Sir, although I agree with Dr Hassan and Dr Nute (BDJ 2006; 200: 493–496) that hospital advice is needed for patients with impacted canines, I am concerned that practitioners reading the introduction to their paper might decide to extract the deciduous canines without asking for such advice. I feel some of the papers need explanation. The authors quote Eriksson and Kurol who showed that 78% of permanent canines erupted following the extraction of deciduous canines. It is important to understand that there was no control group in this investigation so that it is possible that the same number of teeth would have erupted without the extractions. Indeed in a randomised controlled trial published in a refereed journal in 2004 by Leonardi et al.1 there was no significant difference between the extraction group and the non extraction control group. However, there was a difference between these two groups and a third group where the deciduous canines were extracted and headgear was used. The significantly improved success rate in this group throws into doubt the suggestion by Hassan and Nute that crowding is not a factor. For this the authors quote a paper by Power et al.; again this paper has no control group so that it compares extractions of deciduous canines in cases with and without crowding and finds no difference between the groups. Of course, if the findings of Leonardi et al. are true and there is no benefit from the extraction of deciduous canines then there would be no difference between the two groups.

A problem here may be the definition of crowding. From the erupting canines point of view this would be a space between the lateral incisor and the first premolar that is too small for the canine. In a typical 11-year-old this could occur in a patient with no overall crowding because the deciduous second molar is much bigger than the second premolar tooth.

Practitioners should remember that even if some patients do benefit from the extraction of deciduous canine teeth, some are worse off, because the option of retaining the deciduous tooth into adult life is lost. It is important that when a deciduous canine with a good crown and no root resorption is extracted that a proper consent is obtained, explaining to the patient that they will require complex orthodontics if the permanent canine fails to erupt.