Maxillo-Mandibular Relationships Flashcards
What are the vertical relationships in max-mandib?
occlusal vertical relation
rest vertical relation
What are the horizontal relationships in max-mandib?
centric relation (CR)
protrusive
R and L lateral (eccentric)
What is the occlusal vertical dimension?
The distance between two points –one above and one below the mouth – measured when the occluding members are in contact
What does having an overclosed occlusal vertical dimenstion mean?
lips collapse and are too close together
What is physiologic rest position?
a postural position the mandible assumes when all muscles that close and open the jaws are in a state of minimal tonic contraction sufficient only to maintain posture
Should the teeth have contact from one arch to the other when at physiologic rest position?
NO CONTACT OF TEETH
What is the physiologic rest vertical dimension?
The distance between two selected points (one above, one below) measured when the mandible is in its physiologic rest position
What is the interocclusal distance (IOD; freeway space)?
The space between the teeth or occluding members when the mandible is in the physiologic rest position
What is the equation for RVD?
OVD + Interocclusal distance (IOD) = RVD
What is the name of the distance when the lips touch?
PRP
What is the name of the distance when the teeth touch?
VDO
What is the difference between the PRP (lips touching) and VDO (teeth touch)?
IOD
What should the IOD distance be in mm?
3 mm
What are the options for establishing occlusal vertical dimension?
- patient’s old dentures
- swallowing treshold
- closest speaking space
- phonetics
- esthetics
- tactile sense
- paralleling posterior ridges
- pre-ext records
- facial measurements
What is the closest speaking space?
the closest relationship of the occlusal surfaces and incisal edges of the mandibular teeth to the maxillary teeth during function and rapid speech (S sounds)
What is a reproducible posterior hinge position of the mandible?
centric relation
What are the 3 objectives for recording jaw relationships?
- maxillary cast mounted to the correct axis by a facebow transfer
- mandibular cast mounted in CR position to the max cast
- casts mounted at the correct vertical distance from each other to allow teeth to be arranged, bases placed in the mouth and teeth occlude at that vertical dimension
What do you need to make sure to remove from the record bases after trying it on the patient?
remove the adhesive (could disrupt the master cast)
What are the factors that affect the centric relation record?
- resiliency of the tissue supporting the denture bases
- stability and retention of record bases
- the TMJ and its neuro muscular mechanism
- technique employed in making the records
- amount of pressure applied in making the records
- skill of the dentist
What is a facebow?
Instrument that carries the relationship between the maxillae and the condyles from the patient to the articulator
What is an arbitrary facebow?
an arbitrary axis is used (external auditory meatus, etc)
What is a kinematic facebow?
the exact transverse hinge axis is located and used (not necessary for dentures)
What is the purpose of the facebow transfer?
to orient the maxillary 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 TMJ of the patient
When should the facebow transfer be used?
- cusp form posterior teeth are used
- balanced occlusion in eccentric positions is desired
- interocclual records are used to verify jaw positions/cast mountings
- the OVD is subject to change
What are the characteristics of the semi-adjustable articulator?
- accepts facebow record
- accepts interocclusal record
- has individually adjustable condylar guidances (vertical and horizontal)
