BETWEEN THE OCCLUSAL PLANE, ALA-TRAGAL LINE &
CAMPER’S PLANE IN DENTULOUS SUBJECTS IN THREE DIFFERENT ANATOMICAL HEAD FORMS
A Dissertation submitted to
THE TAMILNADU DR. MGR MEDICAL UNIVERSITY
In partial fulfillment of the requirements for the degree of
MASTER OF DENTAL SURGERY
(BRANCH – I)
(PROSTHODONTICS AND CROWN & BRIDGE)
2014 – 2017
This is to certify that Dr. P. A. MANOJ KUMAR, Post Graduate student (2014 - 2017) in the Department of Prosthodontics and Crown and Bridge, has done this dissertation titled “A CEPHALOMETRIC STUDY ON THE RELATIONSHIP BETWEEN THE OCCLUSAL PLANE, ALA- TRAGAL LINE AND CAMPER’S PLANE IN DENTULOUS SUBJECTS IN THREE DIFFERENT ANATOMICAL HEAD FORMS ” under my direct guidance and supervision in partial fulfillment of the regulations laid down by The Tamil Nadu Dr. M.G.R. Medical University, Guindy, Chennai – 32 for M.D.S. in Prosthodontics and Crown & Bridge (Branch I) Degree Examination.
Guided by Head of the institution
Prof. Dr.C.SABARIGIRINATHAN.M.D.S. Prof. Dr.B.SARAVANAN.M.D.S.,Ph.D.
Head of the Department PRINCIPAL
Department of Prosthodontics, Tamil Nadu Govt Dental College Tamilnadu Govt Dental College & and Hospital, Chennai - 600 003.
Hospital, Chennai – 600 003.
I, Dr. P. A. MANOJ KUMAR, do hereby declare that the dissertation titled
“A CEPHALOMETRIC STUDY ON THE RELATIONSHIP BETWEEN THE OCCLUSAL PLANE, ALA-TRAGAL LINE AND CAMPER’S PLANE IN DENTULOUS SUBJECTS IN THREE DIFFERENT ANATOMICAL HEAD FORMS” was done in the Department of Prosthodontics, Tamil Nadu Government Dental College & Hospital, Chennai 600 003. I have utilized the facilities provided in the Government Dental College for the study in partial fulfilment of the requirements for the degree of Master of Dental Surgery in the speciality of Prosthodontics and Crown & Bridge (Branch I) during the course period 2014-2017 under the conceptualization and guidance of my dissertation guide, PROF. Dr. C. SABARIGIRINATHAN.MDS.,
I declare that no part of the dissertation will be utilized for gaining financial assistance for research or other promotions without obtaining prior permission from the Tamil Nadu Government Dental College & Hospital.
I also declare that no part of this work will be published either in the print or electronic media except with those who have been actively involved in this dissertation work and I firmly affirm that the right to preserve or publish this work rests solely with the prior permission of the Principal, Tamil Nadu Government Dental College &
Hospital, Chennai 600 003, but with the vested right that I shall be cited as the author(s).
Signature of the PG student Signature of the HOD
Signature of the Head of the Institution
This agreement herein after the “Agreement” is entered into on this day, December 23, 2016 between the Tamil Nadu Government Dental College and Hospital represented by its Principal having address at Tamil Nadu Government Dental College and Hospital, Chennai-3, (hereafter referred to as, ‘the College’)
And
Dr. C. SABARIGIRINATHAN,M.D.S., aged 50 years working as Professor and Head of Department of Prosthodontics and crown and bridge at Tamil Nadu Government Dental College and Hospital, Chennai-3 having residence address at E/32, Anna Nagar (East), Chennai- 102 (herein after referred to as the ‘Researcher and Principal investigator’)
And
Dr. P. A. MANOJ KUMAR aged 26 years currently studying as Post Graduate student in the Department of Prosthodontics and Crown & Bridge, Tamil Nadu Government Dental College and Hospital, Chennai-3 (herein after referred to as the
‘PG/Research student and Co- investigator’).
Whereas the ‘PG/Research student as part of her curriculum undertakes to research on the study titled “A CEPHALOMETRIC STUDY ON THE RELATIONSHIP BETWEEN THE OCCLUSAL PLANE, ALA-TRAGAL LINE AND CAMPER’S PLANE IN DENTULOUS SUBJECTS IN THREE DIFFERENT ANATOMICAL HEAD FORMS” for which purpose the Researcher and Principal investigator shall act as Principal investigator and the College shall provide the requisite infrastructure based on availability and also provide facility to the PG/Research student as to the extent possible as a Co-investigator
Whereas the parties, by this agreement have mutually agreed to the various issues including in particular the copyright and confidentiality issues that arise in this regard. Now this agreement witness as follows:
1. The parties agree that all the research material and ownership therein shall become the vested right of the college, including in particular all the copyright in the literature including the study, research and all other related papers.
2. To the extent that the College has legal right to do go, shall grant to licence or assign the copyright do vested with it for medical and/or commercial usage of interested persons/entities subject to a reasonable terms/conditions including royalty as deemed by the college.
circumstances deal with the copyright, confidential information and know how generated during the course of research/study in any manner whatsoever, while shall sole vest with the manner whatsoever and for any purpose without the express written consent of the college.
5. All expenses pertaining to the research shall be decided upon by the Principal investigator/Co-investigator or borne sole by the PG/Research student (Co- investigator).
6. The College shall provide all infrastructure and access facilities within and in other institutes to the extent possible. This includes patient interactions, introductory letters, recommendation letters and such other acts required in this regard.
7. The principal investigator shall suitably guide the student research right from selection of the research topic and area till its completion. However the selection and conduct of research, topic and area research by the student researcher under guidance from the principal investigator shall be subject to the prior approval, recommendations and comments of the Ethical Committee of the college constituted for this purpose.
8. It is agreed that as regards other aspects not covered under this agreement, but which pertain to the research undertaken by the Student Researcher, under guidance from the Principal Investigator, the decision of the college shall be binding and final.
9. If any dispute arises as to the matters related or connected to this agreement herein, it shall be referred to arbitration in accordance with the provisions of the Arbitration and Conciliation Act, 1996.
