hinge axis and facebow transfer

1. Presented By;
Dr. SADAF KAZMI
PGT 2ND YEAR

2. CONTENTS
• INTRODUCTION
• HINGE AXIS
• TERMINAL HINGE AXIS
• BIOLOGICAL SIGNIFICANCE
• CLINICAL USE
• HISTORY
• CONTROVERSY
• REVIEW OF LITERATURE
• DIFFERENT SCHOOL OF THOUGHT
• METHODS OF LOCATING

3. • FACEBOW
• HISTORY
• PARTS
• CLASSIFICATION
• INDICATION
• ADVANTAGE
• ADVANCES
• CONCLUSION
• REFERENCES

4. Introduction
When the teeth of both jaws come in
contact, maxilla becomes related to
the mandible so that entire
craniomaxillary complex is
articulated with a moving bone,
which is the mandible.

5. NEED FOR ORIENTATION
• The maxilla is positioned uniquely to the lower jaw which varies
for every person.
• And even its relation to the TMJ also vary in all persons.
• The opening movement to bring the jaw from occlusal to rest
position is almost a pure hinge movement.
• Here the mandible moves on an arc of a circle with a definite
radius from the temporo mandibular joint. This path of the
condyle is determined by the curvature of the condylar head and
the curvature of glenoid fossa.

6. Radius is not constant
• It has to be determined for every
individual patient, i.e., the relation
of maxilla to the opening and
closing axis has to be determined.

7. THE PLANE OF ORIENTATION
• The maxillary cast in the articulator is the baseline from which all occlusal
relationships start.
• Therefore it should be positioned in space by identifying three points
• Two points are located posterior to the maxillae and one point located
anterior to it.
• The posterior points are referred to as the posterior points of reference and
the anterior one known as the anterior reference point.

8. The spatial plane formed by joining
the anterior and posterior
reference points is called plane of
orientation.

9. HINGE AXIS
 Definition: Hinge axis is an
imaginary line passing through the
two mandibular condyles around
which the mandible rotates without
translatory motion..(GPT)

10. TERMINAL HINGE AXIS
Terminal Hinge Axis (G.P.T-9): an
imaginary line around which the
mandible may rotate within the
sagittal plane .

11.  Pure rotation of condyles takes
place in the first 10-15 degree arc
of mandibular opening and closing
or during the initial mouth
opening of 20-25mm.
 Later the condyles and disc
translates along slopes of articular
fossa. This movement is a
combination of rotation and
translation.

12. BIOLOGICAL SIGNIFICANCE OF HINGE
AXIS LOCATION
 In the fully dentulous condition with the full compliment of teeth the
maximum intercuspation position is a position where in the maxillary and
mandibular teeth are in complete intercuspation. This may or may not
coincide with the centric relation position.
 Whereas in case of fully edentulous condition these proprioceptive signals
in periodontal ligament are absent hence the guidance mechanism is lost.
 These signals are activated only when condyle is in CR or Hinge position.
 These signals when activated can guide the mandible during opening and
closing movement. It is for this reason that the hinge axis determination is
essential.

13. CLINICAL USE OF 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.
 The transverse hinge axis can be recorded physiologically by the use of a
gnathoscope but the facebow mountings record it as an anatomic average
within 5mm of error.

14. Like centric relation ,hinge axis is
• Stable
• Learnable
• Recordable
• Reproducible and
• Repeatable
Therefore it is used as an important reference in mounting casts in the
articulator, so that the opening axis of the articulator coincides with the
terminal hinge axis of the patient.

15. CONTROVERSY
There has been a considerable debate about whether:
• A hinge axis exists
• Hinge axis can be accurately located
• One or more hinge axis
• Is it clinically useful to locate the axis
• An arbitrary point can be satisfactorily substituted for a kinematic axis.

16. REVIEW OF LITERATURE

17. L. E. KURTH & I. K. FEINSTEIN (1951)
• With the aid of an articulator & working model, they demonstrated that
more than one point may serve as hinge axis.
• They concluded that infinite number of points exist which may serve as
hinge points. It is unlikely to locate the hinge axis accurately.

