Occlusion concepts in fixed partial dentures / dental implant courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

 INTRODUCTION
TERMINOLOGIES
 DETERMINANTS OF OCCLUSION
VERTICAL DETERMINANTS
HORIZONTAL DETERMINANTS
 EVOLUTION OF OCCLUSION
 GNATHOLOGY
 OCCLUSION IN NATURAL DENTITION
 OPTIMUM FUNCTIONAL TOOTH CONTACTS
 CONCEPTS OF OCCLUSION

Terminologies
 OCCLUSION is defined as the act or process of closure
or of being closed or shut off or the static relationship
between the incising or masticating surfaces of the
maxillary or mandibular teeth or tooth analogues (GPT-
8).
 Ramfjord and Ash- “multifactorial functional relationship
between the teeth and other components of the
masticatory system as well as with other areas of the
head and neck that directly or indirectly relate to
function, parafunction or dysfunction of the masticatory
system.”

ARTICULATION is defined as the static and
dynamic contact relationship between the
occlusal surfaces of teeth during function GPT-8.
BALANCED ARTICULATION/OCCLUSION is defined as
bilateral, simultaneous, anterior, and posterior
occlusal contact of the teeth in centric and
eccentric positions.

 GNATHOLOGY: is the Science that deals with
the biologics of the masticating mechanisms; that is,
the morphology, anatomy, histology, physiology,
pathology and the therapeutics of the oral organ,
especially the jaws and teeth and the vital relations
of the organ to the rest of the body.
 MUTUALY PROTECTED
ARTICULATION:
An occlusal scheme in which the posterior teeth
prevent excessive contact of the anterior teeth in
maximum intercuspation, and the anterior teeth
disengage the posterior teeth in all mandibular
excursive movements.

 CANINE PROTECTED ARTICULATION a form of
mutually protected articulation in which the vertical and
horizontal overlap of the canine teeth disengage the
posterior teeth in the excursive movements of the
mandible
(ANTERIOR PROTECTED ARTICULATION).
 FUNCTIONAL ARTICULATION is defined as the
occlusal contacts of the maxillary and the mandibular
teeth during mastication and deglutition.
GPT 7, 1999
 “The maxillomandibular relationship in which the condyles
articulate with the thinnest avascular position of their
respective discs with the complex in the anterior-superior
position against the slopes of the articular eminences.www.indiandentalacademy.com

 MONOPLANE ARTICULATION the arrangement of
teeth by which they are positioned in a single plane.
 LINGUALIZED ARTICULATION the maxillary
lingual cusps articulate with the mandibular occlusal
surfaces in the centric working and non-working
mandibular positions.

DETERMINANTS OF OCCLUSAL MORPHOLOGY :
 Anatomy of the teeth functions in harmony with the
structures controlling the movement patterns of the
mandible.
 It is important to examine each of these structures and
appreciate how the anatomic of each can determine the
occlusal morphology necessary to achieve an optimal
occlusal relationship.

Posterior controlling factors (condylar
guidance):
 The condylar movement
 The rate at which it moves down depends on the
steepness of eminence.
 The angle at which the condyle moves away from the
horizontal reference plane is referred as condylar
guidance angle.

Anterior controlling factors ( anterior guidance)
 The anterior teeth moves
 As the mandible protrudes or moves laterally the incisal
edges of mandibular teeth touches lingual surface of the
maxillary anteriors.
 The steepness of the lingual surface of maxillary
anteriors determine the amount of downward movement
of the mandible.
 It is considered to be variable rather than fixed
It can be changed by
Orthodontic movement.
Restorations
Extractions
Habits
Tooth wear. www.indiandentalacademy.com

Nearer the tooth to the TMJ more the influence
of joint anatomy on the occlusal morphology

Vertical determinants :
The factors that influence the height of cusps and depth of
fossa. These are determined by
 Anterior controlling factors.
 Posterior controlling factors.
 Nearness of cusps to these factors.
 Cuspal inclination indicates the angle of movement of
mandible during eccentric movement from the centric
relation.