In witness whereof the parties herein above mentioned have on this the day month and year herein above mentioned set their hands to this agreement in the presence of the following two witnesses.
College represented by its Principal Guide Witnesses PG Student 1.
2.
I am extremely thankful to my chief Dr. C. SABARIGIRINATHAN, M.D.S., Professor and Head of the Department and my Guide, Department of prosthodontics, Tamil Nadu Government Dental College and Hospital, Chennai, I consider it my utmost privilege and honor to express my most sincere and heartfelt gratitude to my esteemed chief for his wholehearted support, constant guidance, help, encouragement, valuable suggestions and support he has rendered at various stages of the dissertation. I also thank him for the valuable guidance; he has given throughout my post graduation.
Without his immense help this dissertation would not have come out in a befitting manner.
My sincere thanks to Prof. Dr. B. SARAVANAN, M.D.S., Ph.D. Principal, Tamil Nadu Government Dental College and Hospital for his kind help, valuable suggestions in this study and permitting me to use all the facilities in the institution. I also thank him for the valuable guidance he has given throughout the period of my post graduate course.
My sincere thanks to Dr. A. MEENAKSHI, M.D.S., Professor, Department of Prosthodontics, Tamilnadu Government Dental College and Hospital for her valuable guidance throughout my study.
My sincere thanks to Dr. K. VINAYAGAVEL, M.D.S., Professor, Department of Prosthodontics, Tamilnadu Government Dental College and Hospital for his valuable guidance throughout my study.
I am thankful to Dr. G. Sriramaprabu, M.D.S., Associate Professor for guiding and helping me at different stages of this study.
Dr. M. Rajakumar, M.D.S., for helping me at different stages of this study.
I am thankful to Assistant Professors, Dr.T.Jeyanthikumari, M.D.S., Dr.S.Vinayagam,M.D.S., Dr.J.Gandhimathi,M.D.S., Dr.V.Parimala,M.D.S., Dr.M.Kanmani,M.D.S., Dr.V.Harishnath,M.D.S., Dr.Preethichandran,M.D.S., and Dr.SivaSakthiKumar,M.D.S., for helping me at different stages of this study.
I thank Dr. Mohammed Junaith, M.D.S., for helping me, to carry out the statistical analysis of the various test results.
My special thanks to My Parents, sister and my close Friends for their constant support and motivation.
I owe my sincere thanks to all my Colleagues, Senior and Junior postgraduates in the department for their constant encouragement and timely help.
Above all I thank the LORD GOD ALMIGHTY for giving me the strength and courage to complete this monumental task.
SL NO. TITLE PAGE NO.
1. INTRODUCTION 1-4
2. AIM AND OBJECTIVES 5
3. REVIEW OF LITERATURE 6-23
4. MATERIALS AND METHODS 24-34
5. RESULTS 35-55
6. DISCUSSION 56-65
7. SUMMARY & CONCLUSION 66-67
9. BIBLIOGRAPHY 68-75
8. ANNEXURE 76-80
SL No. ABBREVIATION EXPANSION
1 mm Millimeter
2 cm Centimeter
3 ft Feet
4 MDM Monitor displayed method
5 HFM Hard copied film based method
6 ANOVA Analysis of variance.
7 DICOM Digital Imaging and Communication in Medicine
8 HIP Hamular Notch-Incisive Papilla plane.
9 ANS Anterior Nasal Spine
10 PNS Posterior Nasal Spine
11 FHP Frankfort Horizontal Plane
SL.NO TITLE
1 Armamentarium for Examination 2 Spreading Caliper
3 Different Anatomical Head Forms 3A Brachycephalic Male
3B Brachycephalic Female 3C Mesocephalic Male 3D Mesocephalic Female 3E Dolichocephalic Male 3F Dolichocephalic Female
4 Measuring Head Width using Spreading Caliper 5 Measuring Head Length using Spreading Caliper
6 1mm Metallic balls adhered to the superior, middle and inferior border of tragus of ear and ala of nose
7 Subject positioned in Cephalostat for Lateral Cephalogram
8 Brachycephalic – Male
8A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
8B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 8C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line
Sella – Gnathion line and Inferior Ala-Tragal Line 8E Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Camper’s Plane
8F Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Occlusal Plane
9 Brachycephalic - Female
9A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
9B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 9C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line 9D Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Inferior Ala-Tragal Line 9E Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Camper’s Plane
9F Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Occlusal Plane
10 Mesocephalic - Male
10A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
10B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 10C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line 10D Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Inferior Ala-Tragal Line
Sella – Gnathion line and Camper’s Plane
10F Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Occlusal Plane
11 Mesocephalic - Female
11A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
11B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 11C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line 11D Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Inferior Ala-Tragal Line 11E Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Camper’s Plane
11F Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Occlusal Plane
12 Dolichocephalic - Male
12A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
12B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 12C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line 12D Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Inferior Ala-Tragal Line 12E Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Camper’s Plane
Sella – Gnathion line and Occlusal Plane 13 Dolichocephalic - Female
13A Lateral Cephalogram shows Radiopaque marks near Tragus of ear & Ala of nose
13B Lateral Cephalogram shows Angle formed between the Sella – Gnathion line and Superior Ala-Tragal Line 13C Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Middle Ala-Tragal Line 13D Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Inferior Ala-Tragal Line 13E Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Camper’s Plane
13F Lateral Cephalogram shows Angle formed between the
Sella – Gnathion line and Occlusal Plane
S. No TITLE Page No
1. Comparison of angle values in Brachycephalic subjects
between males and females by Group statistics. 36
2. Comparison of angle values in Mesocephalic subjects between
males and females by Group statistics. 36
3. Comparison of angle values in Dolichocephalic subjects
between males and females by Group statistics. 36
4. Inter group comparison of different angles in Brachycephalic
subjects between males and females by Independent samples test. 37
5. Inter group comparison of different angles in Mesocephalic
subjects between males and females by Independent samples test. 37
6. Inter group comparison of different angles in Dolichocephalic
subjects between males and females by Independent samples test. 38
7. Comparison of angle values in different head forms for the Male
Subjects by Descriptive Statistics. 38
8. Comparison of angle values in different head forms for the
Female Subjects by Descriptive Statistics. 39
9. One way ANOVA test to compare the different angles in Male
subjects in between groups and within group. 40
10. One way ANOVA test to compare the different angles in Female
subjects in between groups and within group. 40
Hoc test in Male Subjects .
