Occlusal plane/ orthodontic seminars

OCCLUSAL PLANE
IN ORTHODONTICS
www.indiandentalacademy.com

 INTRODUCTION
 DEFINITION
Occlusal plane
Functional occlusal plane
 SIGNIFICANCE OF OCCLUSAL PLANE
 DIFFERENT OCCLUSAL PLANES
 EXTENT OF OCCLUSAL PLANE
 OCCLUSAL CURVES
 LOCATING THE OCCLUSAL PLANE

 CANT OF THE OCCLUSAL PLANE
 OCCLUSAL PLANE IN DIAGNOSIS
 OCCLUSAL PLANE IN TREATRMENT
PLANNING
 OCCLUSAL PLANE SUBSTITUTES
 CONCLUSION

INTRODUCTION
In orthodontics various planes are used as
reference planes in diagnosis and
treatment planning
The occlusal plane in being the plane of
dentition occupies a prime position in
cephalometrics ,treatment mechanics

DEFINITION-various authors
 Enlow:
Occlusal plane
“A line passing through one half of the cusp
heights of the first permanent molars and one
half of the overbite of the incisors”
Functional occlusal plane
A horizontal line from the posterior most
occlusal contact of the last fully erupted
mandibular molars extending anteriorly to the
anterior most occlusal contact of the fully
erupted premolars

CHACONAS:
“Denture plane
which bisects the
posterior occlusion of
the permanent molars
and premolars and
extends anteriorly”

DOWN”S:
Occlusal plane is the line
bisecting the overlapping cusps
of the first molars and incisor
overbite

OKASON:
The plane of occlusion is an
imaginary line touching the incisal
edges of the maxillary anterior
teeth and the cusps of the
maxillary posterior teeth

HARVOLD:
Defines the functional occlusal plane as
the line which represents the functional
table of occlusion in the first permanent
molar, second pre molar and first pre
molars areas
The level and inclination of the functional
occlusal plane is the result of the neuro
muscular growth and developmental
forces acting on the dentition

SIGNIFICANCE OF OCCLUSAL
PLANE
The configuration of the occlusal plane is
important as slight variations will lead to
occlusal instability.
It should be in harmony with other
components of the masticatory system.
It forms the basis by which occlusal
surfaces of teeth can be related to one
another and to other structures of the
head. www.indiandentalacademy.com

OCCLUSAL PLANE
Occlusal plane or plane of occlusion refers
to a imaginary surface that theoretically
touches the incisal edges of the incisors
and the tips of the occluding surfaces of
the posterior teeth.

OCCLUSAL CANT
It is defined as
the rotation of the
object in its
longitudinal
plane.

OCCLUSAL LINE
By definition a line is one which connects
two points in space
Occlusal line refers to the line connecting
the overlap of the first permanent molars
and incisors
In orthodontics the terms occlusal plane
and occlusal line are used interchangingly
and can mean one or the other

Different occlusal planes
 Thayers in 1990 AJO has given three
different occlusal planes.they are
Bisected occlusal plane
Functional occlusal plane
Lower incisor occlusal plane
Upper occlusal plane
Lower occlusal plane

BISECTED OCCLUSAL
PLANE
Occlusal plane in
this case refers to
a bisecting line
through overlap of
distobuccal cusps
of first permanent
molars and
incisors

FUNCTIONAL OCCLUSAL PLANE
The functional occlusal
plane refers to the line
bisecting the molars and
premolars
It passes posteriorly
through the Xi point
Anteriorly it passes
slightly below the lip
embrasure

LOWER INCISOR OCCLUSAL
PLANE
Lower incisor
occlusal plane refers
to line drawn from bi
section of
distobuccal cusps of
first permanent
molars to tip of lower
incisor

Upper occlusal plane
connects the incisal edges of the the
upper central incisors with a point 0.5 mm
occlusal to the mesiobuccal cusp tip of the
first permanent molar
Lower occlusal plane
connects the incisal edges of the
lower central incisors with a point 0.5 mm
occlusal to the mesiobuccal cusp tip of the
first permanent molar

Esthetic plane of occlusion
The upper incisor lies commonly 3mm
below a relaxed upper lip. So a line joining
this point and distobuccal cusp tip of the
upper first molar represents the esthetic
occlusal plane

Treatment plane of occlusion
There are two occlusal planes ,the
upper and lower .The treatment occlusal
plane may take either as the reference or a
compromise plane can be taken
depending on the utility to the patient

Factors determining treatment plane
of occlusion
Natural plane of occlusion
Esthetic plane of occlusion
Distribution of alveolar process
A-B difference to plane of
occlusion

Natural plane of
occlusion
Maintain a good posterior occlusion
which already exists
Changing the occlusal plane would
alter the axial inclinations of teeth
which might affect stability
So the treatment plane of occlusion
should alter axial inclinations
minimally

Esthetic plane of
occlusion
When the esthetic plane of occlusion
does not coincide with natural plane of
occlusion,a decision as to which plane
should be taken as treatment plane
should be decided

Distribution of
alveolar process
The distribution of alveolar process in the
upper and lower arches can be described
as a ratio of the distance from the lower
incisor to Me in relation to the distance
from ANS to Me.
This ratio is about 0.61

Altering the occlusal plane
and its effect on A-B
differenceThe AB
difference
varies with
the cant of
the occlusal
plane.
The occlusal
plane maybe
flat or steep.

