Vertical jaw relations/ dentistry course in india

Vertical Jaw
Relations
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

According to GPT
Vertical jaw relation are those
established by the amount of separation
of maxillae & mandible under specific
conditions.

The physiologic rest position of the
mandible as related to the maxillae and
the relations of the mandible to the
maxillae when the teeth are in
occlusion are the two dimensions of
jaw separation of primary concern in
complete denture construction.

Thus Vertical Jaw Relations are
classified as
(1) The Vertical Relation of Rest
position
(2) The Vertical Relation of Occlusion
and
(3) The differences between the vertical
relation of rest and the occluding
vertical relation, the “Interocclusal
Rest Space” also known as “Freeway
Space”

According to GPT :
 “Physiologic rest position” is
The postural relation of the mandible to the
maxillae when the patient is resting
comfortably in the upright position and the
condyles are in a neutral unstrained position
in glenoid fossa.

When observations of physiologic rest
position are being made, the patient’s
head should be upright and
unsupported.

The force applied by the jaw opening
muscles is added to the force of
gravity, when the head is upright.
 In a reclining patient, gravity does not
pull the mandible down and so one
may find the distance between the jaws
to be less than it is when the head is
upright.

Rest vertical dimension = Occlusal vertical
dimension + Interocclusal distance.
 During the construction of complete
dentures, the Rest Vertical Dimension is
determined first and then reduced or closed
to the Vertical Dimension at occlusion.

The second thing that establishes the
vertical relation of the mandible to the
maxillae is the occlusal stop provided
by teeth or occlusion rims.

Vertical dimension of occlusion:
It is defined as the distance measured
between two points when occluding
members are in contact (GPT 99).

“Why is interocclusal space
necessary???”
The health of the periodontal
membranes that support the natural
teeth and the health of the mucosa of
the basal seat for dentures depends on
rest from occlusal forces to maintain
their health.

For this reason, an interocclusal rest
space between the maxillary and
mandibular teeth is essential for the
opening and closing muscles and
gravity to be in balance when the
muscles are in a state of minimum
tonic contraction.

The interocclusal rest space is the
difference between the rest vertical
relation and the occlusal vertical
relation and amounts to 2-4 mm in a
vertical direction if observed at the
position of the first pre molars.

Once the vertical relation of rest
position has been determined, it is easy
to adjust the vertical relation of the
occlusion rims sufficiently to provide
for the necessary interocclusal
distance.

Methods To Record
Vertical JawRelation

The methods for determining the
vertical Maxillomandibular relations
can be grouped roughly into two
categories
(1) Mechanical methods
(2) Physiologic methods
The use of esthetics as a guide
combines both the mechanical and the
physiologic approaches to the problem.

MECHANICAL METHOD
Ridge relations
A) Distance of incisive papilla from
mandibular incisors.
The incisive papilla is used to measure
the patients vertical relation since it is a
stable land mark and is changed little
by resorption of the residual alveolar
ridge.

The distance of the incisive papilla
from the incisal edge of the mandibular
incisors is about 4 mm in the natural
dentition.
The incisal edge of the maxillary
central incisor is an average of 6mm
below the incisive papilla

So the average vertical overlap of the
opposing central incisor is about 2 mm.
The disadvantage of this method is the
absence of lower teeth and so is useful
in treatment of single dentures

B)Parallelism of the ridges
Paralleling of the ridges, plus a 5
degree opening in the posterior region
as suggested by Sears, often gives a
clue to the correct amount of jaw
separation.

This theory if used alone, is not
reliable, because many patients present
such marked resorption that the use of
this rule would generally close the
vertical relation.
But when considered with other
observations, it may be of value.
However, in most patients the teeth are
lost at irregular intervals and the
residual ridges are no longer parallel.

2) Measurement of former dentures:
Measurements are made between the
borders of the maxillary and
mandibular dentures by means of a
boley gauge and corresponding
alterations can be made in the new
denture to compensate the occlusal
wear.

If the teeth click or if the closest
speaking space is obliterated
during speech, the Vertical
Dimension should be reduced and
the amount of reduction is
determined arbitrarily.

