The document discusses articulators, which are mechanical devices that simulate jaw movement for denture fabrication. It defines articulators and covers their history from early plaster models to modern computerized devices. Key points include: - Articulators allow dentures to be worked on externally while simulating jaw movements for a more accurate fit. - Early models were simple hinged or plaster devices, while modern ones can record complex jaw trajectories electronically. - Articulators are classified based on the type of jaw movement they allow (hinged, average paths, patient-specific paths) and how they are adjusted (interocclusal records, graphic records, facebow transfer). - An ideal articulator accurately

1. ARTICULATORS
INTRODUCTION
It is well adjudged that the mouth comprising bi-maxilla and the two
tempero-mandibular joints as the abest articulator. But due to the inumerable
procedures carried out to fabricate a prosthesis, a mechanical device
stimulating the two jaws and the tempero-mandibular joints is needed for ease
of work and comfort of the patient. This device is called and
“ARTICULATOR”.
DEFINATION:
Articulator is a mechanical device that represents the tempero-
mandibular joints and the jaw members to which maxillary and mandibular
casts may be attached to simulate some or all the mandibular movements.
Many devices that are called articulators do not satisfy this defination.
Some of these devices make no attempt to represent the tempero-mandibular
joints (face bow transfer) or their paths of motion (eccentric registration).
Some instruments allow eccentric motion determined by inadequate
registrations (positional registration). Some utilize average or equivalent
pathways. Some attempt to reproduce the eccentric pathways of the patient
from three dimensional registration. Some other articulators record even the
fourth dimension, i.e., the timing of the Benett movement.
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2. HISTORY:
The history of articulators paralles that of the varying concepts of
occlusion. Attempts were made to record anatomics relationships of reproduce
functional movements of the mandible and transfer this to the mechanical
devices to stimulate the conception of natural movements.
More sophisticated instruments evolved as more learned about the
anatomy, mandibular movements and mechanical principles. The objective
was always the same: to produce or reproduce occlusal relationships
extraorally.
The plaster articulator deviced by Philip pfaff in 1756 consisted of
plaster extension on the distal portion of maxilarry and mandibular casts
grooved to each other. This was commonly known as slab articulator.
The first mechanical articulator was described in 1805 by J.B. Gariot.
He designed the hinge joint articulator which consisted of two metal frames to
which the casts were attached, a hinge to join them and set crew to hold the
frames in a fixed vertical position.
In 1840, Cameron and Evans made attempts to device the plane line
articulator.
Bon will, a mathematician, in 1858 developed an a articulator based on
his theory of occlusion on the theory of equilateral triangle, with which he
demonstrated the anatomic and balanced occlusion.
W.E. Walter in 1896 said that dentures which balanced on Bonwill’s
articulator did not balanced in the mouth and pointed the absence of condylar
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3. inclination as the dictating factor. He deviced the Clinometer which had
provision for gothic arch tracings.
Later every investigator tried to reproduce the individual movements of
the patients mandible. They said that the condyle path varied from person to
peron and even in the same person, it differs.
George B. Snow in 1899 first deviced the face-bow. Later in 1906,
articulator knows as New Century Instrument was developed. He improved the
Gritmann articulator of 1899 by adding the adjustable condylar paths and a
tension spring for a greater range of movement. This articulator was developed
in accordance with Bonwill’s theory. In the modified version of the New
Century Articulator, incisal pin was incorporated.
This articulator was developed in accordance with Bonwill’s theory. In
the modified version of the New Century Articulator, incisal pin was
incorporated.
The ‘Acme’ articulator was an elaboration of Snow’s New Century
Instrument which had straight condylar path, adjustable condylar inclination
and provision for Benett movement.
Alfred Gysi in 1910 introduced the Gysi Adaptable Articulator. In
1914, the Gysi Simplek’ was introduced as a mean value articulator which had
fixed condylar guidance at 33 degrees.
Hall (1915) and Monson (1918) developed the Anatomic articulator and
Maxillo-mandibular instrument based on Conical theory and the theory of
Spherical articulator respectively.
