Facebow in orthodontics /certified fixed orthodontic courses by Indian dental academy

FACE BOW

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


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


HISTORY AND DEVELOPMENT OF
FACE BOW




In 1866, Francis H Balkwill introduced 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°

 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.

FRANKFORT PLANE

CAMPER’S PLANE

GYSI PROSTHETIC
PLANE


 In 1896, WILLIAM E.WALKER introduced
the facial 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

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. HAYES introduced 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.

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 snow type 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.

In 1908, GYSI developed a face bow primarily to
record the paths of the condyle.
Gysi used the prosthetic plane which is similar
to the camper’s plane as the plane of reference
In 1902,JOHN B.PARFITT introduced 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.

In 1924,WADSWORTH introduced 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.


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.

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

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.

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.

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


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


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.


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

 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

 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


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

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












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 www.indiandentalacademy.com
hinge axis

ARBITRARY HINGE AXIS






Most indirect techniques in dentistry does not require
the accuracy of locating the true hinge axis
WEINBERG in 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’

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

 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

 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

 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


INDICATIONS







Cusp form of teeth are used
Balanced occlusion in the eccentric position
are desired
Inter occlusal 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

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


REFERENCES:
1. Essentials of complete denture prosthodonticsSheldon winkler
2. Syllabus of complete dentures- Charles M.Heartwell
3. Prosthodontic treatment for edentulous patientsGeorge A.Zarb
4. History of articulators from face bow to gnathographJPD vol:10 dec2001
5. Appearance and early history of face bows- Journal of
prosthodontics vol:9 sep2000

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Facebow in orthodontics /certified fixed orthodontic courses by Indian dental academy

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