EFFECT OF CONDYLAR
GUIDANCE ON CUSP HEIGHT :

EFFECT OF ANTERIOR
GUIDANCE ON CUSP HEIGHT :

EFFECT OF PLANE OF
OCCLUSION ON CUSP HEIGHT :

EFFECT OF CURVE OF SPEE ON
CUSP HEIGHT :

EFFECT OF MANDIBULAR LATERAL
SHIFT ON CUSP HEIGHT :

Amount of lateral translation :

Direction of lateral translation :

Timing of lateral translation :
Immediate and progressive side shift

Horizontal Determinants:
 The factors that influence the direction of
ridges and grooves and also influence the
placement of cusps.
 Each cusp tip generated both laterotrusive
and mediotrusive pathways across the
opposing tooth. These pathways are
formed by cusp rotating around the
rotating condyle.

Effect of distance from rotating
condyle on ridge & groove direction :

Effect of distance from the mid
saggital plane on ridge & groove
direction :

Effect of distance from the mid saggital
plane & rotating condyle on ridge &
groove direction :

Effect on mandibular lateral
translation on ridge & groove
direction :

Effect of inter condylar distance on
ridge & groove directon :

 The maxillary posterior occlusion was
fabricated to the mandibular occlusal
form by using the maxillary anterior
teeth as guides for the “chew in”
registration as advocated by Meyer.
 A suspension instrument was used for
articulating the casts, which had no
functional movement capability.
 It was argued that articulator
movement was unnecessary because
functional limits were recorded with the
“chew-in” registration.

 A few years later Schuyler joined with Pankey and Mann
to evolve what is now known as the P.M.S (Panky,
Mann, Schuyler) system.
 This occlusal system retained the Monson spherical
theory and the functionally generated path technique;
however, under Schuyler’s influence

 (1) the balancing side contacts were eliminated.
 (2) the importance of incisal guidance was elevated.
 (3) the concept of “long centric” or “functional centric
occlusion” was proposed in which centric occlusion is
thought of as an area of contact rather than a point
contact, and
 (4) the Hanau occlusal instrument with arbitrary face bow
and Broadrick occlusal plane analyzer was adopted.

Gnathology
At approximately the same time that Pankey and Mann
were formulating their concepts of occlusion, another
group of researchers headed by McCollum.
Gnathologic theory explains:
(1) establishing via a hinge axis location the rotational
centers of the condyles;
(2) recording the three dimensional envelope of motion of
the condyles via the pantographic tracing;
(3) maximum intercuspation of the teeth when the condyles
are in their hinge position; and
(4) bilateral balance with eccentric jaw movements.

 Because these Gnathologic researchers felt that
the condyles were the determinants of occlusal
schemes, they discovered that the side shift of
the condyle would greatly affect cuspal position,
especially if bilateral balance was deemed
beneficial.

 Stallard and Stuart, felt that the basic theory of mandibular
movement was fundamentally correct, but the application
of this knowledge was misdirected.
 They proposed eliminating the balancing contacts in
eccentric jaw movements by having the canines on the
working side disclude the posterior teeth; they named it
the Cuspid Protection Theory.
 This also became known as the Mutually Protected
System.

 A number of other technical
developments evolved during the
1940s and 1950s that helped the
popularity and accessibility of the
gnathologic concepts.
 Payne and Thomas developed
systematic waxing techniques that
allowed for the development of an
acceptable occlusal scheme when
all the posterior teeth had been
prepared.
 Stuart improved the design of the
Gnathologic instrument

•Guichet greatly simplified
the pantographic recorder
and developed gnathologic
instrument,which he called
the Denar articulator.

•Occlusion in natural dentition
 A normal occlusion is often referred as “imaginary
ideal occlusion” which rarely exists in humans.
 The concept of ideal occlusion is based more on a
neuromuscular than morphological position of teeth.
 Theoretically features of ideal occlusion are as
follows:

 All components of masticatory system are present.
 Centric occlusion is in harmony with centric relation.
 In centric occlusion, the supporting cusps of all
posterior teeth occlude with marginal ridges, except
for the distal buccal cusps of mandibular molars and
the mesial lingual cusps of maxillary molars which
occlude with central fossae of their opposing arch.

