Introduction to Occlusion

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Introduction to Occlusion
Occlusion 6800 6804
Course Introduction and Characteristics of an
Ideal Occlusion
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Course Textbook References

• Textbook Management of Temporomandibular
  Disorders and Occlusion Jeffrey P. Okeson. 5th
  Edition
• Secondary Reference Course Manual
• Main Reference PowerPoint Files

Exam Format and Use of References
All examination questions will be obtained from
the PowerPoint files that all students have
access to. Textbook reading is secondary, but
still somewhat essential to the understanding of
the material. Exam questions are multiple choice
format (40 for mid-term and 50 for final
examination).
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Occlusion 6800 6804 Course Schedules
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Introduction to Occlusion
Occlusion 6800 6804 - Evaluation
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Lecture Lab Quizzes
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Occlusion 6800 6804 Course Descriptions
Moving Occlusion Diagrams Practical
Examination You will be given a flash card
booklet with quadrant diagrams displaying various
mandibular movements. This booklet will be the
entire basis of the moving occlusion practical
examination. The National Board has about 3 or 4
of these questions on the exam every
year. Interferences and Muscle Actions Practical
Examination It is important for the student to
know the location of various mandibular-maxillary
tooth interferences and which muscles are
involved as a result of these types of
interferences. All of the questions for this
practical examination will be taken from the
PowerPoint exercise.
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D-1 Occlusion Download Sitehttp//www.carcoria.c
om/bcd-d1-occ-2012/d1occlusion-2012.htm
Constant Communication from me to you. Updated
at least once each week.
Right click on your mouse and save the files to
your drive
Note this is a different web-site than the
Dental Anatomy Course
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Introduction to OcclusionCriteria for Optimum
Functional Occlusion
Key Anatomical Landmarks Temporal Bone a
portion of this bone forms the glenoid or
mandibular fossa. The shape of this fossa
determines many of the limits of mandibular
movement Mandible a moveable structure which is
suspended by musculature and whose movement is
limited by ligaments. Condyle the portion of
the mandible that articulates in the mandibular
fossa. There is a right and left condyle, about
which movement of the mandible occurs. The shape
of the heads of the condyles determine many of
the limits of mandibular movement. The mandible
is the only bone in the human body that possesses
two axes of rotation. Dentition the size,
shape and alignment of the teeth determine many
of the limits of mandibular movements. The role
of the dentition is considered to be secondary to
the role of muscles, ligaments and the bony
structures which comprise the temporomandibular
joint.
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Basic Structure of the TMJ
Two TMJ When one moves, the other must move as
well.
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Basic Structure of the TMJ
Glenoid or mandibular fossa
Articular eminence
Movement is characterized by position of condyle
in glenoid fossa
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Basic Structures of the Temporomandibular Joint
Articular Disc
Condyle
gtMandibular/Glenoid Fossa
gtArticular eminence 1) Posterior slope, 2)
Steepness/flatness guides movement
gtSynovial cavities 1) Joint lubrication, 2)
boundary lubrication from motion
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Ligaments Supporting the TMJ and the Mandible

• Limit movement
• Protect muscles
• Non-elastic

Medial Side of Mandible (inside)
Lateral Side of Mandible (outside)
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The Temporomandibular JointBasic Structures

• Condyle
• Anatomic variations guide mandibular movement
• Retrodiscal tissue
• elasticity
• Highly innervated and vascular
• Loading is painful
• Trauma can cause inflammation

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The Temporomandibular Disc

• Fibrous connective tissue
• Interface between bones, somewhat pliable
• Bi-concave shape
• Collateral ligaments
• No Innervation
• No Vascularization

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Terminology Related to Mandibular Position and
Tooth Position

• Basic Premises
• When the mandible closes against the maxilla
• There is an ideal way for the teeth to contact
• There is an ideal place for the condyle and disc
  to be situated.

