Orientation jaw relation

Orientation Jaw Relation And Face
Bow Transfer
B. Ravi
Dept of Prosthodontics

Contents
• Introduction
• Jaw Relations
• Orientation Jaw Relation
• Hinge Axis
• Clinical use of the Terminal Hinge Axis
• Controversies
• Review of Literature
• Location Of Hinge Axis

Contents
• Facebow
• History of Facebow
• Parts of Facebow
• Types of Facebow
• Anterior and Posterior Reference Point
• Facebow Transfer
• Conclusion
• References

Introduction
• The missing teeth are restored by the CD,FPD,RPD
to restore function & esthetics.
• It is essential to develop proper occlusion for
maintaining health of supporting structures, orofacial
musculature, and TMJ.

Introduction
• So there is a need for accurately locating the hinge
axis, recording and transferring the same on to the
articulator, to enable the accurate reproduction of
occlusal relationship on an articulator.
• This is achieved by Facebow which records the
position of jaws in relation to the condylar
mechanism & aids in transferring the same relation
onto the articulator.

Jaw Relations
• Definition:
Jaw relations are defined as any one of the many
relations of the mandible to the maxillae (Boucher -3)
Maxillomandibular relationship is defined as any
spatial relationship of the maxillae to the mandible;
any one of the infinite relationships of the mandible
to the maxilla. (GPT)

Jaw Relations
• These relations may be of orientation, vertical and
horizontal relations. They are grouped as such
because the relationship of the mandible to the
maxillae is in the three dimensions of space i.e.,
sagittal, vertical and horizontal planes. (Gunnar E
Carlson)

Jaw Relations
• Classifications
Jaw relations are classified into three
groups to make them more easily understood:
They are
1) Orientation jaw relations
2) Vertical jaw relations
3) Horizontal jaw relations

Orientation jaw relation
• The orientation jaw relations are those that orient the
mandible to the cranium in such a way that, When the
mandible is kept in its most posterior position, it can
rotate in the sagittal plane around an imaginary
transvers axis passing through or near the condyles.

Hinge axis
• The hinge axis is defined as an imaginary line
passing through the two mandibular condyles &
around which the mandible may rotate without
translatory movement. (GPT)

• Gray recognized that mandible moves by rotations,
forward & lateral movements of the condyle in the
glenoid fossa.
• Balkwell of England in 1824 called attention to the
sliding action
• Bonwill assumed that forward motion of joint was on
a straight line in forward direction.
• After 40 yrs Walker proved that the motion was
forward & downward.
History of the Hinge Axis

• Bennett of England unaware of Balkwell`s proposals
showed that condyles in all individuals make a side
shift motion to a greater or lesser extent in the lateral
movements called as Bennett movement.

• Snow in 1899 recognized the importance of hinge
axis & he constructed a face bow.
• Camplon in 1905 concluded that the dental casts
should be mounted onto the articulator in such away
that the rotational axis of articulator coincides with
opening axis of mandible.
• In 1921 Dr. B.B. McCollum, along with Dr.Robert
Harlan located the first actual kinematic axis.

Terminal Hinge Axis
• When the condyles are in the most superior position in the
articular fossae and the mouth is purely rotated open , the axis
around which movement occurs is called as Terminal hinge
axis.
• Maximum range of terminal hinge rotation- about 12˚
• Inter incisal opening: 18-25 mm

Terminal Hinge Axis
The terminal hinge position is significant because it is
learnable, repeatable, and recordable position that
coincides with the position of centric relation

Clinical Use Of The Terminal Hinge Axis
• The location of the transverse hinge axis serves only
to orientate the maxilla and to record the static
starting point for functional mandibular movements.
• It does not record centric relation or condylar
movements.
• Allows the transfer of the opening axis of jaws to the
articulator so that occlusion would be on the same arc
of closure as in the patients mouth

Clinical Use Of The Terminal Hinge Axis
• The hinge axis recording is required to check the
accuracy of two centric records.
• Helps in proper positioning of the casts in relation to
intercondylar shaft.
• Vertical dimension of occlusion can be altered on the
articulator

Hinge axis
Controversies
There has been a considerable debate about whether:
• A hinge axis exists
• Hinge axis can be accurately located
• There is only one hinge axis
• It is clinically useful to locate the axis
• An arbitrary point can be satisfactorily substituted
for a kinematic axis

Hinge axis
Controversies
• Sloane stated that The hinge axis is not a theoretical
assumption, but definitely demonstrable
biomechanical factor.
• Sicher stated that The terminal hinge position is the
most retruded position of the mandible, the centric
position .

