Gnathology / periodontics courses

GNATHOLOGY
MUSCLE+ JOINTS+TEETH=
NEUROMUSCULAR DENTISTRY
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

CONTENTS OF THE SEMINAR
1.INTRODUCTION
2.DEFINITION
3.AIMS AND OBJECTIVES OF GNATHOLOGY
4. THE NUTRIMENTAL FOUNDATION OF GNATHOLOGY
5.ORGANIC OCCLUSION THE GOAL OF GNATHOLOGY
6.THE TOOLS F0R GNATHOLOGIC MEASUREMENTS
7.TEN CHARECTERISTICS OF ORGANIC OCCLUSION
8.GNATHOLOGICAL CONCEPT OF COMPLETE DENTURE
CONSTRUCTION
9.CONCLUSION
10.BIBLIOGRAPHY www.indiandentalacademy.com

Introduction-
Though the primary function of teeth is
mastication ,teeth are not chewing organs by
themselves.They are capable of performing their
function only when it is used collectively with the
other components of the stomatognathic system
which include the maxilla,mandible,the
temperomandibular joints,the teeth with their
investing periodontal membranes,and the
neuromuscular mechanism.These are collectively
known as the masticatory apparatus and should be
treated as one unit which is the goal of Gnathology

Definition-
The science that treats the biology of the masticatory
mechanism as a whole i.e the morphology,
anatomy,histology,physiology,pathology, therapeutics of the
masticatory system and the teeth as they relate to the health of
the whole body including applicable diagnostic,therapeutic and
rehabilitation procedures.

Aims and objectives of Gnathology
1.Optimum oral health
2.Anatomic harmony
3.Functional harmony
4.Occlusal stability

THE NUTRIMENTAL FOUNDATION OF GNATHOLOGY
In dental science and practice we as professional healers have got
the cart before the horse i.e we are trying to cure the disease
problems only after they have been allowed to manifest
themselves.
Because it has been a well observed fact that primitive people had
generally less dental problems,well formed dental arches &
uncrowded teeth where as in comparison to the modern man who
has caries index approaching 98% & a malocclusion index
approaching the same magnitude depending on what criteria one
uses for defining malocclusion.www.indiandentalacademy.com

The role that nutrition plays in physical
wholesomeness is profoundly complex &
extremely complicated in its minute details.
The physical degeneration of isolated
primitive people when they took up the
prevalent diet of the modern man is lesson
that we all should understand before we cope
with the daily administrations of our
treatments of diseased teeth , jaws & their
relationships.
we should direct our efforts towards to
return the modern man to the whole grain
nutrition in his breads,cereals and flours & if
we could do these things collectively &
individually we could realize the health &
wholeness inherent in our well being and
eliminate the need for gnathology

FUNCTIONAL GNATHOLOGY IS
NUTRITION
Gnathology is the science that treats the
biologics of the masticatory
system,considering it as a single functional
unit.Nutrition is the act of supporting life &
causing it to grow by supplying matter to any
living tissue or organized body & the structural
form is a resultant of matter applied by
function.
Nutrition concerns every human being every
single day of life & nutrition is truly
incorporation of the environment into our well
being. Nutrition is the one science that can
least afford to remain in the laboratory & it
concerns every single human being every
single day of life.

GNATHOLOGYS ROLE
Gnathology has a
biological role in the solution of mans oral
ills.This role is to demonstrate that the
wholeness of the food & breath has a
relationship to the structure jaws & the
whole body. If there is any imbalance
between at the gross anatomic level & the
molecular level than the resultant gross
structure will not reach its true or optimum
form.

Mc COLLUMS KEY
Beverly McCollum the father of Gnathology has said that the
function of the mouth is the key to biological dentistry & keeping
the physiological integrity of the oral organ as intact as possible
is the basic aim of all our preventive work & no other
professional group should earnestly desire to practice prevention
than dentists.