Measurement of former dentures
using Boley’s gauge

3)Pre-extraction records :
It is frequently possible to see the
patient before he or she becomes
edentulous. In such cases, one can
usually establish the occlusal position,
record it in some manner and transfer
this record to the edentulous situation.
This is a relatively easy procedure and
can be accomplished in several ways.

A)Profile radiograph:
The exposure of a full lateral
radiograph is made with the teeth in
occlusion, and after extraction
occlusion rims are made to an
apparently correct vertical relation.
They are inserted, the patient closes on
them and another radiograph is taken.
The two films are compared and any
necessary adjustment is made to bring
the mandible in correct position as in
the initial film.

Radiographs:

Disadvantages
Additional Patient exposure to
radiation.
Additional time (Time consuming)
Conventional radiographic equipment
used to provide profile R/g is not
available in most dentists offices.
Inaccuracy due to enlargement of the
image www.indiandentalacademy.com

B) Profile photographs
Profile photographs are made and
enlarged to life size.
Measurements of anatomic landmarks
on the photograph are compared with
measurements using the same anatomic
landmarks on the face

The photographs should be made with
the teeth in max occlusion
This was explained by W.H. Wright in
1939 certain measurements made from
previous patients photographs to
measurements on the patients face,
such as interpupillary distance and the
distances from lop of the eyebrows to
the base of the chin.

These measurements can be compared
when the records are made and again
when the artificial teeth are tried in.
Disadvantage of this method is that the
angulations of the photograph might
differ with the patients.

.
C) Profile Silhouettes:
An accurate reproduction of the profile
in silhouette can be cut out in
cardboard or contoured in wire.
The silhouette can be repositioned to
the face after the Vertical Dimension
has the established at the initial
recording and / or when the artificial
teeth are tried in

i)Lead wire adaptation:
Lead wires may be adapted carefully to
pre extraction profiles, and this contour
is transferred to a cardboard.
The resultant cutout is stored until after
extraction.

When the dentist estimates the vertical
relation using the trial plates, the
cardboard cutout is placed against the
profile in order to see whether the
facial contour has been maintained or
re-established.
 It is not in common use today.

ii)Swenson’s method(1959):
...
 Swenson suggested that acrylic resin face
masks made before the extraction and later
when the patient is rendered edentulous, it
is fitted on the fact to see whether the
vertical relation has been restored properly.
 This method is rather impractical because it
requires a great deal of time and is little
more accurate than the lead–wire technique.

Swenson’s method (1959)

Drawbacks of this method
It is time consuming
Requires lot of skill and experience
with the use of facial impressions and
casts for the fabrication of artificial
facial parts
Lastly the face assumes a different
topography in the erect posture from
that in the recumbent or semi-
recumbent position

D)Facial Measurements :
Various devices for Matching facial
measurements have been used in many
different forms.

i) The Dakometer

ii) Willi’s gauge:
This instrument is used for
recording vertical height before
extraction.
The arm is placed in contact with the
base of the nose, and the arm is moved
along the slide till it lightly but
firmly touches the
lower border of the chin.

It is locked in position by the screw.
The distance on the scale is recorded
on the patient’s chart.
It is not an accurate method as there
may be variations is applying pressure

G) Articulated casts:
 These are of practical value in the
assessment of the vertical relation.
Measurements can be made of the casts in
occlusion and relatively stable points.
 Such as the incisive papilla and the crest of
the lower ridge the sulcus depth, the
extended height of the upper and lower
buccal frena or the hamular notch and
retromolar pad.

The casts also assist in the selection of
size, shape and position of the teeth.

4)POST EXTRACTION METHODS
a) Niswonger’s method:
Niswonger in 1934 suggested a method
for determining the vertical dimension
that is commonly used today.
 The patient is seated so that the Ala-
Tragal line is parallel with the floor.
Two markings are made, one on the
upper lip below the nasal septum other
in the most prominent part of the chin.

