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OCCLUSION
Occlusion : 1- the act or process of
closure or of being closed or shut off
2: the static relationship between the
incising or masticating surfaces of
the maxillary or mandibular teeth or
tooth analogues
 occlusion analysis : a systematic
examination of the masticatory system with
special consideration to the effect of tooth
occlusion on the teeth and their related
structures
 Angle’s classification of occlusion [Edward Harley Angle, American
orthodontist for a classification system of occlusion based on the
interdigitation of the first molar teeth originally described by Angle as
four major groups depending on the antero- posterior jaw relationship.
Class IV is no longer in use.
 Class I (normal occlusion or neutrooclusion): the dental relationship in
which there is normal anteroposterior relationship of the jaws, as
indicated by correct interdigitation of maxillary and mandibular molars,
but with crowding and rotation of teeth elsewhere, i.e., a dental
dysplasia or arch length deficiency.
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Class II (distoclusion): the dental relationship in which the mandibular
dental arch is posterior to the maxillary dental arch in one or both lateral
segments; the mandibular first molar is distal to the maxillary first molar.
Class II can be further subdivided into two divisions:.
Angle’s classification of
occlusion
Division 1: bilateral distal retrusion with a narrow maxillary arch and
protruding maxillary incisors. Subdivisions include right or left
(unilaterally distal with other characteristics being the same).
Division 2: bilateral distal with a normal or square-shaped maxillary arch,
retruded maxillary central incisors, labially malposed maxillary lateral
incisors, and an excessive vertical overlap.
Subdivisions include right or left (unilaterally distal with other
characteristics the same).
Class III (mesioocclusion): the dental relationship in which the mandibular
arch is anterior to the maxillary arch in one or both lateral segments; the
mandibular first molar is mesial to the maxillary first molar. The
mandibular incisors are usually in anterior cross bite. Subdivisions
include right or left (unilaterally mesial with other characteristics the
same).
Class IV: the dental relationship in which the occlusal relations of the dental
arches present the peculiar condition of being in distal occlusion in one
lateral half and in mesial occlusion in the other (no longer used).
Acquired eccentric relation : any eccentric
relationship position of the mandible relative
to the maxilla, whether conditioned or
learned by habit, which will bring the teeth
into contact .
 Centric occlusion : the occlusion of opposing
teeth when the mandible is in centric relation.
This may or may not coincide with the maximal
intercuspal position.
 Centric position : the position of the mandible
when the jaws are in centric relation.
Centric relation:
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1- The maxillomandibular relationship in which the condyles articulate with the
thinnest a vascular portion of their respective disks with the complex in the anteriorsuperior position against the shapes of the articular eminencies. This position is
independent of tooth contact. This position is clinically discernible when the mandible
is directed superior and anteriorly. It is restricted to a purely rotary movement about
the transverse horizontal axis
2: The most retruded physiologic relation of the mandible to the maxillae to and from
which the individual can make lateral movements. It is a condition that can exist at
various degrees of jaw separation. It occurs around the terminal hinge axis .
3: the most retruded relation of the mandible to the maxillae when the condyles are in
the most posterior unstrained position in the glenoid fossae from which lateral
movement can be made at any given degree of jaw separation
4: The most posterior relation of the lower to the upper jaw from which lateral
movements can be made at a given vertical dimension
5: a maxilla to mandible relationship in which the condyles and disks are thought to be
in the midmost, uppermost position. The position has been difficult to define
anatomically but is determined clinically by assessing when the jaw can hinge on a
fixed terminal axis (up to 25 mm).
 Acquired occlusal position : the relationship
of teeth in maximum intercuspation
regardless of jaw position
 Anatomic occlusion : an occlusal
arrangement for dental prostheses wherein
the posterior artificial teeth have masticatory
surfaces that closely resemble those of the
natural healthy dentition and articulate with
similar natural or artificial surfaces—called
also anatomical occlusion.
Anatomic teeth : artificial teeth that duplicate the
anatomic forms of natural teeth.
2: teeth that have prominent cusps on the masticating surfaces
and that are designed to articulate with the teeth of the
opposing natural or prosthetic dentition.
3: anatomic teeth with cuspal inclinations greater than 0
degrees that tend to replica natural tooth anatomy—usage
cusp teeth (30 to 45 degrees) are considered anatomic teeth.
Modified occlusal forms are those with a 20-degree cusp
incline or less—called also anatomical teeth.
 zero-degree teeth :posterior denture teeth
having 0-degree cuspal angles in relation to
the plane established by the horizontal
occlusal surface of the tooth— called also
 zero-degree nonanatomic teeth
 Supporting area 1: the surface of the mouth
available for support of a denture 2: those areas of the
maxillary and mandibular edentulous ridges that are
considered best suited to carry the forces of mastication
when the dentures
are in function
 Supporting cusps : those cusps or incisal edges of teeth that
contact in and support maximum intercuspation.
Usually facial cusps of the mandibular posterior teeth, the
maxillary palatal cusps, and the incisal edges of the
mandibular anterior teeth
Anteroposterior curve (CURVE OF SPEE) : the
anatomic curve established by the occlusal
alignment of the teeth, as projected onto the
median plane, beginning with the cusp tip of the
mandibular canine and following the buccal cusp
tips of the premolar and molar teeth, continuing
through the anterior border of the mandibular
ramus, ending with the anterior most portion of
the mandibular condyle.
Bonwill triangle
 eponym for a 4 inch equilateral triangle bounded
by lines connecting the contact points of the
mandibular central incisor’s incisal edge (or the
mid-line of the mandibular residual ridge) to
each condyle (usually its mid point) and from one
condyle to the other, first described by
Bonwill in 1858 while introducing his Anatomical
Articulator
 Bilateral balanced articulation: also termed
balanced articulation, the bilateral,
simultaneous anterior and posterior occlusal
contact of teeth in centric and excentric
positions.
 working side contacts : contacts of teeth made
on the side of the articulation toward which the
mandible is moved during working movements.
 working side : the condyle on the working side
 working side condyle path: the path the
condyle travels on the working side when the
mandible moves in a lateral excursion.
Camper’s plane
 a plane established by the inferior border of
the ala of the nose (or the average between
the two) and the superior border of the tragus
of each ear.
called also acanthion-external auditory meatus
plane
ala-tragus line (CAMPER’S
LINE)
 a line running from the inferior border of the ala of the
nose to some defined point on the tragus of the ear,
usually considered to be the tip of the tragus. It is
frequently used, with a third point on the opposing
tragus, for the purpose of establishing the ala tragus
plane. Ideally the ala-tragus plane is considered to be
parallel to the occlusal plane. The occlusal plane is at
an angle of approximately 10 degrees relative to the
Frankfort horizontal plane, when viewed in the midsagittal plane.
 Bennett angle : the angle formed between
the sagittal plane and the average path of the
advancing condyle as viewed in the
horizontal plane during lateral mandibular
movements.
Christensen’s phenomenon
 [Carl Christensen, Danish dentist and
educator]: eponym for the space that occurs
between opposing occlusal surfaces during
mandibular protrusion.
 Transverse horizontal axis:
an imaginary line around which the mandible may
rotate within the sagittal plane .
 Adjustable articulator : an articulator that
allows some limited adjustment in the
sagittal and horizontal planes to replicate
recorded mandibular movements.