MaxilloMandibular Relationships Occlusal Vertical Dimension And Hinge Axis

Maxillo-Mandibular Relationships Occlusal Vertical Dimension And Hinge Axis Relation

Occlusal Vertical Dimension Amount of separation between mandible & maxilla when denture teeth contact

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

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

Programming the Articulator Protrusive Relationship • Simulate relationship of maxilla to mandible in excursions • Denture teeth set in harmonious relationship for function

Record Bases (Baseplates) and Occlusion Rims • Used to relate casts on an articulator • Record bases simulate the finished denture base

Record Bases and Occlusion Rims • Wax occlusion rims simulate the position of the teeth

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

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

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

Occlusal Vertical Dimension Video

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

Use a Hot Scapel Blade

Use Hot Wax Former or Metal Spatula

Maxillary Occlusion Rim Adjustment • Maxillary rim slightly facial to compensate for ridge resorption

Maxillary Occlusion Rim Adjustment • Anterior height 12 mm below the lip at rest/when the patient slightly smiles

Wax rim/tooth display can be adjusted with sex, age, and lip length (Vig: JPD 1978). Lip Length Incisal Display 10 -20 mm 3 -4 mm 20 -25 mm 26 -30 mm 1 mm >30 mm 0 Sex & Age Young Middle Old Female +2 +1 0 Male +1 0 -1

Position of Maxillary Incisal Edge • Edge of rim touches wet line of lower lip when ‘F’ or ‘V’ sounds • Count ‘ 50 -60’

Lip Support • • Lips should be unstrained Naso-labial angle ≈ 90° Philtrum depressed Vermilion border showing

Occlusion Rim Angulation • Occlusal plane parallel to the ala-tragus line

Occlusion Rim Occlusal Plane • Mediolaterally, parallels the pupils • Fox plane can be used

Fox Plane • Helps orient occlusal plane

Centered Occlusion Rim • Centered over ridge to maximize stability

Posterior Occlusion Rim Height • Posteriorly, the occlusion rim intersects 1/2 - 2/3 up the retromolar pad

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

Facial Occlusion Rim Relations • 1 -2 mm horizontal overlap in anterior & posterior in centric position

Proper Lip Support • Unstrained lips • Vermilion border showing

Occlusal Vertical Dimension (OVD) • Distance between maxilla & mandible when teeth or wax rims contact in centric position

Physiologic Rest Position (PRP) • At rest, lips barely touching • Occlusion rims should not touch Intraorally no contact

Interocclusal Distance (ID) • Space between wax rims at physiologic rest position • Usually 2 -4 mm

Establishing Occlusal Vertical Dimension PRP = ID + OVD

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

Establishing Occlusal Vertical Dimension • Check with three techniques to ensure acceptable OVD • No one technique 100% correct

Patient Sits Bolt Upright Soft tissue position affected by posture

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

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

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

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

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

Establishing OVD Phonetics Test • • • Closest Speaking Space Confirms OVD Sibilant sounds ("s", "z", sh", ch") Rims should be at least 1 mm apart Don’t worry about sounds yet

Excessive OVD Wax 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

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

Adjusting Wax Rim Height • Scribe lines parallel to opposing occlusal rim • Use as a guides during reduction

Eliminating Record Base or Wax Rim Interferences • Patient in Centric Position • Scribe three widely separated lines between maxillary & mandibular rims

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

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

Excessive Occlusal Vertical Dimension • • Sore muscles Soft tissue sore spots Rapid bone resorption Dentures click during speech

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