The patient is told to swallow and
relax.
The distance between the marks are
recorded.
Subsequently, the occlusion rims are
constructed so that when they occlude,
the measured distance is 1/8” less than
the original measurement.
This 1/8” average freeway space falls
within 2-4 mm.

This method has the disadvantage that
the marks moves with the skin and
sometimes it is difficult to obtain two
constant measurements of the rest
position.
However, when combined with other
observations this technique is
reasonably reliable.


b)Willi’s method:
Willis believed that the distance from
the pupil of the eye to the rima oris
should be equal to the distance from
the base of the nose to the inferior
border of the chin, when the occlusion
rims are in contact.

c)Concept of equal-thirds
Some observers suggested that the face
can be divided into equal thirds, the
forehead, the nose and the lips and
chin.
This concept is of little practical value
for a variety of reasons

d)Silverman’s closest speaking space
which measures the vertical relation in
the phonetic method must not be
confused with the freeway space.
The freeway space established vertical
relation when the muscles involved are
at minimal tonic contraction and the
mandible is in its rest position.

The closest speaking space measures
the vertical relation when the mandible
and muscles involved are in
physiologic function of speech.

The occlusion rims are placed in the
mouth and the height is adjusted until a
min of 2 mm of space exists when the
patient pronounces the letter ‘s’.
 It may vary from 1-10mm, but the
2mm average will generally prevent an
increase in vertical relation.
Disadvantage of this method is that the
patient who has 8– 10 mm closest
speaking space will require other
means for determination of the vertical
relation.

e) Boos method (Power point)
Boos (1940) found that there is a point
of maximum biting power. He states
that the patient registers the greatest
amount of pressure on a spring
dynometer at a point considerably
more open than the denture occlusion.

The bimeter is attached to an
accurately adapted mandibular record
base.
A metal plate is attached to the vault of
an accurately adapted maxillary record
base to provide a central bearing point.

The vertical relation is adjusted by
turning the cap.
The gauge indicating the pounds of
pressure generated during closure at
different degrees of jaw separation

When the maximum power point has
been determined the set is locked.
Plaster registrations are made and the
cast is transferred to an articulator.
Investigators agree that such a device
offers no more accuracy than
Niswonger’s or Silverman’s method.

6) Lytle’s method (Neuromuscular
perception)
 The patients tactile sense is used as a
guide to determine the correct
occlusal vertical relation
An adjustable central bearing screw is
attached in the palate of maxillary
occlusion rim and a central bearing
plate in the mandible.

The screw is adjusted first so it is
obviously too long .Then in
progressive steps the screw is adjusted
until the patient indicates that the jaws
are closing too far.
The procedure is repeated until patient
indicates that the teeth feel too long.
The screw is then adjusted until the
patient indicates that the length feels
right
.

This method is not very effective
with senile patients or those who
have impaired neuromuscular
coordination

G)Electromyography
Rest position of the mandible can be
determined by means of
electromyography which would record
the minimal activity of the muscles.
All muscles show greater activity in
other positions than in rest position.

Physiologic Methods:
1) Physiologic rest position:
Registration of the jaws in physiologic
rest position gives an indication to a
relatively correct vertical relation when
used with other methods.
After the insertion of the occlusion
rims into the patient’s mouth, the
patient is asked to swallow and let the
jaws relax.

Then the lips are carefully parted to see
how much space is present between the
occlusion rims.
The patients must allow the dentist to
separate the lips without moving the
jaws or lips.
This interocclusal rest space should be
between 2-4 mm when viewed in the
premolar region.

The interarch space and rest position can be
measured by indelible dots or adhesive
tapes on the face.
If the difference is greater than 4mm the
occlusal vertical relation would be
considered too small.
If the occlusal vertical relation is less than
2mm the occlusal vertical relation would be
assumed to be too great.

2) Phonetics:
Speech is used as an aid in
determining the vertical relation.
Phonetics tests of vertical
dimension consist more of
listening to speech sounds
production than of observing the
relationship of teeth during speech

The patient is asked to repeat the
letter ‘M’ until he is aware of the
contacting of the lips.
The patient is asked to stop all jaw
movements when the lips touch
and the distance between the two
points of reference are measured.