Extent of the occlusal
plane
APOcc –
ANTERIOR POINT
FOR THE
OCCLUSAL PLANE
A constructed
point, the mid point
of the incisor
overbite in occlusion

Extent of the occlusal
plane
PPOcc – POSTERIOR
POINT FOR THE
OCCLUSAL PLANE
A constructed
point, the most distal
point of contact
between the most
posterior molars in
occlusion

OCCLUSAL CURVES
 Curve of spee
 Curve of wilson
 Curve of monson

CURVE OF SPEE
Introduced by graph
von spee
Is an anteroposterior
curve extending from
the tip of the
mandibular canine
along the buccal cusp
tips of the mandibular
posterior teeth

If the curve is extended, it would form a
circle of about 4 inches diameter
The curve results from variations in axial
alignment of lower teeth. The long axis of
the each lower teeth is aligned nearly parallel
to its individual arc of closure around the
condylar axis
This requires a gradual progressive
increased mesial tilting of the teeth towards
molars which creates the curve of spee

FACTORS AFFECTING
THE CURVE OF SPEE
Degree of curve
Orientation of curve

DEGREE OF CURVE
When the radius of the curve is longer,
a flat plane of occlusion is present.

When the radius of the curve is shorter,
an acute plane of occlusion is present

ORIENTATION OF
THE CURVE OF SPEE
Refers to the relationship of its radius
to a horizontal reference plane
Also influences how the height of the
individual posterior teeth is affected
thereby affecting the acuity of the plane
of occlusion

Radius perpendicular to a horizontal
reference plane
Posterior teeth located distal to the radius
need shorter cusps than those located mesial to
the radius

If the plane of occlusion is rotated
more posteriorly
All the posterior teeth can have shorter
cusps as they are positioned distal to the
perpendicular from the reference plan

If the plane of occlusion is rotated
more anteriorly
All the posterior teeth can have taller
cusps as they are positioned mesial to the
perpendicular from the reference plan

CURVE OF WILSON
A curve that
contacts the
buccal and
lingual cusp tips
of the
mandibular
buccal teeth
It is mediolateral
on each side of
the arch

CURVE OF WILSON
Teeth are aligned parallel to the
medial pterygoid for optimum
resistance to masticatory stresses
The elevated buccal cusps
prevent food from going past the
occlusal table

CURVE OF MONSON
It is a curve obtained by extending
the curve of spee and curve of
wilson to all cusps and incisal
edges.

CANT OF THE OCCLUSAL
PLANE
1997 AJO - Stanley Braun, DDS, MME,
and Harry L. Legan, DDS
Changes in occlusion related to
the cant of the occlusal plane

 Dental occlusion is influenced by changes in the cant
of the occlusal plane.
 As a general clinical guide, each degree of rotation of
the occlusal plane will result in a half millimeter change in
the dental occlusal relationship.
 This is of importance, because changes in the cant of
the occlusal plane are sometimes unintentional, as well
as intentional, during orthodontic therapy.
 An earlier study has also documented that the occlusal
plane rotates naturally upward and forward approximately
6° during growth and development.

when the occlusal plane is rotated downward
and backward (steepened—as seen in the
sagittal plane), a Class II dental occlusion
will approach a Class I relation. This rotation
may be achieved by the use of Class II
elastics.
On the other hand, when the occlusal plane
is rotated upward and forward (flattened), a
Class III dental occlusion will tend toward
Class I. This can be achieved through Class
III elastic wear.

METHODS AND MATERIALS
For purposes of this study, the occlusal
plane as defined by Downs has been used.
(The plane extends from the midpoint of a
line connecting the anterior cusp tip of the
mandibular first molar to the anterior cusp
tip of the maxillary first molar, posteriorly, to
the midpoint of a line connecting the incisal
tip of the mandibular central incisor to the
incisal tip of the maxillary central incisor,
anteriorly.)

It is assumed the maxillary and
mandibular dental arches each rotate
about a point approximating their
respective centers of resistance. This is
also true for a group of teeth joined
together by a relatively stiff arch wire.
The group will rotate about a point
approximating its combined center of
resistance.