 During protrusion, the posterior teeth should discclude.
 Tonic activity of the masticatory muscles should be
healthy
 During lateral movement, the teeth on the non working
side should disocclude and contact between opposing
canines on the working side either alone or together with
one or more pair of adjacent posterior teeth.

 The dentition is in harmony with the basal bone and
aligned such that functional occlusal forces directed
along the long axes of teeth.
 Adequate interocclusal distance in postural rest position.
 Should have normal masticatory, deglutition, speech,
esthetic and respiratory functions.
 No signs or symptoms of pain or dysfunction from any
component of masticatory system.

•Difference between natural and
artificial occlusion.
 Natural dentition:
 A healthy, natural angle class I occlusion
characterized by simultaneous, equalized contact of
all teeth (anterior and posterior) in maximum
intercuspation (centric occlusion).
 Centric occlusion is generally not coincidental with
the terminal arc of closure (centric relation).

 In protrusion, the anterior teeth disocclude all
posterior teeth.
 In a lateral excursion, the working canine may
disocclude posterior teeth on the working side
(canine disclusion), or may permit posterior
teeth on the working side to occlude
simultaneously (group function).
 Frequently there is a combination of canine
disclusion and group function in the same
patient.

Occlusion in fixed Prosthodontics.
 An occlusion restored with fixed restorations often differs
from a natural dentition. When the major of the occlusal
surface are restored the patient’s pre existing centric
occlusal position cannot be preserved.
 Therefore, the restored centric occlusion is planned to
coincide the centric relation- a repeatable position.
 All interceptive occlusal contacts along the terminal arc of
closure on teeth not receiving the artificial crowns are
eliminated with selective grinding.

 The restored centric occlusion is a
simultaneous, equalized contact of all teeth
(anterior and posterior) coincidental with
centric relation.
 Usually cusp to fossa occlusion is prescribed to
enhance stability and reduce interproximal food
implication.
 Occlusal tables are narrowed to maintain
forces within confines of the root system and to
minimize non working contacts.
 The anterior teeth disclude posterior teeth in
straight protrusion, lateral working position may
be canine disclusion or group function.

OPTIMUM FUNCTIONAL TOOTH CONTACTS
 Criteria for optimum functional occlusion
 The criteria for optimum functional occlusion described as
even and simultaneous contact of all possible teeth when
the mandibular condyles are in their most supero-anterior
position, resting against the posterior slopes of the articular
eminences, with the discs properly interposed. In other
words, the musculoskeletal stable position of the condyles
(centric relation) coincides with the maximum intercuspal
position of the teeth.

 1. Direction of force placed on the
teeth if a tooth is contacted such that
the resultant forces are directed
through its long axis (vertically) the
periodontal agreement ligament is
quite efficient in accepting the forces
and breakdown is less likely.
 If a tooth is contacted in such a
manner that horizontal forces are
applied to the supportive structures,
however, the likelihood of pathologic
•Occlusal contact patterns

 The process of directing occlusal forces through the long axis is
known as Axial Loading.
 It can achieved in two methods
 Through the development of contacts on either cusp tips or
relatively flat surfaces that are perpendicular to he long axis of
the tooth. These flat surfaces can be the crest of marginal
ridges or bottom of fossa. With this type of contact ,forces are
directed along long axis .

 The other method is Tripodization. It is logical to see but
difficult to accomplish (Burch1980) It requires each cusp
contacting an opposing fossae be developed. Such that it
produces three contacts surrounding the actual tip. When
this achieved, the resultant force is directed through long
axis of tooth. The final result is 10 -12 contacts per molar
restoration.
 Both methods eliminate off axis forces, thereby allowing
periodontal ligament of effectively accept potentially
damaging forces and reduce them.

2. Amount of force
 The lever system of the mandible can be compared to a
nutcracker.
 When a nut is being cracked, it is placed between the
levers of the nutcracker and force is applied.
 If it is extremely hard, it is placed closure to the fulcrum to
increase the likelihood of its being cracked.
 This demonstrates that greater forces can be applied to an
object as its position nears the fulcrum. The same can be
said of the masticatory system.www.indiandentalacademy.com

 if a hard nut is to be cracked between the teeth, the most
desirable position is not between the anterior teeth but
between the posterior teeth, because as the nut is
positioned closer to the fulcrum (the TMJ) and the area
of the applied to the posterior teeth than to the anterior
teeth.

