4. Definition
• Jaw Relation:
Any one of the infinite spatial relationship of the
maxilla to the mandible.
• Jaw relation record
A registration of any positional relationship of the
mandible relative to the maxillae. These records may
be made at any vertical horizontal or lateral
orientation. (GPT-8)
5. Orientation relations
• Are those that orient the
mandible to the cranium
in such a
way, that, when
mandible is kept in its
most posterior
position, the mandible
can rotate in sagittal
plane around an
imaginary transverse
axis passing through or
near the condyles.
– Boucher 10th Ed.
6. • This axis can be
located by means
of a Kinematic
Facebow or hinge
bow, or it can be
approximated by
the use of an
arbitrary type of
facebow.
7. Transverse hinge axis
• An imaginary line
around which the
mandible may
rotate within the
sagittal plane.
– GPT-8
8. Sagittal plane
• Any vertical plane
or section parallel
to the median
plane of the body,
that divides a
body into right
and left portions.
GPT -8
9. Terminal Hinge position
• Also called the Retruded
contact position, it is that
guided occlusal
relationship, occurring at
the most retruded position
of the condyles in joint
cavities. GPT -8.
• Maximum range of terminal
hinge rotation- about 12˚
• Inter incisal opening: 18-25
mm
10. Facebow
• A caliper like
instrument used to
record the spatial
relationship of the
maxillary arch to some
anatomic reference
points, and then
transfer this
relationship to an
articulator. (GPT-8)
11. Facebow (definition contd..)
• It orients the dental cast in
same relationship to the
opening axis of articulator.
• Customarily the anatomic
references are the
mandibular condyles
transverse horizontal axis
and one other selected
anterior point.
• Also called Hinge bow,
Earbow, Kinematic facebow.
(GPT-8)
18. Planes and facebow
• Planes are the flat
section defined by
atleast three points in
space.
• Facebow captures the
relationship between
occlusal plane and the
horizontal reference.
19. Plane of orientation
The spatial plane formed by
joining the anterior and posterior
reference points.
The horizontal plane is established
on the face of the patient by 1
anterior & 2 posterior points,
from which measurements of the
posterior anatomic determinants
of occlusion and mandibular
motion are made”.
20. 1. Orbitale (B) Located by Hanau
facebow with help of orbital pointer.
2. Orbitale minus 7 mm. (C) This plane
represents Frankfort plane.
3. Nasion (A) Used with quick mount
facebow (Whip mix)
4. Ala of nose (D) This plane represents
campers plane
5. 43 mm superior from lower border
of upper lip (Denar reference plane
locator – Denar facebow uses this
reference point)
VARIOUS ANTERIOR REFERENCE POINTS
21. ORBITALE
• Lowest Point on the infraorbital
rim, palpated through tissue and skin.
• One orbit and two posterior points
determine the Axis-Orbital plane.
• It is used because of ease of location
and the concept is easy to teach and
understand.
22. ORBITALE MINUS 7MM
• The F-H plane passes through
both porion and orbital point.
• Because porion is a fixed point on
the skull it is considered as a posterior
landmark on the patient.
• Most articulator do not have reference
point of this landmark .
23. NASION MINUS 23MM
• According to Sicher another skull
landmark Nasion is located in the
head as the deepest part of the
midline depression just below the
level of the eyebrow.
• The nasion guide is designed to
be used with whipmix articulator
,which fits in the depression.
24. ALAE OF THE NOSE
• The tentative occlusal plane should be
parallel to horizontal plane.
• This can be achieved in 2 ways-
The line from the alae of the nose to
centre of the auditory meatus -
Camper’s line.
1. Pointer on right or left alae
2. Occlusal rim parallel to
camper line ,transfer with
face bow .
25. Advantages of anterior reference point
Determines which plane in the head will become
the plane of reference.
Determines the level at which the casts are
mounted
To establish a baseline for comparative studies
between patient.
Can visualize anterior teeth & occlusion in the
articulator in the same frame of reference.
26. 26
Posterior reference points
• Posterior reference points
– A---Beyron point – 13 mm ant to post
margin of tragus of outer canthus of
eye
– B---Gysi – 13mm ant to ant margin of
EOM
– C---Snow – 11 -13 mm ant to tragus
– D---Denar’s – 12 mm ant to post
border of tragus and 5 mm inferior to
line from EOM and outer canthus
27. Facebow record
• Accurate mounting - three points
• Criteria for selection of points
– Ease of location
– Convenience
– Reproducibility
28. Taking a face bow record
• Seating the patient
• Marking the points for condylar position
• Attach fork to occlusal rims
• Placing the frame of face bow
• Reading on condylar rod scales are made equivalent
• Anterior reference point is recorded
• Fork is tightened to frame
• Face bow is removed and record transferred to
articulator
40. 40
Errors in face bow recording
• Movement of the skin
• Unstable edentulous ridges
• Angle of opening is small – 10º--12º
• Inter-observer error
41. Types of facebow
• Two basic types
– Kinematic
And
- Arbitrary
- Facia type
- Earpiece type.
