• Provides optimal
maxilla and mandible.
• Tooth : Acts as a
• If not measured
accurately, the joint will
• Musculature : Opening
and closing muscles
tend to be in a state of
• If the VD is altered,
severe discomfort to
both TMJ and muscles
dimension of rest
• Vertical separation of
the jaws when the
opening and closing
muscles of mandible
are in a state of
only to maintain
• Vertical separation of
the jaws when the
teeth or occlusion rims
are in contact.
Interocclusal Distance (IOD)
It is generally considered that the teeth should not be in
contact when the jaws are at the vertical dimension of
rest position. The 2 to 4mm distance between the upper
and lower teeth when the mandible is at physiologic rest
position is called interocclusal distance (IOD) frequently
referred to as the “free way space”.
INCREASE IN VDO /
DECREASE IN IOD
• The chin-nose distance will
increase, and then patients
will have an appearance of
• Constant pressure to the
basal seat area which will
lead to bone resorption.
• Soreness of the tissues of
the basal seat.
• “Clicking”, of dentures
DECREASE IN VDO /
INCREASE IN IO
• Potentially damaging to the
• The normal tongue space is
limited. Facial distortion
appears more noticeable with
• The muscles of facial
expression lose their tonicity
and the face appears flabby
instead of firm and full.
• Over closure of jaws may lead
• Improper phonetics
to angular chelitis
relationship in which
the condyles articulate
with the thinnest
avascular portion of
their respective discs
with the complex in the
position against the
shapes of the articular
TYPES OF HORIZONTAL
Reference relation with
which the desired
occlusion can be
coordinated and is
constant for each
patient, provided that
the soft tissue
structures in the
joints are healthy
Any relationship of
mandible to maxilla
other than centric
relation which include
protrusive and lateral
ORIENTATION OF THE
Selection of shade
Color and shade of tooth
The shade consist of:
a. Hue i.e specific color
b. Saturation i.e. amount of color
per unit area.
c. Translucency i.e ability of color
to permit light to pas through it.
Patients age – With
while lighter teeth
are suitable for
teeth for fair skin, blue eyes,
dark teeth usually for dark
skin and black eyes.
The color should be matched
with the skin of the cheeks
The following facts are true for nearly all natural
a.The neck of the tooth has a more pronounced
color than the incisive edge.
b.The incisive edge if not worn, is more transluscent
that the body of the tooth and is usually of a
bluish shade (composed entirely of enamel)
c.The upper central incisors are lightest teeth in the mouth
followed by the laterals and canines. Posterior teeth are
usually uniform in color.
d.Teeth darken slightly with age.
- Aid for selecting the shade
Shade guides – The shade guide tooth should be moistened
and selection made in the normal light.
a.Outside the mouth along the side of the nose.
b.Under the lip with the incisal edge exposed
c.Under the lip with only the cervical end covered and the
Correction of speech defects
Preservation of the remaining tissue
and muscle tone
- Primary selection of the teeth must be
carried out at the first appointment.
Selection of size
Selection of size (width and length)
Size of the face and head
Size of the contour of the maxillary arch
i. In class I – Normal relationship, the teeth in one
arch are compatible with the teeth in the other
ii. In class II – The mandible is retruded
and the mandibular teeth are frequently smaller
iii. In class III – The mandibular teeth are
frequently larger than normal
Width of the anterior teeth
Bizygomatic width – The average width of the
maxillary central incisor is estimated to be 1-16 of the
bizygomatic width that is, the distance between the
cheek bones measured just in front of the ears.
Some simple devices are available from tooth
manufacturers for making this determination or
caliper may be used to measure this distance.
A face bow maybe used as caliper to make this
determination. The combined width of the six
maxillary anteriors is slightly less than one third the
Selection of the form:
• Guides for selecting
the form of anterior
• Shape of the arch.
Posterior teeth selection
Posterior teeth selection – Posterior teeth should have a
small bucco-lingual width to keep forces on the
supporting structure to a minimum.
The mesiodistal measurements of the upper posterior
teeth is taken from the distal surface of the canine to
the prominence of the tuberosity. The total mesiodistal
width of the four posterior teeth is often used as a
mould number. The lower posterior teeth should not
extend posterior to the mesial border of the retromolar
The master cast must
be accuretly positioned
on an articulator so
that proper occlusion
will be developed
during the tooth
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