Facebow

Facebow

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FACE BOW

2. FACE BOW
“A Caliper like device which is used to record
the relationship of the jaws to the
tempromandibular joint and to orient the casts
on the articulator to the relationship of the
opening axis of the tempromandibular joint” -
GPT
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3. HISTORY AND DEVELOPMENT OF FACE
BOW
In 1866, Francis H Balkwillintroduced an
instrument for measuring the angle formed
between the plane of two lines drawn from
the articulating surfaces of the condyle on to
the incisal point and the occlusal plane.
He estimated this angle now known as the
BALKWILL’S ANGLE.
-It has an average value of 26°
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In 1889,CHARLES E.LUCE used what he called
the photographic method to record the relative
movements of 3 points on the mandible, the condyle,
the angle and the symphisis.
Luces results corroborated Balkwill’s findings and
there was considerable individual variations in the
relative movement of the condyle, the angle and the
symphisis.

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FRANKFORT PLANE
CAMPER’S PLANE
GYSI PROSTHETIC
PLANE

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In 1896, WILLIAM E.WALKER introduced
thefacial clinometer
-designed to determine the angle of the
condylar paths on the face
Origin of extraoral method for recording
mandibular movements
It didn’t allow for active transfer of the cast in
the articulator

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In 1884, GEORGE K. BAGBY, obtained a
patent for the Jaw gauge.
This is described as the attachment to determine
the location of the impression models in the
articulators.
In 1889, RICHMOND S. HAYESintroduced the
first example of a functional face bow like device.
It was used for locating the position of casts
correctly in the articulator and he named it as the
Articulating caliper.

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In 1889,GEORGE B.SNOW developed the face
bow which carries the relationship between the
maxilla and the condyles, from the patient to the
articulator.
The snowtype of face bow uses estimated
marks on the skin at the condyle points as the hinge
axis position.
Snow used the ala-tragus line as the plane of
reference.

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In 1908, GYSI developed a face bow primarily to
record the paths of the condyle.
Gysiused the prosthetic plane which is similar
to the camper’s plane as the plane of reference
In 1902,JOHN B.PARFITTintroduced his
anatomical articulator also called a model jaw.
PARFITT introduced two mandibular face bows
one to transfer the casts to the articulator and
another one to produce the record of the contour of
the condylar path.

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In 1924,WADSWORTHintroduced a
‘T’attachment type of a face bow.
It used a third point of reference indicator to
determine the vertical position.
This reference point is based on the naso-optic
condylar triangle.

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Many modifications evolved out of the snow face
bow.
The new trend of using the infra orbital pointer
as the third point of reference was invented in the
late 1920’s.
The Hanau, Bergstrom and the Dentatus
company where among the first to adopt it.
it’s true origin is unknown.

18. CLASSIFICATION
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ARBITRARY FACEBOW
i) Facia facebow
ii) Ear piece facebow
-with orbital indicator
-with nasal relator
ACTUAL VALUE FACEBOW
(kinematic or hinge axis facebow)

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20. PARTS OF A FACE BOW
“U” shaped frame
-all other components of the face bow are
attached to the frame with the clamps.
-it records the plane of the cranium.
Condylar rods
-these are two small metallic rods on either
side of the free end of the “U”shaped frame
-it helps to locate the hinge axis or the
opening axis of the TMJ.
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Bite fork
-it’s a U shaped plate which is attached to the
occlusal rims while recording the orientation
relationship.
Locking device
-part of the face bow that attaches the bite fork to
the U shaped frame.
-also supports the face bow,occlusal rims and the
casts during articulation.