ORGANIC OCCLUSION THE ULTIMATE GOAL OF
GNATHOLOGY
Organic occlusion can be defined as the parts that are mutually
dependant or intrinsically related and having a systematic
coordination with each each other.
To be a good Prosthodontist one must also be a gnathologist &
should use the face bow, the mounted casts to understand &
diagnose the structural deformities which must be corrected to
achieve an organic occlusion.
The goal of the gnathologist is to combat the inevitable wear &
tear of the human masticatory system so that it remains in
optimal chewing and digestive function for a life time.

THE ORGANIC MASTICATORY SYSTEM
The awakening began in the 1970’s as to the effect of the jaw
system has on the health & function of distant parts of the body as
cranial osteopaths.kinesiologists & dentists have been documenting
ailments that are organically oriented.
All related structures
jaws,joints,teeth,muscles,ligaments,tongue,lips & cheeks all serve in
an interrelating dynamic harmony which promotes the usefulness &
longevity of the entire system and we may discover to our own
dismay that our therapies can be the cause as well as the cure of this
dysfunction

THE DEVELOPMENT OF ORGANIC OCCLUSION
The first teeth to meet in occlusion are the primary incisors and
when the molars erupt they become related to the incisors by
means of their occlusion & vertical dimension.Interocclusal space,
mandibular rest position,the hard & soft tissues have an effect on
the development of organic occlusion.
Nature organizes the posterior occlusion by coupling the anterior
teeth first & if this coupling does not occur due to cross bites or
open bites then organic problems will surely develop.
Stallard stated that an organic occlusion is the highest mechanical
arrangement that can be given to the teethwww.indiandentalacademy.com

Gnathological instruments have made it possible to analyze the components of organic
occlusion.
Dr.McCollum in 1921 discovered the first positive method of locating the most
retruded position of the mandibular hinge axis & a repeatable baseline was established
from which measurements could be made.
REFERANCE PLANES-A BASE LINE FOR FOR
MEASUREMENTS IN GNATHOLOGY
Axis orbital plane
Sagittal plane
Coronal plane

THE TOOLS FOR GNATHOLOGICAL MEASUREMENTS
1.Mandibular movement recorders
2.A Gnathological instrument for routine mounting of the casts
1.Mandibular movement
recorders
The first mandibular movement recorder
was introduced by Dr.Stuart in 1950 which
to till date is unchanged & unequalled in
precision,sturdiness &
practicality.Dr.Stuart’s recorders had a
horizontal condylar styli in line with the
hinge axis & therefore recorded the effects
of the condyle movement with a
magnification,reliability & legibility that
opened new horizons for study & gave
dentistry the repeatable precision it needs
for Gnathological restorations

2.A Gnathological instrument for routine
mounting of the casts
The whip mix face bow establishes the axis-orbital
plane by the indigenious use of anatomical
structures & it can be accurately repeated to a
tolerance level of 1mm
The correspondence of the whip mix anatomical
face bow to the kinematic location of the hinge axis
was within 6mm,75.5% of the time which in
contrast to the arbitrary face bow had 33%.
The reason for the high correspondence to the hinge
axis is that the leading edge of the ear plug is
closely aligned with the axis.

Thus the whip mix face bow & articulator can be used to accurately relate the
maxilla & the maxillary teeth to the axis orbital plane in a manner that can be
repeated and consecutively referred in order to assess the three dimensional
effects on tooth position.

1.CENTRIC RELATION OCCLUSION
2.UNIFORM CONTACTS IN CENTRIC RELATION
3.CUSP FOSSA OCCLUSION
4.PRIMARY MARGINAL RIDGE CONTACTS
5.TRIPODISM
6.CROSS TOOTH STABILITY(TWIN CENTRIC)
7.FORCES ALONG THE LONG AXIS
8.NARROW OCCLUSAL TABLE
9.MAXIMUM CUSP HIEGHT AND FOSSA DEPTH
10.DISCLUSION
i) Ridge and groove directions
ii) the effects of transtrusion on ridge and groove direction
iii) Principles of obtaining disclusion
iv) Canine disclusion
vi) Disclusive prematurities
TEN CHARECTERISTICS OF ORGANIC OCCLUSION

1.CENTRIC RELATION OCCLUSION
Centric relation occlusion is the morphologic position of the mandible in the centric
relation when the posterior teeth are intercusped in occlusion.As such it represents the
true profile of the face.The mandible is muscularly suspended in centric relation
occlusion by the external pterygoid muscles posteriorly & the genioglossus muscle
anteriorly.All forces acting upon the TMJ and the periodontal membranes are
reciprocated which results in equilibrium and balance.

