J Adv Prosthodont.  2013 Feb;5(1):58-66. 10.4047/jap.2013.5.1.58.

Cephalometrically assessing the validity of superior, middle and inferior tragus points on ala-tragus line while establishing the occlusal plane in edentulous patient

Affiliations
  • 1Department of Prosthodontics, Career Post Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India. dr.saurabh.chaturvedi@gmail.com
  • 2Department of Prosthodontics, Vice-Dean, Sharad Pawar Dental College, Sawangi, (Meghe), Wardha, Maharashtra, India.

Abstract

PURPOSE
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.
MATERIALS AND 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 9.76degrees, 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 10.40degrees and 10.56degrees 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 2.46degrees which showed that this ala-tragus line was nearly parallel to occlusal plane.
CONCLUSION
The inferior point marked on tragus is the most appropriate point for marking ala-tragus line.

Keyword

Occlusal plane; Angle measuring device; Downs analysis; Ala-tragus line

MeSH Terms

Dental Occlusion
Female
Humans
Male
Nose
Sample Size

Figure

  • Fig. 1 Occlusal plane analyzer assembled, 1-lateral scale 1, 2-lateral scale 2, 3-front scale, 4-lower stainless steel plate, 5-vertical threaded rods, 6-nuts to fix position of scale with vertical rods.

  • Fig. 2 Adjusted occlusal rim with adapted metal foil on top surface. A: Frontal view, B: Occlusal view.

  • Fig. 3 Establishing plane of occlusion of maxillary rim using occlusal plane analyzer. A: Frontal view, B: Profile view (Using superior point on tragus).

  • Fig. 4 Angle measuring device with modified protractor.

  • Fig. 5 A: Placement of stainless steel balls at the located points of tragus and ala, B: Adjusting subject with cephalostat for shooting lateral cephalograph.

  • Fig. 6 A: Points and planes used in study, B: Angles measured in study SFH, SOP, C: Angles measured in study MFH, MOP, D: Angles measured in study IFH, IOP.

  • Fig. 7 A: Tracing of lateral cephalograph of dentulous subject, B: Tracing of lateral cephalograph of edentulous subject.


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