Retrospective Analysis of the Correlation Between the Facial Biotype and the Inclination of the Upper Canine Cusp Axis to the Occlusal Plane

Abstract

Permanent maxillary canines are the second most frequently impacted teeth and the prevalence of this clinical condition is estimated to be 1-2% in the general population (1). Females are twice as frequently affected (1.17%) as males (0.51%) (2). This atypical limited eruption is most likely due to an extended tooth development period and to a long, difficult path of eruption because of anatomic limitations (3). Palatally displaced canines are three times more frequent than the buccal displacements (2). There are many possible etiologic factors associated with canine impaction. Bishara (4) lists the most common causes as the result of any one or a combination of the following factors: tooth size, arch length discrepancies, prolonged retention or early loss of the deciduous canine, abnormal position of the tooth bud, the presence of an alveolar cleft, ankylosis, cystic or SUMMARYPermanent maxillary canines are the second most frequently impacted teeth and the prevalence of this clinical condition is estimated to be 1-2% in the general population. The diagnosis of maxillary canine impaction should be based on both clinical and radiographic examinations. The aim of this study was to evaluate the presence of a correlation between the facial biotype and the inclination of the upper cusp axis. A correlation between the total radicular length of the lateral incisors was also evaluated, by comparing the side of impaction with the healthy side. Twenty three patients with a diagnosis of unilateral upper cusp impaction were recruited. For each patient, dental casts and radiographic material (panoramic radiographs and lateral cephalograms) were examined. Statistical analyses were done with Spearman's rank correlation coefficient or Spearman's rho (ρ). X-ray examinations demonstrated that canine impaction was associated to other dental anomalies (32% of the sample). The mean α angle measurements were 22.9° ± 4.1°, and mean values of the β angle were 34.7°± 4.0°. The mean distance "d" value was 14.6 mm ± 1.2 mm. The mean values of the angle between the upper cusp axis and the perpendicular-to-Fh plane were 20.8 °± 2.6°. Among the 23 subjects recruited, 5 showed values included in the range 25°-45° and 1 an inclination > 45°. The results obtained in the present study demonstrate a significant inverse correlation between the MM angle and the inclination of the upper cusp axis to the perpendicular-to-Fh plane.

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“…It has been recently suggested that maxillary impacted canines and facial biotype are correlated, 7 and that the impacted canines in hyperdivergent subjects may have a better prognosis. 8 In our opinion, the facial biotype should be taken into account in patients with impacted canines not only for diagnosis but also for treatment planning. We are aware that further longitudinal research is necessary to confirm these relationships.…”