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1. FACE BOW
HISTORY :
If we wish to know something about face bow, how this
instrument is used and the significance of its application a short historical
survey of the ideas connected with these problems, and the working
'methods and instruments that they have given rise to, will give us clear
picture of the features to be remembered in this aspect.
About mid 18th century it began to be realised that in fabrications
of complete dentures it was important to mount the casts inthe articulator in
a given positional relation to the condylar elements. According to
Bonwill, 1860 the distance from he center of each condyle to the median
incisal point of the lower teeth is 10 cm and he advocated this
measurement to be followed while mounting but he did not mention
however at what level (vertically) the occlusal plane be paced in
relation to condyal mechanism. It appears that he advised the casts to be
mounted midway between the upper and lower parts of the articulator.
In 1866 an English dentist by name Balkwill devised methods
that were improvement on those proposed by Bonwill.
Balkwill demonstrated on apparatus with which he could measure
the angle formed by occlusal plane and the line joining condylar
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2. centers to the incisal point of the lower teeth and the angle varied from,
22° to 30°.
An other method for localizing the casts in the articulator was
constructed by Hayes in 1880 and the apparatus was called caliper.
However again there was no proper orientation possible.
Then in 1890 walker invented Clinometer with which it was
possible to obtain a good position of the cast in articulator. He used
mainly this instrument as instrument for condylar inclination
measurement device. A little later Gysi about the turn of the century
developed an instrument similar to a facebow primarily to record position
of the condyles however, it could be used to mount casts. But the
credit goes to Snow for inventing a Actual Facebow on which most of the
present day facebows are based. Snow introduced the facebow in 1899
and patented it in 1907.
In 1914 Dalbey introduced the use of ear type of facebow but it
was not until late 60's the ear type did gain popularity.
We are justified in staling that snow's facebow inspite of its very
simple construction was Epoch making in prosthetic dentistry. Since the
introduction of Snow's apparatus, no fundamental changes have been
made in the face bow design. Because snow determined the position of
the casts in the articulator not only in regard to distance of the mid incisal
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3. point from the condyles but also the other points of the occlusal plane
were given the correct relationship in relation to condyles.
PRINCIPLE OF FACE BOW USE :
The movements of the teeth are results of the rotation and slidings
made by the condyles. The better the casts on the articulator duplicate
the distances to the rotational condylar centres, the less the potential
errors produced by difference in the arcs of closure of the mandible and
the articulator.
The use of facebow is an integral part in procedures in analyzing
and studying occlusion, developing the occlusion for complete dentures
and other restoration.
The occlusal plane is related by making it parallel to a horizontal
plane so that it easier to relate it the articulator.
Snow recommended that the occlusal plane be made parallel with a
plane extending from the bottom of the glenoid fossa and passing
through the anterior nasal spine. This plane cannot be determined
directly on a living persons but it approximately, corresponds With a line
drawn from the upper parts the Tragus to the lower edge of the Nostil or
Alatragal line. This plane in European literature is referred as camper's
plane, in Americal literature it is referred so as Bromell's plane. Gysi and
kohler used a plane called as prosthetic plane which extends fro, the
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4. lower part of the tragus to the Ala of the nose. Wads-worth employed a
different plane which from the condyle area and runs at right angles to
a line that connects the most prominent points of the chin and forehead.
Over recent years, there has been a growing tendency to employ a
plane (i.e.) the Frankfort horizontal plane which is usually parallel to the
floor when an individual is in a upright position. Cephaornetrically the
Frankfort's plane is described a horizontal plane that passes through the
right and left portion (the mid point on the upper margin of external
auditory meatas) and the orbitale (the lowest point on interorbital rim).
The Horizontal plane forms a plane which is called as the Axis-
ORBITAL plane. This plane formed by the two posterior points of
reference and the one anterior point of reference which is usually the
infraorbital notch indicated by the pointer fixed on the face 'bow and the
posterior points of reference are those where the condylar rods are placed
thus when utilizing the two posterior (points) and anterior points the
occlusal plane is related to the face bow and through the face bow
franfered on to the articulator.
In the articulator there is a condylar plane estab lished by the
condylar spheres and a indicator for the anterior point of reference the
condular rods approximating the condyles through it the hinge axis are
attached to the centre at the condylar spheres of the articulator.
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5. Principle face bow use :
The prosthesis or indirect restorations that are planned and
fabricated with help of articulators should have the same relationship as
they have with articulator’s axis of opening as well as the patients
mandibular arc of movement.
Since it is practically difficult to orient the mandible to the
articulator, the maxillary cast is related to the articulator with same
relationship with the existing relationship between maxillary and
condyles of TMJ which is center of mandibular movements, the
mandibular cast is related to maxillary cast which in turn is oriented in the
articulator. To accomplish this act of orientation the device face bow is
utilized.
Before we (study) know more about the facebow and its use a
brief description about the terminal hinge Axis will help us in better
understanding of the face bow.
The terminal hinge axis is an imaginary axis around which the
condyle can rotate without translation and this axis is assumed from
