A determination of occlusal plane comparing different levels of the tragus to form ala-tragal line or Camper's line: A photographic study

PURPOSE: The purpose of this study was to determine accurately the part of the tragus to be used to form the Ala-Tragal line or Camper's line in orthognathic profile patients. MATERIALS AND METHODS: 150 dentate subjects with age of 18-40 years with orthognathic profile were sampled. Life-size lateral digital photographs of the face with fox plane were taken in natural head position. Different angles between Eye-Ear plane and occlusal plane (OT(1)-OP), Eye-Ear plane and ala-superior border of tragus (OT(1)-AT(1)), Eye-Ear plane and ala-middle border of tragus (OT(1)-AT(2)) and Eye-Ear plane and ala-inferior border of tragus (OT(1)-AT(3)) were calculated using computer software package, AutoCAD 2004. From the three angles formed by the Eye-ear plane (OT(1) or FH plane) and the ala-tragal lines, the one closest to the angle formed between Eye-Ear plane (OT(1)) and occlusal plane (OP) was used to determine the occlusal plane of orientation. The obtained results were subjected to ANOVA F test, Tukey's Honestly significant difference test, followed by Karl Pearson coefficient of correlation test. P values of less than 0.05 were taken as statistically significant. RESULTS: The mean of base line angle i.e. OT(1)-OP angle (11.96 ± 4.36) was found to be close to OT(1)-AT(2) angle (13.67 ± 1.93) and OT(1)-AT(3) angle (10.31 ± 2.03), but OT(1)-OP angle was found to be more closer to OT(1)-AT(3) angle. Comparison of mean angles showed that OT(1)-OP angle in both males (11.68) and females (12.51) is close to OT(1)-AT(3) angle (males- 11.01, females- 11.95). CONCLUSION: The line joining from ala to the lower border of the tragus was parallel to the occlusal plane in 53.3% of the subjects. There was no influence of the sex on the level of occlusal plane.