 12 year old girl)

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Occasionally, the canine may be too severely impacted and an early exposure with a short period of uprighting would help significantly. Below is an example of a 11 year old where the CBCT film showed the 33 canine to be labial and contacting the apices of the lower incisors. After 7 months of careful uprighting and lateral movement, assisted by a lower lingual arch, 33 was safely uprighted. The tooth was observed to have held its corrected position over a course of 6 weeks and no orthodontic retention was needed after. 

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So to summarise, early referral to an orthodontist upon detection of an abnormal erupting canine is recommended as it can help to minimize or avoid resorption of adjacent incisor roots and can help to simplify future orthodontic treatment, both in terms of case complexity, reducing risks and potentially reducing overall treatment times.

A screening OPG x-ray at the initial examination is needed to often detect this.

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