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.
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 was the research?
A systematic review 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.
Who conducted the research?
The research was conducted by a team led by Philip E. Benson of the University of Sheffield School of Clinical Dentistry, Sheffield, UK on behalf of Cochrane Oral Health. Amarpreet Atwal, Farhan Bazargani, Nicola Parkin and Bikram Thind were also on the team.
What evidence was included in the review?
We included four randomised controlled trials, which had 199 children participating.
What did the evidence say?
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.
How good was the evidence?
The review authors found the reliability of the evidence to be very low.
What are the implications for dentists and the general public?
General dentists may find it helpful to seek the opinion of a specialist orthodontist if they suspect an upper permanent canine is palatally displaced in a young person after the age of nine years to determine whether intervention either in the form of extraction of the primary canine or space creation is appropriate.
If the unerupted PDC has not erupted by 18 months following any intervention then the probability of eruption may be low and alternative methods of management should be considered.
What should researchers look at in the future?
Further clinical trials are required to confirm if and when extraction of the primary canine increases the probability that a PDC will erupt into the mouth without surgical intervention.
The effectiveness of other interventions, such as creating space within the dental arch, to increase the probability that a PDC will erupt into the mouth without surgical intervention need to be investigated with well‐designed clinical trials.
The primary outcome of these trials should be whether the PDC successfully erupts without surgical intervention.
Link
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.
This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.
Cochrane Oral Health 