[A study on effects of unilateral maxillary canine impaction on the dento-maxillofacial three-dimensional structure]

To investigate the three-dimensional structure characteristics of unilateral impacted teeth by cone-beam CT (CBCT), and to evaluate the risk factors for upper impacted teeth, so as to provide evidence for early clinical intervention in orthodontics.

Thirty patients with unilateral maxillary canine impaction were included. Their CBCT images were measured by three-dimensional reconstruction of Romexis software. The differences of the three-dimensional structure characteristics between two sides were measured and compared with SPSS17.0 software package. Paired t test and regression analysis of related data were performed.

Significant difference in inclination of both canine and lateral incisor was found between impacted side and normal eruption side, with canine mesially inclined and lateral incisor distally inclined (P<0.001). Volumes of the canines were significantly bigger and those of the lateral incisor were significantly smaller on the impacted side compared with the normal eruption side (P<0.05). The occurrence of impacted canine increased with the increase of the volume of the canine and decrease of the volume of the lateral incisor. Significant difference in arch length and arch width in canine and premolar area was found between impacted side and normal eruption side (P<0.001). There was no significant difference in width in molar area between both sides(P>0.05). There was no significant difference in arch length in canine, premolar and molar region (P>0.05).

Maxillary impacted canines can lead to three-dimensional abnormalities of the ipsilateral teeth and alveolar bone, the severity of maxillary impacted canine is closely related to surrounding dental structural abnormalities, suggesting that maxillary impacted canines can be predicted, early diagnosed, and early effectively intervened as well.