Hinge axis
Controversies
• The proponents of Gnathology Stated that there is
one transverse hinge axis & it can be accurately
located.
• The proponents of transographics claims that
Transograph is the only instrument that can duplicate
it.
• Others claim that Better to use articulator like Hanau,
that utilizes a Face-bow mounting & an average of
several readings for excursive movements.

Four Main Schools Of Thought
• Group 1 ---Absolute location of hinge axis. There is a definite
transverse axis & should be located accurately.
• The proponents of this group claims that: with the aid of the
face bow it is possible to relate the maxillary cast to the
transverse axis of the articulator in the same relationship as the
maxillae are related to the anatomic mandibular axis through
the condyles

• Group 1:
• The critics of this theory claim that most of the articulators are
designed on the assumption that the transverse hinge axis is an
imaginary line connecting a point in the centre of one condyle
with a point in the centre of the opposite condyle.
• However, this optimum conditions do not exist in the
mandibular apparatus, which is asymmetrical in shape and
size.
• The condyloid processes are joined at the symphysis with no
connection between the condyles. And also the condyles do
not lie in a common plane of orientation

• Group 2 ---Arbitrary location of hinge axis. Believe that
arbitrary location of hinge axis is reliable, even though
accurate location is valuable.
• The critics of this group claim that group II fails to recognize
that if the hinge axis of the articulator does not coincide with
the hinge axis of the patient the path of closure will not be the
same.

• Group 3 --Non believers in transverse hinge axis location. It
is impossible to locate hinge axis with accuracy. More
theoretical than practical.
The critics of this group claim that the main motion is pure
rotation plus slight translatory movements, the composite of
which adds up to a common centre of rotation.
Since this performance is repeatable, it becomes a reliable
point of orientation.

Group 4 --Split axis rotation. Believe that the condyles rotate
independent of each other.
As the mandible is not bilaterally symmetrical and the terminal
hinge position mark on one side of the face is usually a little
higher than it is on the other, there cannot be a common axis.
There must be two axis parallel to each other with both axes at
right angle to the opening and closing movements of the
mandible. The condyles are irregular and hence to not have a
single point of rotation.

Location of hinge axis
• ARBITRARY METHOD OF LOCATING HINGE
AXIS
• The arbitrary method is an accepted technique for
locating the mandibular hinge axis.
• Although many studies have compared various
arbitrary hinge axis points with kinematic location,
there is no consensus as to which arbitrary point most
closely and consistently lies on or near the kinematic
axis.

Location of hinge axis
KINEMATIC METHOD OF LOCATING HINGE AXIS
• Posselt stated that maximum separation of incisal edges in
hinge motion to vary from 15 to 20mm or 10 to 13 degree
opening & closing arc available for hinge axis location.
• In terminal hinge position the mouth opening is 12.5mm.
Kurth & Feinstein located the hinge axis within 2mm of
area for 10 degree arc of opening.
• Borgh & posselt located within 1mm of area for 15
degree & 1.5mm for 10 degree of opening arc.

Variables affecting hinge axis location
Patient variables affecting the THA
• locations Condyle
• Asymmetry
• Inability to locate a true hinge axis
• Myospasm or joint pathosis
• Emotional conditions of patient

Variables affecting hinge axis location
Factors of the recording system affecting Transvers
Hinge Axis
• Right angle, non-right angle system of the bow
• Length of stylus arms and sharpness of styli

Review of the literature
Study conducted by L. E. Kurth & I. K. Feinstein in
1951.
• With the aid of an articulator & working model,
they demonstrated that more than one point may
serve as hinge axis.
• So they concluded that infinite no.of points exist
which may serve as hinge points.
• It is unlikely to locate the hinge axis accurately

study conducted by Robert G Schollhorn in 1957 ,
• He recorded the arbitrary center & true hinge axis
in 70 dental students.
• He concluded that arbitrary axis of rotation which is
13mm anterior to the posterior margin of the tragus
on tragal canthus line lies close to an average
determined axis.
• In 95% of subjects Kinematic center lies within
5mm radius , which is considered to be within normal
limits. So determining kinematic center is not
necessary.