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Orbital pointer
-it marks the anterior reference point
-it can be locked in positioned with a clamp
-it only present in the arbitary face bow

23. KINEMATIC FACEBOW
Used to locate the true terminal hinge axis
Difficult to perform accurately in edentulous
situations due to REALEFF
Indicated for the fabrication of FPD
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25. ARBITRARY FACEBOW
The condylar rods are positioned
approximately 13mm anterior to the auditory
meatus on the cantho-tragal line.
This locates the rods within 5mm of the true
hinge axis of the jaw.
This is commonly used in complete denture
constuction.
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27. TYPES
Facia type
-Posterior reference point is 13mm anterior to
external auditory meatus
-Anterior reference point is the orbitale
Ear piece type
-Posterior reference point is the EAM
-Anterior reference point is the orbitale
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Denar facebow
-Ant. reference is 43mm above the incisal
edge of right central or lateral incisor
-It is marked using a denar reference plane
locator
Twirl bow
-It relates the maxillary arch with the
frankfort horizontal plane
-It doesn’t require any physical attachment
to the article

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Whipmix facebow (quick mount FB)
-Nasion related assembly with a plastic nose
piece which determines the anterior reference
point
-It has a built in hinge axis locator ;
automatically locates the hinge axis

31. HINGE AXIS
Hinge axis is an imaginary line around which the
condyles can rotate without translation
In 1921,McCollum,Stuart reported the discovery
of first method locating hinge axis
Controversies as to the presence of a single
axis,the method and validity of recording the
position on the skin have arisen because
mechanical equipment is used to record
movements involving living tissues
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32. TERMINAL HINGE AXIS
(TRANSVERSE HINGE AXIS)
It is an imaginary line which passes horizontally
through the rotational centers of the right and
left condyles when they are in the most distal
retruded position in their respective glenoid
fossa
The technique for locating the terminal hinge
axis position is the same for dentulous and
edentulous patients
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33. The hinge axis locating bow is attached rigidly to
the mandible by means of a clutch
Clutch is cemented over the teeth or clamp to
the edentulous ridge
Mandible is manipulated to the centric relation
The patient makes guided opening and closing
movements within the range of hinge opening
Adjustments are made untill the stylii on the
hinge axis bow only spin
This indicates that the stylii are co-linear with
the mandibular hinge axis
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34. ARBITRARY HINGE AXIS
Most indirect techniques in dentistry does not
require the accuracy of locating the true hinge
axis
WEINBERGin a study evaluated the degree of
error of axis location and its relationship to the
occlusion of teeth
He concluded that ‘the transverse hinge axis
location and the subsequent face bow transfer
within a 5mm error is a practical and dependable
method for orienting the maxillary cast’
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35. FACEBOW TRANSFER
ARBITRARY AXIS FOR HANAU FACEBOW
-Richey condylar marker is used to scribe an
arc 13mm anterior to the external auditory
meatus.
-using a ruler, a line is drawn from outer
canthus of the eye to the tragus of the ear.
-the point where the line intersects the arc
locates the arbitrary axis
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The bite fork is heated and inserted in to the
maxillary rim parallel to the occlusal plane.
The recording base is inserted into the mouth, the
extension rod is pass through the locking device.
The condylar rods are oriented over the arbitrary
centres of rotation.
They are moved from side to side untill the
readings on the condyle rod scales are same on
both sides

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The cross bars should be parallel to a line between
the pupils of the eye
The lock nuts at the condyle rods are tightened to
suspend the facebow and the bite fork is securely
attached
Condylar lock nuts are released and the facebow
and occlusal rim are transferred to the articulator
The instrument is locked in centric with the
incisal pin flush with the upper member

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The facebow is adjusted by the elevating screw
to align the occlusal plane with the groove mark
on the half-way point of the incisal pin
A hanau mounting support or prop may be
necessary to support the weight of maxillary cast
and plaster during mounting

42. INDICATIONS
Cusp form of teeth are used
Balanced occlusion in the eccentric position
are desired
Interocclusal check records are used for
verification of jaw position
Occlusal vertical dimension is subject to
change and alteration of tooth occlusal
surfaces are necessary to accommodate the
changes
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43. CONCLUSION
Blind orientation of the maxillary casts on a
articulator will result in errors
The elimination of errors that can be
produced by failure to use a facebow where
indicated, justifies the time required and the
procedures involved in the facebow transfer
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REFERENCES:
1.Essentials of complete denture prosthodontics-
Sheldon winkler
2.Syllabus of complete dentures-Charles M.Heartwell
3.Prosthodontic treatment for edentulous patients-
George A.Zarb
4.History of articulators from face bow to gnathograph-
JPD vol:10 dec2001
5.Appearance and early history of face bows-Journal of
prosthodontics vol:9 sep2000

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