18. ROBERT G SCHOLL HORN (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.

19. FOUR MAIN SCHOOLS OF THOUGHT
REGARDING HINGE AXIS

20. GROUP 1
ABSOLUTE LOCATION OF HINGE AXIS
•The hinge axis is a component of every masticatory movement and can not
be disregarded.
•If the hinge axis of the articulator is not the same as the hinge axis of the
patient then the mechanical reproduction of jaw motions are impossible.
•Believe that there is a definitive transvers axis and should be located

21. GROUP 2
ARBITRARY LOCATION OF HINGE AXIS
• This group believes that accurate location of hinge axis would be of very
little value and proposes the effortless and arbitrary location is sufficient.

22. GROUP 3
NON BELIEVERS
• The third group believes that hinge axis is theoretical and not practical.
• It is not possible to locate hinge axis with accuracy.

23. GROUP 4
SPLIT AXIS GROUP
• These were called the Transograph men. This group believes there are two
axis of rotation ( one in each condyle) and they parallel each other.
1. The horizontal axis is a hypothetical line connecting the two horizontal
rotation centers of the two condyles of the mandible.
2. There is one hinge location.

24. METHODS TO LOCATE HINGE AXIS
The methods of locating hinge axis are:
1.The arbitrary method
2.The kinematic method
3.Modified method

25. ARBITRARY METHOD
• Also called the Anatomic method of locating hinge axis. Most commonly
used method especially in complete dentures because of the ease of
technique.
• Various anatomic landmarks were used to locate hinge axis arbitrarily.
According to them this method provided enough accuracy for restoration
of mouth, if occlusal vertical dimension is not going to be altered to a
significant extent.

26. Various hinge axis points proposed by the proponents of
this group are as follows:
1. Denar – 12mm anterior to
posterior border of the tragus
and 5mm inferior to the line
extending from the superior
border of the tragus to the outer
canthus of the eye.
2. Snow-11-13 mm anterior to
tragus

27. 3.Prothero – on line from superior
margin of the external acoustic
meatus to outer canthus of the
eye intersecting with line 13mm
anterior to anterior edge of
external acoustic meatus
according to Richley’s condyle
marker.
4. Gysi– 13mm anterior to anterior
margin of external acoustic
meatus on line from superior
margin of external acoustic
meatus to outer canthus of eye

28. 5.Beyron – 13mm anterior to
posterior margin of tragus on line
from the centre of tragus to the
outer canthus of the eye
6. Bergstrom – 11mm anterior to
centre of spherical insert of his
face bow and 7mm below
Frankfort plane

29. ADVANTAGES OF ARBITRARY METHOD
OF LOCATING HINGE AXIS
1. Less time consuming procedure
2. The technique is very simple to practice
3. Uncomplicated procedure leads to reduction in of errors in location
4. Records almost 5mm around the absolute location by kinematic method
which is quite considerable
5. Transferring the facebow record to articulator becomes simple
6. Can be used with a semi-adjustable articulator

30. Kinematic Method
The kinematic method is not the commonly used method of locating hinge
axis because of the complexity in procedure. It is used only in fixed prosthesis
warranting a reorganized approach.
The device consists of the following parts:
1. Clutch/ bite fork
2. Cross bar and stud
3. Axis indicator
4. Graph pad
5. Universal clamp/ screws

31.  The recording is started with the
patient seated in upright position
away from the back or head rest.
 The clutch is attached to the
mandibular teeth or the occlusion
rim. It is stabilized to teeth using
impression compound.
 The graph pad is positioned over
the condyle.
 The cross bar is attached to the
clutch by means of universal clamp.
 The axis indicator is attached to the
assembly and positioned over the
graph pad over the condyle.

32.  The axis indicators are adjusted
such that when the patient
opens and closes the mouth the
indicator no longer moves in an
arc, rather it rotates on a single
point.
 The graph background is
removed and that point is
marked on skin. The assembly is
then removed.