Study was conducted by Richard l . Christiansen in the
year 1959.
• He mounted the maxillary casts arbitrarily with
face bow records & studied the errors in occlusion.
• He concluded that it is advantageous to simulate on
the articulator, the anatomic relationships of residual
ridges to the condyles for more harmoniously
occluding complete dentures.

Study conducted by T. D Foster in 1959.
• He stated that permanent study casts would be of
more value if they are mounted in correct relationship
to the FH plane particularly in facial deformity
involving the jaws..

Study was conducted by
Arne Lauritzen & George H. Bodner in 1961.
• They marked true hinge axis & arbitrary hinge axis
by 3 methods .
• They concluded that in 67% of cases the true hinge
axis was 5 to 13mm away from the arbitrarily located
hinge axis points

Study was conducted by Vincent R. Trappazzan , Jhon
B.Lazzari in 1961.
• They conducted the study on 14 subjects.
• They concluded that in 57.2% of the subjects, more
than one hinge axis point was located on either one or
both sides.
• In 42.8% of the subjects showed single hinge axis
point on left & right side of the face

• Study was conducted by Lauritzen & Wolford in 1961.
• An experimental instrument was designed to
determine how accurately the centers of 15, 10, 5
degree arc of movement could be located
consistently.
• The result indicated that 10 degree range of
movement is sufficient for hinge axis location .
• The attainable accuracy by an experienced operator in
locating the the center of 10 degree arc is within
0.2mm.

Study was conducted by Arthur F. Aull in 1963.
• He concluded that the horizontal axis is a
hypothetical line.
• Terminal hinge position is most posterior position.
• Arbitrary location fails to satisfy the requirements.
• Do not support the split axis theory.
• No evidence found to believe that there is more than
one hinge location.

Study was conducted by Vincent R. Trapazzan &John
B. Lazzari in 1967.
• They concluded that the patient should be relaxed &
two operators are required for location.
• Because of the presence of multiple hinge axis
points, increasing or decreasing of the vertical
dimension on the articulator needs new interocclusal
record.

Study was conducted by Edwin R. Thorp , Dale E.
Smith, & Jack I. Nicholls in 1978.
• They compared 3 arbitrarily located axis to the true
hinge axis locations. they concluded 57% of the
arbitrary locations were within 6mm of the true hinge
axis.
• The results revealed very small difference in
accuracy between hinge axis face bow, Hanau –132
SM face bow& Whip mix face bow.

Study was conducted by Keki R. Kotwal in 1979.
• He made the casts of the dental arches of the skull &
made interocclusal records, mounted the casts with &
without face bow on to the Whip Mix articulator .
• He concluded that face bow transfer allows more
accurate arc of closure on the articulator when the
inter occlusal records are removed.

Study was conducted by F.M. WALKER in 1980.
• He concluded that arbitrary hinge axis location does
not exist.
• Arbitrary axis locations recommended in the
literature will create 6mm or more error.
• The true axis located inferior to tragus canthus line

Study was conducted by Mahmoud Khanics Abdel
razek in1981
• He located the arbitrary hinge axis by 5 methods in
120 dentulous patients & compared with true hinge
axis location .
• He concluded that none of the methods was ideal,
Dawson`s palpatory method is acceptable .

Study was conducted by Jhon H. Pitchford in 1991.
• He concluded that a compromised esthetic result
can be produced by an anterior Reference point not in
harmony with design of articulator.
• Minor variation of the face bow , position of
orbitale pointer & indicator will allow an average
value transfer of the esthetic reference position to an
articulator

Study was conducted by William W. Nagy, Thomas J.
Smithly & Carl G. Wirth in 2002.
• More than 96% of the pre-determined points were
within 2mm of the kinematic axis, 67% were within
1mm no significant difference between right & left
side.
• They concluded that predetermined axis point was
well within 5mm clinical norms for estimated
location of transverse horizontal mandibular axis for
the population studied.

• Study was conducted by Virgillo Ferrario, Chairello
Sforza, Graziano Serrao & Johannes H. Schmitz in
2002
• They assessed reliability of the postural face bow by
comparing the values with those obtained by
computerized non invasive instrument.
• They concluded that postural face bow reliably
reproduced the spatial orientation of the occlusal
plane relative to the true horizontal plane.

