Asian Journal of Medical and Clinical Sciences A cephalometric study to determine the relation of ala-tragus line with different posterior reference points from a standard occlusal plane in completely edentulous patients 3 D.B. Nandeeshwar, S. Ashwin Kumar, Sharad Acharya 1 Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere. 2 Vasan Dental Care Hospitals, 79/11, Sir Shanmugam road, R.S.Puram, Coimbatore, Tamilnadu 3 Department of Prosthodontics, Lecturer, Tatyasaheb kore dental college and research centre, Kolhapur. Abstract Original Article The purpose of this study is to evaluate the most parallel occlusal plane relationship between the Hamular Notch-Incisive Papilla Plane and 3 different Ala-Tragus lines established with three posterior reference point (superior, middle and, inferior border of tragus) and a common anterior reference point (inferior border of Ala of the nose). The study was conducted on 2 completely edentulous randomly selected subjects. Metallic balls were placed on the Ala-Tragus line at 3 different posterior reference points and a common anterior reference point and Hamular Notch, Incisive Papilla plane and right lateral cephalometric radiograph was made for each subject. Results indicated that Ala-Tragus line drawn with inferior point of tragus as posterior reference point occurred more frequently parallel to the standard occlusal plane. It was concluded that Ala-Tragus line with Inferior border of tragus as a posterior reference point can be utilized as a standard occlusal plane in completely edentulous patients. Key Words: Ala-Tragus line, Hamular Notch, Incisive papilla plane, posterior reference point, occlusal plane. Received : 1 Sep 212 Accepted : 2 Sep 212 Published: 3 Dec 212 INTRODUCTION n complete denture fabrication the prosthodontist is Iresponsible for restoring the natural esthetics and functional movements of mandible. According to contemporary concepts, the position of the occlusal plane in complete denture should be as close as possible to the position which was previously occupied by the occlusal plane of natural teeth. Establishment of the natural level of the occlusal plane in the edentulous mouth enables the normal function of cheek and tongue muscles and surrounding structures. Ala-Tragus line is one of the most commonly used occlusal reference plane for complete denture construction. But, the use of Ala-Tragus line to orient the occlusal plane has been a topic of debate. This controversy is primarily due to [1] disagreement on the exact point of reference for this line. Hamular Notch is the palpable notch formed by the junction of the maxilla and the pterygoid hamulus of the sphenoid bone. The incisive papilla is the elevation of soft tissue that [2] covers the foramen of the incisive or nasopalatine canal. Hamular notch-incisive papilla plane (HIP) has been proved by [3] various authors as a standard reference plane in complete denture construction. Hence a study was conducted to find the relationship of the Ala-tragus line established with three different posterior Address for correspondence* Dr. D.B. Nandeeshwar M.D.S., Professor and Head, Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere-5774. Email: nandeeshwardb@yahoo.com reference points, with the Hamular notch- Incisive Papilla plane (HIP). METHODOLOGY This cross-sectional, descriptive,clinical short study was conducted in Department of Prosthdontics, Bapuji Dental College and Hospital, Davangere. Materials used in the study Auto-Polymerizing acrylic resin,(rr Self cure acrylic repair material, Denstply India, Gurgaon, India). High fusing impression compound(dpi Pinnacle, Mumbai, India). Low fusing impression compound,(dpi Pinnacle Tracing sticks, Mumbai, India). Tray acrylic resin (MP Sai enterprises, Mumbai, India). Zinc Oxide eugenol impression material( DPI impression paste, India). Dental stone (VIP chemicals, India). Dental plaster (Kaldent, Kalabhai, India). Armamentarium used for the study Metallic balls - 3mm diameter, Cephalometric radiographic unit(orthoralix 92;Gendex dental systems, Milan, Italy), Acetate paper, Adhesive tapes, Indelible pencil, Cyanoacrylate glue, Scale, Protractor. Selection of Subjects: Data was collected from Lateral Cephalometric 111
