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ASIAN JOURNAL OF
SCIENCE AND TECHNOLOGY

Asian Journal of Science and Technology

ISSN: 0976-3376 Vol. 10, Issue, 04, pp.9639-9641, April, 2019

REVIEW ARTICLE
HINGE AXIS: CONCEPTS, THEORIES AND CLINICAL SIGNIFICANCE - A REVIEW
*Dr. Dipankar Pal
Department of Prosthodontics, NBDC&H, Sushrutanagar, West Bengal, India

ARTICLE INFO ABSTRACT

Article History: The hinge axis is an imaginary line around which the condyles can rotate without translation. Terminal
Received 17th January, 2019 hinge position is the most retruded hinge position and it is significant because it is a learnable,
Received in revised form repeatable and recordable position that coincides with the position of centric relation. There are many
24th February, 2019 schools of thought regarding hinge axis. The proponents of Gnathology say that there is one transverse
Accepted 20th March, 2019 hinge axis common to both condyles which can be accurately located. The proponents of transographics
Published online 30th April, 2019
claim that each condyle has a different transverse hinge axis and that a transograph is the only
Key words: instrument that can duplicate this. Still others claim that an exact duplication of jaw movement is not
Hinge Axis, Arbitrary, Absolute,
possible on any machine. The aim of this article is to throw light on concepts, various thoeries and
Split axis, Transographics. rationale of hinge axis.
*Corresponding author: Dr. Dipankar Pal

Citation: Dr. Dipankar Pal, 2019. “Hinge Axis: concepts, theories and clinical significance - A review”, Asian Journal of Science and Technology, 10, (04),
9639-9641.

Copyright © 2019, Dipankar Pal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.

first edition of Gray’s anatomy. Gray and those following him

INTRODUCTION recognised that the mandible moves on a hinge as well as by
the forward and lateral movement of the condyles in the
The subject of occlusion and mandibular movements has been
glenoid fossa. The temporomandibular orientation was called a
studied for many years. Though not thoroughly understood, its
“ginglymo-arthroidal” joint by Gray. Until the time of
significance to all aspects of dentistry is widely accepted. One
Bonwill, American dentists treated the joint as if it had only
pertinent aspect of the subject which has led to much
hinge action. This is evidenced by the hinge-like articulators
discussion, arguments and confusion is the theory of hinge
they invented and patented during that period. Balkwell of
axis. We know that all the elements of the stomatognathic
England, in 1824, called attention to the sliding actions of the
system (i.e. muscles, teeth and condyles) must work in
joint. However dentists nowhere in the world paid heed to his
harmony along with co ordination of the neuromuscular
proposal. Bonwill assumed that the forward motion of the joint
system guided by proprioceptors for successful function of the
was on a straight line in a forward direction. This idea held
masticatory system. Any dysfunction among any one of these
precedence for 40 years, until Walker proved that the motion
elements will lead to symptomatic changes in the weakest
was forward and downward. Snow recognised the importance
member. In pursuit of this aim, the management and
of hinge axis to other jaw motions and he contrived the face
establishment of proper maxillomandibular relationships is of
bow for transferring this axis to a mounting instrument.
virtual importance. The first step in establishing correct jaw
(Campion, 1902, 1905) stated that there was no axis but the
relationship is the face bow transfer. The only axis about
movements were a complex one, consisting first of rotation
which mandibular movement takes place in a pure form is the
and secondly of a forward and downward one. He probably
horizontal or hinge axis of the mandible. This axis therefore
produced the first graphic records of mandibular movements
has an immense importance in orienting the jaws in proper
on a patient. (Bennett, 1908) was of the opinion that there was
relationship.
no single fixed rotation since centre of rotation constantly
Definition: Boucher has defined hinge axis as “an imaginary shifted for movements in a sagittal plane. Mandible was
line between the mandibular condyles around which the capable of two independent movements, angular rotation and
mandible can rotate without translatory movement”. translatory movements. He probably produced the first graphic
According to Sicher, “the hinge position or the terminal hinge records of mandibular movements on a patient. (Gysi, 1920)
position is that position of the mandible from which or in stated that natural condyles are not considered as true rotation
which pure hinge movement of a variably wide range is points but as fixed guides of mandible. “The mandible opens,
possible”. closes and rotates on another rotational centre which has no
influence in the setting up of the teeth on articulators.
History and development of the hinge axis concept: The Therefore need not be considered in the construction of an
written story of the mandibular hinge axis goes back into the articulator”. (Needles, 1923) agreed with Bennett and
9640 Dipankar Pal, Hinge Axis: concepts, theories and clinical significance - A review

