imaginary axis

2. HINGE AXIS AND its location

3. CONTENTS
• Introduction
• Definition
• Hinge axis
• Terminal hinge axis
• Kinematic hinge axis
• Review of literature
• Mechanism of hinge axis
• Schools of thought
• Methods of locating hinge axis
• facebow
• Importance of hinge axis

4. REFERENCE
PLANES

5. • It is described as projections
in three perpendicular planes.
•SAGITTAL PLANE
•TRANSVERSE PLANE
•CORONAL PLANE

6. Sagittal axis Frontal
(vertical) axis
Horizontal axis
AXIS:
A straight line about which a body or object rotates

7. ROTATION-rotation
the body is turning
about an axis .
TRANSLATION-When
all the points within a
body have identical
motion

8. HINGE AXIS
It is defined as imaginary line between mandibular
condyles around which mandible can rotate through the
saggital plane (GPT-8)

9. TERMINAL HINGE AXIS
•When the condyles are in their most superior
position in the articular fossae and the mouth is
purely rotated , the axis around which movement
occurs is called the ‘Terminal Hinge Axis’.(gpt-8)

10.  Horizontal axis around which condyles rotate during opening
closing movement up to a range of 20-25 mm.
 Hinge axis ---- stable, reproducible and repeatable.
 Used as an important reference in mounting casts onto articulator

11.  When patient closes
the mandible in
trained circular
motion the transverse
hinge axis is center of
its circular motion &
not moving
Weinberg LA J Prosthet Dent 1958; 11: 32-42.

12. When patient opens
his mouth normally
condyles translate &
transverse hinge axis
moves
Weinberg ; JPD(1958)

13. KINEMATICS AND KINEMATIC AXIS
Kinematic axis - The tranverse horizontal axis
connecting the rotational centres of the right and
left condyles.(GPT-8)

14. •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 TM J

15. •Relation of maxilla to the
opening and closing axis has
to be determined
•Opening and closing axis can
be located when the
mandible is in its most
posterior position by means
of a FACE BOW

16. REVIEW OF LITERATURE
campion
• first graphic record of mandibular movements on
patient. He used a basic form of pantograph
Bennet
• point out that the mandible was capable of two
independent movements; one, an angular rotation
about the condyle, the other a translation movement
produced by the gliding of the condyle along its path.
Mc
collum
• Reported discovery of the postive method of locating
this axis.(1921)

17. REVIEW OF LITERATURE….
Kurth &
Feinstein
• Hinge axis location was an approximate and
could not be located with a high degree of
accuracy.
TRAPAZZANO
&
LAZZARI
• Patients have more than one terminal hinge axis.
• The concept that only one terminal hinge axis exists is
fallacious.
PAGE
• In 1951 suggested the existence of 2 mutually
independent non-collinear axes. He theorized that since
mandible is asymmetric in shape and size, condyles
can’t lie in a common plane of orientation

18. REVIEW OF LITERATURE….
GRANGE
R (1954)
• Put an end to misconception of split hinge axis saying
that it was not possible for a rigid body to revolve around
two diff axes
POSSELT
(1958)
• Said that the pure hinge movement can be isolated & be
used as a landmark for jaw registration & be reproduced
on the articulator
WIENBERG
(1959)
• Has been the leading authority on this subject & found
that marked deviation of hinge axis resulting from
arbitrary location could cause marked anteroposterior
mandibular displacement even with small change in
vertical dimension

19. SCHOOLS OF THOUGHT
Group I
Absolute location
of hinge axis
Group II
Group III
Group IV
Arbitrary location
of hinge axis
Non believers in
transverse axis
location
Split axis location

20. •masticatory movement and can not be disregarded.
• hinge axis of the articulator is not the same as the hinge axis
of the patient
mechanical reproduction of jaw motions are impossible.
Absolute location of the axis
THE TRANSVERSE HINGE AXIS: REAL OR IMAGINARY:JPD:Oct.1, 959
Believe that there is a definitive transvers axis and should
be located