which all the mandibular movements of opening and closing take place.
The THA is the most retruded hinge position and is significant because
it learnable, repeatable and recordable that coincides with the centric
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6. relation. The limits of the hinge movement in this position is about 12°-
15° at condyles or 19-21 mm in the incisal region.
The condyles are in a definite position in the fossa during the
rotation. Snow recognised the importance of this axis and to transfer this
axis to the articulator led to development of facebow and in 1921
McCollum, Stuart and others reported the first method of transferring this
axis. Since then many have put forward views that are very diverse from
each other.
Sloane stated
"The mandibular axis is not a theoretical assumption but difinitely
demonstrable biomechanical fact. It is the axis which on the mandible
rotates in an opening and closing function when comfortably but not
forcibly retruded."
"The hinge position or terminal hinge position is that position of
mandible from which or in which hinge movements of a variable wide
range is possible.
But contrary to them Brekke, Trapozzano and Lazzari and Lucia
questioned existence of the single hinge like axis of rotation for mandible
since the ideal mechanical set up is never found in living tissues.
Controversy arises as to the presence of single relationship of TH
position to entire portion. There are differences in concepts and
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7. interpretations of the findings. These differences in findings are
understandable and these seems to be general agreement that when the
mandible is in centric relation the mandible is in its most posterior
unstrained position from which a trained individual can voluntarily open
and close the mandible in hinge movement. Since it is a repeatable and
recordable position it is a point of return.
Therefore we strive to capture this imaginary axis and transfer this
to the articulator and depending upon how accurately the face bow
capture and transfer this to articulator led to the coining of words like
Kinematic face bow and Arbitrary face bows.
The occlusal plane or the wax rim is related to the TMJ by using a
horizontal plane and this relationship is transferred to the articulator using
a facebow register the GLENO MAXILLARY.
Relationship in three plane of:
o Anterio-posterior sagital plane
o Transvers or frontal
o Vertically
The maxilla is related to a horizontal plane usually formed by 3
points of references.
Two posterior points of reference
One anterior point of reference
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8. If the inaxillary cast is positioned without the correct maxilla hinge
axis relationship arcs of movement in the articulator will occur which
are different from those of patient.
Occlusion that is restored to an incorrect arc of closure will have
interceptive and deflective tooth contacts.
Such contacts are undersirable and contribute to:
o Periodontal problem
o Muscle spasm
o TMJ pain
o Loss of supporting bone
Location of hinge axis was discussed by Campion first time told
that axis of opening should coincide with the articulator axis.
Theoretically unless the extra THA is located and transferred
the inter occlusal space used for recording in jaw relations will induce
errors in casts mounted on articulators. The error produced may not have
serious consequence in removable prosthesis with non-rigid attachments
in such conditions the intended tolerances and mobility of the supporting
tissues make the precise location of THA a exercise with no great
advantages. On the other hand fixed and removable prosthesis of rigid
attachments demand close tolerances in cusp path ways.
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9. Facebow Transfer:
Use of kinematic face bow : The technique for locating the axis
for dentulous and edentulous patients is same except for the mode of
attachment of the clutch to the mandible. The clutch directly cemented
on the teeth and in case of edentulous condition clutch is attached to
mandibular wax rim and the chin clamp is used to stabilize the
mandibular denture base because of the instability and soft tissue mobility,
inaccuracy creep in which defeat the purpose of axis location. The patient
is trained to make a limited opening and closing movements of about 19-
20mm in insial region within the rotational movement of the condyles.
These points are directly marked on the skin or flag or grid with graph
paper placed on it and this distance is measured from the tragus and is
used as the posterior reference point and the facebow transfer is done in
usual means.
In case of Arbitrary type facebow the posterior points are selected
on a anatomical average of l3mm anterior to the tragus on a line from
tragus to the outer cantus of the eye and the fork is attached to the
maxillary teeth or wax rim. The fork is either inserted in the rim or a
index is used. The condylars (elements) rods are adjusted till the fork is
centered and the pointer for third point of reference of orbital pointer or
the nasion relator is adjusted and once all the locknuts or secured the
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10. facebow should support by itself without any movement than the
condylar lock nuts are released and the face bow transferred to the
articulator with the condylar rods approximating the condylar spheres of
the articulator and the pointer pointing to the built in orbital indicator and
the cast is placed in the record base and mounted.
Thus the plane of occlusion when viewed on the articulator will be
similar to that of the patient in an upright position and the occlusion
plane is placed in a similar, relation in the articulator as that exists in the
patient's mouth.
Description of Facebow :
The facebow consists of 'U' shaped frame or assembly i.e. large enough
to extend from the region of the TMJ to a position 2-3 inches in front of
the face and wide enough to avoid contact with sides of the face. In the
condular region there are condylar rods with graduation extending from
the main assembly which are placed over the posterior reference points,
the reading the condylar rods help us to center the facebow. Once the
facebow is adjusted there are locknuts that are tightened. The part of the
assembly that is attached to wax rim is called bite plane or fork through
the stem or yolk. The fork is attached to the main frame and there are
pointer for the third point of reference like orbital pointer or nasion
relator.
10

