7 More canine problems
Cases 1 and 2
The term used is transposition (positional interchange of two adjacent teeth or tooth development/eruption in a position normally occupied by a non-adjacent tooth). In the general population, prevalence remains under 1% but varies according to the sample investigated.
Transposition is more common in the upper arch, where it most commonly affects the canine and first premolar, followed by the canine and lateral incisor. In the lower arch, it seems to affect exclusively the canine and lateral incisor. The left side seems to be favoured in the upper arch and the right side in the lower arch.
Although several theories have been proposed – interchange of developing tooth buds, altered eruption paths, presence of retained primary teeth, trauma – the aetiology is now suggested to be multifactorial with involvement of complex relationships between genetic and environmental factors. There is evidence of associated gender predilection, hypodontia, peg-shaped maxillary lateral incisors and retained primary teeth.
|Underlying malocclusion, facial aesthetics, degree of crowding||These will influence need for extraction(s)|
|Stage of dental development and position of root apices||When root development is complete, interception (by extraction of primary teeth) is unlikely to lead to spontaneous improvement in tooth position|
|With complete transposition and root apices closed, acceptance of transposition may be best due to the root resorption and periodontal (e.g. gingival recession, alveolar dehiscence) risks involved in correction|
|Dental morphology||If transposition is to be maintained, re-shaping is necessary to disguise for incorrect tooth position|
|Occlusal considerations||Judicious grinding of the palatal cusp of a maxillary first premolar will be required where it is aligned in the canine position|