Our task is to accomplish these two criteria in
as non-obtrusive fashion as possible
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Terminology Describing Tooth Position MAXIMUM
INTERCUSPATION

• a.k.a. centric occlusion (CO)
• Habitual occlusion, habitual centric
• Maximum intercuspation describes an occlusal
  relationship
• Teeth are contacting in a position that the
  patient finds the most comfortable
• Easily achievable, but not always reproducible,
  by the patient

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MAXIMUM INTERCUSPATIONWhat is considered
Ideal?

• Angle Class I 1st Molars and Canines
  relationship
• Adequate Overlap
• Long axis of teeth
• Simultaneous contact
• Posterior tooth dominance
• Anterior tooth passive contact
• Multiple contacts on all teeth adequately
  distributes forces

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Term Describing Mandibular PositionCENTRIC
RELATION

• Centric Relation
• A condylar position
• Superior and Anterior
• Thin portion of disc
• Describes the most stable position of the condyle
• Superior and anterior position of the mandible
  with the disc properly interposed

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Terms Describing Mandibular Position

• Centric Relation
• Why a superior and anterior position?
• The Muscles of Mastication drive this process

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In an Ideal Occlusion, CR and MI Occur
Simultaneously.
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Maximum Intercuspation

• An occlusal position
• If CR and MI do not coincide, the patient will
  have a slide
• Most patients have some degree of a slide into
  maximum intercuspation (approximately 1-2 mm)
• MI is simultaneous contact
• Forces concentrated on long axis
• Posterior contacts should dominate

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Slide from CR to MI

• Only 15 of the population have no CR to MI
  discrepancy
• After the first contact in CR (usually on 2 or
  more posterior teeth), the patient continues to
  close, and the teeth come together more
  completely (MI). The condyles must move out of
  their most ideal position when the teeth come
  fully together.

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An ideal occlusion

• Basic Premises
• When the mandible closes,
• There is an ideal way for the teeth to contact
• There is an ideal place for the condyle and disc
  to be situated.

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Characteristics of an Ideal Occlusion
The condyle seats in CR simultaneous with the
teeth occluding in MI. No slide occurs.
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Terms for Describing Eccentric Movements of the
Mandible

• Protrusive - anterior movement of the mandible
• Retrusive - posterior movement of the mandible
• Eccentric - movement away from a centric position
  (CR or MI)

Protrusive
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Terms for Describing Eccentric Movements of the
Mandible

• In an ideal occlusion, protrusive movement is
  guided by anterior teeth.

Early lateral movements are ideally canine-guided.
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Terms for Describing Eccentric Movements of the
Mandible

• Lateral movements-moving the mandible to the left
  or to the right.

Shown is a left lateral movement
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Terms for Describing Eccentric Movements of the
Mandible

• Lateral movements-
• During a left lateral movement, the left side of
  the arch is considered to be the working side.

Shown is a left lateral movement
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Terms for Describing Eccentric Movements of the
Mandible

• Lateral movements-
• During a left lateral movement, the right side is
  considered to be the balancing side or
  non-working side.

Shown is a left lateral movement
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Terms for Describing Eccentric Movements of the
Mandible

• Lateral movements are guided by either

group function (secondary choice)
canine guidance (ideal)
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Terms for Describing Eccentric Movements of the
Mandible

• Crossover is an extreme movement where the
  mandibular canine crosses over the maxillary
  canine.

• This position is outside the envelope of
  function
• It is critical to the success of anterior
  restorations.

Extended lateral movements should smoothly
transfer from the canines to the incisors
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Summary of Characteristics of an Ideal Occlusion

• CR and MI occur simultaneously
• All teeth contact simultaneously
• All occlusal forces are longitudinal
• Posterior tooth contacts dominate
• Eccentric movements are anterior-guided
• No cross-over contacts on posterior teeth

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Summary of Criteria for an Optimal Functional
Occlusion

• Condylar position- Centric relation
• Tooth position- Maximum intercuspation
• Protrusive movements are guided by anterior teeth
• Lateral movements are canine guided.
• Axial loading of occlusal forces
• In MI, posterior tooth contacts dominate.
• During crossover, guidance is smoothly
  transferred to the incisors.