An interim analysis of the maxillary canine in determining the maxillary occlusal plane

Abstract

Aim: A pilot study on dentate subjects was done to evaluate the relationship of the incisal edge exposures of the maxillary central incisor (CI) and maxillary canine to the maxillary lip at rest, to the maxillary lip length, and the influential effects of incisal wear and anteroposterior skeletal relation. Materials and Methods: Thirty males and 67 females of Indian origin and age group 15-59 years were examined. A calibrated manual vernier caliper was used to record the incisal exposures of the maxillary left CI and canine to the maxillary lip at rest and the maxillary lip length. The tooth wear index by Smith and Knight (1984) was used to assess the extent and severity of the incisal attrition. Anteroposterior skeletal relation was assessed using soft tissue cephalometric points. A descriptive statistical analysis and Pearson's correlation analysis was done. Results: On descriptive analysis of the data recorded, 94% of the female subjects recorded a mean CI exposure of 3.25 mm to the maxillary lip at rest while 91% of the female subjects recorded a mean canine exposure of 0.29 mm. 93% of the male subjects recorded a mean CI exposure of 2.63 mm to the maxillary lip at rest. 80% of the male subjects recorded a mean canine exposure of −0.42 mm to the maxillary lip at rest. Canine displayed a narrow range of tooth visibility. In both genders, CI exposure to the mean lip length averaged 1-3 mm and the canine exposure to the mean lip length averaged −1-0 mm. CI and canine incisal edge exposures decreased with an increased incisal wear. CI exposure averaged 0-3 mm and canine exposures averaged −1-1 mm. Class II and Class I skeletal relation observed an increased CI exposure of 3 mm and 2.4 mm respectively compared to Class III (2.125 mm). Increased canine exposures were observed for Class III (0.3 mm) and Class II (0 mm) compared to Class I (−0.7 mm). Pearson's correlative analysis demonstrated a highly significant positive correlation of the canine with a P value of 0.01. Conclusion: Within the scope of this study, descriptive analysis demonstrated a linear favorable relationship of the canine to the CI. Correlative analysis also demonstrated a favorable relationship of canine to CI with borderline significance of anteroposterior relationship.