contact, the dip in the upper line is created when the upper and
lower canines pass edge-to-edge.
• Movement of the mandible is continued further till the maximum
• From this position, the opening movement is started and continued
with the mandible in the extreme right lateral position until the
maximum opening occurs at the point MO.
• From MO, the mandible is moved to the extreme left lateral position
till the opposing teeth contacts.
• Again, there is dip in the left side representing the edge-to-edge
contact of the upper and the lower canines.
• Finally, the mandible moves back to the CO position.
• The masticatory cycle starts in the centre of the graph in the position
of CO representing the teeth penetrating the food bolus.
• The masticatory cycle moves downwards and then upwards to end
• In the frontal plane, the rest position lies slightly downwards from
FIGURE 5-5 Envelope of motion in the frontal plane.
Envelope of motion in the horizontal plane (fig. 5-
• The Gothic arch tracers are used to record the envelope of motion in
• It consists of the recording plate attached to the maxillary arch and
the recording stylus attached to the mandibular arch.
• As the mandible moves, the border movements are recorded on the
• Condyles are in the CR position and the mandible moves to the left
• When the mandible reaches the maximum left lateral position, it is
continued to the protrusive movement.
• This protrusion continues till both the upper and lower teeth are in
• At this time, the jaw is opened and is closed in the CR position.
• The mandible then moves to the right lateral position.
• This movement continues to the maximum right lateral position and
then to the protrusive movement.
• Gothic arch tracing is the graphic method used to record the centric
FIGURE 5-6 Envelope of motion in the horizontal plane.
Facebow is defined as ‘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 8th Ed)
• In 1860, W.G.A. Bonwill concluded that the distance from the centre
of the condyle to the median incisal point of the lower teeth is 10
• In 1866, F.E. Balkwill demonstrated an apparatus to measure the
angle formed by the occlusal plane of lower teeth and the plane
passing through the condyles and incisal plane of lower teeth.
• In 1880, R.A. Hayes constructed an apparatus called caliper with
median incisal point localized in relation to the two condyles.
• In 1890, W.E. Walker invented clinometer that is used to obtain the
relative position of the lower cast in relation to the condylar
• At about a turn of the nineteenth century, A. Gysi constructed an
instrument for registering the condylar path which is also used as
• In 1899, George B. Snow constructed a simple instrument which has
become the prototype for all the facebows constructed in present
• It is a metallic U-shaped bar which forms the main form of the
• The remaining components are attached to the frame by clamps.
• It is large enough to extend from the region of TMJ or external
acoustic meatus to a distance of 2–3 inches in front of the face.
• Wide enough to avoid contact with the side of the face.
FIGURE 5-7 Diagrammatic representation of facebow and its
• These are placed on a line extending from the outer canthus of the
eye to the top of the tragus of ear and are 13 mm in front of the
• This placement generally locates the rods within 5 mm of the true
centre of the opening hinge axis of the jaw.
• These consist of a stem and prongs.
• These are attached to the maxillary occlusal rims.
• In a kinematic facebow, it is attached to the mandibular rims.
It helps to attach the bite fork to the U-shaped frame.
• It is used to make contact with the infraorbital notch which serves as
• Clamp secures the orbital pointer in position.
• These are placed in the external auditory meatus.
• On the articulator, the location of these rods compensates for the
position of the meatuses which are posterior to the transverse
It allows sliding of the bite fork.
• When cusp form teeth are used.
• Definite cusp–fossa relationship is desired.
• Interocclusal check record is used to verify jaw position.
• When vertical dimension of occlusion (VDO) is subject to change.
• Balanced occlusion in eccentric position is desired.
• When nonanatomic teeth are used.
• When interocclusal check records are not used.
• When there is no alteration of occluding surfaces of the teeth that
would necessitate changes in VDO originally recorded.
• When articulator is not designed to accept facebow transfer.
Facebows are usually of the following two types:
Kinematic Facebow Arbitrary Facebow
Opening axis is located physiologically Axis is located using anatomical landmarks
Rotational points located by attaching clutches to mandible
as the patient opens and closes his mouth; a stylus is
adjusted until true hinge axis is located
Centres of rotation are located 13 mm
anterior to external auditory meatus on line
Locates the true hinge axis with exceptional accuracy Locates the rods within 5 mm of true hinge
Requires complex equipment and is time consuming Simple to use and faster
Used in full mouth rehabilitation, occlusal equilibration and
Used in fabrication of complete dentures
Expensive Comparatively cheaper
• In this type, the axis is located using anatomical landmarks.
