Retrospective analysis of the correlation between the facial biotype and the inclination of the upper canine cusp axis to the occlusal plane

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. 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 (V). X-ray examinations demonstrated that canine impaction was associated to other dental anomalies (32% of the sample). The mean S angle measurements were 22.9° ± 4.1°, and mean values of the T 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