Asian J Med Cli Sci Sep -Dec 212 Vol-1 Issue- 3 radiographs of 2 completely edentulous subjects. All the subjects were selected randomly from out patients, Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere. All the study subjects were informed and explained in detail about the nature of the research procedure in the language, which they understand and a written consent was obtained from every volunteer for the radiography and documenting for purposes of advancing dental education. Criteria for selection of subjects: Completely edentulous arches; Subjects free of oral diseases; No signs and symptoms of TMJ disorders; No history of Craniofacial surgery/trauma; No facial asymmetries; No bony abnormalities. Method followed to establish HIP: Dental stone casts of maxillary edentulous ridges of all subjects were made by conventional way after mucocompressive preliminary impression [4] and selective pressure final impression[5] after proper border moulding procedure was done. The centre of the incisive papilla and the deepest point in both hamular notches were marked on these stone cast with indelible pencil respectively. Three metallic spherical balls of diameter mm were attached on these points using cyanoacrylate glue. Then using autopolymerizing acrylic resin (RR self cure repair material, Gurgaon, India) temporary denture bases were constructed [3]. [Fig.I] Method followed to mark three different Ala-Tragus lines Fig.I Incisive papilla and Hamular Notch marked on master cast and Denture Base constructed with metallic balls in place Fig.II Anterior and Posterior reference points marked on the patient's skin In order to establish three different Ala-Tragus planes; one anterior reference point(inferior border of ala of nose) and three posterior reference points (i.e., points are superior, middle and inferior border of tragus of ear) were marked over each subject's skin using a marker pen[fig.ii]. Then using two adhesive stripes the 4 spherical metallic balls of 3mm diameter were fixed correspondingly to the reference points markings made over subject's skin [Fig.III]. Obtaining the Lateral cephalometric radiographs and Tracings Later, the maxillary denture bases(attached with metal balls) were inserted by checking the accuracy of fit to establish the HIP plane[fig.iv]. Right lateral cephalometric radiographs were made in subject's natural head position[fig.v] with an exposure of 74 kv for seconds and magnification of 1:1. Fig.III Metallic spherical balls placed on anterior and posterior reference points Cephalometric tracing for identifying the reference planes Finally, cephalometric tracings were done for all subjects on acetate paper for identification of the reference planes [Fig.VI]. By considering the centre of the metal balls, lines were drawn corresponding to the different Ala-Tragus lines and HIP plane. The following reference markings were made on the cephalometric tracings: S- Line joining the superior point of tragus to the anterior reference point M- Line joining the middle point of tragus to the anterior reference point, I- Line joining the inferior point of tragus to the anterior reference point, A-Ala of the nose, H- Hamular Notch IP- Incisive Papilla. Fig.IV Intraoral photograph showing denture bases with metallic balls attached over incisive papilla and hamular notch in either side. 112
Asian J Med Cli Sci Sep -Dec 212 Vol-1 Issue- 3 Fig.V Lateral cephalometric radiograph showing radioopaque metallic balls in incisive papilla, hamular notch, ala of nose and superior, middle and inferior border of tragus. Fig.VI Cephalometric tracing done and following points were marked. S- Line joining the superior point of tragus to the anterior reference point, M- Line joining the middle point of tragus to the anterior reference point, I- Line joining the inferior point of tragus to the anterior reference point, Ala of the nose, H- Hamular Notch,IP- Incisive Papilla. TABLE-1. Master chart showing the difference between D2 and D1 for lines I, M and S in mm from the measurements obtained from the cephalometric tracings, including the significance value calculated using the Oneway ANOVA test for 2 subjects. Study Subjects PATIENT 1 PATIENT 2 PATIENT 3 PATIENT 4 PATIENT 5 PATIENT 6 PATIENT 7 PATIENT 8 PATIENT 9 PATIENT 1 PATIENT 11 PATIENT 12 PATIENT 13 PATIENT 14 PATIENT 15 PATIENT 16 PATIENT 17 PATIENT 18 PATIENT 19 PATIENT 2 line I (mm) -.2 - -.5.1 -.5 -.2.2.2.5 - -.1 -.65 - -.6 line M (mm).25.6.4.25.15 1.2.55.5.75.5 -.25 -.15 - line S ( mm).4.9.9.75.5 1.55.7 1.1.7.6.1 1.15.2 * P value calculated using Oneway ANOVA P<.1 Highly significant P=.5 Significant P>.5 Not significant 113 F Value 17.494 Significance*.1
Asian J Med Cli Sci Sep -Dec 212 Vol-1 Issue- 3 Measuring the parallelism between the planes Two lines L and L were drawn perpendicular to HIP line. The line L was drawn anteriorly from the point I and L was 1 P 2 drawn posteriorly from the point H. The points where the anterior line L meets the line I,M,S are I,M,S respectively. Similarly, 1 1 1 1 the points where the posterior line L meets the line I,M,S are 2 I,M,S respectively. Two parallel lines should measure the same 2 2 2 distance at any two different points, from a standard reference line. Based on this idea, parallelism of lines was evaluated by measuring the distance in mm between the lines I,M and S and HIP at two different points. Then the distance between the points I and I and H and I were calculated as D and D respectively. P The difference between D and D was calculated. Similarly, the D and D values were obtained for the lines M and S. Now the differences obtained for the lines I, M and S were compared and the line with least difference was considered to be the most