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4. According to Monson-Hall school, the articulation of teeth during
mastication guides the mandibular movements. Failure of these articulators
based on theories is because provision was not made for variations from the
theoretical relationship that occurred in different persons.
Rudolph L. Hansu, an engineer, during the time of First World War in
1921 developed a research model called the Mansu Model C Articulator which
had provision for controlled movement with more accurate and accessible
controls, and its adjustments and operation much simplified. Later in 1923, he
devised the
‘Kinoscope’ which provided exact measurement of mandibular
movements. In the later years, Mansu introduced more measurements such as
model 110 which had individual condylar guidance adjustments in both sagittal
and horizontal planes and the lateral icondylar angle calculated by the formula
L= H/B + 12, H = Horizontal condylar angle. In 1927, he modified the model
110 with the introduction of ‘Incisal guide table’.
Wadsworth believed in Monson’s Spherical theory but did not accept
the bilaterlal condylar symmetry. In 1924, he developed the articulator for
which facebow was used to mount the cast. It had an adjustable intercondylar
distance and the condylar paths were slightly curved.
Staneberry in 1929, designed the ‘Tripod Articulator’. He did not
accept all positional records. This instrument does not have a hinge nor
mechanical equivalent or representation of condyles. The articulator
reproduces positions but not movements.
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5. Charles Stuart in 1989 designed the Fully Adjustable Articulator.
Later, in 1964, he introduced the Whip-Mix Semi adjustable Arcon Articulator
with three intercondylar adjustments – small, medium and large.
Later, Granger, Stuart. Ney and Guichet introduced the ‘Pantographic
Tradings’.
Recent advances in electronic and computer technology facilated the
development of electronic techniques tp record the motion of the mandible.
The main advantage of these technique is that, they could accurately record the
dynamic motion of the mandible. Because of their reduced size, these devices
provide negligible interferences with the natural motion of the mandible.
The three dimensional kinematic characteristics of the temepro-
mandibular joints during any mandibular activity can be measured, analyzed
and described using these devices. These devices do not require head fixation,
does not alter or inteerface with natural occlusion and is light in weight.
An electronic, computerized pantograph was compared with mechanical
pantograph and was found 93% of immediate size shift measurement with
0.3mm., 92.5% of progressive side shift measurement with 4 degree, 87% of
protrussive inclination measurement within 6 degrees.
Using electronic and computerized pantograph, errors occuring in the
transfer of measurement can be minimized.
RELATING ARTICULATOR TO PATIENTS DENTAL MECHANISM
The articulator is a rigid device with movement patterns determined by
solid pathways, whereas the mandible is guided by muscles, ligaments and
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6. non-rigid joint surfaces, by the teeth and by complex neuro-muscular system.
The mandible suspended by the ligaments and muscles is resilient and flexes
under normal biologic stresses and the teeth are suspended in the membranes
that respond to stresses in an elastic manner.
The more adjustable the articulator, the factors of mandibular
movements can be reproduced with a greater degre of accuracy. At the same
time, more complicated the devfice, more the human errors involved.
ESSENTIAL REQUIREMENTS:
In view of the importance of athe co-ordinated functions of anatomy,
physiology and geometrics and their relation to prosthotic technique, it is a
must that an articulator have certain characteristics which enable it to accept
and maintain various functions.
The condyle spheres should be situated on the lower member and the
fossa on the upper member, to ensure that all rotations (axial, centers of
rotation) become the sole functions – Benett protrusive, Lateral Protrussive
with curvilinear paths of condylar guidance should be attributed to the upper
member.
Since protrusive and lateral excursions ae registered while the jaw is in
an open position, an articulator is set for these excursions in the same open
position, an articulator must be capable of accepting a hinge axle mounting.
It should have provision to adjust intercondylar distance since this
dimension in correlation with the benett adjustment, determines horizontal radi
and is a necessary factor in the duplication of a given path of cusp tip.
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7. When the intercondylar distance is adjusted, the axis should not distort
in any way, so that the magnitude and direction of the axis remains constant.
Provision should be made for benett adjustment.