The sagittal tracing of the envelope of motion will demonstrate centric relation
occlusion to be at the uppermost end of the arc which is traced at the rearmost hinge
axis & organic occlusion can be established at any point on this arc.
Centric relation occlusion can only be demonstrated with axis oriented casts
mounted on an articulator and the elimination of centric prematurities is necessary
to gain centric relation occlusion

2.UNIFORM CONTACTS IN CENTRIC RELATION
When all the posterior teeth meet at once in centric relation,the mandible is
tripodized by means of the two temperomandibular joints and the teeth in unison
acting as one unit.The elimination of centric prematurities is necessary to
establish uniform contacts in centric relation.If the centric prematurities are not
removed there are four possible effects
i) Faceting & wear-The first teeth to contact on the arc of centric relation closure
will show faceting at the initial point of contact. The mandible will be deflected
forward by these prematurities and the wear of the incisors will result .If the
deflection is laterally the tips of the cuspids are seen to wear off.
ii) TMJ Dysfunctioning & muscle soreness-If centric prematurities are present
than they will result in soreness of the posterior belly of the digastrics and the
middle temporal muscles.If there is unilateral closure which precedes or replaces
bilateral closure than it will result in soreness of the middle temporal,medial
pterygoid and masseter muscles.
iii) Infrabony periodontal bone loss.
iv) Recession and gingival erosion

3.CUSP FOSSA OCCLUSION
One of the primary goals of restorative gnathologists is cusp fossa
occlusion.Cusp to fossa is a paired relationship between the one upper & one lower
teeth whereby the teeth in occlusion act as a single column or a unit of
occlusion.The buccal cusp of the lower bicuspid is received by the mesial fossa of
the upper & the palatal cusp of the upper bicuspid is received by the distal of the
lower bicuspid and thus one balances the other.
In case of the molars the three lower buccal cusps oppose the fossae and the upper
palatal cusps oppose the central and the distal fossae of the lower molar,thus a
natural dove tail is established which has the effect of a loose mortoise when the
teeth are in occlusion.

The tip of the lower first bicuspid should fit into the mesial fossae of the upper
bicuspid front of the triangular ridge which is essential for proper vertical
development,stability and function.
This design lends much stability & reciprocation of the forces of occlusion and
when cusps fit into fossae instead of inclined planes is assures that the centric
relation will be the most closed position of the mandible.
Cusp fossa relation is always preferable to cusp embrasure occlusion but are
not always achievable ,this is when occlusal adjustments procedures become
necessary or else teeth will not be in contact and there will have to be
diastemas at some places. www.indiandentalacademy.com

4.PRIMARY MARGINAL RIDGE
CONTACTS
This is a sagittal plane projection wherein there
is contact of the distal incline of the upper
mesial marginal ridge against the mesial
marginal ridge of the lower buccal cusp .The
distal marginal has a similar contact with the
mesial incline of the opposing distal marginal
ridge & these contacts are called as closure
stoppers as they resist the forward component
of the arc of closure
The significant aspect of these closure stoppers
is in case the posterior teeth are lost & the
vertical dimension decreases the upper anterior
teeth will be splayed & if the posterior teeth are
present the closure stoppers prevent the wear
and possible separation of the anteriors.

5.TRIPODISM
In a cusp fossa occlusion every closure stopper is coupled with a contact
on the distal incline of the lower triangular ridge or the mesial incline of
the upper triangular ridge.This contributes to mesio-distal stability to the
occlusion.
Every cusp has four ridges i.e. a mesial marginal ridge,a distal marginal
ridge,a triangular ridge and a central ridge.three out of these four ridges
can contact an opposing cusp in cusp fossa occlusion.In gnathology this
tripodism is a goal because the tripod is the most stable system in
mechanics.