33. ADVANTAGES OF KINEMATIC METHOD
OF LOCATING HINGE AXIS
1. Hinge axis location is exact
2. This leads to very much decreased chair side time required for trimming
3. Occlusal discrepancies are well visualized, corrected and kept to minimum
especially in cases of full mouth rehabilitation, thus increasing the
prognosis and patient comfort.

34. DISADVANTAGES OF KINEMATIC
TECHNIQUE
1. Patient comfort is compromised while recording because of the
armamentarium used
2. The insertion of clutches might lead to altered position of condyle which
might interfere with the absolute location
3. It is technique sensitive .
4. It can be used only with a fully adjustable articulator
5. The procedure is time consuming.

35. Other method for recording true
hinge axis

36.  Pantograph: The pantograph is an apparatus consisting of two face bows,
one fixed to the maxilla and the other to the mandible. One holds writing
devices, the other recording tables. In practice six writings or records are
made at three places on each side of the head. One is anterior for an arrow
point tracing, one is nears the condyle to trace the horizontal movement
path of a point near the condyles, and the last is usually fixed perpendicular
to the second to record the vertical movement path of a point near the
condyle.

37.  Transograph: This was introduced in 1952 which is essentially a hinge
axis-face bow modified later to serve as an articulator. Transograph
means “a writing jaw movements carried over to an articulator’.The
theory of Transographics was postulated by Bererly Mc Collum and
the Gnathological Society .In this instrument, the patient’s inter
condylar distance ultimately formed the inter condylar distance in the
articulator. Transographics is based upon the split axis theory.

38. • Using a virtual procedure, the maxillary digital cast is transferred to a virtual
articulator by means of reverse engineering devices.
• The following devices necessary to carry out this protocol are avaible in many
contemporary practices: an intraoral scanner, a digital camera, and specific
software.
• Results prove the viability of integrating different tools and software and of
completely integrating this procedure into a dental digital workflow.
 Digital face-bow transfer technique

39. • Using reverse engineering software
(Rapid for CAD 2006; INUS Technology)
Scan maxillary/mandibular arches
and register their occlusal relationship
using an optical intraoral scanner
(TRIOS; 3shape, copenhagen,
denmark). Export the scans as
standard triangle language (STL) files.
Scan bite record to align maxillary and
mandibular arches.

40. • The choice of anterior reference
plane should be based on the
articulator system in the CAD
software.
• To locate the rotation center of the
mandible, bergstrom’s point was
selected, which could be found on the 3D
model constructed from CBCT.

41. • Align the hinge axis of the skull
with the joint axis of the virtual
articulator, making the reference
plane (Frankfort horizontal plane
was used in the present
demonstration) parallel to the
upper arm of the articulator

42. FACEBOW
The facebow is a caliper like device that is used to record the relationship
of the jaws to the temporomandibular joints or the opening axis of the
jaws and to orient the casts in the same relationship to the opening axis
of the articulator.
Boucher 11th edition
An instrument used to record the spatial relationship of the maxillary
arch to some anatomic reference point or points and then transfer this
relationship to an articulator, it orients the dental cast in the same
relationship to the opening axis of the articulator, customarily the
anatomic references are the mandibular transverse horizontal axis and
one other selected anterior reference point .
GPT 9

43. HISTORY AND EVOLUTION
OF FACE BOW

44. • Hayes (1880) –introduced first example of
functional face bow like device. He
named the device as articulating caliper
• Prothero , Thomas L. Gilmer -first to
suggest the principle of a facebow
• Walker (1890)- invented clinometer for
determining position of the lower cast in
relation to the condylar mechanism.

45. • George K Bagby(1894) -device that
determined the distance from the midline
of the anterior occlusal rims to one of the
condyles
• Gysi(1895) -constructed an instrument for
registering the condyle path.