12.
Multiple comparison between groups using Tukey HSD Post – Hoc test in Female subjects.
42
13.
Comparison of three different Ala tragal line, Occlusal plane and Campers plane in Brachycephalic male and female subjects by Descriptive statistics.
42
14.
Comparison of three different Ala tragal line, Occlusal plane and Campers plane in Mesocephalic male and female subjects by Descriptive statistics.
43
15.
Comparison of three different Ala tragal line, Occlusal plane and Campers plane in Dolichocephalic male and female subjects by Descriptive statistics.
44
16.
One way ANOVA test to compare the angles of different anatomical head forms in Male Subjects in between groups and within group.
44
17.
One way ANOVA test to compare the angles of different anatomical head forms in Female Subjects in between groups and within group.
45
18.
Multiple comparison between three different Ala tragal line, Campers plane and Occlusal plane in Brachycephalic subjects by Tukey HSD Post Hoc test.
45
19.
Multiple comparison between three different Ala tragal line, Campers plane and Occlusal plane in Mesocephalic subjects by Tukey HSD Post Hoc test.
46
20.
Multiple comparison between three different Ala tragal line, Campers plane and Occlusal plane in Dolichocephalic subjects by Tukey HSD Post Hoc test.
46
LIST OF BAR DIAGRAMS
S. No TITLE
Fig.1 Comparison of Mean angle values between male and female in Brachycephalic subjects.
Fig.2 Comparison of Mean angle values between males and females in Mesocephalic subjects.
Fig.3 Comparison of Mean angle values between males and females in Dolichocephalic subjects.
Fig.4 Comparison of Mean Angle values between three different anatomical head forms in Male subjects.
Fig.5 Comparison of Mean Angle values between three different anatomical head forms in Female subjects.
Fig.6 Comparison of Mean Angle values of different angles in Brachycephalic subjects.
Fig.7 Comparison of Mean Angle values of different angles in Mesocephalic subjects.
Fig.8 Comparison of Mean Angle values of different angles in Dolichocephalic subjects.
Introduction: Occlusal plane orientation is one of the most vital clinical procedures in rehabilitating edentulous patients with complete denture prosthesis because it will have a direct effect on aesthetics, function and denture stability. The use of Ala-tragal line still remains controversial. It is mainly due to the disagreement, as to which point on the tragus whether superior, middle or inferior point to be used as exact point of reference to establish the Ala-tragal line in various situations. The present study was undertaken to determine the relative parallelism of the different Ala-Tragal lines and Camper’s plane to the occlusal plane in dentulous subjects having three different anatomical head forms using landmarks on a lateral cephalograms.
Keywords: Occlusal plane, Ala-tragal line, Camper’s plane, Lateral cephalograms, Complete denture, Anatomical head form.
Aim: To determine the most appropriate point on tragus to be used as a posterior reference point at the time of marking ala tragus line while establishing occlusal plane in three different anatomical head forms.
Materials and methods: 60 Dentate subjects were selected as per predetermined criteria. They were grouped according to their cephalic index values into three groups as Brachycephalic, Mesocephalic and Dolichocephalic head form. Further they were subdivided into male and female. Markings with Radiopaque marker of 1mm diameter were adhered against the superior, middle and inferior border of the tragus and against the lower border of ala of the nose. Lateral cephalograms were obtained for all the subjects. Tracings were performed digitally for all of these radiographs using DICOM software.
Results: In Brachycephalic male subjects the middle ala-tragal line was found to be relatively parallel to the occlusal plane than the camper’s plane. In brachycephalic female subjects the middle ala tragal line was found to be relatively parallel to the occlusal plane and there is no relationship between the camper’s plane and occlusal plane and camper’s plane and three different ala-tragal lines. In Mesocephalic male subjects the inferior ala-tragal line was found to be relatively parallel to the occlusal plane and there is no relationship between the camper’s plane and occlusal plane and camper’s plane and three different ala-tragal lines. In Mesocephalic female subjects the superior ala-tragal line was found to be relatively parallel to the occlusal plane than the camper’s plane. In Dolichocephalic male subjects the middle ala-tragal line was found to be relatively parallel to the occlusal plane and there is no relationship between the camper’s plane and occlusal plane and camper’s plane and three different ala-tragal lines. In Dolichocephalic female subjects the inferior ala-tragal line was found to be relatively parallel to the occlusal plane than the camper’s plane.
Conclusion: For Brachycephalic male and female subjects the posterior reference point for establishing the ala-tragal line was found to be middle part of the tragus of ear. For Mesocephalic male subjects the posterior reference point for establishing the ala-tragal line was found to be inferior border and for female it was superior border of the tragus of ear. For Dolichocephalic male subjects the posterior reference point for establishing the ala-tragal line was found to be middle part and for female it was inferior border of the tragus of ear.
1
INTRODUCTION
Occlusal plane orientation is one of the most vital clinical procedures in rehabilitating edentulous patients because it will have a direct effect on aesthetics, function and denture stability. Hence it should be recreated as identical as possible to the occlusal plane of missing natural teeth1. For normal basic functioning of the stomatognathic system especially the functions of mastication and articulation the specifically formed occlusal complex becomes the foundation2.
By establishing the occlusal plane to its natural level in the edentulous mouth it aids in normal function of cheek and tongue muscles and surrounding structures3. Improperly orienting the occlusal plane will affect the interaction between tongue and buccinator muscle which results in tongue biting and food collection between the sulcus and cheeck4.
The Glossary of Prosthodontics term – 8 defines occlusal plane as “the average plane established by the incisal and occlusal surface of the teeth.” Generally, it is not a plane but represents the planar mean of the curvatures of these surfaces5. Even though orienting occlusal plane is under the control of the clinician several factors has to be taken into considerations like esthetics, phonetics and biomechanical factors. Various guidelines have been postulated for orienting the occlusal plane and many clinicians have used a number of intra oral and extra oral landmarks to determine and orient the occlusal plane in the process of fabricating complete dentures6.