parallel line to the HIP. The 'p' value of.5 was considered to be significant. Statistical analysis was done using Oneway Anova followed by Post-Hoc Tukey test. RESULTS [Table-1] shows the master chart showing the difference between D 2 and D 1 for lines I,M and S in mm from the measurements obtained from the cephalometric tracings, including the significance value calculated using the Oneway ANOVA test for 2 subjects. The range of the values obtained for difference between D1 and D 2 for line I, is to -.65. The range of the values obtained for difference between D1 and D 2 for line M, is.75 to -. The range of the values obtained for difference between D 1 and D 2 for line S, is 1.55 to. Results calculated using Oneway ANOVA showed that P value <.1 which is highly significant. Post-Hoc tests showed the deviation of Superior line(s) was greatest, followed by Middle line (M) and least amount of deviation in relation to Inferior line (I). Overall results indicate Inferior line (I), line joining the inferior point of tragus to the anterior reference point, least deviates from the HIP line in majority of the subjects. This implies Line joining Ala of nose and Inferior border of tragus is more parallel to HIP. Middle Line (M) deviates more frequently than the inferior from the HIP and the Superior line (S) the most in these subjects. DISCUSSION 2 randomly selected edentulous subjects selected age ranged between 38 years and 7 years (4 subjects were aged between 38-5 years, 1 subjects aged between 5-6 years and 6 subjects between 6-7 years). Out of which 12 subjects were males and 8 were female. According to glossary of prosthodontic terms, Ala- Tragus is a line running from inferior border of ala to some defined point on the tragus of the ear, usually considered to the tip [2] of the tragus. Various authors have given their own definition for Ala-Tragus Line. According to Spartley, it is a line joining [6] centre of ala to centre of tragus. According to Van Niekerk conclued from his study that Ala-Tragus line determined using inferior point of tragus, could be used as a landmark for orienting [7] the maxillary occlusal plane. Boucher defines Ala-Tragus line as an imaginary line that runs from the inferior border of nose to the [4] superior border of the tragus of the ear. According to Ismail and Bowman, it is a line passing from Ala of nose to the centre of the [8] tragus Ḣamular notch, Incisive papilla plane (HIP) has been proved by various authors as a standard reference plane in [9-12] complete denture construction. Hence this plane was taken as a standard plane for comparison. Thus relationship Ala tragus line with 3 different posterior reference points with the HIP was established in this study. In majority of subjects (16 out of 2) inferior line (I) was parallel to the HIP. Middle(M) and Superior(S) were found parallel in 2 subjects each. Out of the subjects, Ala Tragus line drawn with inferior point as posterior reference point, occured more frequently parallel in both male and females subjects. Also it was more frequently parallel to inferior line in all the age groups included in the study 38-5, 5-6 and 6-7 years. Clinical Implications of the study 1) This study helps the clinician to overcome the confusion in marking the posterior reference point while establishing the ala tragus line during jaw relation procedures for complete denture patients. 2) Utilizing the ala tragus line with inferior border of tragus as an occlusal plane also gives the advantage of availability of more space for arrangement of maxillary posterior teeth. Limitations of the study 1) The study was conducted only in a small population, considering only one geographical location and hence the results may vary with morphological changes(in facial/skeletal features) among geographically distributed people. 2) The variations due to gender differences in occlusal plane were not considered in the present study. 3) The anterio-posterior tilt of the occlusal plane was not evaluated in the study. Scope for further research 1) Further studies are required on occlusal plane considering the wider geographical distribution of population and among different racial subgroups. 2) A software program to evaluate the angle of deviation from the standard reference plane can be developed for accurate measurements. 3) A more specific radioopaque material, like gutta percha can be used to precise location of the reference marks. 4) The changes in the occlusal plane among various age groups can be considered in future research. CONCLUSION Within the limits of the study, it can be said that Ala Tragus line drawn with Inferior border of tragus as posterior reference point is more frequently parallel to standard occlusal plane among the study subjects. Ala Tragus line with Inferior border of tragus as a posterior reference point can be utilized as a standard occlusal plane in completely edentulous patients. 114
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