Principles of Occlusal Practice In Simple Restorative

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Principles of Occlusal Practice In Simple
Restorative Dentistry

• Dr Wael AL-Omari
• BDSMDent.Sci.Ph.D.

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Why Clinical occlusion should be studied?

• 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

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• The masticatory system is made up of
• Teeth.
• Periodontal tissues
• Articluatory system

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What is occlusion?
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• The Articulatory System
• TMJ as the hinge
• Masticatory muscles as
• the motor
• Dental occlusion as the
• contacts
• Interdependent
• elements make a system

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Articulatrory system and masticatory system are
very interrelated and interdependent systems
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• Analysis of Occlusion
• Occlusion is defined as Contacts between the
  teeth when mandible is closed and when is moving.
• Static Occlusion
• I- Centric Occlusion
• -Maximum intercuspation
• It is how unarticualted models fit together
• It is the habitual bite
• - Significance Occlusal forces directed
  axially.

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II- Centric Relation - It is not an occlusion
but a jaw relation that is reproducible with or
without teeth present.- Described Anatomically,
conceptionally and geometrically -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.
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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 anterior crowns 5- If
restoring anterior teeth and CR contact results
in strong anterior thrust against teeth to
be prepared
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Sliding from CR to CO
Freedom in Centric (Long Centric)
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Dynamic Occlusion

• Def. Occlusal contacts during the mandibular
  movements relative to the maxilla.
• Mandible movements are guided by muscles, teeth,
  and TMJ.
• Posterior guidance TMJ
• Determined by intra-articular disc and
  articulatory
• surfaces of glenoid fossa
• Anterior guidance Teeth.
• Any teeth contacts during eccentric movements.

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Anterior Guidance

• Classified into
• 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.

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Canine Guidance
Group function
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The Mandibular Movements are influenced by 1-
Neuromuscular control muscles and nervous
system2- Guidance system TMJ and teeth
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• Function
• Elevation (closing) of the mandible
• Temporslis muscle (anterior fibers), masseter
  muscle medial pterygoid muscle.
• Retrusion of the mandible Temporalis muscle
  (posterior fibers).
• Protrusion Right and left lateral pterygoid
  acts together, medial pterygoid
• Opening the mandible Digastric and Inferior
  pterygoid.

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• Neural Pathways-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

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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
• Bennet angle.
• Immediate side shift Bennet movement

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Working side. Condyle pivots
Balancing side. Condyle has downward path
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Occulsal Interferences 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.

• Significance
• May result in destructive oblique forces
• May interfere with TMJ guidance

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Occulsal Interferences in Centric Relation
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Non Working Side Occulsal Interferences
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• Protrusive occlusal interference

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Ideal Occlusion 1- The coincidence of CO and
CR,with freedom in CO 2- When mandible moves
there is immediate and lasting posterior
disocclusion Significance 1- Pretreatment
record 2- Treatment of TMD 3- Conformative versus
reorganized approach.
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Requirements of Stable Occlusion
1- Stable stops on all the teeth when the
condyles are in Centric Relation (CR).
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Centric Stops
Point contacts are on lingual cusp tips
of maxillary posterior teeth, buccal cusp tips of
mandibular posterior teeth, central pits
or marginal ridges on posterior teeth,
incisals of lower anteriors and linguals of
upper anteriors.
Brian Palmer, 2004
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Ideal bite 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
posterior teeth. 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 teeth.
(Brian Palmer, 2004)
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2- Disocclusion of posterior teeth in protrusive
mandibular movements 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
relation
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Correct Excursive Contacts Marked in Green
(Brian Palmer, 2004)
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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.

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Recording of the occlusion

• Two dimensional records of the patients
  occlusion
• 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 the
  teeth.

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Maintain the pre-existing occlusion
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General Recommendations

• EDEC (examine design, execute, check) Rule.
• Examine and record occlusion at preoperative
  stage.
• Design where to place the point contacts on the
  restoration (tripodal)
• Remove heavy point contacts on the inclines and
  restoration margins
• Re-establish the preoperative occlusal contacts
  at the same intensity and poitions.

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• Avoid both static and dynamic occlusal contacts
  with the margins of the restoration

• Weakening of tooth by deep or wide (gt1/3
  occl.surface) filling may indicate a provision of
  cast restoration

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Thank You