In unworn or less worn dentitions the total area of maximum
intermaxillary contacts in occlusion does not exceed three or four
square millimeters.
Since all the ridges are rounded in all three dimensions and when
these two rounded surfaces meet at a point the contacts will be
small.If this type of tangency is obtained there will be a built in
adjustability to wear and the cusp tips will be preserved & the
occlusion “will wear in” not “wear out”.The ridges will wear
evenly and thus preventing the formation of non-uniform contacts

6.CROSS TOOTH STABILITY (TWIN CENTRIC)
This is a coronal projection of the tooth contacts.In this view one can appreciate
that the functional cusps of the upper & the lower posterior teeth occupy nearly
60% of the total bucco-lingual width of the tooth & occlude near the center of
the opposing fossae.These are also designated as stamp cusps as these are
responsible of the maximum shearing capability of the mammalian dentitions.

The contact patterns of these stamp cusps in the coronal plane are designated
as A-B-C contacts.
The A-contacts are between the upper buccal triangular ridge & the central
ridge of the lower buccal cusps.
The B-contacts are between the triangular ridges of the upper lingual & lower
buccal cusps & it is the common contact between the stamp cusps.
The C-contacts are between the convex central ridge of the upper lingual
cusp & the lower lingual triangular ridge.Any contacts between the lingual
cusps is a C-contact.
The Bucco-lingual stability results from these contacts being present.
If the B-contact is lost torquing forces will result in a deflective occlusion.The
B-contact cannot be seen unless a medium is placed between the teeth which
will mark it.

7.FORCES ALONG THE LONG AXIS
The sixth character of organic occlusion which relates the tooth contacts
is by which the forces of occlusion are directed along the long axis of
the tooth.
All of the previous factors described i.e. the cusp fossa relations,closure
stoppers & equalizers,tripodal contacts,the ABC contacts & the narrow
occlusal table tend to balance the occlusal forces & keep them directed
within the perimeters of the root thereby minimizing the destructive off-
axial forces. www.indiandentalacademy.com

8.NARROW OCCLUSAL TABLE
Natural teeth with little wear have a narrow occlusal tables.
The average distance from the buccal cusp tip to the lingual cusp tip is 55% of the total
bucco-lingual width
The remaining 45% should be divided with 15% from the tip of the shear cusp to the
height of contour & 30%from the tip of the stamp cusp to the height of contour so the
average distance between the A & C contacts is 45% of the total bucco-lingual width.
If the occlusal table of the artificial teeth is kept within these perimeters the forces of
closure will be kept within the perimeters of the teeth and directed along the long axis
of the teeth.
The key to narrow occlusal table is to protect the natural tooth from wear by deflectivewww.indiandentalacademy.com

9.MAXIMUM CUSP HIEGHT AND FOSSA DEPTH
The restorative gnathologist must attempt to
restore the teeth with tallest cusps possible as
they offer the greatest shear efficiency.
This can be done by mounting the casts in
centric relation & correctly programming the
eccentrics of the articulator & the determinants
of the cusp height can be outlined as follows.
A) Angle of eminence(sagittal plane
determinant)
Rule-The more the condyles detrude beneath
the eminences the cups should be shorter and if
the eminence is steeper the cusps should be
longer
B) Transtrusion(side shift-coronal plane
determinant)
Rule-if the side shift is greater the cusps should
be shorter

C) Vertical laterotrusion of the working
condyle(coronal plane determinant)
Rule-the rotating condyle move laterally & if
the condyle moves upward as it goes laterally
than the cusps should be short & if it moves
downward as it goes laterally (latero-
detrusion) the cusps must be longer.
D) Inclination of the occlusal plane
Rule-The more nearly the plane of
occlusion parallels the the angle of the
eminentia the cusps should be shorterwww.indiandentalacademy.com

10.DISCLUSION
The principle of disclusion is next to centric
relation occlusion & the most important
characteristic of organic occlusion.
Disclude means to separate,unclose or keep
apart.its exists in the post-canine teeth so that
they contact only in centric relation occlusion.
The disclusive characteristic of organic occlusion
allows each part of the dentition to perform that
function for which it is best suited (e.g.) the
incisors are designed for fine nibbling,cutting
into food & each incisor should be free to
contact the opposing incisor at an edge to edge
relationship without any other tooth in the mouth
contacting.Thus a mutually protective mechanism results whereby the anterior teeth disclude the
posterior teeth in eccentrics & the posterior teeth disclude the anterior teeth in centric
occlusion