11. The facebow or hinge bow for kinematic is also similar in
construction except that instead of the fork attached to maxilla it is
attached to the mandible and there are attachments where the flages or
grids with graph paper are attached to frame which either attached to the
maxi, teeth or held by head straps or worn as spectacles. The clutch or the
fork on the mandible in case of edentulous patiet is stabilized using a chin
clamp.
The arbitrary axis of rotation as set forth by Snow, Gilmer, Hanau,
Gysi and others of 13mm anterior to the tragus on the tragus-canthus line
very close to an average determined axis.
The procedures locating hinge axis calls for rather lengthy and
difficult procedure, which require use of a large and bulky apparatus,
which pose problems of attaching the apparatus to the mobile mandible
securely and this problem is more compounded in edentulous jaws where
the soft tissues and mandibular denture bases are unstable.
This lead Craddok and Symmons in 1952 to state that "search for
the axis in addition to being trounlesome is of no more that academic
interest for it will never be found to lie more than few milimeters distant
from the assumed center of the condule itself. This can be done
palpation 10-13mm anterior to tragus.
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12. The T.H.A. is not only difficult to locate but also difficult to
relocate the same point of axis. Kenneth and Fein-Stein attempted to
locate the axis and were successful only in relocating it within a radius of
2mm.
Borjh and Posselt could relocate it within 1.5mm.
USE OF F.B. AND RELATION TO THE ARTICULATORS
REFERENCE POINTS
One recommended method of positioning, the maxillary cast vertically in
Hanan articulator is to relate the maxillary cast with the F.B. still attached
to the articulator till the maxillary central incisors .edges or the maxwax
rim are aligned to the level of Incisal Reference Notch. 30mm below the
Horizontal condylar plane described by the centers of the condyles and the
infra-orbital indicator, unfortunately there is no Anatomic relationship
between the anterior reference point of orbital and I. R. Notch in other
words the 30mm is not the correct distance between orbitals and maxi
incisal edges. There are other incisal reference notches placed 37, 54
and 47mm below the condylae place. But according to Gonzalers and
kingery the centre of the condyle is 7mm below the porion which forms the
frankforth horizontal plane and therefore the axis-orbital plane should be
placed 7mm below to set a proper parallelism and therefore the
infraorbital foramina should be used as anterior points of reference.
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13. POSTERIOR POINTS OF REFERENCE
Often the posterior points are located by measuring prescribed
distances from skin surface landmarks. Some of the commonly used
posterior points were shown by beck to be clinically near the hinge axis.
He concluded that pergstorm point followed by beyron point were most
frequently close to hinge axis. It is known that balanced occlusion is
necessary for the stability of the dentures and for the health of the oral
tissues. An accurate place of orientation does appear to be essential step
in C.D. fabrication.
An error of this size may not have serious consequence in
removable prosthesis with non rigid (connectory) attachments, in
such conditions the intended tolerances and mobility of the supporting
tissues make the precise location of the Hinge axis a en... with no great
advantage on the other hand fixed and removable prosthesis with rigid
attachment demand close tolerances in cusp path ways.
Verifications of the mandibular cast portioning by use of inter
occlusal records made at increased vertical dimensions of occlusion will
be difficult if not impossible when the interocclusal records are made at
same thickness. Changes in vertical dimensions of occlusion.
Bergstorm point : 10mm anterior to the centre of spherical insert
for the auditory meantus and 7mm below the Frankforth H. plane.
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14. Beyron point 13mm anterior to the posterior margin of the tragus of the
ear on a line from the centre of the margins to the corner of the eye.
The selection of the (anterior) points of reference is useful so that
different maxillary casts of the same patient can be positioned in the
articulator in the same relative position. The points give the procedure
the value of constant determination and also reduce time with
complicated time consuming recording techniques such as pantographic
tracings to repeat the records each time the technique calls for a new casts.
For this reason it is important to identify the mark permanently or be able
to repeatively measure a anterior reference, point as well as the posterior
points of reference.
Selection of Anterior Point of Reference
1. Obritale : In the skull orbitate is the lowest point on the
infraorbital rim. On a patient it can be palpated through overlying
skin and orbitate and the the posterior points that determine the
horizontal axis is defined as the axis - orbital plane. Practically the
axis orbitory plane is used because of the ease of locating and points
easy to understand.
This plane can be transferred to articulator with the help of the
orbital pointer and indicator on the articulator.
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15. 2. Orbitale minus 7Tnm : The frankfort ' s horizontal plane passes
through the poria and one orbitale because these points are (skull)
bony landmarks. Sicher recommends using the mid point of the
external auditory meatus as the posterior cranial landmark. Most
articulators do not have reference point for these posterior land marks
lies 7mm superior to the axis and recommends composition by making
anterior point of reference 7mm below the orbitale or positioning the
orbitale pointer 7mm above in the articulator to the orbitale indicator.
3. Nasion minus 23mm : Again according to Sicher another skull
landmark the Nasion can be used as the anterior reference point. The
nasian guide or positioner which relates to the deepest part of the
midline depression just below the level of eyebrows, as used in whip-
mix and SAM quick mount face bow is designed so that it moves in
and out but not up and down from its attachments to the cross bar.
The cross bar is located approximately 23mm below the nasion. When
the face bow is positioned the cross bar will at the level of the orbitale.
The disadvantages of using this kind of face is that this technique
depends upon the large nasion guide the morphologic characteristics
of the Nasion notch and the variance of the Nasion orbitale
measurements from 23mm in the patient.
4. Incisal edge plus anterior midpoint to articulator axis
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16. Horizontal plane distance.
Guichet - Emphasized that a logical position of casts in the articulator
would be one which would position the plane of occlusion near the mid
horizontal plane or articulator. The the mid horizontal distance to the
axis condyler plane is measured, this measured distance measured onto
the patients from the existing incisal edges or planned occlusal plane and
then transfer is done.
5. Alae of the Nose : The occlusal plane actually parallels the
horizontal plane which was concluded by Angsbreber in review of
literature that the occlusal plane parallels the campu's line with minor
variations knowing this we can transfer camper plane from the patient
to the articulator by using either right or Ala as the anterior reference
point.
Importance of selection of anterior reference point
1. A planned choice of anterior reference point will allow the
dentist and auxiliaries to visualize and anterior teeth and
occlusion in the articulator in the same frame of reference that
would in patient i.e. as if patient standing in normal postural
position with eyes looking straight ahead.
2. The act of affixing a maxillary cast with its determined hinge
axis to an articulator with its axis in the condyler
16