Occlusal plane can be oriented to coincide with intra oral landmarks like the lower one-third of the retro molar pad7 or lateral border of the tongue8. Other
2
suggested theories include occlusal plane should be at a distance of 2.56mm below the parotid papilla, occlusal plane should be 1.37mm above the commissure of lip, occlusal plane can be established 0.94mm above the buccinator grooves9 occlusal plane can be established parallel to Hamular – Incisive papilla plane10 and one of the newer concepts of establishing occlusal plane suggest placing it parallel to and mid-way between the residual ridges11.
The suggested Extra oral landmarks are anteriorly the occlusal plane is established according to aesthetics and phonetics requirements of patient12. It should be parallel to inter pupillary line and 1-3 mm below the resting upper lip. In natural smile, the incisal tips follow the curve of the lower lip4.
Posteriorly the occlusal plane should be parallel to the Ala – Tragus line12. According to GPT-7 Ala – Tragus line is defined as a “line running from the inferior border of the ala of the nose to some defined point on the tragus of the ear usually considered to be the tip of the tragus5. Ala – Tragus line was postulated in the year 1780 by the Dutch Anatomist Peter Camper. It is most commonly used as a third point on the opposing tragus for the purpose of establishing the ala tragus line13. According to GPT- 8 Camper’s plane is defined as “A plane established by the inferior border of the ala of the nose (or the average between the two) and the superior border of the tragus of each ear: a plane passing from the acanthion to the center of each bony external auditory meatus; called also acanthion- external auditory meatus plane”5.
Even though the most commonly used extra oral landmark to establish the posterior occlusal plane in edentulous patients is ala – tragus line, its use still remains controversial. It is mainly due to the disagreement, as to which point on the
3
tragus whether superior, middle or inferior point to be used as exact point of reference to establish the ala – tragus line in various situations14.
Clapp15in 1910 was the first to relate ala – tragus line to occlusal plane.
Lloyd16, Miller17 and Boucher18 define it as a line running from the inferior border of the ala of the nose to the superior border of the tragus of ear. Trapozzano19,20 used the upper border of the tragus as a reference point. Ismail and Bowman21 describe it as a line passing from the ala of the nose to the center of the tragus of external auditory meatus.
A study carried out by Karkazi and Polyzois22 advocates the use of the inferior border of tragus as a posterior landmark. Their cephalometric analysis concluded that the ala – tragus line extending from the lower border of the ala of the nose to the inferior border of the external auditory meatus represents the closest relationship to the natural occlusal plane23,24.
However, ala – tragal line is the most controversial extra oral landmark in occlusal plane orientation, it is reliable as both its end do not change with age25,26. Cephalometric analysis is an important diagnostic tool which is widely used in the fields of orthodontics and dental research, in prosthodontics the importance of cephalometric lies in the ability to recreate or reestablish the spatial position of lost structure27.
It can be used to identify predictable relationship between the teeth and other cranial landmarks that are not subjected to post extraction changes. Hence a correlation will be there between the plane of occlusion of edentulous patients and stable cranial landmarks. If scientifically determined such a correlation can be applied to determine the plane of occlusion in completely edentulous patients28.
4
Also there has been no studies indicating the method of locating the proper position on the tragus while establishing the occlusal plane in case of various anatomical head forms. Hence the present study was undertaken to determine the relative parallelism of the different Ala – Tragal lines and Camper’s plane to the occlusal plane in dentulous subjects with various anatomical head forms.
In this clinical study occlusal plane is established by placing a 1 mm metallic balls in the inferior border of the ala of the nose and three 1 mm metallic balls in the superior, middle and inferior border of the tragus of the ear respectively were used as a reference points. And later through the digital lateral cephalometric radiographs and PHILIPS DICOM SOFTWARE the relative parallelism between the occlusal plane, campers plane and three different Ala–tragal line in dentulous subjects having three different anatomical head forms were calculated.
The purpose of this study was to determine the most reliable ala – tragal line as a guide for the orientation of the occlusal plane in dentulous subjects having three different anatomical head forms.
5
AIM AND OBJECTIVES
AIM:
The aim of the study is to determine the most appropriate point on tragus to be used as a posterior reference point at the time of marking ala tragal line while establishing occlusal plane in three different anatomical head forms.
OBJECTIVES:
1. To study and observe the relationship between the occlusal plane to the different variants of the ala-tragal lines in three different anatomical head forms by cephalometric analysis using Dicom software
2. To study and observe the relationship between the occlusal plane to the Camper’s plane in three different anatomical head forms by cephalometric analysis using Dicom software.
3. To determine the best possible soft tissue indices, by which the inclination of the occlusal plane in complete dentures could be established.
6
REVIEW OF LITERATURE
Sloane, Cook, L’Estrange & Vig (1953)29 They conducted a study on 26 dry skulls and they concluded that the occlusal plane is strongly correlated to a line extending from the anterior nasal spine and hamular notch, which also represents the skeletal base of maxilla. Later using cephalometric method, they found that the angulation of the occlusal plane to the maxillary one is related to the length and height of the maxillomandibular space.
Ismail Y H & Bowman J F (1968)21 Conducted a study in each subject to compare the prosthetically established occlusal plane with the one that existed before extraction of the teeth. In 20 subjects they took lateral cephalograms with their teeth in centric occlusion. Denture construction was done using a standardized technique following extraction of teeth. They determined occlusal plane tentatively. Maxillary occlusal rim height in the anterior region was placed 1-3mm below the resting upper lip and made parallel to the ala-tragus line posteriorly. He told camper’s line is a anthropologic measurement projected to the living head as a line extending from the ala of the nose to the center of the tragus of the ear. During wax trial the occlusal plane was modified anteriorly to meet the esthetic requirements and posteriorly up to the middle third of the retromolar pad. After the complete dentures were placed again lateral cephalograms were made.