 The jaw, however, is more complex. Whereas the fulcrum
of the nutcracker is fixed, the fulcrum (the TMJ) of the
masticatory system is free to move.
 As a result, when heavy forces are applied to an object on
the posterior teeth, the mandible is capable of shifting
downward and forward to obtain the occlusal relationship
that best completes the desired task.
 This shifting of the condyles creates an unstable
mandibular position.

 Additional muscle groups such as the inferior and
superior lateral pterygoid muscles and the temporal
muscles are then called on to stabilize the mandible,
resulting in a more complex system than that of a simple
nutcracker, understanding this concept and realizing that
heavy forces applied to the teeth can create pathologic
changes lead to an obvious conclusion.

 The damaging horizontal forces of eccentric movement
must be directed to the anterior teeth, which are position
farthest from the fulcrum and the force vectors, since the
amount of force that can be applied to the anterior teeth is
less than that which can be applied to the posterior teeth
the likelihood of breakdown is minimized.

BILATERAL BALANCED OCCLUSION
 The concept of balanced occlusion itself is often credited to
Ferdinand Graf Spee
 It was one of the earliest proposed theories -Bilateral
Balanced Occlusion. Although earlier applied to natural
dentition, it is now limited to complete denture
 Bilateral, Simultaneous, Anterior and Posterior Occlusal
Contact of Maxillary and Mandibular Teeth in Centric and
Eccentric Position

 When the principles of bilateral balanced
occlusion were introduced in Fixed
Prosthodontics, there was a high rate of failure
even with specific attention to detail and use of
sophisticated articulators.
 Failure was due to Increased occlusal wear,
Increased/accelerated periodontal breakdown,
TMJ and neuromuscular disturbances

The Demise of Balanced Occlusion
in restoring natural dentition
 Clyde Schuyler(1929) believed in harmony between
centric relation and centric occlusion and said that such
arrangements would result in high efficiency in
mastication
 But he recognized the essential differences between
edentulous and dentulous conditions and did not set any
rigid anatomical standards on occlusion which if not
complied with would result in pathology
 This concept was referred to as Functionalism

 In 1935, Schuyler developed the first detailed technique
for occlusal adjustment based on careful grinding of
specific occlusal inclines
 He believed that there was relationship between functioning
occlusal inclines and potential stress to periodontium and
occlusal adjustment was a way to reduce this stress.

 By 1953 he began to observe failure of natural dentition
restored with balance .
 He said that he failed to see the value of nonfunctional
contacts
 His observations and suggestions effectively signaled
the end of BALANCE as a acceptable treatment
approach for the dentulous patient

 Stuart and Stallard (1960)noted that balanced occlusion in
reconstructed natural dentitions

 1. Often required injudicious increase in occlusal vertical
dimension to achieve balance.
 2. Often led to instability of occlusion.
 3. Frequently showed increased wear of teeth and
restorations
 4. Provided poor group usage of teeth.

 5. Extraordinary technical demands
 6. Esthetic character of the restored occlusions was notwww.indiandentalacademy.com

 SCHUYLER (1961) stated that an ideal occlusion
has coincident maximum intercuspation position
and Centric relation position but this rarely
occurs in clinical situations
 UNILATERAL BALANCED OCCLUSION
 GROUP FUNCTION
Definition:-
 Multiple contact relations between maxillary
and mandibular teeth in lateral movements on
the working side, whereby simultaneous contact
of several teeth acts as a Group to distribute
occlusal forces-GPT 8

 The most desirable group function consists of canine,
premolar and mesiobuccal cusp of first molar
 Any laterotrusive contact more posterior than mesial
portion of first molar are not desirable because of the
increased amount of force that can be placed as the near
the fulcrum and force vectors .
 Horizontal pressures during lateral movements are
distributed to one half of the arch on the working side.
This scheme eliminates cross tooth and cross arch
balance seen with balanced occlusion