17. determinants achieves greater importance by the use of the
three points of easy reference where are constant and
repeatable.
To use or not use :
The value of the face bow has been the topic of considerable
discussion and contraversy in prosthesis dentistry for many years. Logan
considered indispensable Craddock and Symmons considered it as futile
exercise. While Stansberry described a technique of positioned records
and told that use of face bow was useless. Lazzari set forth the advantages
of using a facebow.
1. It permits a more accurate use of lateral rotational points for
arrangement of teeth.
2. It aids in securing anterioposterior positioning of the cast in
relation to the condyles.
3. A correct horizontal plane is established. Therefore the
incisor plane is also properly established.
4. It helps in vertical positioning of the cast in articulators.
• Face bow transfer is not required in following conditions.
The articulators developed not to receive face bow transfer.
17

18. • Some theories of occlusion specially the Monson's
spherical theory of occlusion.
• When monoplane teeth are arranged in a occlusal
balance.
• No alteration of occluding surfaces of the teeth that
necessitates the changes in verticle dimension.
• No inter occlusion check reports that would be of different
thickness.
But when we analyse the above said facts it is very clear that by
simply stating that the articulator is not designed to accept the face bow,
we cannot forget the step of facebow transfer and incorporate the errors
due to blind orientation of the casts on the articulator and we cannot
have single predetermined scheme of occlusal for all patients and we
cannot use mono plane teeth for all cases in fact when we are cusped form
of teeth facebow transfer becomes a must to achieve balance in entire
positions. Changes do occur in vertical dimensions in complete dentures
due to processing and dimension if to be retorations requires a facebow
transfer and in case any remound is desired any change is there in occlusal
records needs a facebow transfer.
Vertical dimension desired and planned on articulator require
facebow transfer. When use the following figures it becomes very clear
18

