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

Abstract

PURPOSEThe 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 METHODSThe 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.RESULTSThe 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.CONCLUSIONThe inferior point marked on tragus is the most appropriate point for marking ala-tragus line.

Position of Occlusal Plane in Dentate Patients with Reference to the Ala‐Tragal Line Using a Custom‐Made Occlusal Plane Analyzer

“…The results of this study are in agreement with a study done by van Niekerk et al, 35 and many others including Rostamkhani et al, 46 Sharifi and Rostamkhani, 47 Hindocha et al, 48 Chaturvedi and Thombare, 49 Hartono, 51 and Kumar et al 52 who reported that the occlusal plane was parallel to a line joining the inferior part of the ala and inferior part of the tragus, and that these landmarks should be used to orient occlusal planes in edentulous patients during complete denture fabrication.…”

“…In the past, research has been carried out by various authors to determine the relationship between the ala‐tragal line and occlusal plane. Some of these studies were cephalometric studies (Rostamkhani et al, Sharifi and Rostamkhani, Hindocha et al, Chaturvedi and Thombare, Al Quran et al), some used the modified Trubyte occlusal plane plate (Hartono) and photography (Kumar et al and Sadr and Sadr), and some used the custom‐made occlusal plane analyzer (Shigli et al, Gupta and Singh).…”

The differences in parallelism between ala-tragus line and occlusal plane of down syndrome and normal individuals

“…The angular values between the occlusal plane and the ala-tragus line (AT1-OP; AT2-OP; and AT3-OP) are not exactly 0°, both in normal individuals and in people with down syndrome. The results of this study are in accordance with the results of Nayar et al, 9 Kumar et al, 10 Chaturvedi et al, 15 and Dean et al 16 in that there is no angle value right at 0°. The results of this study show that the ala-tragus line, which is the most parallel to the occlusal plane in a normal individual, is the inferior Al-tragus line (AT3).…”

“…This is consistent with the finding of the previous researches stating that the line from the lower border of the ala nose to the inferior tragus is the most parallel ala-tragus line to the occlusal plane and can be used as a guide to determine the parallelism of the occlusal orientation plane in dentures fabrication. 9,10,15,16 The results of the Venugopalan et al, 11 showed that the occlusal plane in normal individuals with class I and III malocclusions is parallel with the line from the lower border of ala nose to the inferior border of tragus, while the occlusal plane in normal individuals with class II malocclusion is parallel with the line from the lower border of ala nose to the middle border of the tragus. Occlusion classifications in this research were not considered in the research criteria.…”

“…The inferior border of the ala nose and ear tragus is an extra oral landmark that can be used as a reference plane to determine the occlusal plane because both are relatively constant and not affected by the aging process. The majority of the previous study showed that the occlusal plane was parallel to the inferior ala-tragus line [9][10][11][12]15,16 but some other studies demonstrated that the occlusal plane is parallel to the superior alatragus line 18 and middle. 11,12,17,19,24 The occlusal plane parallelism should be determined not only from one anatomical landmark but also from a combination of other anatomical landmarks.…”