What are the types of facebow?
- maxillary
- mandibular
What is the definition of maxillary facebow?
device used to record the relationship between maxilla and TMJ and transfer this relation to the articulator
What are the parts of the facebow?
U-shaped bow that has those parts connected to it
- bite fork = parallel to occlusal plane and attached to the bow by a universal joint and clamp
- 2 posterior reference point indicators = at each end of the bow, there is graduated condylar rod and a clamp, they are attached to assumed condylar position
- anterior reference point indicator = relates the whole assembly to a fixed cranial third point of view
- upper member = upper cast
- lower member = lower cast
- infra-orbital pin
- condylar rods = should both be equal in slight tension and resemble a sphere on facebow
- universal joint of clamp
What is another name for mandibular facebow?
kynematic facebow
What are the types of maxillary facebow?
- fascia facebow
- earpiece facebow
What is fascia facebow?
- posterior reference point indicators are attached to the patient’s skin over the position of the condyle
- the position of the condyle can be either determined kinematically or arbitrary (canthus-tragus line)
What is earpiece facebow?
posterior reference point indicators are inserted into the external auditory meatus
What does the mandibular (kinematic) facebow consist of?
- attached to the mandible by means of a clamp that fits under the chin and fixes the bow by means of a universal joint
- 2 pointed condylar rods are attached to he bow
- the position of the condylar rods can be adjusted by a screw
What are the uses of kinematic facebow?
- record centric relation
- locate exact terminal hinge axis (center of condyle) before using of maxillary facebow
What is the most standardised maxillary facebow?
earpiece facebow
Do we need to use mandibular facebow if earpiece facebow is used?
no
How to determine arbitrary terminal hinge axis location?
placing it 11-13mm anterior to the superior border of the tragus of the ear on a line extending from the outer canthus of the eye to the upper margin of the external auditory meatus
How to determine kinematically exact location of terminal hinge axis?
- arbitrarily determine the location of the hinge axis
- the kinematic facebow is attached to the mandible
- patient is asked to open and close his mouth while mandible is in its most retruded position
- each condylar rod will draw an arc on the paper attached to the skin
- the position of the condylar rods is adjusted toward the center of these arcs
- with further repetition of this procedure, the size of the arcs drawn by the condylar rods will be progressively decreased in size until the rods rotate in a point
- this point represents the terminal hinge axis of the condles and is usually termed “still point