The center of resistance for the arch
viewed in the sagittal plane is located as
follows: in the maxilla, 1.53 mm anterior
to the first premolar distal contact and
14.20 mm perpendicular and apical to its
occlusal surface

The center of resistance for the arch
viewed in the sagittal plane in the
mandible, 1.25 mm anterior to the first
premolar distal contact and 14.24 mm
perpendicular and apical to its occlusal
surface.

The dimensional relationships in the maxillary
arch along the occlusal plane resulting from a
downward and backward rotation of the
occlusal plane.A similar coordinate dimensional
relationships in the mandibular arch resulting
from the same downward and backward rotation
of the occlusal plane.

The derived relationships were used to
calculate occlusal articulation changes
corresponding to angular changes of the
occlusal plane in the sagittal plane in both
downward and backward and upward and
forward directions in one degree increments
from 0° to 12°.
There is an approximately 0.5 mm change in
the occlusal relationship for each degree of
occlusal plane rotation in either downward
and backward or upward and forward
directions.

Inference of the study
This study reveals that small changes in the
cant of the occlusal plane significantly effect
dental occlusion. As an example, if the
premolars are in an end-on Class II relation, a
7.2° downward and backward rotation
(steepening) of the occlusal plane will result
in a change to Class I occlusion
Correspondingly, if the premolars exhibit a
Class III relationship, an upward and forward
rotation (flattening) of 7.2° will result in a
change to Class I occlusion.

From a clinician's viewpoint, a general
guide that may be used is for each degree
of occlusal plane angular change, a half
millimeter change in occlusion results.
It is apparent that small angular
differences (intentional or unintentional
during orthodontic treatment) will result in
significant alterations in occlusion.

OCCLUSAL PLANE IN
DIAGNOSIS
In cephalometrics
Down’s analysis.
Steiner’s analysis.
Witt’s analysis.
Sassouni’s analysis.
COGS analysis.
Proportional analysis.

DOWN’S ANALYSIS
Reference plane – FH plane
OCCLUSAL PLANE
A line bisecting the
occlusion of the first molars
and central incisors.
Should either incisor lack
full eruption or be in supra
occlusion the occlusion plane
is determine by the pre molars.
Mean - 9.3 degrees ± 3

STEINER’S
ANALYSIS.
Reference plane – SN plane
OCCLUSAL PLANE
A line bisecting the overlap of molars
and the incisor overbite.
Mean – 14.5 ± 2 degree

Witt’s analysis.
Reference line –
functional occlusal
plane
Occlusal plane - the line
bisecting the molars and
pre molar overlapswww.indiandentalacademy.com

SASSOUNI’S ANALYSIS
In this analysis , the occlusal
plane is the bisector of molar
and incisor overbite
Mean
Upper occ plane angle-9 deg
Lower occ plane angle-15 deg

COGS analysis
In this analysis the upper
and lower occlusal plane
are drawn seperately
REFERENCE PLANE –true
horizontal
Mean values
Upper occ plane--6.2±5.1
deg

Proportional
analysis.Developed by koski
and Virolainon in
1965
Based on comparison
of the various angles
to establish relations
between separate
parts of the skeleton
REFERENCE PLANES
op-n & op-pog
Values are given in
percentages

Occlusal plane during
treatment
-upper-Lowering the upper
occlusal plane
In patients with
vertical maxillary
deficiency,the
occlusal plane can
be lowered with the
use of a cervical
headgear with outer
bows bent upward
Elastics may also
be used opposite to
cRES to avoid rotation
between the archeswww.indiandentalacademy.com

RAISING THE UPPER OCCLUSAL
PLANE
Occipital head gear pull thro cres to get
entire upper jaw “ankylosed”.
When genuine intrusion is needed lefort I
is indicated

FLATTENING THE UPPER
OCCLUSAL PLANE
Class III elastics
Vertical elastics
thro cres of upper
jaw
Occipital head
gear with short
outer bow(ant to
C resof upper jaw)
Combination
type head gear
with occi pull>
cervical pull) www.indiandentalacademy.com

STEEPENING THE OCCLUSAL
PLANE
ROBIN HOOD TYPE OF HEAD GEAR
used in
Anterior open bites
upper lip length redundencies
cleft lip & palate patients

Use of class II Elastics and a cervical
pull head gear

Vertical elastics anterior to the C RES of the
upper jaw combined with cervical head
gear to the lower jaw with anterior hooks
and a short outer bow

Occipital head gear with long outer bow
Effective in treatment of open bites

CHANGES IN LOWER
OCCLUSAL PLANE DURING
TREATMENT
Lowering the lower occlusal plane
A cervical head gear thro C RES of
lower arch will hold the lower arch or
intrude it