42. Kinematic facebow
• The kinematic face bow
allows for the precise
determination of the
patient's hinge axis
(terminal hinge axis).
43. Arbitrary face bow
43
• Uses arbitrary or
approximate points on
the face as the posterior
points and condylar rods
are positioned on these
points.
• They are a widely used
type of face bow and are
sufficient for fabrication
of most complete
denture, fixed partial and
removable partial
denture.
44. 44
Facia type face bow
This face bow takes its name from the fact that it
rests upon the face, like the kinematic bow.
45. 45
Ear piece type
• This type of face
bows uses the
external auditory
meatus as an
arbitrary reference
point which is
aligned with ear
pieces.
46. • Articulators whose
programming make use of
arbitrary Ear bow type
face bows feature an
artificial correction
whereby the position of
the bow, which should be
placed behind the actual
hinge axis, is moved
forward by about 11-13
mm, or rather by the
average distance between
the acoustic meatus and
the terminal hinge axis.
47. 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
48. • The one piece design of bow eliminates the
moving parts and maintenance problems
encountered with other models.
• Easy and efficient to use.
• Sterilazable parts.
• Direct/indirect mounting capability.
• However, the inter condylar distance cannot
be measured with this.
49. 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
50. Slidematic 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.
51. 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
52. 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.
53. • A definite cusp fossa or cusp tip to tip incline relation
is desired.
• When interocclusal check records are used for
verification of jaw positions.
• When the occlusal vertical dimension is subjected to
change, and alterations of tooth occlusal surfaces are
necessary to accommodate the change.
• To diagnose existing occlusion in patients mouth
Indications for use of facebow
54. 54
Advantages of using
face bow
“Lazzari”
• It aids in securing the antero-posterior cast
position with relation to condyles of the mandible.
• It acts as an aid in the vertical positioning of the
cast on the articulator.
• It assists in correctly transferring the inclination of
the occlusal plane to the articulator.
55. 55
Situations where face bow
is not required
• Monoplane teeth are arranged in balance
occlusion and mandible in most retruded
position at acceptable VD
• No intended change in VDO
• Articulator doesn't accept the transfer
58. Recording the transverse hinge axis
•Mandibular hinging
movement around the
transverse hinge axis is
repeatable
•It is a starting point of
lateral movements
•Opening and closing
movements of the
mandible are reproduced
in the articulator .
59. Controversies regarding hinge axis
• Controversies have arisen over the presence
of a single axis,
• the methods used to locate the axis,
• the method and validity of recording the
positions on the skin for future reference,
• and the relation of the terminal hinge
position to the position of centric relation.
60. Four main schools of thoughts
• Group 1 --- Absolute location of hinge axis. -----
McCollum(1939)
• Group 2 --- Arbitrary location of hinge axis ------Craddock &
Simmons(1952)
• Group 3 -- Non believers in transverse hinge axis location. ------
Beck(1959)
• Group 4 -- Split axis rotation -----Slavens(1961)
61. Accuracy in locating a true hinge axis
- Kurth and Feinstein said within 2 mm when
restricting opening to ¾ inch at the incisal pin.
- Borgh and Posselt said within 1.5 mm when a 10
degree arc was used and within 1.0 mm when a
15 degree arc was used.
- Lauritzen and Wolford were able to achieve an
accuracy of 0.2 mm when using a 10 degree arc
of movement.
62. A method to locate true hinge axis
• Observing the motion of a
stylus on a kinematic bow,
as created by jaw
movements, in relation to a
flag fixed over the patients
axis area. When the stylus
no longer translates but
rotates then the point is
accepted.
63. Accuracy of an arbitrarily selected axis
• Scallhorn found that 95% of the axis points
located 13 mm anterior to the posterior margin
of the tragus on the tragus-canthus line to be
within a 5 mm radius of the kinematically located
axis.
• Beyron found that approximately 87% of the
located points were within a 5 mm radius of the
arbitrary points.
• Lauritizen and Bodner found only 33% of the true
axis points to be located with in a 5 mm radius of
the arbitrary points. Teteruck and Lundeen found
similar results.