supported that there is both hinge and sliding parameters. but the search for the axis , in addition to being troublesome, is
There is no fixed centre of rotation in the temporomandibular of no more than academic interest, for it will never be found to
joint and there is instant and constant shifting of rotational lie more than a few millimetres distant from the assumed
centres. (Wadsworth, 1925) gave an anatomist’s conclusion in centre in the condyle itself”. This may be determined by
stating that the first movement is around a transverse axis simple palpation or by following the convention of measuring
passing through the condyles which remain seated in the a distance of about 1cm anteriorly along a line drawn from the
fossae. The second movement occurs on articular eminence. upper free margin of the tragus of the ear to the corner of the
(Hall, 1929) concluded that “the condyle is not the centre of eye.
rotation”. (McCollum, 1939) was considered a leading
advocate of the hinge axis theory. He confirmed definite C. Non believers of the transverse axis location: According to
opening and closing axis by using face bow minimising the this group, it is impossible to locate the terminal hinge position
use of external landmarks. Rotation occurs during 0.5 inch at with accuracy. (Kurth and Feinstein), using a Hanau
incisors for most people although some can open even 1inch. articulator, concluded that the axis location could be limited to
(Stuart, 1939) completed the work of McCollum in 2mm radius, when opening was restricted to 3/4th inch. They
reproducing he movements on articulator in duplicating the concluded that with all the variables which operated in the
jaw movements. Both of them were considered as pioneers of determination of the hinge point such as perception, anatomy,
gnathology. According to (McLean, 1944), “the diagnosis of physiology, the ability of the patient to follow instructions, it
pathological occlusion depended on the fact that the final was unlikely that the hinge axis could be located accurately.
phase of jaw closure was a pure hinge movement”. (Lauritzen, (Borgh and Posselt) found the accuracy of location to be
1951) thought that articulation would be understood more within 1.5mm when there is a10 degree opening and within
easily if the TMJ was regarded as two separate joints. The only 1mm when the arc of movement was increased to 15 degrees.
movement which could take place in the ‘menisco-condylar’ On the other hand, Lauritzen and Wolford were able to locate
part of the joint while opening and closing is a purely the axis within 0.2mm radius in 95% cases with a 10 degree
rotational movement. In all patients, the anterior teeth could be arc of movement. (Trapozzano and Lazzari) found that in
separated by at least 12mm in the rotational hinge relation. 37.2% of the subjects, more than one condylar hinge axis
(Posselt, 1952) concluded that hinge opening is obtained if points were located on either one or both sides of the face.
patient is in passive or trained active motion. He could not They concluded that findings indicate that, since multiple
prove that this movement was habitual. According to him, condylar hinge axis points were located, the high degree of
hinge axis opening was around 1.9cm. (Kornfield & Granger infallibility attributed to hinge axis points may be seriously
1955) stated that the only position at which it was possible to questioned.
locate and reproduce hinge axis was at centric relation.
(Trapozzano, 1955) stated that hinge axis represented a border D. Split axis rotation: (The collinear – non collinear
movement that could be recorded repeatedly with unfailing controversy): A major challenge to the traditional concept of a
accuracy. (Weinberg, 1959) conceptualised hinge axis based single intercondylar axis was hurled by Harry Page in his
on asymmetry of condyles. Off-centre opening and closing proposal of the transographic concepts. He postulated the
movements were perpendicular to hinge axis and he concluded existence of two mutually independent non collinear axes or
that movement in one direction in one plane can have only one simply that each condyle had its own axis of rotation. Page
axis of rotation. theorised that since the mandible is flexible, such
independence from a mutual axis is mechanically possible and
Theories of hinge axis: (Aull, 1963) classified theories of anatomically allowable. Since the mandible is not bilaterally
hinge axis based upon four schools of thought. They are; symmetrical and the terminal hinge position mark on one side
of the face is usually a little higher than on the other side, it
a. The absolute location of the hinge axis school would follow that there cannot be a common axis. There must
b. The arbitrary location of the hinge axis school be two axes parallel to each other with both axes at right
c. The non-believers of transverse axis location school angles to the opening and closing movements of the mandible.
d. The split hinge axis school (Collinear – non collinear Slavens stated, “By definition, an axis is always a line never a
controversy) point”. Again, by definition, an axis is invariably
perpendicular to the same plane of opening and closing
A. Absolute location of the hinge axis: Believers of this rotation, they are parallel to each other even though
school were of the opinion that there is a definite transverse asymmetrically positioned, and by definition, parallel lines
axis and it should be located as accurately as possible. With never meet. So again, the single, intercondylar transverse axis
the aid of the face bow, it is possible to relate the maxillary is proved to be impossibility.
cast to the transverse axis of the articulator in the same
relationship as the maxillae are related to the anatomic The advocates of this concept developed an articulator called a
mandibular axis of the condyles. The mandibular hinge axis is ‘transograph’. This articulator tried to overcome the problem
coincided with and related to the maxillary hinge axis by of irregular condyles which made it impossible for the various
means of a centric relation record. The path of closure on the individual axes to be constant even in simple rotation. This
terminal hinge will therefore be the same on the articulator as instrument made use of a transverse split hinge axis. On the
it is in the mouth. The cusps of the teeth should be so arranged subject of transographics or the two transverse hinge axis
that they will coincide during this border mandibular theory, Weinberg pointed out that much of the concept was
movement. based on the asymmetry of the condyles. However, he pointed
out that ‘off-centre’ opening and closing movements of the
B. Arbitrary location of the axis: Followers of this school mandible were still perpendicular to the transverse hinge axis.
stated that the value of actually locating the exact hinge axis is He concluded that marked “off-centre” opening was due to
not worth the effort. In relation to this, Craddock stated that “ pathologic unilateral condylar limitation of movement.
9641 Asian Journal of Science and Technology, Vol. 10, Issue, 04, pp.9639-9641, April, 2019

Clinical Significance of Hinge-axis determination: By REFERENCES

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