46. • George B. Snow (1899)- Invented a device
which became prototype for modern face
bow.
• The Snow facebow, (1924)- the first
instrument used by B. B. McCollum to locate
the “hinge axis.”
• A.D. Grit man(1900)- Term Facebow

47. PARTS OF FACE BOW
• U-shaped frame
• Condylar rods or earpiece.
• Bite fork
• Locking device
• Third reference point.

48. U-SHAPED FRAME
• It forms the main frame of the face bow . All other components are
attached to this frame.
• It extends from the region of TMJ on one side to the other side without
contacting the face.

49. CONDYLAR RODS
• Two small metallic rods on either side of the free end of the U shaped
frame that contact the skin over the TMJ.
• They are used to locate the hinge axis and transfer it to the articulator.
• Some face bows have ear piece that fit into the external auditory meatus.

50. BITE FORK
•“U” shaped plate, which is attached to the occlusal rims, while recording the
orientation relation. It is attached to the frame with the help of a rod called
the stem.

51. LOCKING DEVICE.
• This part of the face bow helps to fix the bite fork to the U-shaped frame
firmly after recording the orientation jaw relation.

52. THIRD REFERENCE POINT
• It is used to orient the face bow assembly to a anatomical reference point
on the face along with the two condylar reference points. It varies in the
different face bows, example orbital pointer-orbitale, Nose piece– Nasion
etc.

53. CLASSIFICATION
Facebow
With Nasal Relator
With Orbital Indicator

54. Arbitrary face bow Kinematic face bow
Use of arbitrary measurements to
locate hinge axis
Locates the hinge axis physiologically with
exceptional accuracy
Bite fork is attached to maxillary
occlusal rims
Bite fork is attached to mandibular
arch
Does not require elaborate equipment's Require specific equipment's
Easy and quick Require skill and time consuming
Practically more acceptable Advantages being more theoretical
Only determine the orientation of
maxilla
Determine orientation relation and
centric relation together
No attachments to mandible so
exceptionally stable record base is not
required
Require stable record bases

55. ARBITRARY FACE BOW
• The hinge axis is approximately located in this type of face bow.
• It is commonly used for complete denture construction.
• This type of face bows generally locate the true Hinge axis within a range of
5 mm
• Uses arbitrary or approximate points on the face as the posterior points and
condylar rods are positioned on these point.

56. FASCIA TYPE
 The fascia type of face bow utilizes
approximate points on the skin
over the temporomandibular
region as the posterior reference
points.
• These points are located by
measuring from certain anatomical
landmarks on the face.

57. DISADVANTAGE
 As the face bow is placed on the skin which is movable there is a tendency
for the condylar rods to displace .
 Also requires an assistant to hold the face bow in place.

58. EAR PIECE TYPE
• It uses the external auditory meatus as an arbitrary reference point which
is aligned with ear pieces similar to those on a stethoscope.
• Accurate relationship for most diagnostic and restorative procedures.

59. ADVANTAGE
• Simple to use.
• Do not require measurements on face
• As accurate as other face bows.
• It provides an average anatomic dimension between the external auditory
meatus and horizontal axis of mandible.

60. SPRING BOW (HANAU’S FACE BOW)
• It is an earpiece face bow made of
spring steel and simply springs
open and close to various head
widths.
• Most commonly used face bow.
• This instrument is designed to
orient the occlusal plane to the
Frankfort horizontal plane by
means for a third point of
reference.

61. ADVANTAGE
• The one piece design of bow eliminates the moving parts and maintenance
problems encountered with other models.
• Easy and efficient to use.
• Sterilizable parts.
• Direct/indirect mounting capability.
Disadvantage :
• Inability to measure inter condylar.

62. TWIRL BOW
• It is an earpiece type of face bow
• 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.

63. SLIDE MATIC FACE BOW
• Type of ear piece Face bow.
• Used with Denar articulator.
• It has an electronic device that gives reading denoting one half of the inter
condylar distance

64. 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
a plastic nose piece

65. Futility of face bow use:
There are thoughts regarding the face bow use.
Consider the use of face bow is a waste of time. It is understandable that
some articulators are not designed for use with the face bow and a face bow
is not used from some concepts of occlusion in complete denture. Hence
these group of dentists question the validity of articulator that require the use
of face bow.

