The effectiveness and cost-effectiveness of early intervention to correct the position of a palatally displaced maxillary permanent canine: a multicentre RCT

Approximately 2-3% of children will have problems with one or both of their permanent or 'adult' canine teeth in the upper jaw. These canine teeth sometimes fail to erupt properly, because they are displaced into the roof of the mouth or palate. These are known as palatally displaced canines, PDC, (Brin et al., 1986, Ericson and Kurol, 1987). In addition to failing to erupt, displaced teeth can cause problems, such as damage to the roots or displacement of the neighbouring teeth (Ericson and Kurol, 1988a, Ericson and Kurol, 2000, Falahat et al., 2008). It has been suggested that if the primary ('baby' or 'milk') canine is extracted at an appropriate time in a child with a suspected palatally displaced canine, then the displaced tooth might spontaneously correct its position (Ericson and Kurol, 1988b) and the extraction of the baby canine when a clinician suspects that the adult canine is displaced has become accepted clinical practice (Short, 2009). This appears to be on the basis of one report of a series of 35 children who received the intervention and no control group (Ericson and Kurol, 1988b). Two recent systematic reviews have examined the evidence for the effectiveness of removal of the primary canine with the aim of correcting the eruption path of a palatally displaced canine. A recent systematic review published in The Cochrane Library in 2021 (Benson et al., 2021) noted that the evidence for any intervention to correct the eruption path of a displaced permanent canine is weak and further research is required. Numerous problems with the reported studies were identified by both reviews. Other authors have suggested that using a RME (Rapid Maxillary expansion) or headgrear (EOT) to create sufficient space within the dental arch for the permanent canine tooth will encourage the tooth to erupt (Baccetti et al., 2011). This approach might be less traumatic to a child who may have had no experience of dental treatment, other than routine check-ups. If either or both approaches are shown to be effective then their widespread use would be advantageous to both the child and the healthcare provider, because the need for an operation, under general anaesthetic, to uncover the tooth and extensive brace treatment to straighten the tooth will be avoided.