Face-bow
• Several things must be considered when transferring
the mouth records of an edentulous patient to the
articulator: the articulator, the face-bow , the tracing
instrument for recording jaw relations, and the health
of the gnathologic system .

Face-bow
• Definition:- The face-bow is a caliper-like instrument
used to orient the maxillary cast on the articulator so
that it has the same relationship to the opening axis
that the maxilla has to the opening axis of the jaws.
(winkler)

Face-bow
• Definition:- Face bow is a caliper like device used to
record the relationship of maxilla to the
temporomandibularjoint.(Heartwell)

Face-bow
History of face-bow
• In 1860 Bonwill concluded that the distance from
the center of the condyles to the median incisal point
of the lower teeth is 10 cm.
10 cm.

Face-bow
• History of face-bow
• In 1866 Balkwell demonstrated an apparatus to
measure the angle formed by the occlusal plane of
lower teeth & the plane passing through the condyles
& incisal plane of lower teeth.

Face-bow
• History of face-bow
• In 1880 Hayes constructed an apparatus called
Caliper with median incisal point localized in
relation to the two condyles.

Face-bow
History of face-bow
• In 1890 Walker invented Clinometer used to obtain
the relative position of the lower cast in relation to
the condylar mechanism

Face-bow
History of face-bow
In 1894 George K Bagby fabricated a device that
determined the distance from the midline of the
anterior occlusal rims to one of the condyles

Face-bow
History of face-bow
• At about a turn of a century Gysi developed an
instrument similar to the face-bow primarily to
records paths of the condyles and also used to
transfer maxillary cast to articulator

Face-bow
History of face-bow
• 1899 About the same time Snow introduced the
snow face-bow. Majority of the face-bows used
today are modifications of snow face-bow

Face-bow
Principle of Face Bow Use
• The axis of opening of the articulator should be similar
to the patient’s mandibular arc of movement when the
prosthesis is fabricated with the help of articulators.
• The mandibular cast is oriented to the maxillary cast,
which in turn is oriented in the articulator. To accomplish
this act of orientation, the face bow is used

Face-bow
Classification
There are two types of facebows:
• Kinematic face bow which locates the true hinge axis
• Arbitrary face bow, which locates the arbitrary hinge
axis.
These are of two types
 fascia type and
 earpiece type

Face-bow
Classification
• Facebows that can be utilized with Hanau articulator
Facia
Ear piece
Twirlbow
Spring bow
Kinematic
• Facebows that can be utilized with Whipmix articulator
Quick mount
Ear piece
Kinematic
• Facebows that can be utilized with Denar articulator
Facia
Ear piece
Slidematic and Kinematic

Face-bow
Arbitraryn Type of Facebow
Definition: A device used to relate the maxillary cast to
the condylar elements of an articulator using average
anatomic landmarks to estimate the position of the
transverse horizontal axis on the face (GPT8).
• Also called ‘average axis facebow’.
• It is the most commonly used face-bow in complete
denture construction.

Face-bow
• This method generally locates the rods within 5 mm of the true
hinge axis of the jaws.
• As this is an arbitrary hinge axis, errors in jaw relation may
produce occlusal discrepancies .
• which should be corrected by minor occlusal adjustments
during insertion..

Face-bow
• Ear piece type of face bow – This type of Face bow
uses the external auditory meatus as an arbitrary
reference point which is aligned with ear pieces.

Face-bow
Facia type of face bow –the centre of condylar
rotation is arbitrarily marked as 13 mm anterior to
the middle of the tragus of the ear, on a line drawn
from the outer canthus of the eye to the middle of the
tragus of the ear – canthotragal line

Face-bow
• The kinematic- A facebow with adjustable caliper
ends used to locate the transverse horizontal axis of
the mandible (GPT8)
• kinematic- This face-bow is generally used for the
fabrication of fixed partial denture and full-mouth
rehabilitation.
• It is generally not used for complete denture fabrication
because it requires a long and complex procedure to
record the orientation jaw relation

Face-bow
• The kinematic- The kinematic is used to locate the
true terminal hinge axis and transfer this record to
the articulator when mounting the maxillary cast.
• It usually requires a fully adjustable articulator.

Face-bow
• The kinematic face bow
allows for the precise
determination of the
patient's hinge axis (terminal
hingeaxis).

