• In Latin: Oc= up clusion= closing
• Occlusion means (closing up)
• When the jaws are closed and teeth are in
contact, this is termed as (static occlusion).
• However, occlusion mainly occurs as momentary
contacts during mandibular movements and is
termed as(dynamic occlusion)
•It is the contact relation ship of
upper & lower teeth during
different mandibular movements.
*Simplistic definition of occlusion:
The way teeth meet and function.
*Tooth positioning is not a random
process but a number of controlling
factors are involved
*Occlusion is not only refer to contact between the
teeth but also to all those factors concerned with the
development and stability of the masticatory system
and with the use of teeth in oral motor behavior
The components of human dental occlusion:
1- The teeth and their investing tissue.
2- The jaws.
3- The temporo-mandibular joint.
4- The muscles of mastication.
* To study occlusion the following items must be understood:
1- Dental arch formation.
2- Compensating curvatures of the dental arch ( curved
3- Compensatory curvatures of individual teeth (curved tooth
4- Angulation of teeth in relation to different planes.
5- Functional form of the teeth at their incisal and occlusal third.
6- Facial and lingual relation of each tooth in one arch to its
antagonist in the opposing arch during centric occlusion.
7- Occlusal contact and inter-cusp relation of all teeth of one arch
with those of the opposing arch in centric occlusion.
8- Occlusal contact and inter-cusp relation of all teeth
during various mandibular movement.
• Parabolic curve.
• Phases of development of permanent dental arch.
• Bonwill triangle.
The maxillary arch is larger than the mandibular arch giving a
horizontal space between upper and lower teeth during
occlusion called overjet.
Also the upper teeth overlap the lower teeth, the vertical
distance between them is named overbite.
Two Types of Overlap
Horizontal Overlap= Overjet
Vertical Overlap= Overbite
The upper &lower dental
arches have a horse-
From an occlusal view the
facial and lingual
outlines of the dental
arch conform to a
2- Middle segment.
3- Posterior segment.
equally bisected by the
Facial surfaces of anterior
teeth and the first
premolar of both sides.
2- Middle segment:
Straight line and
continuous with the
anterior segment in buccal
direction. Included the first
and second premolars and
the mesial half of the first
3- Posterior segment:
Straight line parallel to the
midline of the jaw& slightly
directed to the midline in
the maxillary dental arch.
Posterior segment: Straight line parallel to the midline of the
jaw but slightly directed to the midline in the maxillary dental
* The buccal outline of the upper molars curves toward the
midline more than the lower due to
1- Second and third maxillary molars located lingual to the
2- Distal convergence of the first maxillary molar.
First phase: Second phase:
At 6 years eruption of the
first permanent molars
lead to increase the
and jaw growth.
Eruption of the permanent
Third phase: Fourth phase:
Premolars replace the
deciduous molars and
spacing of teeth occur
due to smaller size of
The canines and the second
permanent molar erupted
nearly at the same time.
The arch is considered to
• Eruption of the third