Advantages:
 Group function of the teeth on the working side
distributes the occlusal load
 The absence of contact on the nonworking side
prevents those from getting subjected to
destructive, obliquely directed forces found in
nonworking interferences.
 It also saves centric holding cusps that is
mandibular buccal cusps and maxillary palatal
cusps from excessive wear

 Group function was felt to be goal for occlusal
adjustments and has easy application
 In the presence of anterior teeth bone loss or
missing canines, mouth should be restored to
group function

 Due to these factors, this concept had broad support from
Pankey , Mann and Schyluer(1960) Ramjford, Ash(1966),
POSSELT(1968), and LAURITZEN(1974).
 It has been adapted by PANKEY and MANN for complete
mouth rehabilitation
 Group Function Occlusion doesn’t have the harmful effects as
seen with Balanced Occlusion and is not as difficult to
fabricate as a Mutually Protected Occlusion.

 Disadvantage:
Group Function Occlusion doesn’t fulfill criteria for ideal
occlusion.
Guichet(1970) described standards for ideal occlusion and
said that there was no one ideal occlusion pattern for all
individuals but an appropriate pattern can be found based
on these criteria.

IDEAL OCCLUSION : Guichet(1970)
 Criteria I- Incorporate into the occlusion those factors
which have to do with the reduction of vertical forces.
 Criteria II- provide a maximum intercuspation of teeth with
the condyles in centric relation position.
 Criteria III- Provide for horizontal movement of the
mandible from the centric position

Characteristics of Group Function
Given by BEYRON (1954)
 Teeth should receive stress along the tooth long axis
 Total stress should be distributed among the tooth
segment in lateral movement
 No interferences occur from closure into intercuspal
position
 Keep proper interocclusal clearance
 Teeth contact in lateral movement without interferences
 He felt that no single occlusion could serve as a general
basis of every individual

 It was suggested that some Freedom of
movement in an anteroposterior direction
should be allowed. This evolved into:
 Theory of Long centric
 The concept of all working side teeth sharing
lateral pressures during lateral movements
 The concept of non working side teeth free from
contacts during lateral movements
 Criteria were an attempt to eliminate the need for
neuromuscular adaptation.

 According to this concept,
 Maximum intercuspation and centric relation are not
coincident but flat areas on the depth of the fossae, on
which opposing cusps occlude, will allow for a certain
degree of freedom in both centric and eccentric
movements without the guiding influences of occlusal
inclines
 Long centric is 0.5mm to 0.75 mm free space between
maximum intercuspation and centric relation position,
without changing vertical dimension of occlusion

 Advantages:
 Freedom to close the mandible in centric relation or
slightly anterior to it without varying vertical dimension.
 If no freedom in centric, the lower incisors may strike the
lingual inclines of upper incisors in a manner that has a
tendency to wedge the upper teeth labially .
 It is this wedging effect that causes most of the instability
in occlusions not provided with a long centric

Three dimensional aspect of Freedom in Centric
Concept.
 There may be freedom in Mesial (M), Distal (D),
Lateral (L) and Median (Md) directions from a
centric contact
(a) Locked in occlusion
(b) Freedom in centric occlusion

PANKEY-MANN-SCHUYER PHILOSOPHY 0f
complete occlusal rehabilitation
Principles include
 Static coordinated occlusal contact of maximum number
of teeth when mandible is in centric relation
 An anterior guidance in harmony with lateral eccentric
positions
 In protrusion dïsclusion of posterior teeth
 In lateral excursions, dïsclusion of all non working teeth
 Group function of all working side inclines

Sequence of Treatment
 Part 1- examination, diagnosis, treatment planning
 Part 2- harmonization of anterior guidance for best
possible esthetics, function and comfort
 Part 3- selection of occlusal plane and restoration
of lower posterior occlusion in harmony with
anterior guidance
 Part 4- restoration of upper posterior occlusion in
harmony with anterior and condylar guidance.

MUTUALLY PROTECTED OCCLUSION
Defn:
An occlusal scheme in which the posterior teeth prevent
excessive contact of the anterior teeth in maximum
intercuspation, and the anterior teeth disengage the
posterior teeth in all mandibular excursive
movements.