If the anterior teeth touch when
these sounds are made, the vertical
relation of occlusion is probably
too great.
 Likewise the occlusal vertical
relation is also considered to be too
great if the teeth click together
during speech.

The position of the tongue and the
relation of the teeth is also an imp
factor.

3)Facial expression:
The experienced dentist learns the
advantage of recognizing the relaxed
facial expression when the jaws are
rest.
A study of the skin of the lips compared
to the skin over other parts of the face
can be used as guide normally the tone
of the skin should be same throughout.

However, it must realized that the
relative anteroposterior positions
of the teeth are at least equally
involved in the vertical relations of
the jaws as in the restoration of
skin tone.

The contour of the lips depends on
their intrinsic structure and support
behind them.
Therefore the dentist must initially
contour the labial surfaces of the
occlusion rims so they closely simulate
the anterioposterior tooth positions and
the contour of the denture base which
in turn,must replace or restore the
tissue support provided by the natural
structures.

The skin around the eyes and over the
chin will be relaxed.
Relaxation around the nares reflects
unobstructed breathing.

Based on harmony of face

4)Swallowing threshold:
The position of the mandible at the
beginning of the swallowing act has
been used as a guide to the vertical
relation.

The theory behind the method
is that when a person swallows, the
teeth come together with very light
contact at the beginning of the
swallowing cycle.

The technique involves building a cone
of soft wax on the lower denture base
so that it contacts the upper occlusion
rim with the jaws too wide open.

The flow of saliva is stimulated and the
repeated action of swallowing will
gradually reduce the height of wax
cone to allow the mandible to reach the
level of occlusal vertical relation.
 The length of time this action is
carried out and relative softness of the
wax cone will affect the results.

The length of time this action is
carried out and the relative softness
of the wax cone will affect the
results
It is difficult to find consistency in
the final vertical positioning of the
mandible by this method.

Maxillary occlusion rim should
be checked for
Labial fullness
Height of occlusal rim
Anterior plane
Anteroposterior plane
Midline
High lip line
Canine lines

Labial fullness
 The lip is normally supported by the
alveolar process and teeth which,at this
stage,are represented by the denture base
and occlusion rim.
 Therefore the labial surface must be cut
back or added to until a natural and pleasing
position of the upper lip is obtained.

 The upper lip may appear too full
because the lower lip at this stage is
unsupported.

The height of occlusal rim
 The incisal edges of the maxillary incisors
will be at the same position as the occlusal
surface of the maxillary occlusal rim.
 There are a number of variations ,which
should act as guide rather than a
rule,depending on the patient
 In most old people less tooth will be visible
owing to attrition of natural teeth and some
loss of tone of orbicularis oris muscle

The anterior plane
The upper anterior teeth are set with
their incisal edges in the same position
as the occlusal surfaces of the rim it is
important for the anterior plane of the
rim to be trimmed to this level.
Generally the plane to which the
anterior teeth to be set and to which the
rim must be trimmed is parallel to an
imaginary line joining the pupils of the
eyes. www.indiandentalacademy.com

Anterior posterior plane
This plane indicates the position of the
occlusal surfaces of the posterior and is
obtained in conjunction with the
anterior plane.
The rim is trimmed parallel to ala-
tragal line.
Studies have shown that the occlusal
plane of the natural teeth is usually
parallel to this line.

Midline
Few human faces are symmetrical therefore
there is no hard and fast rule for
determining midline.
Following aids help in deciding the vertical
line on labial surface of upper rim

Imaginary line from center of brows to
center of skin
Immediately below center of philtrum
At the bisection of the line from
corner to corner of the mouth when lips
are relaxed
where it crossed by a line at right
angles to the inter pupillary line from a
point midway between the pupils when
the patient is looking directly forward

Lip line
Lip line is a straight line just in contact
with the inferior border of the upper lip
when relaxed
High lip line is a line just in contact
with the lower border of the upper lip
when it is raised as high as possible
unaided such as in smile or laughing

High lip line indicates the amount of
denture which may be seen in normal
conditions and thus assists in
determining the length of tooth needed.

