Face bo wfn/ dental courses

FACE BOW
A REQUIRED ENTITY FOR LOCATION OF THE HINGE AXIS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

CONTENTS
Introduction
Definition of Face Bow and Hinge Axis
Review of the literature about Hinge axis & Face Bow
History of Hinge axis & Face Bow
Importance of locating hinge axis
Concepts regarding hinge axis
Location of hinge axis__ Arbitrary
__ Kinematic
Face bow -Parts
Types of face bow

Anterior & posterior points of reference
Face bow recording procedure
Mounting on to the articulator
Significance of using face bow
Indications for using face bow
Summary & 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,TMJ. So there is a need for accurately locating the
hinge axis & recording & transferring the same on to the
articulator, to enable the accurate reproduction of occlusal
relationship on an articulator. This is achieved by Face bow
which records the position of jaws in relation to the condylar
mechanism & aids in transferring the same relation onto the
articulator. www.indiandentalacademy.com

Definition of the face bow
 The face bow is a caliper like device that is used to record the
relationship of jaws to the opening axis of jaws and to orient the
cast in this same relationship to the opening axis of articulator.-
GPT
Definition of hinge axis
 The hinge axis is defind as an imaginary line passing through
the two mandibular condyles & around which the mandible may
rotate without translatory movement.- GPT
 Terminal hinge axis
It is an imaginary line which passes horizontally through
the rotation centers of the right & left condyles when the
condyles are in their most distal / retruded , unstrained position
in their respective articular / glenoid fossa.

REVIEW OF LITERATURE OF HINGE AXIS & FACE
BOW
 Study was 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 .

 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 ant.
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 ,
Arstad considered to be within normal limits.
So determining kinematic center is not necessary.

 Study conducted by Borgh &Posselt in 1958.
Hinge axis points were registered by using Kinematic face bow mounted
on a modified Hanau adjustable articulator. They
conducted the experiment with 10 &15 degree openings. They
concluded that the range of variation in location of hinge axis point were
1.5 mm for 10 degree opening & 1mm for 15 degree opening.

 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 13 mm 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. 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 of10 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 here is more than one
hinge location.

 Study was conducted by Walter R. Teteruck in 1966
He recorded the hinge axis by ear piece face bow, hinge axis
technique, conventional transfer procedures.
He concluded that 33% of the conventional axis locations were
within 6mm of the true hinge axis as compared to 56.4%
located by ear piece face bow.

 Study was conducted by Vincent R. Trapazzano
&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 dose 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 C.C. Beard, J.A. Clayton in
1981.
They concluded that Trapazzano & Lazzari `s study was
reproduced & the results were different when a different means
of determining the arcing of the styli were used.
So
the study substantiates other studies that reported the
presence of only one terminal hinge axis & also for accurate
location high degree interpretation & operator`s perception
are required.

 Study was conducted by Jhon H. Pitchford in 1991.
He concluded that a compromised esthetic result can be
produced by an ant. 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 predetermined 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.

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.
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.
HISTORY OF THE HINGE AXIS

Snow in 1899 recognized the importance of hinge axis & he
constructed the 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.

HISTORY OF THE FACE BOW
In 1860 Bonwill concluded that the distance from the center of the
condyle to the median incisal point of the lower teeth is 10 cm.
In 1866 Balkwill 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.

In 1880 Hayes
constructed an apparatus
called Caliper with
median incisal point
localized in relation to the
two condyles.

In 1890 Walker invented
Clinometer used to obtain
the relative position of the
lower cast in relation to the
condylar mechanism

At about a turn of a century Gysi
constructed an instrument for
registering the condylar path &
used as face bow also.
Snow 1899 constructed simple
instrument which has become
prototype for all the face bows
constructed in present days.

CONCEPTS REGARDING HINGE AXIS
 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 .

FOUR MAIN SCHOOLS OF THOUGHTS
 Group 1 ---Absolute location of hinge axis.
There is a definite transverse axis & should be located
accurately.
 Group 2 ---Arbitrary location of hinge axis
Believe that arbitrary location of hinge axis is reliable, even
though accurate location is valuable.
Craddock & Symmons stated that – The search for
the axis is troublesome , more of academic interest as it
will never be found more than few mms distant from the
true center of the condylar rotations .
.