Lundqiust D.O Luther W.W (1970)9 He studied the relationship between the occlusal plane and various intra oral soft tissue landmarks in subjects with ideal occlusions in natural teeth. The various soft tissue landmarks that are used were parotid papilla, retromolar pad, commissar of lips and buccinator groove. He concluded that a strong correlation was there between the occlusal plane, commissar of lips and
7
buccinators groove exist. The vestibular impression technique for determining the occlusal plane in edentulous patient was introduced by him.
Javid NS (1974)30 He studied the use of aluminum device in the shape of J called J plane to establish occlusal plane along with fox plane. J plane was used to orient the anterior part of occlusal rim by placing it in the nasion so that its long axis is parallel to the inter papillary line and later fox plane was adjusted parallel to J plane. For orientation of posterior part of occlusal rim, the J plane was oriented under the ala of the nose with its narrow part to the middle of tragus.
L’E Strange P R (1975)31 He did a study comparing the occlusal plane in edentulous and dentulous subjects and concluded that a close angular affinity present between the maxillary plane and occlusal plane in both edentulous and dentulous subjects. A significant correlation was found between the inclination of maxillary plane and maxillo - mandibular space to occlusal plane in dentulous subject group. In short and high type of maxillo – mandibular space the occlusal plane was more steeply angulated to maxillary plane. In long and low type of maxillo – mandibular space the occlusal plane was more parallel to maxillary plane.
Donald H. Enlow, Henry J. Bianco, Andstephen Ek Lund(1975)32 They did a study on the resorption pattern of mandible in edentulous subjects and concluded that unlike the child’s mandible, the posterior border of the ramus is more prone for resorption hence the antero posterior dimension of the mandibular ramus is reduced and narrowed along with the resorption of anterior border of ramus.
Spartely M H (1980)33 He concluded in his article that occlusal plane is parallel to line that runs from the center of the ala of nose to the center of tragus.
8
Van Neikerk FW, Miller (1985)34 In complete denture prosthodontics a study was conducted on ala tragus line. In this study without considering the ala tragal line occlusal plane was established. Then it was concluded that while establishing the maxillary occlusal plane inferior part of tragus can be used as a posterior reference point.
Monteith, Chow et al (1985)35 They found the Po Na ANS angle is related inversely to the Frankfort - occlusal plane angle. A strong correlation ( r2 = 76%, P< 0.005 ) between the two angles was found when they subjected their results to a regression &
correlation analysis. They repeated their measurements on a sample of 32 cantonese men and they reported a low coefficient of determination r2 = 26%, “ a value that is essentially useless in a predictive application”. According to their results, none of the three mentioned parameters ( ANS-PNS, Cook’s plane and Po Na ANS ) could be used to determine the occlusal plane angulation through a regression formula.
O W Rkk Djeng S K (1990)36 Using lateral cephalometric radiograph a comparative study in 28 chinese – Singaporean dentulous adults was conducted on orientation of occlusal plane. The relationship between various cranio-facial reference lines to maxillary occlusal plane was studied. They concluded that the occlusal plane inclination was significantly different between Chinese adults and Singaporean white adults. The Frankfort horizontal plane was not considered as a standard reference plane because its inclination varies and was found to be misleading in Chinese- Singaporean white adults.
Neill Nairn (1991)37 According to him to fulfill the esthetic requirement anterior maxillary occlusal rim was adjusted accordingly and posterior part of maxillary occlusal rim is made parallel to ala-tragal line. A pictorial representation of ala-tragal
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line was made in that it extends from the middle of the tragus to the lower border of ala of the nose.
Okuda (1991)38 He studied the relationship of the stomatognathic system and oro- facial morphology to the occlusal plane orientation. In 30 normal adults cephalograms were taken and electromyogram of anterior and masseter were recorded during chewing, clenching and tapping. Correlation analysis were performed later. A strong relationship between orofacial morphology and occlusal plane was showed in the results. It was finalized that the important factor which harmonizes the morphology and the function of stomatognathic system is the orientation of occlusal plane.
Bates, Huggett, Stafford (1991)39 They concluded that the patients lip length was a major factor in establishing the lower border of the maxillary occlusal rim anteriorly which represents the lower edge of the incisors. In normal individuals ideally it should be 1mm below the resting lip position. Posteriorly made parallel to the camper’s plane.
Rosen (1993)40 He conducted a study on aesthetic enhancement in mandibular micrognathia and occlusal plane rotation. In extreme mandibular micrognathia patients the mandibular ramus was deficient vertically and mandibular bodies was deficient sagittally. Hence the posterior facial height was decreased and there is a increase in anterior facial height to compensate it along with steep occlusal and mandibular plane.
Eleven patients having micrognathic mandible undergone surgery to correct the rotation of occlusal plane to its normal orientation relative to Frankfort horizontal plane.
Chemello. PD (1994)41 he conducted a study on altering the occlusal palne orientation in patients undergoing orthoganthic surgery. According to the author the patients with high occlusal plane or low occlusal plane facial type alteration of occlusal plane is
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required. To achieve optimal, functional and esthetics results the occlusal plane angle has to be increased or decreased by surgery.
Fenn, Linddelow, Gimson (1994)42 They defined the camper’s plane is a line which extends from the superior border of tragus of ear to the inferior border of ala of the nose.
Ferrario (1994)43 He concluded that in natural head posture, the Frankfurt plane is extended with the orbitale higher than the tragus or transverse horizontal axis females showed a downward tendency and men showed an upward tendency. This study shows an overly steep angulation of the occlusal plane with the incisal edges of the maxillary anteriors placed inferiorly when compared to natural head posture. They concluded that the two Frankfurt plane were never coincident in all on average the porion – orbitale – tragus angle was about 6 degree.
T.Kuno M. Hasegawa M. (1994)44 He did a study on comparing the functional occlusal plane in adults with class-3 malocclusion showing non-open bite and open bite. For both the groups lateral cephalometric radiographs were taken and he found that there was a significant difference between the SN-upper and lower occlusal plane, MP-upper and lower occlusal plane and FH-upper and lower occlusal plane. Occlusal plane angle has wide variations in both the groups compare to normal groups according to their results.
