title: Cephalometrically assessing the validity of superior, middle and inferior tragus points on ala-tragus line while establishing the occlusal plane in edentulous patient.
abstract: OBJECTIVE
  The purpose of this study was to decide the most appropriate point on tragus to be used as a reference point at time of marking ala tragus line while establishing occlusal plane.
  
  
  METHODS
  THE DATA WAS COLLECTED IN TWO GROUPS OF SUBJECTS: 1) Dentulous 2) Edentulous group having sample size of 30 for each group with equal gender distribution (15 males, 15 females each). Downs analysis was used for base value. Lateral cephalographs were taken for all selected subjects. Three points were marked on tragus as Superior (S), Middle (M), and Inferior (I) and were joined with ala (A) of the nose to form ala-tragus lines. The angle formed by each line (SA plane, MA plane, IA plane) with Frankfort Horizontal (FH) plane was measured by using custom made device and modified protractor in all dentulous and edentulous subjects. Also, in dentulous subjects angle between Frankfort Horizontal plane and natural occlusal plane was measured. The measurements obtained were subjected to the following statistical tests; descriptive analysis, Student's unpaired t-test and Pearson's correlation coefficient.
  
  
  RESULTS
  The results demonstrated, the mean angle COO (cant of occlusal plane) as 9.76°, inferior point on tragus had given the mean angular value of IFH [Angle between IA plane (plane formed by joining inferior point-I on tragus and ala of nose- A) and FH plane) as 10.40° and 10.56° in dentulous and edentulous subjects respectively which was the closest value to the angle COO and was comparable with the values of angle COO value in Downs analysis. Angulations of ala-tragus line marked from inferior point with occlusal plane in dentulous subject had given the smallest value 2.46° which showed that this ala-tragus line was nearly parallel to occlusal plane.
  
  
  CONCLUSIONS
  The inferior point marked on tragus is the most appropriate point for marking ala-tragus line.
authors.affiliation: Department of Prosthodontics, Career Post Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Chaturvedi
authors.forename: Ram
authors.initials: R
authors.lastname: Thombare
keywords: Ala-tragus line; Angle measuring device; Downs analysis; Occlusal plane