Reference plane/ oral surgery courses

Introduction
The configuration of
occlusal plane is one of the
most beautiful designs
that can be found in
nature……. (Applegate)
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education

“A two dimensional study
comparing the relationship
between two constant and two
variable reference planes”

A constant thirst for selecting
an appropriate reference plane
closest to that of the occlusal,
has led to innumerable planes….
But which one lies
closest to that which
once existed is a big
question mark ???

www.indiandentalacademy.com
What an occlusal plane
is ?
•“It is an average plane
established by the incisal and
occlusal surfaces of the teeth.
Generally it is not a plane but
represents the planar mean of
curvature of these surfaces”.
(GPT 8 )

Wheeler states:" Nothing
anatomic may be reduced to
the mathematical exactness
of geometric terms”

Most commonly used
Reference Planes:
•Horizontal Plane Of
Reference
•Frankfort’s Horizontal
Plane
•Camper’s Plane

Camper’s Plane……
•Most commonly used plane
of reference
•Confusion exists as in
which part of the tragus
and what portion of
ala ???

Camper’s Plane
•“A plane established by the inferior
border of the right or left ala of the
nose and the superior border of
tragus of both ears”
• Acanthion- external auditory meatus
plane

Ala Tragus Line
•“A line running from inferior
border of ala of the nose to some
defined point on the tragus of the
ear, usually considered to be tip
of the tragus.”

Ala Tragus Line
(Applegate)
•“A line running from superior
border of ala of the nose to
superior border of tragus of
both ears.”

Camper’s Plane
Applega
teCamper’s Plane
Ala tragus
Line

• Inspite of such a huge variation,
it is still the most commonly used
plane of reference for 2 reasons;
1. It is more closer to occlusal plane
than other planes of reference,
inducing less errors during
transfer
2. Because it is a soft tissue
landmark ; easy orientation to the
occlusal plane clinically

Purpose :
•Thus a cephalometric study
was carried out to check
which plane is closest to that
of occlusal plane by
considering two constant and
two variable planes

•Constant plane of reference:
Horizontal Plane Of Reference
(HPR)
 Frankfort’s Horizontal Plane
(FHP)
•Two variable planes :
Camper’s Plane (CP)

Following angles were
calculated:1. HPR to FH
2. HPR to Occlusal plane
3. FH to Occlusal plane
4. Superior border of tragus to
occlusal plane
5. Middle border of tragus to
occlusal plane
6. Inferior border of tragus to
occlusal plane

Materials & Methods
•50 dental students
between age group of
22-25 years from
M.S.Ramaiah Dental
College, Bangalore

Inclusion Criteria
•Angle’s Class I dentition
•Age group between 22-25
years
•No missing teeth or
replacement for the same

Exclusion Criteria
•Subjects treated
orthodontically
•History of
temporomandibular
disorders
•Impacted 3rd
molar

Procedure
S
M
I
A

Cephalograp
h

FH
c1
C2
C3
OP
HP
R

Occlusal Plane
•L’Estrange (1973) : The point
midway between the incisal tips of
the maxillary and mandibular
incisors to the point midway
between the mesiobuccal cusps of
maxillary and mandibular first
permanent molars.

O
P
OP
C3
C3,
C2
C2
C1
C
1
F
H
FH
HPR

Results
Results
….
Results
….

Stastical Analysis
•Results were stastically assessed
using SPSS software ;Version 10.
•Mean angle, standard deviation, t
value and probability was
calculated using independent t test.

SL.N
O
Planes Mean SD t P
1 HPR to FH 3.54 2.75 9.104 0.001
2 HPR to OP 4.68 3.54 9.342 0.001
3 FH to OP 5.08 4.52 9.953 0.001
4 C1 to OP 7.08 3.85 12.99
1
0.001
5 C2 to OP 4.08 3.60 8.022 0.001
6 C3 to OP 3.22 2.67 8.532 0.001

3.54º
5.12º
4.64º
HPR
FHP
OP

C1
C3
C2
OP
7.08º
4.08º
3.22º

Discussion
Present cephalometric study
shows that inferior border of
tragus is closest to that of
occlusal plane by 3.22º
•Previous studies showed that the
angle varied from 2.88º (Karkazis and
Polyzois ) to

•Clapp(1910), Dalby(1914),
Wilson(1917), Hartono and
Niekerk(1967), Miller and
Bibby(1985) et al suggested
inferior border of tragus as
reference plane.

•GPT8, Trench(1926), Winkler,
Heartwell and Boucher(1953)
suggested superior border of
tragus
•Solomon et al (2000) suggested
superior border and middle of
tragus(41.5%) and inferior border
as a poor reference (2.3%)

The second most significant
plane was middle border of tragus
making an angle of 4.08º with
occlusal plane
•Landa(1947) & Nikzad
Javid(1974) suggested middle of
tragus as reference of choice

The third most significant
finding is the close association of
HPR to occlusal plane, by an
angle of 4.64º
•Petreicevic et al stated that at
NHP, occlusal plane is almost
parallel to HPR ,

Limitations
Tragus form was not
evaluated
Age changes related to
tragus and occlusal plane
were not considered
Gender variation
No specific population was

Summary
After analyzing various
reference planes; we can
conclude that inferior
border of the tragus bears
close association with
occlusal plane both by
distance and by the angle
formed between them.

3.22º
4.64º
C3
HP
R
OP

Conclusion
“ Transferring the reference plane
accurately is a great challenge .
But our goal should be to reduce
these by proper selection and
transfer of appropriate reference
plane so that………….

…we restore the nature’s best
design as it is !!!

Acknowledgement
Dr. Kashinath K.R (HOD)
Dr. Vibha Shetty
Dr .Anandakrishna
Dr. Vahini Reddy
Dr. Sivaranjani

References :
1. L’Estrange” A comparitive study of the occlusal
plane in dentulous and edentulous subjects” JPD
1973:33(5):495-503
2. Ogawa “ The relationship between inclination of the
occlusal plane and jaw closing path” JPD
1996:76:576-80
3. Wilkie “ The anterior point of reference” JPD
1979:41(5):488-496

4 Petricevic “ Natural head position and
inclination of craniofacial planes” IJP
2006;19:279-80
5. Wylie “ The naso meatal line as a guide fot
the determination of the occlusal
plane”1944
6. Nissan “ Relationship between occlusal
plane determinants and craniofacial
structures”J Oral Rehab 2003;30:587-91

7. Dr.Solomon” Reliability of tragus morphology and
its reference to establish camper’s plane” JIPS
2000,11(1)16-22
8. Ciancaglini” Orientation of craniofacial planes
and temporomandibular disorder in young adults
with normal occlusion” J Oral Rehab
2003;30:878-886
9. Seifert “ Relations of reference planes for
orientation of the prosthetic plane”Acta Stomat
Croat 2000;413-16

10. Lundquist “Occlusal plane determination”
JPD 1970;23(5)489-98
11. Augsberger” Occlusal plane relation to
facial type” JP 1953;6(3)755-70
12. Glossary of Prosthetic Terms 8

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