Vukusie N, Lapter M (1994)45 They conducted a study and evaluated the parallelism between the ala-tragal line and occlusal plane. For the 90 dentulous subjects lateral cephalograms were taken and the results showed that the occlusal plane is parallel to the ala-tragal line which extends from the middle of the tragus of ear to the lower border of ala of the nose. The regression equation reveals “Line of closest fitting”.
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During the construction of complete dentures for 50 edentulous subjects this concept was applied and it showed good clinical results. Hence it was concluded that for determining the occlusal plane orientation clinically the inferior point of ala of nose and the middle of the tragus represents the proper reference points.
Celebic A (1995)46 He conducted a study for orienting the occlusal plane by intra oral method. In this study the upper level of the retromolar pad was taken as a reference point for orienting the occlusal plane. For 34 edentulous subjects and 30 dentate subjects stone cast was obtained with quick mount face bow transfer stone cast was mounted on semi adjustable articulator. In both the groups the angle between the occlusal plane and horizontal plane of articulator were measured. Significant statistical difference were found. Results of this study showed that the occlusal plane of artificial denture was found to be very close to the natural occlusal plane by this method.
D’Souza, N.L Bhargava K (1996)47 In edentulous and dentulous subjects a cephalometric study was done to compare the relationship between the maxillo- mandibular space to the occlusal plane. In edentulous subjects this study validates whether the camper’s plane can be used as a guide to determine the orientation of occlusal plane. Based on the values derived from the cephalometric tracings of 40 edentulous and dentulous and with the help of significant correlation of the maxillo – mandibular space variables obtained from the dentulous group, the edentulous and dentulous groups were further classified into four sub divisions based on the length and maxillo mandibular angle. The similarities between the two groups were checked by comparing the occlusal plane/maxillary plane angle and the occlusal plane/mandibular plane angles.
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Fushima K (1996)48 He conducted a study in class 2 div 1 malocclusion to find the significance of the cant of posterior occlusal plane. In this study 50 adult females with angles class 2 div 1 malocclusion having skeletal and dental problems were recorded.
Skeletal problems that were found are small retruded mandible along with backward rotation of mandible. For the assessment of relationship between the skeletal and dental pattern the posterior and anterior occlusal plane cant is studied in detail. From the results of this study it was indicated that the steep cant of posterior occlusal plane was strongly correlated with a short vertical height of maxillary second molar and distal inclination of maxillary molar, small retruded mandible with backward rotation as skeletal pattern.
Ogawa, Koyana (1996)49 They studied the relationship between the jaw closing path and the orientation of occlusal plane. Values are obtained from thirty eight young subjects with a system that evaluate the jaw movements. Regardless of the orientation of occlusal plane it was identified that there was a consistent perpendicular relationship present between the jaw closing pathway and occlusal plane. Hence it was concluded that the development of the occlusal plane orientation is in relation to the formation of the muscles of mastication.
Sinobad.D. Postic SD (1996)50 In natural and artificial dentition he studied the Roentgen craniometric indicators of the position of the occlusal plane. The angular relationship between the six variants of ala-tragal line used in clinical practice and the occlusal plane were investigated by taking the lateral cephalometric radiographs for 41 subjects. In class 2 jaw relationship the ala tragal line that extends from the upper border of tragus to the lower border of the ala of the nose is recommended. In class 3 jaw relationship the ala tragal line that extends from the lower border of tragus to the
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lower border of the ala of the nose is recommended. In class 1 jaw relationship the ala tragal line that extends from the middle of the tragus of the ear to the lower border of the ala of the nose is recommended.
Brauns, Legan ML (1997)51 They studied the relationship between the changes in occlusion and the cant of the occlusal plane. It was known that the dental occlusion is influenced by the change in the cant of occlusal plane. As a general clinical guide a half a millimeter change in dental occlusal relationship is directly related to change in each degree angulation in the cant of the occlusal plane angle. A previous study also reported that during development and growth period there occurs natural rotation of the occlusal plane in upward and forward direction to approximately 6 degree.
Ogawa, Koyana(1997)52 They conducted a study to learn about the characteristics of the masticatory movements in relation to the orientation of the occlusal plane in young 41 adults. The masticatory closing pattern influences the inclination of occlusal plane in sagittal sections. The anterior closing pattern was dominated when the occlusal plane is inclined in anterior direction and the posteriorly inclined occlusal plane was influenced by the posterior closing pattern. A harmonious relationship between tooth guidance, occlusal plane with other peripheral control was obtained from the results of this study.
The functional background for the significance of orientation of occlusal plane is served by the correlation between the inclination of occlusal plane and masticatory closing movement.
Zarb bolender, Carlsson (1997)53 They concluded that the orientation of occlusal plane posteriorly should be parallel to the ala-tragal line on the basis of the natural occlusal plane position.
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Ogawa, Koyana (1998)54 In this study they described the relationship between the orientation of the occlusal plane and masticatory movements. They described the masticatory movements were measured with the help of 3-D mandibular movements analyzing system. In sagittal plane the three dimensional digitizer measures the inclination of occlusal plane. Regardless of inter individual variations it was identified that there was a consistent perpendicular relationship exist between the masticatory closing path and occlusal plane orientation in sagittal plane. Vertical closing path was showed by subjects with anteriorly inclined plane and flat masticatory closing path was showed by subjects with posteriorly inclined occlusal plane. These characteristic features are explained by the variations on the balancing side condylar return which is correlated with inclination of occlusal plane orientation. In this study it was concluded that there is a significant correlation exists between the direction in which the jaw closes during masticatory movements and the orientation of the occlusal plane.
Ogawa, Koyana (1998)55 They studied the orientation of the occlusal plane and occlusal guidance as a contributing factors in the act of mastication. The inclination of the occlusal plane mainly influences the masticatory path of closure outside the inter cuspal position and the occlusal guidance mainly influences the masticatory path of closure near the inter cuspal range. The results of this study showed in posteriorly inclined occlusal plane gliding type of masticatory movement pattern is observed and in anteriorly inclined occlusal plane chopping type of masticatory movements pattern is observed. Later it was concluded that the influence of orientation of occlusal plane to masticatory movement was more than the occlusal guidance throughout the closing phase except near the inter cuspal range.