For the normal functional movements of the patient to be stimulated, the
construction of an articulator should permit the change of the condyle path to
that of a specific curvature dictated by the patient.
An articulator should have an incisal table that is capable of rotation
about the frontyal axis and being locked in a determined position. This is
necessary to accommodate the amount of overbite dictated by the anterior
guidance in relation with the straight protrusive movement dictated by the
condyle path.
An incisal table should have lateral incisal guide planes, capable of
limited rotation about the sagittal axis and being locked in a determined
position to accommodate the amount of overbite dictated by the canine in
relation with the lateral lexcursive movement dictated by the condyle path.
It should also contain a point on which the incisal guide pin rests in
centric position and has the capability of being raised or lowered and locked in
a determined position.
The incisal guide table can be a plastic table which is customized with
auto polymerizing resin.
The construction of an articular should be accurate, rigid and of a non-
corrosive material. The moving parts should resist wear. Adjustments should
be able to move freely and be definitely secured.
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8. It should have provision for easy removable and to reattach the casts
without loosing their correct horizontal and vertical relationship.
Functionally, an articulator should be sturdy and exact in construction,
simple but efficient in mechanics of operation, and capable of maintaining
constants and duplicating desired movements. It should accept pantographic
registrations and accurate mandibular movements which controls the accuracy
of the fabricated prosthesis.
USES: Articulators are used to mount diagnostic casts, to study the oclusion of
a patient and as an aid in planning treatment procedures.
It is used to hold the opposing casts in a predetermined fixed
relationship.
As an aid in the fabrication of dental restorations and lost gental parts.
In the arrangement of artificial teeth for complete dentures, removable
partial dentures and waxing in field partial dentures.
ADVANTAGES:
Better visualization of the casts in occlusion from the lingual view.
The resiliency and like effect of the supporting tissues or denture bases
hinders the operation in refining the complete denture occlusion in the oral
cavity.
Chair side and patient appointment time is reduced along with saliva,
tongue and cheek being absent.
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9. LIMITATIONS:
An articulator is a mechanical instrument. It is subject to eror in tooling
and errors resulting from fatigue and wear.
An articulator can stimulate but not duplicate jaw movements.
Since the articulator may not reproduce exactly intraborder and
functional movements, the mouth would be the best place to complete the
occlusion, but using the jaws as an articulator also has limitations:
- Inability of humans to detect visually the finer changes in the motion.
- Making accurate marks in the presence of saliva.
- Exact location of the condyles
- The resiliency of the supporting structures.
- The dentures are movable.
Effectiveness of an articulator depends on the person who understands
its contruction and purpose, the anatomy of the joints, their movements and the
neuromuscular system, precision and accuracy in registering law relations and
the sensitivity of the instrument to record these.
CLASIFICATION OF ARTICULATORS:
1. Articulators based on theories of occlusion.
2. BONWILL’S THEORY OF OCCLUSION
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10. Teeth move in relation to each other as guided by the condylar control
and the incisal point.
It is also known as the theory of equilateral traingle which has a 4 inch
(10cms) distance between the condyles and between each condyle and to the
lower central incisor point.
Eg: Bonwill’s articulator, Gysi simplex articulator
Since condylar guidances were not adjustable, only movement in
horizontal plane is permitted.
b) CONICAL THEORY OF OCCLUSION:
Lower teeth move over the surfaces of the upper teeth as over the
surface of a cone, with a generating angle of 45 degrees and the central axis of
the cone tipped at 45 degrees to the occlusal plane. Eg. Hall Automatic
articulator-teeth with 45 degrees cusps were necessary for constructing
dentures on this type of articulator.
c) SPHERICAL THEORY OF OCCLUSION:
Proposed by G.S. Monson in 1918. The lower teeth move over the
surface of the upper teeth as over the surface of a sphere with a diameter of 8
inches (20cms). The centre of the sphere is located in the region of the glabella
and the surface of the sphere passes through the glenold fossa along the
articulating eminences or concentric with them.
This theory was based on observations of natural teeth and skulls by
Van Spee, a German anatomist.
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11. Eg: Monson’s Maxillo-Mandibular Instrument.
