Maxillo-Mandibular Relationships

1
Maxillo-Mandibular Relationships

• Occlusal Vertical Dimension
• And Hinge Axis Relation

2
Occlusal Vertical Dimension

• Amount of separation between mandible maxilla
  when denture teeth contact

3
Hinge Axis Location

• Use earbow to record relationship of maxilla to
  transverse horizontal axis
• Locate anterior reference point

4
Centric Position

• Relationship of maxilla mandible
• Anterior/posterior medio-lateral)
• Maximum intercuspation of denture teeth

5
Programming the ArticulatorProtrusive
Relationship

• Simulate relationship of maxilla to mandible in
  excursions
• Denture teeth set in harmonious relationship for
  function

6
Record Bases (Baseplates) and Occlusion Rims

• Used to relate casts on an articulator
• Record bases simulate the finished denture base

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Record Bases and Occlusion Rims

• Wax occlusion rims simulate the position of the
  teeth

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Occlusion Rim Dimensions

• Occlusion rims slightly bulkier
• Provide additional stability during record making

9
Record Base Retention

• Required for record making phonetic tests
• Inaccurate if loose
• Use denture adhesive if slightly loose
• Pronounced looseness - REMAKE

10
Record Base Retention

• Causes of Poor Retention
• Poor adaptation of resin to cast
• Over- or under-extension
• Excessive block-out

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Occlusal Vertical Dimension

• Video

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Arbitrary Adjustment of Occlusion Rims

• Adjust separately using average dimensions
• Maxillary - 23 mm
• Mandibular - 18 mm
• Starting Point
• Fairly rapid adjustment
• 15 minutes per arch

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Use a Hot Scapel Blade
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Use Hot Wax Former or Metal Spatula
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Maxillary Occlusion Rim Adjustment

• Maxillary rim slightly facial to compensate for
  ridge resorption

16
Maxillary Occlusion Rim Adjustment

• Anterior height 1-2 mm below the lip at rest/when
  the patient slightly smiles

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Wax rim/tooth display can be adjusted with sex,
age, and lip length (Vig JPD 1978).
Lip Length
Incisal Display
10-20mm 3-4mm
20-25mm 2mm
26-30mm 1mm
gt30mm 0
Sex Age Female Male Youn
g 2 1 Middle 1 0 Old 0 -1
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Position of Maxillary Incisal Edge

• Edge of rim touches wet line of lower lip when
  F or V sounds
• Count 50-60

19
Lip Support

• Lips should be unstrained
• Naso-labial angle 90
• Philtrum depressed
• Vermilion border showing

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Occlusion Rim Angulation

• Occlusal plane parallel to the ala-tragus line

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Occlusion Rim Occlusal Plane

• Mediolaterally, parallels the pupils
• Fox plane can be used

22
Fox Plane

• Helps orient occlusal plane

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Centered Occlusion Rim

• Centered over ridge to maximize stability

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Posterior Occlusion Rim Height

• Posteriorly, the occlusion rim intersects 1/2 -
  2/3 up the retromolar pad

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Mandibular Rim Height

• Anterior height even with the corners of mouth
  when lip is relaxed

26
Facial Occlusion Rim Relations

• 1-2 mm horizontal overlap in anterior posterior
  in centric position

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Proper Lip Support

• Unstrained lips
• Vermilion border showing

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Occlusal Vertical Dimension (OVD)

• Distance between maxilla mandible when teeth or
  wax rims contact in centric position

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Physiologic Rest Position (PRP)

• At rest, lips barely touching
• Occlusion rims should not touch

Intraorally no contact
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Interocclusal Distance (ID)

• Space between wax rims at physiologic rest
  position
• Usually 2-4 mm

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Establishing Occlusal Vertical Dimension

• PRP ID OVD

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Establishing Occlusal Vertical Dimension

• 1. Measure difference between PRP OVD
• 2. Feel to ensure movement of mandible
• 3. Phonetics tests Closest Speaking Space
• Patient sitting bolt upright

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Establishing Occlusal Vertical Dimension

• Check with three techniques to ensure acceptable
  OVD
• No one technique 100 correct

34
Patient Sits Bolt Upright Soft tissue position
affected by posture
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Measurements OVD PRP

• Use external points for ease of measurement
• Small dots under columnella mid-symphisis
• Use Boley Gauge, not ruler

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Measuring Occlusal Vertical Dimension

• Measure the distance between dots
• At PRP
• At OVD
• Difference is ID
• Measurements change each day (position of dots)

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Measuring Physiologic Rest Postion

• Open and close until lips barely touch -
  Physiologic Rest Position (PRP)
• Measure distance between dots

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Measuring Occlusal Vertical Dimension

• Open and close until rims touch
• Measure distance between dots (OVD)
• Measurement will be different each appointment

39
Establishing OVD Feel for Interocclusal Distance

• Close until lips barely touch - PRP
• Place finger on chin
• Look away
• Patient closes until rims touch (OVD)
• Feel for movement of the mandible

40
Establishing OVDPhonetics Test

• Closest Speaking Space
• Confirms OVD
• Sibilant sounds ("s", "z", sh", ch")
• Rims should be at least 1 mm apart
• Dont worry about sounds yet

41
Excessive OVDWax Rims Too High

• Insufficient interocclusal distance
• Remove wax from one or both of the rims
• Use large wax formers
• 5 7 wax spatulas
• Red-handled knife
• Bunsen burner and torch

42
Wax Rim Adjustment at OVD

• Flat even contact along entire occlusal surface
• EXTREMELY CRITICAL
• If uneven contact, patient may be forced into
  eccentric position

43
Adjusting Wax Rim Height

• Scribe lines parallel to opposing occlusal rim
• Use as a guides during reduction

44
Eliminating Record Base or Wax Rim Interferences

• Patient in Centric Position
• Scribe three widely separated lines between
  maxillary mandibular rims

45
Establishing OVD

• Remove, superimpose lines
• Eliminate contacts between record bases, record
  base/occlusion rims/casts
• Only contact should be rim to rim

46
Adjusting Occlusion Rims

• Continue to adjust the rims until
• interocclusal distance is 2-4 mm
• even contact along rims in centric position.

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Excessive Occlusal Vertical Dimension

• Sore muscles
• Soft tissue sore spots
• Rapid bone resorption
• Dentures click during speech

48
Inadequate Occlusal Vertical Dimension

• Collapsed Appearance - chin too close to the nose
  or protruding jaw
• Fatigue when chewing
• Sore muscles or joints

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Hinge Axis Location

• Face-bow or ear-bow used
• Record relationship of maxilla to transverse
  horizontal hinge axis of mandible

50
Hinge Axis

• Transferred to the articulator
• Important to prevent occlusal errors,
  particularly when cusped teeth are used in
  dentures.

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Facebow (Earbow) TransferMount Maxillary Cast

• 2 Video Clips

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Attach cast with mounting plaster in two steps