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Santana Penin UA (1998)56 A new device was introduced in this study called as occlusal plane indicator for determining the orientation of the occlusal plane.
Determining the exact orientation of the occlusal plane is mandatory in many clinical situations. This device can be used to finalize the exact development of dentition in children, providing the norms for non anatomic tooth design during the preparation of fixed prosthesis and helps to take decision whether to do extrusion or intrusion.
Seifert D, Muretic Z (1998)57 This study examined the relationship of the basic Roentgen cephalometric parameters applied and to find their reliability. By applying proper statistical parameters and the correlation analysis on 86 lateral cephalometric radiographs of subjects having normal occlusion they analyzed the five angulation variable: OP-MDP, OP-CP, OP-PP, and OP-SNP. The results provide the mean value of the determined variables and their mutual correlation, that can be used while determining the individual’s occlusal plane orientation. Parameters like SNP and FP have provided significant stability and reliability that can be successfully applied in prosthodontics.
Solomon EGR, Shetty Sridhar Marla (2000)58 They evaluated the location of various landmarks and anatomical features variation of tragus to ala – tragal line in the aspect of its importance as a valuable reference in establishing camper’s plane. They observed 2048 tragi in subjects of 18 – 25 age groups of both sexes. They concluded that tragus had a various morphological variants. They classified the shape of tragus as pointed, notched, rudimentary and rounded. Occlusal plane was found parallel to campers plane when ala tragal line was extending from the lower border of the ala of the nose to the point between middle and superior of the tragus.
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Chen, Chen, Chang, Chen (2000)59 they conducted a study to assess landmark identification on original radiography in comparison with those obtained from digital images. They randomly selected 10 cephalometric radiographs. 19 cephalometric landmarks on both the original radiographs and the digital images were identified by 7 orthodontic residents. In their computerized digital cephalometric analysis he concluded that the differences of landmark location between digital and original cephalometric radiographs were statistically significant. Except for the points Po, Ar, PNS, and UM the remaining landmarks identification in digital images was comparable to that in original radiographs. The landmarks with lower reliability should be scrutinized more carefully in digital images when we take potential advantages of the use of digital cephalometry.
Vukusie N, Lapter M (2000)45 This study determined the changes in the orientation of occlusal plane during development and growth. After tracing the radiographs six angular cephalometric variable were compared with the help of different reference lines. Mandibular base, Maxillary base, Cranial base, Posterior face height, Anterior face height and Frankfort horizontal plane. It was observed that there was rotation of occlusal plane in anterior direction during the growth. Significant change of occlusal plane was found using variables, cranial base, maxillary base, Frankfort horizontal plane.
J.Nissan, E.Barnea (2003)60 They conducted a study to check the relationship between the craniofacial structures and occlusal plane determinants. For 34 denture wearers lateral cephalometric radiographs were taken to study the relationship. The results showed that there was no correlation between the gonial angle, shape of skeletal face verses the location of retromolar pad, length of mandible, camper’s and occlusal
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plane. However a significant linear correlation was found between location of camper’s plane and facial skeletal shapes designated SN-PoG.
Chen, Chen, Yao, Chang (2004)61 Conducted a study to identify the impact of variability in landmark identification on the values of cephalometric measurements of digital cephalograms in comparison to the original radiograph. From the orthodontic patients records ten cephalometric radiographs were selected randomly. In original and digital radiograph 19 cephalometric landmarks were identified by 7 orthodontic residents. In a customized computer aided program 27 cephalometric measurements were computed. To identify the concordance between the cephalometric measurements obtained from landmarks measured on the original radiographs and those from digital counterpart the measurements of twenty seven cephalometric values were assessed to quantify the correct value of measurements variations and the inter observer errors between these two methods. He identified that the measurement differences between the digital images and original cephalograms are statistically significant but clinically acceptable. The inter observer errors for cephalometric measurements in the digitized cephalometric images were generally comparable with that of original radiographs. The results substantiated the benefits of digital cephalometry in terms of reliability of cephalometric analysis.
Sivakumar Jayachandran (2008)62 He conducted a study to identify whether occlusal plane is parallel to Hamular notch Incisive papilla plane. From 60 Dentate subjects stone cast was obtained and with the help of Wills surveyor tripoding of the cast was done in such a way that the hamular notch incisive papilla plane was made parallel to horizontal plane. Later the distance between the cast and the base of surveyor was measured at four points. He concluded that the hamular notch incisive papilla plane
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was parallel to the occlusal plane since the measured values are equal. Later he established occlusal plane in 30 edentulous patient by considering ala tragal line as a reference plane. To check the parallelism between the hamular notch incisive papilla plane and occlusal plane lateral cephalometric radiographs were taken. Then it was concluded that the occlusal plane was parallel to the HIP. Hence it is considered as a viable reference in complete denture prosthodontics.
Yu, Nahn and Back (2008)63 They did a comparative study to validate the reliability of identifying landmarks with monitor displayed images from digital lateral cephalograms Vs hard copied film images in 50 orthodontic patients. The cephalometric landmarks were identified and digitized for 3 times at 2 weeks interval by 2 observers. There was no significant statistical difference in identifying landmarks by hard copied film based method (HFM) and the monitor displayed method (MDM).
Reena Mittal (2008)64 To compare the occlusal plane in edentulous and dentulous patients this study was conducted. Subjects in this study were divided into two groups.
Dentulous subjects with angles class I relation forms the first group and edentulous subjects with conventional complete denture forms the second group. Various angular measurements were recorded and lateral cephalometric radiographs were taken. All the subjects in both category is further divided into four groups based on average values of length and height of maxilla – mandibular space. A significant correlation was derived from the results between the occluso maxillary and maxillo mandibular height and length.
Roden – Johnson, English & Gallerano (2008)65 They conducted a study to compare the ability of the quick ceph 2000 ( quick ceph systems, Inc, San Diego, Calif ) to measure the angular and linear measurements with that of hand traced method. To
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investigate the differences in identifying landmarks between the digital and film cephalometric tracings. To compare hand traced method of superimposition to the quick ceph 2000 superimposition which are currently agreed by the American board of orthodontics. They concluded that there are no variations in identifying the cephalometric landmarks made digitally with quick ceph 2000 Vs manually made and there were no variations in the regional superimpositions of maxilla, mandible and cranial base manually Vs digitally with quick ceph 2000.