 Group 3 --Non believers in transverse hinge axis
location.
It is impossible to locate hinge axis with accuracy. More
theoretical than practical.
 Group 4 --Split axis rotation
Believe that the condyles rotate independent of each other.
The proponents of Transographic theory.
Page first suggested & Frank supported this.

 The proponents of Gnathology State
that there is one transverse hinge axis & it can be accurately
located.
 The proponents of transographics claim 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.

IMPORTANCE OF HINGE AXIS LOCATION RECORD &
TRANSFERRING ON TO ARTICULATOR
 Determination of terminal hinge position.
 The hinge axis recording is required to check the accuracy of
two centric records.
 It is the starting point of lateral 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
 It permits vertical dimension to be changed in the articulator.

 Opening & closing movements of the mandible reproduced in
the articulator.
 Helps in proper positioning of the casts in relation to
intercondylar shaft.

LOCATION OF HINGE AXIS

ARBITRARY METHOD OF LOCATING HINGE AXIS
1) Beyron`s point
2)Bergstrom`s point
3)Dawson`s palpatory method
4)Gysi`s point

5) Lejoyeux point- 10 to 11mm infront of the ear on aline to the
canthus & 5mm below it.
6) Abdal-Hadi point-It is based on the high co relation between
the width profile of the face &X co-ordinate of kinematic
point. Y = 9.5+0.95(X)
A constant distance equal to 0.5 m was used
above the line passing from center of the external auditory
meatus to canthus to locate the supero inferior position.
7) Lauritzen-Bodner axis-10 to 12mm anterior & 5mm below the
porion on Frankfort horizontal plane

Study was conducted by Heinz O. Beck in 1959
He concluded that 83% of Bergstrom,53% of Beyron, 17% of
Gysi points were within 5mm of the Kinematic axis.
Study conducted by Craddock& Symmon.
Study was conducted by Walker in 1980
He concluded that arbitrary location of hinge axis dose not
exist& wide dispersion from true hinge axis point will create
large errors & poor accuracy.

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.

Fabrication of the clutch–
Attach clutch tray to lower teeth.
Assemble the hinge axis locator.
Attach the side arms to the cross bar in mounting column.
Attach the assembled hinge axis locator to the Stem of the
clutch tray.
Mark approximate center of condyle on the subject`s face.
Adjust the hinge axis locator.
Place the graph paper .
Location of the hinge axis points.

OTHER METHODS OF RECORDING HINGE
AXIS
• Pantograph– two face bows, one holds six recording tables
attached to the mandible & other with 6 styluses attached to
the maxillae.
• Transograph.
• Stereograph
• Computerized Axiograph

FACE BOW
 PARTS OF THE FACE BOW
-U shaped frame
-Condylar rods
-Ear pieces
-Bite fork
-Locking device
-Orbital pointer

TYPES OF THE FACE BOW
Arbitrary type –Facia type
--Ear piece type.
Kinematic type of face bow.
ARBITRARY TYPE OF FACE BOW
In this type the axis is located by using anatomical
land marks. Condyle rods of the face bow are placed over the
arbitrarily marked centers of hinge axis.
Facia type --The approximate points on the skin over the TMJ
region are used as posterior points of reference &the condyle
rods of the face bow are placed over it.

Ear piece type of face bow –the ear pieces of the face bow are
placed into external auditory meatus . An
average distance from the external auditory meatus to an arbitrary hinge
axis is built into the face bow design. This distance is compensated for
in the articulator by offsetting the mounting point by an equivalent
amount.
KINEMATIC TYPE OF THE FACE BOW
Locates the opening axis physiologically with exceptional accuracy.

ANTERIOR &POSTERIOR POINTS OF
REFERENCE
The selection of anterior point of reference determines which
plane in the prosthesis becomes the plane of reference.
The objective of the natural appearance in the form &the
position of the teeth is achieved by mounting the maxillary cast
relative to the FH plane.
The objective of the natural appearance in the occlusal plane is
achieved by mounting the cast relative to the Camper`s plane.
To establish a standard line for comparison between the
patients & for the same patient FH plane is frequently used for
this purpose.

