Occlusion /certified fixed orthodontic courses by Indian dental academy

OCCLUSION
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


CONTENTS
 Introduction
 History
 Alignment and occlusion of the dentition
-Factors and forces that determine tooth
position
-Intra-arch tooth alignment
-Inter-arch tooth alignment
-Occlusal contacts during mandibular
movements
 Summary
 References


INTRODUCTION
According to Glossary of Prosthodontic Terms:
“Occlusion is the act or process of closure or of
being closed or shut off”
Ramfjord and
between teeth

Ash:

Occlusion

=

Contacts

“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.”

Teeth

Masticatory
system

Periodontium

Articulatory
system

Muscles


TMJ

Occlusion

HISTORY
Development of concept of occlusion-Three periods:
1. Fictional period (prior to 1900)
2. Hypothetical period (1900-1930)
3. Factual period (1930 to present)


1.Fictional period:
Fuller, Clark and Imrie-Antagonism,meeting
or gliding of teeth.
Kingsley(1880)– “Norm”
Talbot’s-(1903)Irregularities of teeth and their
treatment.

2.Hypothetical period:

Edward H. Angle(1899)- “Old Glory” and “Key
to Occlusion”.
Matthew Cryer and Calvin Case-Occlusion
referred to the closure of the teeth one upon
the other.

Bennett
(1908)-Functional
analysis
or
dynamic approach to occlusion.
Turner(1903)-Concept of physiologic rest.
Lister and Simon(1922)-Related teeth to the
rest of the face and cranium.
Milo Hellman-Racial variations in normal
occlusions.

3.Factual period:

Difference between
concepts of occlusion.

static

and

dynamic

Broadbent and Planer-(1930)
Occlusion=Interdigitation of teeth + Status of
controlling musculature and functional factors.

Alignment and occlusion of the dentition:
Tooth positions are determined by various
controlling factors such as:
1. Factors and forces that determine tooth
position.
2. Intra-arch tooth alignment.
3. Inter-arch tooth alignment.

1.Factors and forces that determine tooth

position.

(a)Surrounding musculature:
Labial to teeth are lips,cheeks-lingually directed
forces
Tongue-labially and bucally directed forces.


Abnormal muscular patternTongue thrust and visceral swallow.
Oral habits-biting on
pipe,musical instruments.
(b)Proximal surfaces:
Proximal contact wearmesial drift( because of
functional
response
of
alveolar bone and gingival
fibres)
(c)Occlusal
contacts:
prevents extrusion.

2.Intra-arch tooth alignment:

-Relationship of the teeth to each other
within dental arch.

Plane of occlusion is not flat.

The curvature of the occlusal plane is due
to the varying degrees of inclination of
teeth in the dental arches.


THE OCCLUSAL SURFACE
The area of tooth between buccal and
lingual cusp tips is called the occlusal
table.


(a) Inner inclines
(b) Outer inclines


3.Inter-arch tooth alignment:

-Relationship of the teeth in one arch to
those in the other.
Arch lengthMaxilla – 128 mm
Mandible – 126 mm
Arch width: Distance across arch.


The
teeth
teeth
areas

buccal cusp of mandibular posterior
and lingual cusp of maxillary posterior
occlude with the opposing central fossa
– Supporting cusps.


The centric cusp are broad and rounded.

The The buccal cusp of maxillary posterior
teeth and lingual cusp of mandibular
posterior teeth– Guiding or non-centric cusps
(sharp, with definite tips)

Functional outer aspect:
Present only on outer aspect of centric cusp.
This area assists in shearing of food therefore
non-centric cusps- shearing cusps.

Non-centric
cusps
provide stability to the
mandible in maximum
intercuspal position.
Guiding cusps.

BUCCOLINGUAL OCCLUSAL CONTACT
REALATIONSHIP


Proximal
contact
areas located slightly
buccal to the C-F
Line-Greater lingual
embrasure
area-Major spillway. www.indiandentalacademy.com

MESIO-DISTAL OCCLUSAL CONTACT
REALATIONSHIP
These cusp typically contacts
1. Central fossa areas: The actual contact point
are called centric stops, holding contacts, as
they serve to hold the teeth in a stable
position.


2.Marginal ridge and embrasure areas:
Marginal ridge is slightly convex areas,
therefore the type of contact is cusp tip
contacting a flat surface.


COMMON OCCLUSAL RELATIONSHIPS OF
POSTERIOR TEETH
CLASS-I


COMMON OCCLUSAL RELATIONSHIPS OF
ANTERIOR TEETH
Maxillary anterior teeth-labial to mandibular
anterior teeth.
Inclined labially (12º-28º).
Normally incisal edges of lower incisors
contacts lingual surfaces of upper incisors in
the lingual fossae which is 4mm gingival to
incisal edges.


In normal occlusion, contacts on the anterior
teeth in the intercuspal position are much
lighter than on the posterior teeth.
Purpose of the anterior teeth-guide the
mandible through various movements.
Anterior guidance- It is the anterior tooth
contact that provide guidance to the mandible.
-determined
by
exact
position
and
relationship of the anterior teeth which can be
examined both horizontally and vertically.

Overjet:distance between
the labial incisal edge of
maxillary incisor and labial
surface
of
mandibular
incisor.
Overbite:distance
between the incisal
edges
of
the
opposing
anterior
teeth.

OCCLUSAL CONTACTS DURING
MANDIBULAR MOVEMENTS
The TMJ’s and the associated muscles allows
the mandible to move in all three planes(Sagittal,Frontal
and
horizontal)
which
ultimately influences contact patterns on the
occlusal surfaces of the posterior teeth.
Eccentric- any movement of the mandible
from the intercuspal position that results in
tooth contact.
Three
types:Protrusive,
Laterotrusive,
Retrusive.

PROTRUSIVE


LATEROTRUSIVE


RETRUSIVE


SUMMARY


REFERENCES
 Occlusion series in BDJ, 2001;191:6-7


Okeson
JP.
Management
Temporomandibular
Disorders
Occlusion, ed. 4th, 1998; Mosby

of
and

 Ash MM and Ramfjord S. Occlusion, ed. 4th,
1966; WB Saunders Company, Michigan


Santos JD. Occlusion Principles and
Concepts,
ed.
2nd,
1999;
Ishiyaku
EuroAmerica, Inc. U.S.A.



Shillingburg HT. Fundamentals of Fixed
Prosthodontics, ed.3rd, 1997;Quintessence

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