 Posterior teeth function most effectively in stopping the
mandible during closure whereas anterior teeth function
most effectively in guiding the mandible during eccentric
movements.
 It is apparent that the posterior teeth should contact slightly
more heavily than anterior teeth in centric relation.
 Stuart found patients over 60 yrs old without attrition and
studied their occlusion.
 He observed that molars did not contact during eccentric
movements but in maximum intercuspation they contacted.

 The molars were said to be responsible for bearing the
vertical occlusal loads
 Stallard found that anterior teeth protect the posterior teeth
and the posterior teeth protect the anterior.
 The concept of mutually protected teeth was based on this
observation
 The centric stops on the posterior teeth also help to
prevent excess stress loading transferred to TMJ
 The incisors protect the canine and posterior teeth during
Protrusion

Lucia in 1961 described the Advantages of mutually
protected occlusion
 Minimum amount of tooth contact is involved –therefore
better penetration of food
 A cusp to fossa relationship produces an interlocking of
upper and lower components- giving a maximum support
in centric relation in all directions
 The force is clearly closer to the long axis of each tooth
 The arrangement of the marginal, transverse and oblique
ridges have a shearing action -make a more efficient
chewing apparatus

CANINE PROTECTED OCCLUSION
 The concept of the cuspid protection mechanism, which is
diametrically opposed to the balanced occlusal concept,
began in 1919 with the work of Nagao.
 This was reinforced by Shaw in 1924 and then gained most
of it’s concepts after the extensive work of D’Amico in 1958.
 D'Amico performed a study on canines in animals and
human beings and advocated a canine guided occlusion
 This theory suggests that the only tooth contact in all
positions of the mandible except CR should be between
maxillary cuspids and mandibular cuspids. Thus he called
canine as NATURE’S STRESS BREAKER.

WHY CANINE??
 Long roots
 Good crown to root ratio
 Surrounded by dense compact bone which
tolerates forces better.
 Location is far from the TMJ thus receiving less
stress .
 It has many receptors in the periodontal ligament
so it controls lateral pressure by directing vertical
masticatory movements.

 D’Amico also claimed that proprioceptors of the
periodontal ligament associated with the canine
teeth are far more responsive than those of any
other teeth
 Another advantage is it appears that fewer
muscles are active when canines contact during
eccentric movements than when posterior teeth
contact.

 Occlusal trauma to the canine teeth is thus
prevented by the reduced muscular tension and
magnitude of the applied force.
 Therefore canines are appropriate teeth to
contact and dissipate the horizontal forces while
disoccluding the posterior teeth.
 When this condition exists the patient is said to
have canine guidance or canine rise.

 Canine protected Occlusion is an important
concept, especially for people who have
 Excessive wear on their teeth,
 Erosion of their roots,
 Gingival recession,
 And suffer from TMD (Temporomandibular joint
dysfunction).

 Nature's Biofeedback Mechanism:
 There is a biofeedback mechanism that comes into
play.
 When the canines touch, nerves send a message
back to the brain which in turn sends a message to
the muscles that close the jaw and then the
muscles relax.
 When you take away that canine protection, the
muscles stay active.

 That's when you can get clenching, grinding of the
teeth, joint pain, fracturing of teeth, excessive
wear of the enamel on top of the tooth, erosion of
the root surface (abfractions), and gingival
recession.
 In many patients, canines however are not in
proper position to accept horizontal forces.
 The most favorable alternative to canine guidance
is group function.

Limitations:
 Controversy arises whether or not the canine
should be the only tooth to bear the pressures
during lateral excursion
 Missing canine and prosthetic canine
 If periodontium is compromised .

Dawson (1974) stated that,
 “When canines cannot be used, lateral movements
have posterior dïsclusion guided by anterior teeth on
the working side, instead of canine alone”
 He called this “Anterior Group Function”
 He defended the ideas that the anterior teeth are more
capable of supporting stresses than are the posteriors
because
 Of the anterior’s mechanical position in relation to the
fulcrum (TMJ) and force( masticatory muscles)
 With a better crown root ratio.