Raising the lower occlusal plane
eruption usually occurs without any
orthodontic intervention
when entire arch requires active
eruption vertical elastics can be used

Flattening the lower occlusal plane
cervical head gear to lower arch with
outer bow bent upward

Steepening the lower
occlusal plane
Cervical pull head gear ,with point of
force application anterior to the C RES of
the lower jaw

CONTROLLING THE
DIFFERENCE IN OCCLUSAL
PLANES BETWEEN RIGHT
AND LEFT SIDES DURING
TREATMENT
Many a time the natural plane of occlusion
on one side is different from the other side
One of these planes will be chosen over
the other as the treatment plane of
occlusion
It is therefore necessary to rotate the other
plane of occlusion to the treatment plane

ASSESSMENT OF
RETRACTION USING THE
OCCLUSAL PLANE AS A
GUIDE
In a group A anchorage case,retraction of
anterior teeth is done in two stages
stage 1 – controlled tipping
stage 2 – root movement

The picture shows the relationship of the
incisal edges of the anterior segment and
the upper natural occlusal plane
This is what one should see clinically if correct
incisor root position is achieved
Stage 1

Stage 2
During the enmasse root retraction stage,
the entire anterior segment is rotated about
the CROT very close to the incisal edges or
brackets of the anterior teeth
The occlusal plane once again is levelled

In group B cases, both the anterior and
the posterior segments can be moved
towards each other in a translatory fashion
The forces must be equal and opposite for
this equal attraction
The natural occlusal plane remains level
and does not change

In group C cases, the protraction of the
posterior segments is needed
The forces are kept high
Second premolars are extracted
Two stage protraction
stage 1 –controlled tipping of
buccal segment
stage 2 –root uprighting

Stage 1
controlled tipping of the buccal segment
occurs which leads to the lifting of that part
of occlusal plane

Stage 2
Root uprighting stage leads to levelling of
the occlusal plane to the natural plane of
occlusion

OCCLUSAL PLANE
SUBSTITUTES
1994 AJO – Hall & scott
The maxillary-mandibular planes
angle (MM°) bisector: A new reference
plane for anteroposterior measurement of
the dental bases

MM Bisector

A new plane, geometrically derived from
the dental base planes, has been tested
as an occlusal plane substitute for the
measurement of anteroposterior jaw
relationships.
It lies close to but at an angle and inferior
to the traditional occlusal planes and is
highly reproducible at all times.

Lateral cephalograms
36 young adults (25 men and 11 women)
43 – 10- to 12-year-old children (24 girls
and 19 boys)
Wits technique of anteroposterior
measurement was used to compare A-B
values measured to the
MM bisector
 functional occlusal plane (FOP)
Bisecting occlusal plane (BOP).

Because of the downward cant of the
bisector anteriorly, B is projected onto
it ahead of A in normal occlusion and
coincides with A in skeletal (2)
malocclusion.
Mean values for normal occlusion were
found to be approximately –
4 mm for the children ( – 4.2
mm girls and – 4.0 mm boys)
4.5 mm for the adults ( – 4 mm
women and – 4.7 mm men).

In this study, the FOP moved in an upward
and forward direction, opposite to that of the
jaws, with age.
This meant that the mean value of the Wits
measurement in the children's group (– 2.65
mm, indicated a skeletal 3 tendency)
changed to 0 mm, measured in the adult
group, suggesting a marked decrease in
mandibular prognathism with age.
This was contradicted by ANB° values for
the two groups, which indicated a slight
increase in prognathism with age.

The BOP, on the other hand, moved in a
downward and backward direction, the same
as the jaws, Wits measurements made to this
plane, in fact, showed a difference between
the two groups (approximately 1 mm) that
changed from a negative value in the
children's group to a positive value in the
adult group, which seemed to suggest a
slight decrease in jaw prognathism with
maturity, again a result at variance with the
ANB° values for the two groups.

The MM° bisector is the summary of the
maxillary and the mandibular base plane
angulations, and its rotation, when measured
as an angle to the PM vertical, will reflect the
direction and the amount of the total growth
rotation of the whole dental complex.
In this study, it was a downward and
backward rotation of 2°, However, Wits
values measured between A and B, projected
onto this plane, differed very little with age.

A and B move with the dental bases, the
same amount and direction, and so clearly
their true AP relationship was being
effectively measured when measuring to this
plane, free of the "change of cant" distortion.
Mean values
children's group– 4 mm
adults group – 4.5 mm,
suggesting a slight increase in
prognathism with age that is in agreement
with the ANB° findings for the two groups.

Conclusion
Occlusal plane in the perspective not
only acts as a reliable plane in making a
good diagnosis but also ensures a
correct progress in treatment when
constantly monitored
So a clinician should always check the
occlusal plane to know if he is heading
the right way to the finish

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