21. 1.With the use of face-bow the articulator axis can
be related to the maxillary cast in the same way as
the anatomic axis is related to human maxilla.
2. The mandibular hinge axis and maxillary hinge
axis are coincided using a centric relation record.
3.path of closure of mandible and the articulator
will be the same
THE TRANSVERSE HINGE AXIS: REAL OR IMAGINARY:JPD:Oct.1, 959

22. •accurate location of hinge axis little value and
proposes the effortless
arbitrary location is sufficient.
Arbitrary location of axis
THE TRANSVERSE HINGE AXIS: REAL OR IMAGINARY:JPD:Oct.1, 959

23. But according to group 1
this group fails to recognize that if the hinge axis of
the patient and the articulator are not coinciding the
path of closure will not be the same.
THE TRANSVERSE HINGE AXIS: REAL OR IMAGINARY:JPD:Oct.1, 959

24. Non Believers In Transverse Axis Location
•Impossible to locate transverse hinge position with accuracy.
•Sense of perception and delicacy of touch are keener in some
individual than in others.
•According to Lauritzen and wolford and kurth and feinsten ‘-
any number of points within the range of 2mm considered
point of rotation
Aull AE J Prosthet Dent 1963; 13: 469-479

25. •Follow Transographic theory.
•Each condyle rotates independently of other.
Split axis theory
THE TRANSVERSE HINGE AXIS: REAL OR IMAGINARY:JPD:Oct.1, 959

26. pa
• Page
• Mandible is asymmetric
the condyles cannot lie
in a common plane of
orientation
• Condyles are gross
irregular objects

29. Methods of Locating Hinge Axis
A. Loma-linda hinge axis recording device and method.
B. Buhnergraph intraoral method.
C. Technique using geometric principle to locate hinge
axis.
D. Abdal-Hadi's technique of locating arbitrary hinge
axis.
Arbitrary methods Kinematic methods
Modified techniques

30. ARBITRARY METHOD
arbitrary posterior reference points based on average,
anatomic landmarks
popular due to their ease of the use compared to
trial-and-error method of locating the kinematic axis.

31. A. Beyron point
B. Gysi point
C. Bergstrom point
D. Denar point

32. An alternative method of locating hinge axis
arbitrarily is by Method of palpation given by
DAWSON.

33. Kinematic Method
• First actual Kinematic location was evolved -California
Gnathological Society
under the leadership of Dr.B.B Mc Collum by the “trial
and error method”.
• The Kinematic face bow is used to locate and transfer the true
hinge axis.

34. Fabrication of
clutches
Attachment
of clutches
to jaws
Attachment of
face bow and
graph paper
assembly
Mandibular
movements to
record THA
points
Tattooing
of THA
points on
the skin
Face bow
transfer to
the
articulator

35. Kinematic Method
• First actual Kinematic location was evolved -California
Gnathological Society
under the leadership of Dr.B.B Mc Collum by the “trial
and error method”.
• The Kinematic face bow is used to locate and transfer the true
hinge axis.

38. Other instruments used to determine true hinge axis
• PANTOGRAPH :

39. Other instruments used to determine true
hinge axis
TRANSOGRAPH :

40. Other methods used to determine true
hinge axis
1. Electronic mathematical method
2. Stereognathography
3. Noire – Fringe Method
4. Digital recording system
5. Computerized axiograph ( Axiotron )

41. Methods of Locating Hinge Axis
A. Loma-linda hinge axis recording device and method.
B. Buhnergraph intraoral method.
C. Technique using geometric principle to locate hinge
axis.
D. Abdal-Hadi's technique of locating arbitrary hinge
axis.
Modified techniques

42. Loma-linda hinge axis recording device and method
• resiliency of the oral mucosa
• added weight to the recording
clutch which tends to shift the
denture base
• time-consuming nature
Loma Linda hinge-axis recording
device and face-bows for use on
edentulous patients.

