Buccal canine displacement

In their article in the August issue, Chaushu et al reported that the buccal displacement in BDC-nc subjects (buccally displaced canine, no arch crowding) might also be the result of lack of guidance from an adjacent anomalous lateral incisor in addition to a genetically based etiology (Chaushu S, Bongart M, Aksoy A, Ben-Bassat Y, Becker A. Buccal ectopia of maxillary canines with no crowding. Am J Orthod Dentofacial Orthop 2009;136:218-23). I agree with them in part. Here are my reasons.

First, many factors can affect canine eruption, including crowding, a deciduous tooth or an abnormal tooth bud, or unhealthy habits such as biting a pencil. The authors didn't tell us that they eliminated the above effects, and we could not ignore the individual differences.

Second, even if we eliminated all the effective factors, as we know, the eruption of canines is later than the eruption of first or second premolars, so a premolar's mesial movement is common. This can also result in canine ectopia buccally without arch crowding.

Third, in the situation of BDC, all patients who had been diagnosed with BDC and crowding less than 2 mm (BDC-nc) formed the experimental sample. BDC became a grouping agent; actually, the authors just investigated the variations in lateral incisors in the 2 groups (crowding and no crowding), and undoubtedly there were significant differences between the groups.

In my opinion, the variation of lateral incisors should be a grouping agent, with all patients with variations in lateral incisors forming the experimental sample; then we could investigate the difference of BDC in the 2 groups. This might better anwer the question.