The failure of these articulators based on theories is because of one
common fault – provision was not made for variations from the theoretical
relationship that occur in different persons.
II. Articulators based on the types of reocrds used for their adjustment:
a) INTROCCLUSAL RECORD ADJUSTMENT:
In this type only one potential relationship is possible in centric,
protrusivae and centric or lateral relation.
Teeth casts on the articulator are accurate only at that posistion where
the interocclusal records are made.
The mechanical features that determine whether or not an articulator can
be adjusted to accommodate interocclusal records includes
- Include adjustable horizontal condylar guidances.
- Variable control for the benett movement.
- Variable intercondylar distance.
- Split axis condylar guidance controls and adjustable incisal guidance
control.
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12. B) GRAPHIC RECORD ADJUSTMENT:
Since the border movments of the mandible is curved and are recorded
graphically, the articulators also should be capable of producing or simulating
these curved movements.
These recordings are difficult and unreliable in edentulous patients.
C) HINGE AXIS LOCATION FOR ADJUSTING ARTICULATORS:
The correct location of the opening axis of the mandible should be
made, if not, the correct adjustment of these instruments are impossible.
III) Many investigators have classified articulators in various methods:
1. Gills (1926), Boucher (1934), Kingery (1934) divided articulator into
adjustable and nonadjustable.
2. Back (1962) classified into suspension instrument, axis instrument and the
tripod movement.
3. Weinberg (1963) – arbitrary, positional, semi-adjustable and fully
adjustable.
4. Possult (1968) – plane line, mean value and adjustable.
5. Thomas (1973) – arbitrary, positional and functional.
6. Sharry (1974) – simple, hinge type, fixed guide type and adjustable.
7. Ralini (1980) – fully adjustable, semi adjustable and non adjustable.
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13. IV. Articulators based on instrument functions:
According to the International Prosthodontic Workshop on Complete
Denture Occlusion at University of Michigan in 1972.
CLASS I:
Simple holding instruments capable of accepting a single static
registration.
The first articulators were coined as “SLAB ARTICULATORS”.
Plastewr indices extended from the posterior portion of the casts and were
keyed to each other bymeans of these indices.
Eg: J.B. Gariot’s hinge articulator (1805).
CLASS II
Instruments that permit horizontal as well as vertical motion but do not
orient the motion to the tempero-mandibular joint with facebow transfer.
CLASS – II – A:
Permit eccentric motion based on average or arbitrary values.
In this type, the condyles are on the lower member and their paths are
inclined at 15 degrees. Casts are amounted to this articulator according to
Bonwill’s theory.
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14. Eg: Gritmann articulator (1899)
Alfred Gysi’ Simplex articulator (1914). Yhis has the condylar path
inclined at 30 degrees and the incisal fixed at 60 degrees.
CLASS II- B
Permit eccentric motion based on arbitrary theories of motion.
Eg. Maxillo-mandibular instrument designed by Monson in 1918 based
on his spherical theory of occlusion.
CLASS II-C:
Permit eccentric motion based on engraved records obtained from the
patient.
CLASS III:
Instruments that simulate condylar pathways by using average or
mechanical equivalents for all or part of the motionand allow for joint
orientation of the casts wsith a facebow transfer.
CLASS – III – A:
Accept facebow transfer and a protrusive interocclusal record.
Eg. Hanau Model H designed by Rudolph Hana in 1923 Dentatus
articulator (1944)
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15. Bergstroms Arcon articulator designed in 1950 similar to Hanau
H, except that the condyles are on the lower member and the condylar guides
are curved and are on the upper member.
Bergstrom’s instrument was not the first arcon instrument, but he was
the first person to coin the “ARCON”. It is believed from Articulator the xxxx
instruments has its condyles on the lower member and the condylar guides on
the upper member.
Back and Morrison said that by fixing the condylar guides to the upper
member of the articulator, theoretically the reproduction of mandibular
movement was more accurate because a constant relationship always exists
between the maxillary occlusal plane and the condular guides at any position of
the upper member.