Huja, Grubaugh, Rummel,Fields,Beck (2009)66 Conducted a study to examine the ability to obtain comparable superimpositions by hand tracing and digital methods and to verify whether any difference exists between the S-N superimpositions and best fit cranial base superimpositions using the digital method. 64 initial and final lateral cephalometric radiographs were obtained. By digital and hand tracing method cranial base and regional superimpositions were completed independently for each pair of radiographs. This study provides support for transition from hand to digital superimposition method by providing that there is no difference between regional and cranial base superimpositions obtained by dolphin imaging version 10 and those that are completed by hand when using the described methods.
AL Quran et al (2011)67 Conducted a study to identify the most reliable Ala – tragal line as a guide for the inclination of the occlusal plane in complete denture patients by using cephalometric landmarks in dentate volunteers. In 47 dentate adults the angles of lateral cephalometric radiographs and their related craniofacial reference lines were prosthodontically analyzed. Using SPSS software data were analyzed and variables were determined. He concluded that the most accurate line for orienting the occlusal
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plane is running from the inferior border of ala of the nose to the superior border of tragus of the ear.
Sc Deogade, PL Gupta, GN Shankaran (2011)68 On lateral cephalometric radiograph they conducted a study an adjunct in orienting the occlusal plane in artificial and natural dentitions as related to other craniofacial planes. For 47 dentate subjects with angle class I relationship lateral cephalometric radiographs were taken. Compared with the ala tragal line that extends from the superior border of the tragus to the lower border of the ala of the nose from the results of this study it was concluded that the occlusal plane angle formed between the campers plane and occlusal had the lowest mean value.
Hence it was concluded that while establishing the occlusal plane a line running from the lower border of ala of the nose to the superior border of the tragus can be used as a reference plane.
Venugopalan et al (2012)14 Conducted a study on 60 subjects with class I, II, III malocclusion to investigate the relative parallelism between the occlusal plane and ala tragal line. 1mm radio opaque markers were adhered to the superior, middle, and inferior border of tragus and one on the lower border of ala of nose. Lateral cephalograms were obtained and tracings was performed. Results of this study showed for individuals having class I and III malocclusion, inferior border of tragus was found to be the posterior reference point and class II malocclusion, middle border of tragus was found to be the posterior reference point.
Manesh Lahori et al (2013)69 Conducted a study among individuals having class I, II, III occlusion on the relationship between the occlusal plane, camper’s line and ala tragal line. For this study 60 subjects were selected, radio opaque markers are adhered to the marked points on the soft tissue and then lateral cephalograms were taken. From
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the results of this study they concluded that for 75% individuals with class I occlusion, mid tragus was found to be the posterior reference point, 60% of individuals with class II occlusion, mid tragus was found to be the posterior reference point, 75% of individuals with class III occlusion, inferior border of tragus was found to be the posterior reference point.
Sandeep kumar et al (2013)4 Conducted a study on 150 dentate subjects with age of 18 – 40 years old to determine accurately which part of the tragus to be used to form the campers line or ala tragal line. Life size lateral digital photographs of the face with fox plane are taken in natural head position. From the results of the study it was concluded that the line running from ala of the nose to the lower border of the tragus of the ear was parallel to the occlusal plane in 53.3% of the subjects. This is no correlation between sex and the level of occlusal plane.
Dipak thapa (2014)70 conducted a study on 48 dentulous subjects having class I occlusion to evaluate the parallelism between the HIP plane and occlusal plane. The maxillary impressions were made and study casts were poured. The maxillary casts were surveyed and the distance between the HIP and several reference points of occlusal plane were measured with digital Vernier caliper. From the results of this study 81% of cases shows parallelism within the range of 2mm and concluded the HIP is relatively parallel to occlusal plane.
Sanath Shetty et al (2015)71 conducted a study on 500 dentate individuals to determine which position on the tragus when connected with the ala of nose for ala- tragal line was relatively parallel to the occlusal plane in dentate patients. To check the parallelism between the occlusal plane and ala-tragal line a custom made occlusal plane analyzer was used. From the result it was concluded that 50.8% of individual had
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inferior part of tragus as posterior reference point and 24.7% had middle part of tragus as posterior reference point and 12% had superior part of tragus as posterior reference point. Hence it was suggested that occlusal plane was found to be parallel to a line connecting ala of the nose to inferior part of tragus of ear.
Deepti Raghav et al (2016)72 concluded that if the occlusal plane was not made parallel to the Frankfurt plane the anteroposterior inclination of the upper model will get decreased and it will affect the position of maxillary anterior. If the occlusal plane was lowered in the posterior portion it will not only harm esthetics but also affect the overall masticatory efficiency of the patients.
References from Text books
Fenn H.R.B, Liddelow K.P and Gimson A.P while recording the occlusion in the patients mouth, the occlusal surface of the records blocks are made parallel to the occlusal plane, which is a horizontal plane parallel to the ala tragus line extending from the external auditory meatus to the lower border of the ala of the nose.
Neill DJ, Naim RI: complete denture prosthetics. Bristol, John Wright sons (1975)Basker Boucher CO: complete denture prosthodontics – state of the art. J Prosthet Dent 1975; 34:372-383.
Grant AA, Johnson W: An introduction to removable denture prosthetics Edinburgh, Churchill livingstone, (1983):
Out of the seven most famous prosthodontics textbooks, only Boucher’s provides a definition, two other text books explains the concept without defining it, while Neill and Naim, Grant and Johnson, Basker et al provides a pictorial representation, illustrating camper’s line running from a point, not from the superior border, but from the center of the tragus of the ear.
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Winkler S Essentials of the complete denture prosthodontics, second edition, page 140-141: after making the occlusal rim according to the prescribed vertical height, the occlusal plane is adjusted until it is made parallel to a line running from the lower border of the ala of the nose to the superior edge of the tragus of the ear. In frontal section the occlusal plane is made parallel to the inter pupillary line, occlusal plane and inter papillary line is also shown in a pictorial diagram.
