Principles of Occlusal
Practice In Simple
Dr Wael AL-Omari
Why Clinical occlusion should be
- Most dental treatments involve occlusal
surfaces of teeth.
- Avoid either over or under treatment.
- Provide therapeutic and successful dental
treatment for patients.
- Reduce the risk of failure
The masticatory system is made up of:
What is occlusion?
The Articulatory System:
-TMJ as the hinge
- Masticatory muscles as
- Dental occlusion as the
elements make a system
Analysis of Occlusion
Occlusion is defined as : Contacts between the teeth when -
mandible is closed and when is moving.
I- Centric Occlusion:
-It is how unarticualted models fit together
- It is the habitual bite
- Significance : Occlusal forces directed axially.
II- Centric Relation:
- It is not an occlusion but a jaw relation that is
reproducible with or without teeth present.
- Described Anatomically, conceptionally and
-Defined as- The position of manidble to the maxilla
with the intra-articular disc in position, and during
closure on its hinge axis, that is with the condyles
maximally seated in their fossa (uppermost and
foremost) and the muscles are at their most relaxed and
least strained position.
Significance of CR record:
1- it is reproducible position with or without teeth present
2- If CR involves tooth to be prepared, better remove
deflective contacts prior to preparation
3- When re-organizing occlusion at new vertical dimension
4- To distalize mandible to create space lingually for
5- If restoring anterior teeth and CR contact results in strong
anterior thrust against teeth to be prepared
Freedom in Centric (Long Centric) Sliding from CR to CO
Def.: Occlusal contacts during the mandibular
movements relative to the maxilla.
Mandible movements are guided by muscles, teeth, and
Posterior guidance = TMJ
Determined by intra-articular disc and articulatory
surfaces of glenoid fossa
Anterior guidance = Teeth.
Any teeth contacts during eccentric movements.
I- Canine guidance
II- Group function (contacts are shared by
several teeth on the working side)
Group function vs working side interferences.
More Ideal if anterior guidance on front teeth.
The Mandibular Movements are
1- Neuromuscular control:
muscles and nervous system
2- Guidance system: TMJ and teeth
• Elevation (closing) of the mandible :
Temporslis muscle (anterior fibers), masseter
muscle & medial pterygoid muscle.
• Retrusion of the mandible: Temporalis muscle
• Protrusion: Right and left lateral pterygoid acts
together, medial pterygoid
• Opening the mandible: Digastric and Inferior
-Mandible is controlled by voluntary movements and reflexes.
- Jaw-closing reflex: protects mandible and associated structures during violent
whole body movement.
- Jaw-opening reflex: protects the teeth during sudden mastication of a hard
object and protects lips, cheeks and tongue during mastication.
- Central and autonomic nervous systems receive input from peripheral
receptors, higher centres and propioceptors.
- Propioceptors are located in deep muscles and periodontal ligaments
- Any occlusal changes are sensed by the nervous system via the propioceptors
Direction of mandibular movement
The head of the condyle on the non-working
side moves: forwards, downwards and medially.
The angle of downwards movement is known
as the ‘condylar angle’
The angle of medial movement is known as the
Immediate side shift = Bennet movement
Balancing side. Working side.
Condyle has downward path Condyle pivots
Any tooth to tooth contact which hamper or hinder smooth
guidance in excursions or closure into CO.
- Working side and non-working side and CR interfernces.
-May result in
Occulsal Interferences in Centric Relation
Non Working Side Occulsal Interferences
Protrusive occlusal interference
1- The coincidence of CO
and CR,with freedom in CO
2- When mandible moves
there is immediate and
lasting posterior disocclusion
1- Pretreatment record
2- Treatment of TMD
3- Conformative versus
Requirements of Stable Occlusion
1- Stable stops on all the teeth when the
condyles are in Centric Relation (CR).
Point contacts are on
lingual cusp tips of
maxillary posterior teeth,
buccal cusp tips of
teeth, central pits or
marginal ridges on
posterior teeth, incisals
of lower anteriors and
linguals of upper
Brian Palmer, 2004
• Should have point contacts of the maxillary posterior
lingual cusp tips and the mandibular posterior buccal cusp
tips to the central fossa or marginal ridges of opposing
• Forces exerted on the posterior teeth should be directed
through the long axis of the teeth.
• ‘Normal’ buccal positioning of the maxillary buccal
cusps should be ‘outside’ or buccal to the mandibular
(Brian Palmer, 2004)
2- Disocclusion of posterior teeth in protrusive
3- Disocclusion of posterior teeth on the working side
during lateral excursive movement.
4- Disocclusion of posterior teeth on the non-working
side during excursive lateral movements
5- Coincidence between Centric occlusion and centric
Contacts Marked in
(Brian Palmer, 2004)
Possible signs of non ideal occlusion:
• Giggling and loosening of teeth.
• Migration and drifting with resultant open contacts.
• Excessive tooth wear.
• Non carious cervical notching (abfraction).
• Misalignment of affected teeth.
• Sensitive or tender teeth.
• Fracture and cracking.
• Recurrent fracture of restorations.
• Bone loss.
• Deviation of mandible on closure.
• TMJ dysfunction symptoms ????
• Tori could develop.
Recording of the occlusion
Two dimensional records of the patient’s
These rely on marking the static
and dynamic occlusal contacts
between the teeth and then
describing those marks in writing,
by diagram or by photograph.
Using of articulating paper, foil,
floss or shimstock
The T-scan uses a computer
program to analyse the relative
hardness of the contacts between
Maintain the pre-
EDEC (examine design, execute, check) Rule.
Examine and record occlusion at preoperative
Design where to place the point contacts on the
Remove heavy point contacts on the inclines
and restoration margins
Re-establish the preoperative occlusal contacts
at the same intensity and poitions.
Avoid both static and dynamic occlusal
contacts with the margins of the restoration
• Weakening of tooth by
deep or wide (>1/3
occl.surface) filling may
indicate a provision of