POSTERIOR POINTS OF REFERENCE
1) Bergstrom point—A point 10 mm anterior to the center of the
spherical insert for the external auditory meatus & 7 mm below
the FH plane.Beck stated that it lies close to hinge axis.
2)Beyron –A point 13 mm anterior to the posterior margin of the
tragus of ear on a line from the center of the tragus to the outer
canthus of the eye

ANTERIOR POINT OF REFERNCE
1) Orbitale—It is the lowest point on the infraorbital rim along
with the two posterior points forms Axis –Orbitale plane.
2) Orbitale minus 7 mm—FH plane Porion to orbital point.
the anterior point of reference marked 7mm below orbitale on
the patient or position 7mm above orbital indicator .
3) Nasion minus 23mm—.
4) Incisal edge plus articulator midpoint to articulator
axis –horizontal plane distance.- in this technique the
occlusal plane will not be parallel to horizontal plane.
5) Alae of the nose—In complete dentures the tentative
occlusal plane is made parallel with the horizontal plane.

FACE BOW TRANSFER PROCEDURE
Seating the patient.
Mark the Arbitrary axis or true hinge axis point.
Mark the anterior point of reference.
Contour the maxillary occlusal rim.
Reduce the mandibular occlusal rim to allow adequate
interocclusal distance for the bite fork & attached wax.

Softened wax is rolled into horse shoe shape & attached to the
bite fork.
Attach the occlusion rim to the bite fork.
In dentulous patients the maxillary teeth indentations are
recorded .
Place the bite fork along with the occlusion rim into the mouth &
ask the patient to close which will help to stabilize maxillary
record base.
Secure the stem of the bite fork into the clamp of the face bow.
Adjust the condyle rods onto the arbitrary axis points.
Earpiece type of face bow.
Adjust the width of the condyle rods equidistant bilaterally.
Place the orbitale pointer over the mark.

EAR PIECE TYPE OF FACE BOW
Preparation of the bite fork .
The facial reference point is marked
The bite fork is inserted into the mouth.
The stem of the bite fork secured into the clamp of the face
bow.
Ear pieces are inserted into external auditory meatus , tighten
the screws.

MOUNTING ON TO THE ARTICULATOR
The condylar rods of the face bow are inserted over the
condylar shaft & centered .
While using the kinematic face bow the condylar shaft is
extended to meet the styli.
Raise or lower the face bow to adjust low lip line of the
occlusion rim in level with groove marked on incisal pin.
Adjust the orbital pointer pin to the orbital indicator.
Support with cast support.
Place the maxillary cast.
Close the articulator to lock the incisal pin.
Mount the upper cast.

Mounting guide is utilized to mount the transfer rod
& attached bite fork.
In Slidematic face bow incisal guide block of
articulator is replaced by articulator mounting index.

SIGNIFICANCE OF FACE BOW
1) Transverse hinge axis can be located with the aid of face bow.
2) Records the position of maxilla in three planes with reference to two
points glenoid fossa.
3) To relate the maxillary casts to the transverse axis of the articulator.
4) Mandibular hinge axis coincided & related to the maxillary by centric
relation record.
5) The path of closure will be similar.
6) It aids in securing the anteroposterior cast position in relation to the
condyles of the mandible.
7) It registers the horizontal relationship of the casts accurately so
assists in incisal plane location.
8) Helps in restoring vertical height in the articulator.

Failure to use face bow can lead to error in occlusion of denture.
Face bow transfer allows more accurate arc of closure on the
articulator when the intetocclusal records are used.
Arbitrary mounting of the cast -
-Lateral deviation of mounting causes occlusal interferences on
rt. or lt. lateral working occlusion.
-Vertical deviation affects the labial inclination .
Anteroposterior position affects the cuspal angulation required
for balance in protrusive occlusion varies.

DISADVANTAGES
 Time consuming .
 Specialized equipments required.