Face-bow
43
Hanau Spring Bow
It is the most commonly used face-bow
• Arbitrary earpiece type,
arbitrary facia type and kinematic
face-bows are also available from hanau
• Reference points-
posterior- Porion, the superior border of external auditory
meatus
anterior -Infra orbital notch
• Plane of reference-Frankfort horizontal plane

Face-bow
43
Hanau Twirl Bow
• It is an earpiece type of facebow
It is not commonly used for CD construction
• Allows the maxillary arch to be transferred to the articulator
without physically attaching the face-bow to the articulator
• Relates the maxillary arch to FH plane
• A horizontal orbital pointer is attached to the right temple arm

Face-bow
43
Whip mix face bow
• Ear piece type of face bow
• It has a built in hinge axis locator.
• Automatically locates the hinge axis when the ear pieces are placed
in the external auditory meatus
• Has a nasion relator assembly with aplastic nose piece

Face-bow
43
Quick Mount Facebow
• It is an earpiece type of facebow
• Used with whipmix articulator
• Reference points- posterior : external auditory meatus
anterior : nasion
• Plane of reference-axis-orbital plane

Face-bow
43
Quick Mount Facebow
• Made up of specially contoured ear pieces on the condylar ends of
the bow
• Consists of a scale that can measure intercondylar distance
• Parts- Bow with plastic ear pieces Crossbar Facebow toggle
assembly Nasion relator assembly with plastic nose piece

Face-bow
43
Slidematic Facebow
• Type of ear piece facebow
• Used with denar articulator
• Reference points- posterior: external auditory meatus
anterior: 43mm above incisal edge of right central incisor in
dentulous patient or 43mm above the lower border of upper lip in
edentulous patient
• Reference plane: anterior reference point is selected so that
occlusal plane will be positioned in the middle of articulator

Face-bow
43
Dentatus (1944, Sweden)
DENTATUS • It is a shaft type instrument.
• The condylar element attached to the upper member & the
condylar path is strraight.
• The intercondylar distance is fixed.
• The articulator received a hinge axis face-bow.
• The features are similar to Hanau mode
Accept static protrusive interocclusal records / registrations +
Accepts a face-bow transfer –

Newer advancements
Today there are more advanced techniques that
make use of ultrasonic arcs, connected to computers
with graphical representations and parameter
calculations for programming the articulator.

Face-bow
• Parts of face-bow

Face-bow
Parts of face-bow
• records the plane of the cranium
U-shaped metal frame

Face-bow
Parts of face-bow
Ear piece type of facebowFacia type of facebow

Face-bow
Orbital pointer with clamp

Face-bow
Bite fork
3mm

Face-bow
bite fork for dentulous patients

Face-bow
1
3
2
Locking device

• Orbitale (B) Located by Hanau facebow with help
of orbital pointer.
• Orbitale minus 7 mm. (C) This plane represents
Frankfortplane.
• Nasion minus 23mm (A) Used with quick
mount facebow (Whipmix)
Anterior Reference Point

• Ala of nose (D) This plane represents campers
plane
• 43 mm superior from lower border of upper lip
/above incisal edges of right central incisors
(Denar reference plane locator – Denar facebow
usesthis referencepoint)
• Incisal edge plus articulator midpoint to
articulator axis: Horizontal plane distance 6.
Anterior Reference Point

Orbitale
•Orbitale is the lowest point of
the infraorbital rim of skull
which can be palpated on the
patient through the overlying
tissues and the skin.
•One orbitale and the two
posterior points that determine
the horizontal axis of rotation
will define the axis – orbital
plane.

•Orbital Minus 7mm
•The Frankfort horizontal plane passes
through both the poria and one orbital
point.
•Because porion is a skeletal landmark,
Sicher’ recommended to use the midpoint
of the upper border of the external
auditory meatus as the posterior cranial
landmark on a patient
7

•Orbital Minus 7mm
•Gonzalez’ pointed out that this posterior
tissue landmark on the average lies 7 mm
superior to the horizontal axis.
•The recommended compensation for this
discrepancy is to mark the anterior point
of reference 7 mm below orbitale on the
patient or to position the orbital pointer 7
mm above the orbital indicator of the
articulator
7

• According to Sicher, another skull landmark, the Nasion can be
approximately located in the head as the deepest part of the midline
depression just below the level of eyebrows.
• The Nasion guide, or positioner, of the Quick-mount facebow,
which is designed to be used with the Whip-Mix articulator, fits
into this depression.
Nasion Minus 23mm