Dawson presented his Theory Of Nutcracker.
 The farther the nut (anterior teeth) was from the
fulcrum (condyles), the lesser would be the force
exerted on the nut.
 The more anterior the initial tooth contact, Class III
lever, longer the lever arm and hence the force
exerted by the musculature will be less effective,
therefore the load placed on the teeth will also be
small.

 Stuart and Stallard (1961) modified features of
mutually protected occlusion and coined the term
“ORGANIC OCCLUSION” in which Centric
relation and maximum intercuspal position
coincide.
 The aim of the Organized Occlusion is to relate
the teeth to be in harmony with the muscles and
joints in function.
 The muscles and joints should determine the
mandibular position of occlusion without tooth
guidance.

Organic occlusion features by
THOMPSON (1967) are:
 CRP and MIP are coincident
 Posterior teeth are in a cusp fossa relation, one tooth to one
tooth contact
 Each functional cusp contacts the occlusal fossa at three
points
 In protrusion maxillary incisors guide the mandible and
disocclude the posteriors
 In lateral movements – lingual surface of maxillary canine
glides along the distal inclines of mandibular canine and
mesial ridge of 1st premolar cusp

BEYRON’S OCCLUSAL CONCEPTS
 Based on functional convenience and avoidance of
discomfort.
 An optimal occlusion would be one that requires less
muscular activity and is in harmony with the neuromuscular
system and TMJ.
 Beyron revealed that the majority of the subjects had
anteroposterior slide, in the Centric Position , in the range
of 0 to 2 mm.
 Only 10% of them presented a coincidence of CO=CR.
 He also advocated freedom in centric concept & canine
guided occlusion.

BIOLOGIC OR PHYSIOLOGIC OCCLUSION:
It is defined as an occlusion in which a functional
equilibrium or state of homeostasis exist
between all tissues of masticatory system.
A physiologic occlusion implies a balance between
occlusal stress and tissue resistance .
The biologic processes and local environmental
factors are in balance.

Importance of Occlusal Harmony
Ideal mandibular function results from harmonious
interrelationship of all the muscles that move the jaw.
Muscle should be allowed to rest.
Muscle should not be forced into prolonged activity without
rest.
When teeth are added to stomatognathic system, they create
a unique influence on the entire inter balance of the
system. Because if the intercuspation of the teeth is not in
harmony with the joint – ligaments, muscle balance, a
stressful and tiresome protective role is forced onto the
muscles.

 When the muscles elevate the mandible in the
absence of any deviating interference, the closing
muscles pull the condyle disc assembly until it is
stopped by bone.
 If the tooth inclines interfere with this position, the
lateral pterygoid muscle is forced into positioning
the mandible to accommodate the teeth.
 The mandible is thus realigned to make the teeth
intercuspate even though to do so requires the
lateral pterygoid muscle to take over the bracing
function normally assigned to bone and ligaments.

 This is because the proprioceptive system is designed in such
a way that it is capable of evaluating the intensity and
direction of stresses on the teeth and designed to program
the lateral pterygoid muscles to position the jaws so that
the elevator muscles can close directly into maximum
occlusal contacts.
 Lateral pterygoid are always involved in any deviation from
centric relation.
 The muscle cannot relax as long as the occlusal
interference is present.
 The unique relationship between the lateral pterygoid and
proprioceptive periodontal receptors is so definite that it
even over rides the normal tendency of the muscle to rest
when it becomes fatigued.
 Elimination of interference permits an almost immediate
return to normal function

RESTORING DIFFERENT
COMBINATIONS
Prosthesis Position
ICP/CR
Articulator
and records
Occlusal
morphology
Single
crown
ICP Simple
hinge
Conform to
occlusal
Morphology
FPD- one
quadrant
ICP Semiadjusta
ble /anterior
guidance
“
Several
quadrants
Long
centric
Fully
adjustable/a
nt guidance
and
condylar
guidance
Group
function is
desired/cusp
to fossa

 Functionally generated path technique can be used to
fabricate single tooth restorations. A pre requisite is
optimal occlusion, because if there are any interferences
this technique will perpetuate those discrepancies.
 Missing, broken down, badly rotated, carious or poorly
restored teeth will not provide the occlusal pathways
needed for shaping the occlusal surfaces.

