Philip E Benson, Amarpreet Atwal, Farhan Bazargani, Nicola Parkin, Bikram Thind
What is the health problem?
Upper permanent canine teeth (commonly known as eye teeth or fang teeth) are positioned in the upper jaw, one on the right and one on the left. In around 1% to 3% of children, they may not erupt (appear from behind the gum and into the mouth) into their correct position. The permanent canine tooth or teeth may grow towards the palate (roof of the mouth) and remain unerupted (buried under the gum). This is known as a palatally displaced canine (PDC). If the permanent canine tooth remains displaced and unerupted, it can damage or change the position of neighbouring teeth, and occasionally it can lead to a cyst.
What are the treatments?
Management of a PDC can take a long time, involving surgery to uncover the tooth and prolonged orthodontic (brace) treatment to straighten it. Various quicker or easier alternatives have been suggested to encourage the tooth or teeth to erupt. These include extraction (taking out) of the primary (baby) canine, extraction of the primary canine and primary first molar (also called double primary tooth extraction), or using braces to create space in children's mouths.
What did we want to find out?
We wanted to find out if any of these treatment alternatives were successful for children aged 9 to 14 years, in terms of encouraging PDCs to erupt without using surgery.
What did we do?
We searched for studies that assessed the effectiveness of different ways to deal with palatally displaced canines up to 3 February 2021.
Where studies measured the same thing in the same or similar ways, we combined the results to give us a clearer idea about the effects of the treatment. We assessed whether the individual studies were at risk of being biased and we judged the overall reliability of the evidence we found.
What were the main findings?
We found four studies involving 199 children (195 analysed).
There is very weak evidence that extraction of the primary canine in children aged between 9 and 14 years may increase the probability that the PDC will successfully erupt into the mouth without the need for surgery by 12 months. There is no evidence it reduces the number of children needing surgery to correct their PDC.
There is no evidence that double extraction of primary teeth increases the proportion of erupted PDCs compared with a single primary tooth extraction by 18 months after treatment or that it reduces the number of children needing surgery to correct the PDC by 48 months.
There is some limited evidence suggesting that the severity of the displacement of the PDC towards the midline may be important in deciding whether or not to intervene. If it is very far from the midline, it may be less likely to be successful.
What does this mean?
The review authors found the reliability of the evidence to be very low so future research is necessary to help us know for sure the best way to deal with upper permanent canines that are not erupting as expected.
Benson PE, Atwal A, Bazargani F, Parkin N, Thind B. Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for surgical exposure, in children aged 9 to 14 years. Cochrane Database of Systematic Reviews 2021, Issue 12. Art. No.: CD012851. DOI: 10.1002/14651858.CD012851.pub2.