Principles of obtaining disclusion-
The degree of detrusion of
lower incisors should be equal or be slightly
greater than the detrusion of the condyles
beneath the eminentia.The horizontal,vertical
overlaps & the inclination of the upper
incisors to the horizontal will affect the angle
of detrusion.
Often the mesial marginal ridge of the buccal
cusp of the lower first bicuspid may assist in
the first of protrusive disclusion by making
contact with the distal incisal edge of the upper
cuspid.keeping the lower first bicuspids
prominent makes this possible

Disclusive prematurities-
These are the most destructive interocclusal
prematurities which occur in the non-working mesial inclines of
the upper lingual cusps & the distal inner inclines of the lower
buccal cusps.These are the ‘B’ contact areas which are
important to obtain centric relation occlusion but must be
avoided in the eccentrics.
If these are not avoided then the muscle groups which are
affected are the lateral pterygoid on the non-working side & the
lateral,medial pterygoid,masseter & the middle temporal
muscles are affected on the working side.

The ten characteristics of organic occlusion evolved from the
research of Dr.McCollum,Dr.Stuart & Dr.Stallard the
founders of gnathology,the impetus they had was to learn, to
preserve the dentition & masticatory function of humans.They
applied the principles of biologics,geometry, physics &
mechanics to decipher the code that God & natural development
of human being wrote on the occlusal surfaces of the teeth.
The achievement of organic occlusion is the greatest challenge &
the highest goal that a restorative dentist will ever have.

Gnathological concept with complete denture
construction
Complete denture construction is a full mouth reconstruction
with extra complications to consider because no teeth are
present.
The TMJ, muscles, meniscus, ligaments, mandible & maxilla
are still there & dentures should be made in harmony & in
consultation with them.
There are similarities in procedures for reconstructing the
mouths with or without teeth,but with dentures the dentist must
restore the teeth with the new freedom of space.
If centric relation & centric occlusion are in harmony,then the
dentures can be reasonably successful.
The goal of completed dentures is to have tripod contacts in the
posterior teeth in centric occlusion.

The balance of nature must be respected.Each part has its own
sphere of activity as well as fusing with & complimenting other
related parts.
Altering one part for instance may affect half a dozen others-most
often to our own disadvantage and it is entirely possible that some
dental therapeutics may not be in the best interest of the patients
and if we as dentists must respond to the awesome responsibility
of treating the dental disease then,every effort should be made to
see that our therapies fit to the patients organic system,otherwise
we may do more harm than good to the patient .
Dentistry should not be just reduced to the level of repair and service
on a trade but gnathology however makes dentistry a true science.

BIBLIOGRAPHY
1.ORTHOPEDIC GNATHOLOGY-JACK.L.HOCKEL
2.MANAGEMENT OF TMJ DISORDERS & OCCLUSION-
JEFERY.P.OKESON
3.EVALUATION,DIAGNOSIS & TREATMENT OF OCLUSAL PROBLEMS-
DAWSON
4.OCCLUSION IN RESTORATIVE DENTISTRY-MARTIN.GROSS
5.SCIENCE & PRACTICE OF OCCLUSION-CHARLES McNeil
6.OCCLUSION:PRINCIPLES & CONCEPTS-JOES DOS SANTOS
7.AN EVALUATION OF 50 YEARS OF RECONSTRUCTIVE DENTISTRY
PART I-JPD;1981;45:383
8.GNATHOLOGIC CONCEPTS OF TOOTH PREPERATION-
CHARLES.STUART
9.TREATMENT OF THE EDENTULOUS PATIENTS-VICTOR.O.LUCIA

Thank youFor more details please visit

Gnathology / periodontics courses

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Gnathology / periodontics courses

Ähnlich wie Gnathology / periodontics courses (20)

Mehr von Indian dental academy

Mehr von Indian dental academy (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Gnathology / periodontics courses