INDICATIONS FOR USING FACE BOW
• Cusp form teeth used.
• Balanced occlusion in eccentric positions desired.
• Definite cusp fossa to marginal ridge relation is desired.
• Interocclusal check records are used for verification.
• The occlusal vertical dimension is subjected to change & the
alteration of tooth occlusal surfaces are necessary to
accommodate the change.

SUMMARY
The FACEBOW records the position of maxilla in three planes in
relation to two points that is glenoid fossae & also aids in mounting
maxillary casts in same relation on to articulator..

CONCLUSION
The use of face bow is indispensable for diagnosis, treatment
planning & treatment procedures.
By using face bow the risk of occlusal errors are minimized
thereby enhancing the accuracy of occlusion of new restoration
or oral appliances upon insertion which facilitates patient
comfort and acceptance of the prosthesis.

REFERENCES
 Boucher’S Prosthodontic Rx for edentulous patient 9th
edition.
 Syllabus of complete dentures by Charles M. Heartwell 4th
edition 5th
edition.
 Essentials of complete Denture Prosthodontics by Sheldon Winkler-2nd
edition.
 Fundamentals of fixed Prosthodontics by Schillingburg 3rd
edition.
 Management of Temporomandibular Disorders & Occlusion 5th
edition.
Jeffrey .P.Okeson.
 Evaluation, diagnosis, and treatment of occlusal Problems, Peter E
Dawson
 Prosthodontic Rx for edentulous patients by Zarb Bolender 12th
edition.
 Hobo|Eiji Ichida |Lily .T .Garcia-Osseointegration & occlusal
rehabilitation.

The hinge axis of the mandible Kurth & Feinstein J.P.D: 1951:327
Recording & Transferring the mandibular axis by Robert B. Sloane
J.P.D. 1952:173.
Evaluation of face bow by Craddock & Symmons J.P.D:1952:633.
The face bow,it’s Significance & Application by Thure Brandrup-
Wognsen J.P.D.:1953:618.
A study of the arbitrary center &the kinematic center of rotation for face
bow mounting by R.G. Schallhorn J.P.D:1957.
Hinge axis registration on articulators Borgh & Posselt J.P.D 1958
Rationale of face bow is maxillary east mounting by Richard L.
Christiansen J.P.D:1959:388.
A clinical evaluation of the Arcon concept of articulator Heinz O.Beck
J.P.D 1959
The use of face bow is making permanent study casts by T.D.Foster
J.D.P : 1959 :717
Hinge axis location on an experimental basis Lauritzen & Wolford J.P.D
1961:1059
A study of Hinge axis determination Vincent R. Trapazzano & John B.
Lazzari.J.P.D:1961:858
The accuracy of an ear face – bow by Walter .R.Teteruck,
Harry.C.Lundeen J.D.P : 1966:16:1039
The anterior point of reference by Noel.D.Wilkie J.D.P 1979:41:5:488

A study of transverse axis Arthur F. Aull J.P.D;1963:469
The physiology of the terminal rotational position of the condyles in the TMJ
J.P.D: 1967:122
The need to use an arbitrary face bow when remounting complete dentures
with Intercellular records by Keki.R.Kotwal in J.D.P. 1979:224
Discrepancies between arbitrary & true hinge axis by F.M. Walker a
J.D.P:1980:43:279.
Studies on validity of terminal hinge axis C.C.Beard, J.A.Clayton J.P.D:
1981:185
Clinical evaluation of methods used in locating the mandibular hinge axis by
Mahmoud Khamics Abdel Razek J.P.D: 1981:369
The hinge axis evaluation of current arbitrary determination methods &
proposal for new recording method J.P.D :1989
Re-evaluation of axis-orbital plane & the use of orbitale in a face bow transfer
record by Jhon H.Pitchford J.P.D.:1991:66:347.
Three dimensional assessment of the reliability of a postural face bow
transfer by Virgillo Ferrario,Chairello Sforza,Graziano Serrao,& Johannes H.
schmitz J.P.D.2002:87:210.
Accuracy of predetermined transverse horizontal mandibular axis point.
William W.Nagy, Thomas J.Smithy,Carl G.Wirth J.P.d :2002:387

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