19. that now varied the cuspal inclination when the casts are placed at
different levels in articulators of course the changes may not be so great in
positions but changes do occur.
Average mountings do not serve the diagnostic imposes in
distrubances that occur to positions teeth face transfer in not only useful
from prosthesis recontractive view that also diagnostic (tool in) procedure
in gnathological studies. The overall opinion to which majority of the
prosthodontics agree in put forward by the academy of denture
prosthodontics favouring the use facebow and concluded that "A
FACEBOW SHOULD BE USED FOR MOUNTING THE UPPER CAST
ON ANY ARTICULATOR THAT HAS A FIXED AXIS OF OPENING".
The correct orientation of the occlusal plane is a important step
and the inclination of the plane that we develop had effect on the
masticatory performance.
Kapoor and Soman showed that the masticatory performance was
influenced by the plane of orientation and Hideaki, Okene and others who
further carried out the research found that maximum clenching force was
greatest when the occlusal plane parallel to the camper's plane and the
force decreased when there was 5° tilt either anterior and posterior.
Modification of face bows and different types of face bows :
1. Accuracy - Kinematic
- Arbitrary - Eartype
19

20. - Fascia
Eartype - Manual lenthing eg. HANAO
- Self centering or quick mount
eg. whip-mix, Bregstorm, SAM
Even though the Snow type FBS are mechanically simple they are
in convient to assembly on patient
- to locate
- to adjust the FB.
On the posterior points of reference directly on the skin. Therefore
in 1914 Dalbeg introduced the use of ear type of facebow where the
posterior ends were modified and may fit in the car but it was not until late
60's the ear type gained populatiry.
Now there are so many articulatory available that each articulator
had to use with special type of FB. Then Kelseg came out with adapter
which permits one type of face bow to be used 'with different articulatory.
Then there came the self centering type or quick mount type of the F.B.
With a built in gear mechanism where only one mechanism help to center
the fork.
- Slidematic facebow
- Quick mount or whipmix
20

21. Bregstorm
21

22. Springbow :
Further simplication of the arbitory lead to development of spring
bow which eliminate the wrencnes and screws and moving parts. It is one
piece low maintenance and lower cost.
Modifications :
Disadvantages of conventional face bow fork :
1. Heatedfork when inserted into the wax rims
distorts the carefully developed contours.
2. The width is fixed and sometimes difficult to
be used with larger or smaller arches.
3. When the face bow transfer is to done after the
centric occlusion interocclusion record, the possibility of the rim
distortion is introduced.
4. In treating the patients (for) immediate
maxillary denture the face bow transfer may be complicate by
remaining natural teeth.
Advantages of modified facebow fork :
1. Does not distort facial contours the wax rim.
2. Provides adjustability and can be used with any size ofarch.
22

23. 3. Minimum or no distortion when facebow transfer is made
after inter occlusal registration.
4. Can be used for immediate denture treatment with the
natural teeth.
It is attached to the palatal portions of the (denture) record base. A
new face bow design was introduced that further simplifies the arbitory
face bow technique.
Advantages include
1. Ease and efficiency of use
2. Steriligable parts
3. One piece low maintenance design
4. Adaptability to many articulators
5. Lower cost than other car piece types
Made up of spring steel and simply springs open and closes to
various head width.
CONCLUSION
Failure to use the facebow leads to error in occlusion.
Hinge axis is a component of every masticatory movement of the
mandible and therefore cannot be disregarded and this hinge axis should
23

24. be accurately captured and transferred to the articulator. So it becomes a
fine representative of the patient and biologically acceptable restoration is
possible.
Whatever may be controversy reasoned by in the use of facebow
but it should form a integral part of one prosthodontic treatment.
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