64. • Walker found that 20% of the true axis points
were located within 5 mm from the arbitrarily
selected point.
• Palik, Nelson, and White found that the
earpiece face-bow related the maxillary cast
to the hinge axis only 50% of the time. 92% of
the time the arbitrary axis was located
anterior to the terminal hinge axis.
65. • Preston, J. D ---- A single transverse horizontal
axis can usually appear to be located. (within the
limits of accuracy of operators, equipment and
patients.)
- When a kinematic axis is located, this is a
worthwhile clinical procedure to transfer the arc
of rotation in the sagittal plane from patient to
the articulator
• Preston, J. D. A reassessment of the mandibular transverse
horizontal axis theory. J Prosthet Dent 41: 605-613, 1979.
-
66. • Granger, E. R. - The hinge axis determines the
arc of closure in every contacting position of
the teeth. The path of closure is different from
each open position of the mandible to tooth
contact. This path results from the closing
rotation combined with a gliding path of the
axis.
• Granger, E. R. Clinical Significance of the Hinge Axis
Mounting. DCNA, Mar 1959:205-213.
67. 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, but, he did not mention at what level below the
condylar mechanism the occlusal plane should be situated.
• 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.
68. In 1880 Hayes constructed
an apparatus called Caliper
with median incisal point
localized in relation to the
two condyles.
69. In 1890 Walker invented
Clinometer used to
obtain the relative
position of the lower cast
in relation to the condylar
mechanism
71. Snow , 1899 ,
constructed simple
instrument which has
become prototype for all
the face bows
constructed in present
days.
72. Facebow
Stansberry (1928) was dubious about
the value of facebow and adjustable
articulators. He thought that since an opening
movement about the hinge axis took
the teeth out of contact the use of these
instruments was ineffective except for the
arrangement of the teeth in centric occlusion.
73. Mclean (1937) stated that the hinge
portion of the joint is the great equalizer
for disharmonies between the
gnathodynamic factors 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.
74. 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 may serve as
hinge points.
75. 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 itself.
76. Sloane(1952) stated “the mandibular
axis is not a theoretical assumption, but a
definite demonstrable biomechanical fact.
It is an axis upon which the mandible rotates
in an opening and closing function
when comfortably, not forcibly retruded.
77. Bandrup-Morgsen (1953) ,discussed
the theory and history of face bows. 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.
78. 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”
79. 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 a semiadjustable
articulator is justified. He said that, in over
95% of the subjects the kinematic center lies
within a radius of 5 mm from the arbitrary
center.
80. 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,
with no connection directly at the condyles.
The assumption of a single intercondylar
transverse axis is, therefore open to serious
question”.
81. 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.
82. 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 second molar.
Lucia VO (1964) described the technique
for recording centric relation with help of
anterior programming device.
83. Teteruck and Lundeen (1966) ,evaluated the
accuracy of the earpiece face bow and
concluded that only 33% of the conventional
axis locations were within 6 mm of true hinge
axis as compared to 56.4% located by ear face-
bow. They also recommended the use of
earpiece bow for its accuracy, speed of
handling, and simplicity of orienting the
maxillary cast.
84. Trapazazano, Lazzari (1967) concluded that,
since multiple condylar hinge axis points were
located, the high degree of infallibility
attributed to hinge axis points may be
seriously questioned.
85. 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 face bow
Hanau 132-sm face bow, and whip mix ear-
bow.
86. Neol D.Wilkie (1979) analyzed and discussed five
commonly used anterior points of reference for a
face bow transfer. He said that not utilizing a third
point of reference may result 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 easy to teach and
understand.
87. REFERENCES
• Boucher’S Prosthodontic Rx for edentulous patient 10th edition.
• Essentials of complete Denture Prosthodontics by Sheldon
Winkler-2nd edition.
• Fundamentals of fixed Prosthodontics by Shillingburg 3rd edition.
• Evaluation, diagnosis, and treatment of occlusal Problems, Peter E
Dawson
• Prosthodontic treatment for edentulous patients by Zarb
Bolender 12th edition.
• Recording & Transferring the mandibular axis by Robert B.
Sloane J.P.D. 1952:173
• Clinical evaluation of methods used in locating the mandibular
hinge axis by Mahmoud Khamics Abdel Razek J.P.D: 1981:369
• Accuracy of predetermined transverse horizontal mandibular axis
point. William W.Nagy, Thomas J.Smithy,Carl G.Wirth J.P.d
:2002:387