66. The face bow is not necessary under the
following condition:
• When monoplane teeth are arranged on a plane in occlusal balance and the
mandible is in the most retruded relation to the maxillae at an acceptable
vertical dimension of jaw separation.
•No alterations of the occluding surfaces of the teeth that would necessitate
changes in the vertical dimension of the occlusion originally recorded .
• No interocclusal check records that would be at a different vertical
dimension from that in the original interocclusal record .
• When articulators that are not designed to accept a face bow transfer are
used in the denture procedures .

67. ADVANTAGES OF USING A FACEBOW:
• Reduce errors in occlusion.
• Permits more accurate programming of articulator.
• Face bow supports the cast while mounting on the articulator.
• Registers the horizontal relationship of the cast quite accurately and thus
assists in correctly locating the incisal plane.
• Patient’s condition is simulated.
• The arc of closure is registered.

68. Prior to aligning the facebow on the
face, the posterior reference points
and the anterior reference point must
be located and marked

69. WHY IS ANTERIOR POINT OF
REFERENCE REQUIRED?
•. To establish a baseline for comparison between patients or for the same
patient at different periods of time.
• When three points are used the position can be repeated.
• To visualize the anterior teeth and their occlusion in the articulator..

70. ORBITALE
• In the skull, orbitale is the lowest
point of the infra orbital rim.
• On a patient it can be palpated
through the overlying tissue and
the skin.
• One orbitale and the two posterior
points that determine the
horizontal axis of rotation will
define the axis orbital plane.

71. ADVANTAGE
• It is easy to locate and mark .
• The concept is easy to teach and understand.
Disadvantage
• Relating the maxillae to the axis orbital plane will slightly lower the
maxillary cast anteriorly from the position that would be established if the
Frankfort horizontal plane were used.

72. NASION MINUS 23 MM
• Deepest part of the midline depression just below the level of the eyebrows.
The nasion guide, or positioner or relator of Quick Mount facebow which is
specially designed to be used with whip mix articulator which fits into the
depression.
• This guide can be moved in and out, but not up and down, from its
attachment.

73. • The cross bar (u-shaped frame) is
located 23mm below the midpoint
of nasion pointer.
• When the face bow is positioned
anteriorly by the nasion guide, the
cross bar will be in the
approximate region of orbitale.

74. ALA OF THE NOSE
• The right or left ala is marked on
the patient and the anterior
reference pointer of the facebow is
set.
• This method uses the Campers
Plane as the plane of orientation
 Easily visualized
 Relationship can be achieved as a
line drawn from ala of nose to the
centre of auditory meatus.

75. Orbitale minus 7mm
• This plane represents Frankfort Horizontal
plane
• The 7 mm difference between orbital plane
and condylar plane is being compensated
• Lauciello and Appelbaum recommended
using orbitale as an anterior reference point
and then adjusting the pointer 7mm above
the condyler plane as the most accurate
method for anatomically orienting the
maxillary cast to an articulator.

76. FACE BOW TRANSFER
• Face bows that can be utilized with Hanau articulator
Fascia
Ear piece
Twirl bow
Spring bow
Kinematic
• Face bows that can be utilized with Whip mix articulator
Quick mount ear piece
Kinematic
• Face bows that can be utilized with Denar articulator
Fascia
Ear piece

77. “I hear and I forget. I see
and I remember. I do and I
understand.”
Demonstration

78. CONCLUSION
• Failure to use the face bow 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 be
accurately captured and transferred to the articulator.

79. REFERENCES
• Boucher’11thProsthodontic Rx for edentulous patient 9 edition.
• Syllabus of tchomplete dtehntures by Charles M. Heartwell 4 edition 5
edition.
• Essentials of complete Denture Prosthodontics by Sheldon Winkler-2nd
edition.
• Fundamentals orfd fixed Prosthodontics by Schillingburg 3 edition.
• 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.

80. THANK YOU