Asian Journal of Medical and Clinical Sciences
Original Article
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
D.B. Nandeeshwar1, S. Ashwin Kumar2, Sharad Acharya3
1
Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere.
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.
2
Abstract
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 20 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 : 10 Sep 2012
Accepted : 20 Sep 2012
INTRODUCTION
I
n complete denture fabrication the prosthodontist is
responsible 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
disagreement on the exact point of reference for this line[1].
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
covers the foramen of the incisive or nasopalatine canal[2].
Hamular notch-Incisive papilla plane (HIP) has been proved by
various authors[3] 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-577004.
Email: [email protected]
111
Published: 30 Dec 2012
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
9200;Gendex dental systems, Milan, Italy),
· Acetate paper,
· Adhesive tapes,
· Indelible pencil,
· Cyanoacrylate glue,
· Scale, Protractor.
Selection of Subjects:
Data was collected from Lateral Cephalometric
Asian J Med Cli Sci |Sep -Dec 2012 |Vol-1 | Issue- 3
radiographs of 20 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
0.3mm 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 0.8 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.
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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 20 subjects.
Study
Subjects
PATIENT 1
PATIENT 2
PATIENT 3
PATIENT 4
PATIENT 5
PATIENT 6
PATIENT 7
PATIENT 8
PATIENT 9
PATIENT 10
PATIENT 11
PATIENT 12
PATIENT 13
PATIENT 14
PATIENT 15
PATIENT 16
PATIENT 17
PATIENT 18
PATIENT 19
PATIENT 20
D2-D1 for the
line I (mm)
-0.2
0
0.3
-0.3
-0.05
0.1
-0.05
-0.2
0.8
0.2
0.2
0.05
0.3
-0.3
-0.1
0
-0.65
0.45
-0.45
-0.6
D2-D1 for the
line M
(mm)
0.25
0.45
0.6
0
0.45
0.4
0.25
0.15
1.2
0.55
0.5
0.45
0.75
0.05
0.3
0.3
-0.25
0.8
-0.15
-0.3
D2-D1 for the
line S ( mm)
0.4
0.9
0.9
0.3
0.8
0.75
0.45
0.5
1.55
0.8
0.8
0.7
1.1
0.45
0.7
0.6
0.1
1.15
0.2
0
* P value calculated using Oneway ANOVA
P<0.01 – Highly significant P=0.05 Significant P>0.05 – Not significant
113
F Value
17.494
Significance*
0.0001
Asian J Med Cli Sci |Sep -Dec 2012 |Vol-1 | Issue- 3
Measuring the parallelism between the planes
Two lines L1 and L2 were drawn perpendicular to HIP line.
The line L1 was drawn anteriorly from the point IP and L2 was
drawn posteriorly from the point H. The points where the anterior
line L1 meets the line I,M,S are I1,M1,S1 respectively. Similarly,
the points where the posterior line L2 meets the line I,M,S are
I2,M2,S2 respectively. Two parallel lines should measure the same
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
IP and I1 and H and I2 were calculated as D1 and D2 respectively.
The difference between D1 and D2 was calculated. Similarly, the
D1 and D2 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 0.05 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 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 20 subjects.
The range of the values obtained for difference between
D1 and D2 for line I, is 0.45 to -0.65. The range of the values
obtained for difference between D1 and D2 for line M, is 0.75 to 0.3. The range of the values obtained for difference between D1
and D2 for line S, is 1.55 to 0.
Results calculated using Oneway ANOVA showed that P
value <0.001 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
20 randomly selected edentulous subjects selected age
ranged between 38 years and 70 years (4 subjects were aged
between 38-50 years, 10 subjects aged between 50-60 years and 6
subjects between 60-70 years). Out of which 12 subjects were
males and 8 were female.
According to glossary of prosthodontic terms, AlaTragus is a line running from inferior border of ala to some
defined point on the tragus of the ear, usually considered to the tip
of the tragus[2]. Various authors have given their own definition
for Ala-Tragus Line. According to Spartley, it is a line joining
centre of ala to centre of tragus[6]. 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
the maxillary occlusal plane[7]. Boucher defines Ala-Tragus line as
an imaginary line that runs from the inferior border of nose to the
superior border of the tragus of the ear[4]. According to Ismail and
Bowman, it is a line passing from Ala of nose to the centre of the
tragus[8].
Hamular notch, Incisive papilla plane (HIP) has been
proved by various authors as a standard reference plane in
complete denture construction[9-12]. 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 20) 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 38-50, 50-60 and 60-70 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.
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Oral Rehabil 1980;7:31-4.
REFERENCES
1.
Takahiro O, Kigoshi koyano ana tsuneu snetgnu. The
relationship between inclination of the occlusal plane and
jaw closing path. J Prosthet Dent 1996;76:576-80.
7.
Van niekerk, Miller VJ, Chem C, Bibby RE. The ala-tragus
line is complete denture prosthodontics. J Prosthet Dent
1985;53:67-9.
2.
The glossary of prosthodontic terms. J Prosthet Dent
1999;81:39-110.
8.
Ismail YH, Bowman JF. Position of the occlusal plane in
natural and artificial teeth. J Prosthet Dent 1968; 20:407.
3.
Jayachandran S, Ramachanran R. Occlusal Plane
Orientation: A statistical and clinical analysis in different
clinical situations. J Prosthodont 2008;17:572-5.
9.
Hosoi T: Occlusal Registration for edentulous patients (ed
1). Tokyo, Ishiyaku, 1995.
4.
Boucher CO. A critical analysis of mid-century impression
techniques. J prosthet dent 1951;1:472-91.
5.
Boucher CO. Complete denture impressions based on the
anatomy of the mouth. J Am dent Assoc 1944;31:17-24.
6.
Spartley MH. A simplified technique for determining
occlusal plane orientation in full denture construction. J
115
10. Sloane RH, Cook J: A guide to orientation of the occlusal
plane. J Prosthet Dent 1953;3:33.
11. Rich H: Evaluation and registration if HIP plane of occlusion.
Aust Dent J 1982;27:162-168.
12. Karkaziz HC ,Polyzois GL: Cephalometrically predicted
occlusal plane: implications in removable prosthodontics. J
Prosthet Dent 1991;65:258-264 .