• Condyle rods of the facebow are placed over the arbitrarily marked
• It is the most commonly used facebow in complete denture
• This type of facebow utilizes an arbitrary point on the skin over the
TMJ as the posterior reference point.
• These points are located by measuring from certain anatomical
• Earpiece type of facebow uses external auditory meatus as the
• The external auditory meatuses are assumed to have a fixed
relationship to the hinge axis.
• An average distance from the external auditory meatus to an
arbitrary hinge axis is built into the facebow design.
• Special condylar compensators are provided on the facebow, which
help the articulator to compensate for this by placing the condylar
inserts at a certain distance behind the rotational axis of the
Earpiece type of facebow is more popular because of the following
• It does not require measurements or markings on the face.
• It is as accurate as other arbitrary types of facebow.
• It is used to determine and locate true hinge axis.
• It locates the opening axis physiologically with exceptional
• A facebow with adjustable calliper ends is used to locate the
transverse horizontal axis of the mandible.
• It is a more complex instrument which requires fabrication of
clutches which are attached to the lower jaws.
• It requires the use of articulator with extendable condylar shafts
which must be extended to meet stylus of the facebow.
• The stylus should not be extended; otherwise, the true hinge axis
• It is indicated for full mouth rehabilitation, occlusal equilibration
and the gnathological studies.
• The facebow is attached to the lower jaw by clutch.
• A graph or grid paper is placed near TMJ to detect the stylus
• Patient is instructed to open and close the mandible to centric
• Initially, the movement of the stylus may be in the shape of arc.
• The stylus is adjusted until the tip rotates instead of arching.
• This point is the true hinge axis and is marked on the skin.
Types of facebows used with commonly used
• The twirl-bow (modified earpiece)
Note: Commonly used ones are fascia, earpiece and
• Quick mount/earpiece facebow
• Kinematic/adjustable axis facebow
• Transverse hinge axis (THA) can be located with the aid of facebow.
• Records the position of maxilla in three planes with one anterior
reference point and two posterior reference points.
• To relate the maxillary casts to the transverse axis of the articulator.
• Mandibular hinge axis coincides and relates to the maxilla by CR
• It aids in securing the anteroposterior cast position in relation to the
• It registers the horizontal relationship of the casts accurately so as to
assist in incisal plane location.
• It helps in restoring vertical height in the articulator.
• Failure to use facebow can lead to error in occlusion of denture.
• Facebow transfer allows more accurate arc of closure on the
articulator when the interocclusal records are used.
Importance of anterior and posterior
Anterior reference point is defined as ‘any point located on the midface
that, together with two posterior reference points, establishes a reference
Posterior reference point is defined as ‘two points, located one on each
side of the face in the area of the transverse horizontal axis, which, together
with an anterior reference point, establishes the horizontal reference plane’.
• 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 and position of
the teeth is achieved by mounting the maxillary cast relative to the
Frankfurt horizontal plane (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 patient’s
FH plane, anterior reference point is frequently used.
Commonly used anterior reference points are as follows:
• Orbitale: It is the lowest point on the infraorbital rim and along with
the two posterior points. It forms axis–orbitale plane (Fig. 5-8).
• Incisal edge plus articulator midpoint to articulator axis: Niles Guichet
emphasized that a logical position of casts in the articulator would
be one which would position the plane of occlusion near the midhorizontal plane of the articulator.
• Alae of the nose: In complete dentures, the tentative occlusal plane is
made parallel with the horizontal plane (Camper’s plane).
FIGURE 5-8 Orbitale used as anterior third point of
• The position of the terminal hinge axis on either side of the face is
generally taken as posterior reference point.
• Prior to aligning the facebow on the face, the posterior reference
points must be located and marked. They are located by either of
Commonly used posterior reference points are as follows:
• Bergstrom point: A point 10 mm anterior to the centre of the spherical
insert for the external auditory meatus and 7 mm below the FH
plane. H.O. Beck stated that it lies closest to the hinge axis. It is
considered to be the most accurate reference point and is located
• Beyron’s point: A point 13 mm anterior to the posterior margin of the
tragus of ear on a line from the centre of the tragus to the outer
canthus of the eye. This point is the second most accurate (Fig. 5-9).
• Denar reference point: A point 12 mm anterior to posterior border of
tragus and 5 mm inferior to the line extending from the superior
border of tragus to outer canthus of the eye.
• Teteruck and Lundeen’s point: A point located 13 mm anterior to the
tragus on a line from the base of the tragus to the outer canthus of
• A.G. Lauritzen and G.H. Bodner point: A point 12 mm anterior to
centre of external auditory meatus and 2 mm inferior to porion–
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