Intro to Occlusion by ZCxBp2

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									Introduction to Occlusion
     Occlusion 6800 & 6804




            Course Introduction
                     and
    Characteristics of an Ideal Occlusion
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).
Occlusion 6800 & 6804 Course Schedules
      Introduction to Occlusion
Occlusion 6800 & 6804 - Evaluation
Lecture &
   Lab
 Quizzes
        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.
       D-1 Occlusion Download Site:
    http://www.carcoria.com/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
  Introduction to Occlusion
Criteria 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.
           Basic Structure of the TMJ


Two TMJ: When one moves, the other must move as well.
        Basic Structure of the TMJ




  Glenoid or
  mandibular fossa
                                                                    Articular
Movement is characterized by position of condyle in glenoid fossa   eminence
           Basic Structures of the
          Temporomandibular Joint




                                                                Articular Disc



               Condyle
>Mandibular/Glenoid Fossa
>Articular eminence: 1) Posterior slope, 2) Steepness/flatness guides movement
>Synovial cavities: 1) Joint lubrication, 2) boundary lubrication from motion
     Ligaments Supporting the TMJ
          and the Mandible
                             •Limit movement
                             •Protect muscles
                             •Non-elastic




                                      Medial Side of Mandible (inside)
Lateral Side of Mandible (outside)
The Temporomandibular Joint
            Basic Structures
Condyle
   Anatomic variations
    guide mandibular
    movement
► Retrodiscal   tissue
   elasticity
   Highly innervated
    and vascular
   Loading is painful
   Trauma can cause
    inflammation
     The Temporomandibular Disc

► Fibrous   connective
  tissue
► Interface between
  bones, somewhat
  pliable
► Bi-concave shape
► Collateral ligaments
► No Innervation
► No Vascularization
  Terminology Related to Mandibular
     Position and Tooth Position
Basic Premises:

►     When the mandible closes against the
      maxilla:

    1. There is an ideal way for the teeth to contact
    2. 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
         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
         MAXIMUM INTERCUSPATION
          What 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
        Term Describing Mandibular
                Position
           CENTRIC 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
 Terms Describing Mandibular
          Position
► Centric   Relation
   Why a superior and
    anterior position?

    The Muscles of
    Mastication drive this
    process
In an Ideal Occlusion, CR and MI
     Occur Simultaneously.
        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
             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.
            An ideal occlusion…
Basic Premises:

►   When the mandible closes,

    1. There is an ideal way for the teeth to contact
    2. There is an ideal place for the condyle and
       disc to be situated.
Characteristics of an Ideal Occlusion




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

► Protrusive - anterior
  movement of the
  mandible
► Retrusive - posterior
  movement of the
  mandible
► Eccentric - movement    Protrusive
  away from a centric
  position (CR or MI)
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.
 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”
  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”
  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”
Terms for Describing Eccentric
 Movements of the Mandible

        Lateral movements are guided by either:




canine guidance (ideal)       group function
                              (secondary choice)
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
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
 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.

								
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