Mandibular occlusion rim
Is trimmed so that when it occludes
evenly with the maxillary rim as a
guide at correct vertical height

EFFECTS OF INCREASED
VERTICAL RELATION
1) Discomfort to the patient
2) Trauma: by the jamming effect of the
teeth coming into contact sooner than
expected may cause not only
discomfort, but also pain owing to the
brusing of the mucous membrane by
these sudden and frequent blows.

3)Loss of freeway space: which may
be due to
(a) muscular fatigue of any one or
group of muscles of mastication.
(b) Trauma caused by the constant
pressure on the mucous membrane and
(c) Annoyance from the inability to
find a comfortable resting position.

4)Clicking teeth – The tongue which has
become accustomed to the presence of
teeth in certain fixed positions and
during speech helps to produce sounds
without the teeth coming into contact.
When there is increase in vertical
height opposing cusps frequently meet
each other, producing an embarrassing
clicking or clattering sound. This
effect is also produced during eating.

5)Appearance – The face has an
elongated appearance since, at rest the
lips are parted and closing them
together will produce an expression of
strain.
6)Bone - Residual alveolar bone
undergoes rapid resorption

EFFECTS OF DECREASED VERTICAL
RELATION:
1)Inefficiency – which is due to the fact
that the pressure with which it is
possible to exert; with the teeth in
contact decreases considerably with
over closure because the muscles of
mastication act from attachments,
which have been brought close
together.

2) Cheek biting – In come cases
where there is a loss of muscular
tone, as well as reduced vertical
height, the flabby cheek tends to
become trapped between the teeth
and bitten during mastication.

3)Appearance: The general effect of
overclosure on facial expression is of
increased age. There is close
approximation of nose to chin, the soft
tissues sag and fall in and the lines on
the face are deepened. The lips loose
their fullness and the vermillion
borders are reduced to approximate a
line.

4) Angular cheilitis : A reduced
vertical relation results in a crease
at the corners of the mouth beyond
the vermillion border and the deep
fold thus formed becomes bathed
in saliva, thus leading to infection
and soreness.

5) Pain in the TMJ: Trauma in the
region of the temporomandibular
fossa may be attributed to a
reduced vertical relation with
symptoms like obscure paints,
discomfort, clicking sounds,
headaches and neuralgia.

6)Costen’s syndrome: is stated to be
the result of prolonged overclosure.

CONCLUSION
The establishment of the vertical
maxillomandibular relations is a phase
of prosthodontic treatment for
edentulous patients in which it is
difficult to arrive at definite
conclusions from a practical view
point.

Since there is no precise scientific
method of determining the correct
vertical relations, the registration of
vertical relations depends upon the
clinical experience and judgment of the
dentist rather than a science.
 This could be the reason why there
are dozens of methods in use and why
one method is as good as another.

Bibliography
Prosthodontic treatment for edentulous
patients – BOUCHER, 11th Edition.
Syllabus of complete dentures –
HEARTWELL ,4th
Edition.
Essentials of complete denture –
WINKLER.
Complete Denture Prosthodontics- John J
Sharry
Clinical Dental Prosthetics - H.R.B Fenn

 Clinical assessment of vertical dimension. JPD
1972,VOL 28(3), 238-246.
 Variations in mandibular rest position with and
without dentures in place. JPD 1976,VOL 36, 159.
 Clinical study of rest position using kinesiograph
and myomonitor. JPD 1979, VOL 41, 456.
 Head angulation and variation in
maxillomandibular relationship, Part-I : The effect
on vertical dimension of occlusion. JPD 1983,
VOL50 96.


Relationship of head posture and rest position of
mandible. JPD 1984 VOL 52 ,111.
Determination of vertical dimension at rest. A
comparative study.JPD 1987, VOL 59, 238.
 Determination of vertical dimension of
occlusion : A literature review.JPD 1988, VOL 59,
327.

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