• Crossbar is located 23 mm below the mid point of Nasion
positioner.
• When the facebow is positioned anteriorly by nasion guide, the
crossbar will be in approximate region of orbitale.
• So, crossbar is the actual anterior reference point locator
• Hence it also employs an approximate axis-orbitale plane.
Nasion Minus 23mm

Alae Of the Nose
•In most of the conventional
complete denture techniques it is
imperative to make tentative or the
actual occlusal plane parallel with
the horizontal plane.
•This relationship can be achieved
as a line from the ala of the nose to
the center of the auditory meatus
that describes Camper’s line.

Advantagesof anterior referencepoint
• Determines which plane in the head will become the plane of
reference.
• Determines the level at which the casts are mounted
• To establish a base line for comparative studies between
patient.
• Can visualize anterior teeth & occlusion in the articulator in
the sameframe of reference.

26
Posteriorreferencepoints
Bergstrom’s point -.
About 10 mm anterior to the center of the spherical insert for the
external auditory meatus and 7 mm below the Frankfort horizontal
plane. Bergstrom point is found to be the most frequently closest to
the hinge axis, and Beyron point is the next most accurate posterior
point of reference
FH

26
Beyron’s point - A point 13mm anterior to the posterior
margin of tragus of the ear on a line from centre of the
tragus to the outer canthus of eye.
FH

26
Gysi point -
Gysi placed it 11–13 mm anterior to the upper third of the tragus
of the ear on a line extending from the upper margin of the
external auditory meatus to the outer canthus of the eye.

26
Lundeens point- 13mm anterior of tragus on line joining base of
tragus to outer canthus of eye.

26
Simpson’s point About 11 mm anterior to the superior border of
tragus on Camper’s line

26
Denar’s – 12 mm anteriror to posterior border of tragus and 5 mm
inferior to line from EOM and outer canthus

Face-bowrecord
• Accurate mounting - three points
• Criteria for selection of points
– Ease of location
– Convenience
– Reproducibility

Mounting Articulator
• Direct Method
• Indirect Method

Indirect mounting
After the direct transfer had been completed, the spring-bow
was unscrewed from the transfer assembly. The mounting
platform was secured on the lower member by the cast support.
The transfer assembly was secured onto the mounting
platform, and the cast support was raised to support the
bitefork index following which the maxillary cast was
mounted.

Indirect mounting
The mandibular casts were then mounted using maximum
intercuspation Alu wax record for both direct and indirect
transfers. A single protrusive record for each subject was made
in Alu wax to program the directly and indirectly transferred
casts.

54
Advantagesof using
facebow
“Lazzari”
• It aids in securing the antero-posterior cast position
with relation to condyles of the mandible.
• It acts asan aid in the vertical positioning of the cast
on the articulator.
• It assists in correctly transferring the inclination of
the occlusal plane to thearticulator.

40
Errorsin facebow recording
• Movement of theskin
• Unstable edentulousridges
• Angleof opening issmall –10º--12º
• Inter-observererror

• A definite cusp fossa or cusp tip to tip incline relation is
desired.
• When interocclusal check records are used for
verification of jawpositions.
• When the occlusal vertical dimension is subjected to
change, and alterations of tooth occlusal surfaces are
necessaryto accommodate thechange.
• Todiagnoseexisting occlusion in patientsmouth
Indications for useof face-bow

55
Situations where facebow is not required
• Monoplane teeth are arranged in balance occlusion and
mandible in most retruded position at acceptableVD
• Nointended changein VDO
• the articulators developed not to receive facebow
transfer

Concepts&Reviewof literature
• Stansberry (1928) was dubious about the value of
facebow andadjustable articulators.
• Hethought that sinceanopening movement about
the hinge axis took the teeth out of contact the use
of these instruments was ineffective except for the
arrangementof the teeth in centric occlusion.

Mclean (1937) stated that the hinge portion of the joint is
the great equalizer for disharmonies between the
gnathodynamicfactors of occlusion.
When occlusion is synthesized on articulator without
accurate hinge axis orientation, there may be minor cuspal
conflicts, which must be removed by selective spot
grinding.

Kurth LE, Feinstein IK (1951) with aid of articulator and
working model, demonstrated that more than one point may
serve as a hinge axis and concluded that an infinite number of
points exist which mayserveas hingepoints.