If insufficient number of natural teeth present
 The position of centric occlusion/ICP can no longer be
determined. Hence guided retruded closure of the
mandible can be used as optimal position.
 The major concern when attempting a Full Mouth
Rehabilitation with restoration of the vertical dimension, is
the transfer of the condylar movement onto an articulator.
 This is necessary to enable the laboratory fabrication of
the prosthesis with appropriate intercuspation as well as
the exact vertical height, which will allow the
temporomandibular joint to function with stability & good
health .

Turner and Misserelian have categorized patients with Excessive
Wear into three groups:
 Category I- Excessive wear with loss of vertical
dimension of occlusion
 Category II- Excessive wear without loss of vertical
dimension of occlusion but with space available.
 Category III-Excessive wear without loss of vertical
dimension of occlusion but with limited space

Excessive wear with loss of vertical
dimension:
 Patients usually have a few posterior teeth, hence unstable
posterior occlusion with excessive wear of anterior teeth
 Treatment: removable occlusal overlay splint that restores
vertical dimension of occlusion to estimated optimum
position.
 Observation for 6-8 weeks with appropriate adjustments.
 Provisional followed by permanent restorations

Excessive wear without loss of occlusal vertical
dimension but with space available:
 Patient shows adequate posterior occlusal support.
 Long history of gradual wear by bruxism. Continuous
eruption has maintained occlusal vertical dimension
 Treatment: equilibration/restoration of posterior teeth for
stability in centric relation and enameloplasty to provide
sufficient space for restorative material.
 Periodontal surgery may be required to gain clinical crown
length

Excessive wear without loss of occlusal
vertical dimension but with limited space :
 Posterior teeth show minimal wear, whereas anterior
teeth show excessive wear.
 Centric relation and centric occlusion are coincident.
 Vertical space must be obtained for restorative
materials.
 This can be accomplished by orthodontic movement,
restorative repositioning, surgical repositioning of
segments and programmed occlusal vertical
dimension modification
 Complex Prosthodontics restorations (multiple
occlusal surfaces involving one or both arches)
where a difference exists between CO and CR, they
are often made to coincide

CONCLUSION
The controversy about occlusion cannot be
resolved for three reasons:
Much knowledge is based upon empirical rather
than scientific information,
The tolerance of the oral organ or the upper and
lower physiologic limits are so broad that
because a certain concept failed in one specific
mouth, it does not mean that it would fail in all
mouths
The tremendous variable factor of the individual
dentist and the standards by which he evaluates,
his completed restorations.”

Since there is no one answer to
occlusal problems, the dentist
should use the philosophy that
works best in his own hands and at
the same time do the most good, or
better yet, the least harm to the
patient.”

REFERENCES
 Curtis M. Becker, Dauid A. Kaiser, Evolution of Occlusion and
Occlusal Instruments J Prosthod 2:33-43, 1993.
 Glossary prosthodontic terms- 8
 Occlusion series in BDJ, 2001;191:6-7
 ALEXANDER-Periodontium and the Canine Function Theory-
JPD 1967,VOL 18, Pg. 571-578
 RICKETTS-Occlusion-the Medium of Dentistry-JPD 1969,VOL
21,Pg. 39-60
 DYER-Dental Articulation and Occlusion-JPD1967, VOL17,
Pg.238-245

 PETER E.DAWSON- Evaluation,diagosis and Treatment of Occlusal
Problems(3RD ED)
 RAMJFORD ASH- Textbook On Occlusion(4th Ed)
 SUMAIYA HOBO -Osseointegration and Occlusal Rehabilitaton
 ROSENSTEIL-Contemporary Fixed Prosthodontics(3RD ED.)
 OKESON-Management of Temporomandibular Disorders and
Occlusion
 SHILLINGBURG- Fundamentals of Fixed Prosthodontics(3RD ED.)

Occlusion concepts in fixed partial dentures / dental implant courses by Indian dental academy

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