Maxilla-Mandibular Relationships Flashcards
Maxillomandibular Relationships (2)
Vertical relationship
Horizontal relationship
vertical relationships (2)
occlusal vertical relation
rest vertical relation
horizontal relationships (3)
centric relation (used in lab)
protrusive
R & L lateral (eccentric)
Occlusal Vertical Dimension
The distance between two points –one above
and one below the mouth –measured when
the occluding members are in contact.
physiological rest position
a postural position the mandible assumes when all muscles that close the haws and all the muscles that open the jaws are in a state of minimal tonic contraction sufficient only to maintain posture
in PRP, equilibrium exists between
opening and closing muscles
At the physiologic rest position, there should be no
contact of
any teeth of one arch with teeth of the
other arch.
Rest Vertical Dimension
The distance between two selected points (one
above, one below) measured when the mandible is
in its physiologic rest position.
Interocclusal distance (Freeway space)
The space between the teeth or occluding members when the
mandible is in the physiologic rest position.
RVD =
OVD + Interocclusal distance
Lips touch-
PRP
Space-
IOD (2-4mm.)
Teeth touch-
VDO
establishing occlusal vertical dimension (3)
no scientific method exists
several methods used with equal results
patients old dentures, swallowing threshold, closest speaking space, phonetics, esthetics, tactile sense, paralleling posterior ridges, pre-ext records, facial measurements
the interocclusal distance (free way space) is the
distance or gap existing between the upper and the lower teeth when the mandible is in the physiological rest position
it is usually 2-4 mm when observed at the position of the first premolars
the closest speaking space is the
closest relationship of the occlusal surfaces and incisal edges of the mandibular teeth to the maxillary teeth during function and rapid speech
OVD-a method (3)
reference marks on the nose and chin
maxillary base/rim in mouth, patient says “M” and holds lips when first touch (rest vertical dimension). record the distance between the two reference points. repeat and take average
insert mandibular base/rim. contour until meets max rim evenly at approx 3 mm less than recorded RVD
Verify with another method (3)
a) Patient swallows, then relaxes
b) Check interocclusal distance
c) Resting measurement should be greater than the occluding measurement
Vertical Relationships: (3)
OVD, RVD, Interocc.
Distance
Horizontal relationships: (3)
Centric
relation, protrusive, L & R lateral
centric relation (2)
a horizontal mandibular position at an established vertical dimension
is reproducible posterior hinge position of the mandible
interocclusal records: 3 parts
- max cast mounted to the correct axis by a face bow transfer
- mand cast mounted in centric relation position to the max cast
- casts mounted at the correct vertical distance from each other to allow teeth to be arranged, based placed in the mouth and teeth occlude at that vertical dimension
to make sure the max baseplate stays in place during the interocclusal bite registration,
sprinkle a small amount of denture adhesive powder on the tissue side of the denture
denture adhesive hygiene (2)
remove adhesive from the record bases before placing the record bases on the master casts
adhesive will result in denture processing errors
the midline and cuspid line are
clearly marked on the max rim
the Mand rim is adjusted so that it fits intimately against the
max rim at the proper vertical dimension
this will provide a
stable base for the interocclusal relationship of the maxilla to the mandible to be recorded accurately at CR
measure the vertical dimension of occlusion (VDO) and the vertical dimension at rest (VDR) and record these neasurements on a tongue blade. the difference between the VDR and the VDO is known as
freeway space and is usually 2-4 mm
boley garage technique is
more precise and easier to use than the tongue blade
the mandibular rim is reduced so that there is adequate space for
a bite registration material (approx 2 mm).
both rims then are scored with a sharp knife to make V shaped cuts about 2 deep that cross in the middle of the cast. this will ensure that the
bite registration will be stable in a lateral direction
Recording CR on a patient (2)
- Remove 2-3 mm of wax off mand. rim distal to canine on both
sides - Place sharp notches in the wax/occlusal rims
CR record: have patient practice closing gently in a — position before making the final record
retruded
making CR records consists of two phases:
- getting the entire mandible retruded (bimanual technique)
- positioning the condyle-disc assembly in the uppermost anterior position
steps 3-6
- practice with patient
- place recording material on posterior rim
- hold bases in place and guide patient to slow closure on back teeth
- hold until material is set
recording jaw relations: why might you remake?
if there is contact between the max and mand rims or bases during the registration
verify records (3)
bases may be returned to mouth, jaw retruded and closure made to verify that correct contact occurs additional record(s) may be made and used to verify the first record if in doubt, remake record and remount cast
The importance of accurate interocclusal records and accurately
mounted casts merit extra time — with the patient.
practicing
Great — is often required of both the patient and the dentist if
accurate records are to be made.
patience
factors that affect the CR record (6)
- resiliency of the tissues supporting the denture bases
- stability and retention of record bases
- the tempura-mandibular joint and its neurons muscular mechanism
- technique employed in making the records
- amount of pressure applied in making the records
- the skill of the dentist
registration should be —, not —
sharp
rounded
1880 –
Hayes –“caliper”
1900 –
Gysi –transfer maxillary cast
1900 –
Snow –most instruments used today are modifications of Snow’s
Facebow
Instrument that carries the relationship between the maxillae and the
condyles from the patient to the articulator.
Facebow Types (2)
Arbitrary
Kinematic
Arbitrary –
an arbitrary axis is used (external auditory meatus, etc)
Kinematic –
the transverse hinge axis is located and used
Arbitrary facebow -
Uses arbitrary landmarks of the face/head to
approximate the
rotational centers of the mandible.
Kinematic facebow
Locates exact
hinge axis points on skin, then transfers cast to articulator in
accurate relation to these points- not necessary for dentures!
if arbitrary location of hinge axis is within 5 mm of transverse hinge axis, and a CR record of 3 mm thickness is used to mount the mandibular cast, the AP error is approx
0.2 mm in second molar region
arbitrary face bow is accurate enough for
CD fabrication
the face bow transfer: purpose
to orient the max cast to the articulator in the same relationship to the opening/closing axis of the articulator as exists between the maxillae and the opening/closing axis of the TM joints of the patient
a simple procedure to orient the max cast at a reasonably accurate radius from the
opening axis
a third point of reference transfers
elevation of cast in relation to the axis orbital plane of the patient
face bow transfer should be used when (4)
- cusp form posterior teeth are used
- balanced occlusion in eccentric positions is desired
- interocclusal records are used to verify jaw positions/ cast mounting
- occlusal vertical dimension is subject to change
how many articulators are there?
over 300, from simple to complex
Semi-adjustable Articulator (3)
Accepts facebow record
Accepts interocclusal records
Has individually adjustable condylar guidances - vertical and horizontal
Fully Adjustable Articulator-Not
needed for
complete dentures
Denar, fully adjustable, not for
denture fabrication, use for
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