Craddock and Symmons (1952) considered that the accurate
determination of the hinge axis was only of academic interest
since it would never be found to be more than a few
millimeters distance form the assumed center in the condyle it
self.

Sloane (1952) stated “the mandibular axis is not a theoretical
assumption,but a definite demonstrable biomechanicalfact.
It is an axis upon which the mandible rotates in an opening and
closingfunction when comfortably, not forciblyretruded.

Bandrup-Morgsen (1953) ,discussed the theory and
history offacebows.
• He quoted the work of Beyron who had
demonstrated that the axis of movement of the
mandible did not always pass through the centers
of the condyles.
• They concluded that complicated forms of
registration were rarely necessary for practical
work.

Lazarri(1955)gave application of Hanau model
”c” facebow.

Sicher (1956) stated “the hinge position or terminal hinge
position is that position of the mandible from which or in
which pure hinge movement of a variable wide range is
possible”

Robert.G.Schallhorn (1957), (studying the arbitrary center and
kinematic center of the mandibular condyle for face bow
mountings.
• He concluded that using the arbitrary axis for face bow
mountings on asemiadjustable articulator isjustified.
• He said that, in over 95% of the subjects the kinematic
center lies within aradiusof 5mm from the arbitrary center.

Brekke (1959) in reference to a single intercondylar transverse
axis stated “unfortunately this optimum condition does not
prevail in mandibular apparatus, which is symmetric in shape
and size, and has its condyloid process joined at the symphysis,
withno connection directly at the condyles.
• The assumption of a single intercondylar transverse axis is,
therefore open toserious question”.

Christiansen RL(1959) studied the rationale of
facebow in maxillary cast mounting and concluded that it
is advantageous to simulate on the articulator the
anatomic relationship of the residual ridges to the
condyles for more harmoniously occluding complete
dentures.

Weinberg (1961) evaluated the facebow mounting and
stated that a deviations from the hinge axis of 5mm will
result in an anteroposterior displacement error of 0.2 mm
at the secondmolar.

LuciaVO (1964) described the technique for recording
centric relation with help of anterior programming
device.

Teteruck and Lundeen (1966) ,evaluated the accuracy of the
earpiece face bow and concluded that only 33% of the
conventional axis locations were within 6mm of true
hinge axisas 56.4% located by earface- bow.
• They also recommended the use of earpiece bow for its
accuracy,speed of handling, and simplicity of orienting the
maxillarycast.

Trapazazano, Lazzari (1967) concluded that, since multiple
condylar hinge axispoints were located, the high degreeof
infallibility attributed to hinge axis points may be
seriouslyquestioned.

Thorp, Smith, and Nicholis (1978), evaluated the use of face bow
in complete denture occlusion.
Their study revealed very small differences between a hinge axis
facebow Hanau132-smfacebow,andwhip mix ear- bow.

Neol D.Wilkie (1979) analyzed and discussed five commonly used
anterior points of reference for a facebow transfer.
• Hesaidthat not utilizing athird point of reference mayresult in
an unnatural appearance in the final prosthesis and even damage
to the supporting tissue.
• He suggests the use of the axis–oribitale plane because of the
ease of making and locating orbitale and therefore the concept is
easyto teach and understand.

Stade E et al(1982) (38) evaluated esthetic
consideration in the use of facebow.

Palik J.F et al(1985) (39) concluded in his study on the
accuracy of earpiece facebow that regardless of any
arbitrary position chosen, a minimum error of 5mm from
the axis can be expected

Conclusion
• Failure to use the facebow leads to error in occlusion.
Hinge axis forms a major component of every
masticatory movement of the mandible and therefore
cannot be disregarded that hinge axis should be
accurately captured and transferred to the articulator, so
that it becomes a fine representative of the patient and
biologically acceptable restoration is possible.
• Thus, the use of facebow should form a integral part of
one prosthodontic treatment.

References
• Boucher's Prosthodontic treatment for edentulous
patient 10th edition.
• Essentials of complete Denture Prosthodontics by
Sheldon Winkler-2nd edition.
• Syllabus of complete dentures by Charles M.
Heartwell 4th edition 5th edition.
• RangaRajan text book of prosthodontics
• Deepak Nallaswami text book of prosthodontics

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