occlusion/jaw relation/ centric registeration 4th year tripoli
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- Centric Records Dr. Muaiyed. Mahmoud. Buzayan, BDS MClinDent
Malaysia AF AAMP USA
- Occlusion the static relationship between the incising or
masticating surfaces of the maxillary or mandibular teeth or tooth
analogues Deals with the static relationship of the opposing teeth.
Articulation Deals with the dynamic relationship of the opposing
teeth. Protrusive and lateral movements
- Centric Relation The maxillomandibular relationship in which
the condyles articulate with the thinnest avascular portion (non
innervated) of their respective disks with the complex in the
anterior-superior position against the shapes of the articular
eminencies. This position is independent of tooth contact. It is
restricted to a purely rotary movement about the transverse
horizontal axis
- Centric Occlusion The occlusion of opposing teeth when the
mandible is in centric relation. This may or may not coincide with
the maximal intercuspal position. Maximal intercuspal position The
complete intercuspation of the opposing teeth independent of
condylar position, sometimes referred to as the best fit of the
teeth regardless of the condylar position
- 1. Hapitual class III (ridge to ridge) 2. Edentulous patients
have more difficulty determining where their denture teeth should
contact (No periodontal membrane) 3. Record base fit (loose) and
wax rim (dimensions) changes confuse some patients
- Occlusal position to be acceptable, it should be: 1. Conducive
to health Harmless to TMJ Painless 2. Relatively repeatable
position can be checked and repeated, before dentures completed CR
is not far from CO at same occlusal vertical dimension
- Terminal Hinge axis An imaginary line around which the mandible
may rotate within the sagittal plane Hinge Position is Repeatable
(axis of circle) relatively centered patient can find stable
occlusal contacts relatively easily allows change in vertical
dimension Can be transferred to the articulator
- 1. When entire occlusion being restored (full mouth
rehabilitation) No remaining posterior centric stops 2. When
complete, or removable partial dentures involve the entire
occlusion 3. Restoring/ Increasing of vertical dimension (OVD)
Tooth surface loss (TSL) erosion, attrition and abrasion
- 1. Stable occlusion 2. Posterior centric stops present 3. No
reason to change current occlusion Use maximal intercuspation
- Occlusal Vertical Dimension
- Plane of occlusion An imaginary surface which is related
anatomically to the incisors and tips of the occluding surfaces of
the posterior teeth. In complete denture prosthodontics, this plane
is parallel to Camper's line. Camper's plane A plane established by
the inferior border of the right or left ala of the nose and the
superior border of the tragus of both ears.
- Physiologic rest position The habitual postural position of the
mandible when the patient is resting in an upright position and the
condyles are in a neutral, unstrained position in the glenoid
fossae. Vertical relation at rest position VDR The length of the
face when the mandible is in the physiologic rest position. The wax
rims should not touch. Vertical dimension of occlusion VDO The
distance measured between two points when the occluding members
(upper and lower Occlusion rims) are in contact. It is about 2-4mm
less than Vertical Relation at Rest Position. Freeway Space
(interoclusal distance) the difference between the vertical
dimension of rest and the vertical dimension while in occlusion.
(2- 4 mm) Freeway space= VDR- VDO Centric relation record A
registration of the relationship of the maxilla and the mandible in
centric relation made at the established vertical relation of
occlusion.
- ????
- Amount of separation between mandible & maxilla when
denture teeth are in contact Over closure VDO Restoring with
prosthesis
- Used to relate casts on an articulator Record bases simulate
the finished denture base Wax occlusion rims simulate the position
of the teeth Occlusion rims slightly bulkier, provide additional
stability during record making
- Required for record making and phonetic tests Centric relation
record will be inaccurate if loose Use denture adhesive if slightly
loose Much looseness REMAKE Causes of Poor Retention 1. Poor
adaptation of resin to cast 2. Over- or under-extension 3.
Excessive block-out of the cast before making the denture base
Starting Point for VDO; adjust the height of the occlusal blocks
separately using average dimensions: Maxillary - 23 mm Mandibular -
18 mm
- Maxillary rim slightly facial to compensate for ridge
resorption. (Incisal display) Anterior height 1-2 mm below the lip
at rest/when the patient slightly smiles 10-20mm 3-4mm 20-25mm 2mm
26-30mm 1mm Lip Length Incisal Display
- Horizental extension; Touches wet line of lower lip (the
vermilion border) when F or V sounds (Count 50-60). The labial
surface of the wax anterior to incisive papilla 8 10 mm Lips should
be unstrained To confirm correct wax block dimensions: 1.