43. Buhnergraph intraoral method
Used to record terminal hinge axis, with the help of an
instrument called Buhnergraph
success of this technique lies in the accurate location of centric
relation at 2 different degrees of jaw separation.
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International Journal of
Clinical Dentistry Volume 5, Number 3

44. Technique using geometric principle
to locate hinge axis
Gunderson and parker
rapid method for locating the mandibular transverse
horizontal axis of a patient with accuracy.
Does not use an arbitrary posterior reference point
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International
Journal of Clinical Dentistry Volume 5, Number 3

45. graph paper attached - facial sidearm
clutch is attached - mandibular teeth
microadjustable axis location
assembly is placed over the
millimeter grid.
graphic stylus
series of arcs-anterior and inferior region

46. • One or more of the arcs are selected from the
anterior and inferior groupings.
• A line perpendicular to a tangent of each of
these arcs .
center of rotation, or the hinge axis reference
point

47. • New arbitrary method
• Y = 9.5 c 0.95 (X)
Y = width profile of the face measured from the
ectocanthion to the center of the external auditory meatus
X = anterioposterior position of kinematic point
Abdal-Hadi's technique
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International Journal of Clinical
Dentistry Volume 5, Number 3

48. FACEBOW
Caliper like 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”.(GPT-8)

49. PARTS OF A FACE BOW

50. Types of face bows
Arbitrary face bow Kinematic face bow
Ear piece type Fascia type
Hanau Spring bow
Denar slidematic
ear bow
Whip-Mix quick
mount
Hanau Spring bow
Hanau fascia
type C- type
Denar fascia
face bow
Hanau Kinematic
model D
Whip-mix quickset
recorder
Denar Kinematic bow

51. Arbitrary face bow Kinematic face bow
• Use of arbitrary measurements to
locate hinge axis
• Bite fork is attached to maxillary
occlusal rims
• Does not require elaborate
equipments
• Locates the hinge axis
physiologically with
exceptional accuracy
• Bite fork is attached to
mandibular arch.
• Require specific equipments

52. • Easy and quick
• Practically more acceptable
• Only determine the orientation
of maxilla
• No attachments to mandible
so exceptionally stable record
base not required
• Require skill and time
consuming
• Advantages being
more theoretical
• Determine orientation
relation and centric
relation together.
• Require stable record
bases

53. Rationale of Hinge axis
• Serves to orientate the maxillae
• To record the static starting point for functional
mandibular movements.
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International Journal of
Clinical Dentistry Volume 5, Number 3

54. Chair-side and laboratory procedures - shortened if an accurate hinge axis
could be located
Once objective is achieved, dentists can
(1) Alter the vertical dimension of occlusion on the articulator.
(2) Obtain centric relation records and verify them at the try-in at an
altered vertical dimension of occlusion.
Rationale of Hinge axis
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International
Journal of Clinical Dentistry Volume 5, Number 3

55. Rationale of Hinge axis
(3) Minimize the remounting procedures to perfect the occlusal
scheme.
(4) Develop an occlusion which would preserve and restore oral
function
Ashu Sharma, R. Rahul, Soorya T. Poduval et al. HINGE AXIS -AN OVERVIEW International Journal of
Clinical Dentistry Volume 5, Number 3

56. `
Arc of curvature Is during opening and closing of mandible.
Each individual Is unique .it has different shape of skull and
condyle. But it is mandatory to find hinge axis using
arbitrary or kinematic method
CONCLUSIONS

57. Reference
• text book of complete denture –heartwell 5th edition
• ashu sharma, r. rahul, soorya t. poduval et al. hinge axis -an
overview international journal of clinical dentistry volume 5,
number 3
• the transverse hinge axis: real or imaginary:jpd:oct 1959
• bouchers prosthodontics treatment for edentulolus patient
• hinge axis part 1 the transverse hinge axis jpd 1960;10;436
• hinge axis part 2 geometric significance of the transverse axis
jpd 1960;10;631