Naso-labial angle 90 2. Philtrum depressed (not full) 3. Vermilion
border showing (not invereted)
- Frontal (Mediolaterally) the occlusal plane parallels the
pupils (Fox plane can be used Anterio-posteriorly, The Maxillary
denture occlusal plane should be parallel to the campers line
- Extension: Posteriorly, the occlusion rim intersects 1/2 - 2/3
up the retromolar pad. Anterior height even with the corners of the
mouth when the lip is relaxed (Buccal corridor 1-2 mm horizontal
overjet Unstrained lips, Vermilion border showing
- Amount of separation between mandible & maxilla when
denture teeth or wax rims are in contact Over closure VDO Restoring
with prosthesis
- The target is to get unstrained Physiologic Rest Position (PRP)
within the average 1. At rest, lips barely touching 2. Occlusion
rims should not touch 3. With INTEROCLUSAL DISTANCE (ID) FWS
between wax rims at physiologic rest position ( 2-4 mm) PRP (OVR) =
ID (2- 4mm) + OVD
- 1. Measure difference between PRP & OVD to get the average
ID 2. Feel to ensure smooth movement of mandible 3. Phonetics tests
Closest Speaking Space 4. Face profile (not long/ short face) Check
with all the previous techniques to ensure acceptable OVD. No one
technique 100% correct.
- 1. place the maxillary record base in the patient's mouth. 2.
Seat the patient in a comfortable upright position unsupported by a
head rest. Soft tissue position affected by posture. Mark a small
dot on on the nose and the chin to serve as reference points. Ask
the patient to swallow and relax the jaw several times. 3. Use
external points for ease of measurement Small dots under columnella
(or on the nose tip) & mid-symphisis Use Boley Gauge or ruler
4. Measure the distance between dots At PRP and OVD, the difference
is ID 5. the operator should adjust the wax rims until the ID is (2
4 mm)
- Open and close until lips barely touch - Physiologic Rest
Position (PRP). Measure distance between dots Open and close until
rims touch without interference and uniformly. Measure distance
between dots (OVD) These measurement will be different each
appointment. However , the ID would be in the same range.
- Closest Speaking Space Sibilant sounds ("s", "z", sh", ch") (,)
Rims should be at least 1 mm apart No need to get clear sounds and
pronunciation yet.
- If there was no ID or ID less than 2mm Excessive OVD Wax Rims
Too High. If there was insufficient interocclusal distance Remove
wax from one or both of the rims Use large wax formers wax spatulas
Bunsen burner and torch
- Flat and even contact along entire occlusal surface If uneven
contact, patient may be forced into eccentric position Scribe lines
parallel to the opposing occlusal rim. Use as a guides during
reduction
- Making three marks on the wax rims, when the patient in Centric
Position Scribe three widely separated lines between maxillary
& mandibular rims Remove, superimpose the lines Eliminate
contacts between record bases, record base/occlusion rims
- Excessive Occlusal Vertical Dimension Inadequate Occlusal
Vertical Dimension Sore muscles Collapsed Appearance Soft tissue
sore spots chin too close to the nose or protruding jaw Rapid bone
resorption Fatigue when chewing Dentures click during speech Sore
muscles or joints Long face Short face
- 1. Bimanual manipulation 2. Chin point guidance
- Generally 1. Patient sit in a slightly supine position 2.
Occlusion rim notched to aid stabilizing the record bases 3. Index
fingers on the rim, thumbs under symphysis (Chin point guidance) 4.
Jiggle the mandible 5. Mandible should freely arc 6. Allow the
patient to close into contact 7. Do NOT push the mandible or
dislodge the record base 8. Medium (record material) must be soft
9. Minimal closing pressure
- 1. Place 3 widely separated lines between the rims in the
centric position 2. CRITICAL! Check that record base heels/rims do
not touch 3. Two sharp V-shaped notches in the molar/premolar area
of each sided wax, depth 1-2 mm
- 1. Place occlusion rims intraorally 2. PVS registration
material, over entire occlusal rim 3. Have patient close into
record 4. Ensure smooth arc of closure, no horizontal deviations 5.
Use index fingers to stabilize lower record base 6. Want flat
record, no excess on sides of rims 7. Excess material recording of
the sides of the rim can cause deflection when checking record
- Ensure record is repeatable Increase the height of incisal pin
1 mm, invert articulator Place wax rims together, lute with sticky
wax - 4 spots