Instruments that have the condyles on the upper member and condylar
guides on the lower member are referred as condylar instruments or non-arcon
instrument.
Advantages of Arcon :
Condyles move in a relationship to their condylar housing that is similar
to the way the condyles move in relationship to the glenoid fossae in the skull.
This makes visualization and understanding of condylar movements easier.
According to Weinberg, arcon and condylar instruments produced the
same motion. The motion resulted from the action of a condylar ball on an
inclined plane and reversing their relationship did not change the motion.
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16. CLASS- III – B
Accept face-bow transfer, protrusive interoclusal records and some
lateral inter-occlusal records.
Eg: Gysi in 1926 introduced the Trubite articulator. It is a non-
arcon instrument with a fixed intercondylar distance. The horizontal condylar
inclinations are individually adjustable, and the individual Benett adjustments
are located near the center of the intercondylar axis. The incisal guide table is
adjustable.
In 1927, Hanau designed the Kinoscope which has a double condylar
posts on each side. The inner-condylar posts have the horizontal condylar
guides and are adjustable mediolaterally to produce mechanical equivalents of
intercondylar distance.
Stanberry in 1928 designed a tripod type articulator, De Pietro in 1960
designed a true arcon instrument –Ney articulator. It is the first araticulator to
have condylar housing that contained adjustable, rear, medial and top walls in
one assembly. The intercondylar distance is adjustable.
The Hanau 130-21 is designed by Richard Ben and James Jaink in 1964.
It had a split horizontal axis that can be adjusted vertically and horizontally,
adjustable intercondylar distance, adjustable Benett guides and adjustable
condylar path guides.
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17. Taledyne articulator designed by Richard Ben in 1975 is an arcon
instrument with adjustable medial and rear walls and adjustable horizontal
condylar guidances. It has a fixed inter condylar path guides.
Teledyne articulator designed by Richard Ben in 1975 is an arcon
instrument with adjustable medial and rear walls and adjustable horizontal
condylar guidances. It has a fixed inter-condylar distance.
CLASS – IV –1:
Instrument accept three dimensional dynamic registration and utilize a
face-bow transfer.
CLASS-IV-A:
The condylar pathways are formed by registrations engraved by the
patient.
Eg: TMJ instruments designed by Kenneth Swanson in 1965.
CLASS –IV – B:
Condylar pathways are selectively angled and customized.
Eg. Gnathoscope designed by Charles Stuart in 1955, Niles Guichet in
1968 designed the Denar (D4A) fully adjustable articulator. The latest
instrument in Denar series is D5A which has the plastic condylar inserts. This
has provision for aboth immediate and progressive side shift Benett adjustment.
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18. HANAU ARTICULATOR – H2:
Hanau articulator is a condylar or non-arcon type. It has a fixed
intercondylar distance of 110mm. The maxillary cast is mounted to the
articulator using a face-bow transfer. Both arbitrary and kinematic face-bows
can be used.
The articulator must have extendible condylar shaft to receive
kinematic face-bow during fixed prosthodontic procedures.
The horizontal condylar inclination is determined by means of
protrusive interocclusal records with height tracers. The amount of lateral
movement is calculated by Benett angel L = H/B + 12. The vertical condylar
posts are then rotated to the calculated Benett angulation.
The araticulator has a mechanical incisal guide table with a single
sagittal adjsutment along with right and left frontal adjustments. These
adjustments are made to compensate for the amount of horizontal and vertical
overlap incorporated in the anterior arrangement of teeth.
The incisal guide pin is straight. Any change in vertical dimension will
alter the positon of the incisal guidetable. This phenomenon is utilized to
adjust the horizontal and verticla overlap during protrusive record.
WHIPMIX ARTICULATOR:
It is an arcon articulator designed by Charles Stuart in 1955. The inter
condylar distance is adjustable in three positions.: Small (s) – 94mm, Medium
(M) –110mm and large (L) –124mm. By means of removalbe condylar
guidance spacers along the horizontal axis for the face –bow record, the
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19. earpiece and kinematic face bows are used. For accurate transfer of the true
hinge axis with kinematic face –bow the articulator has the hinge axis transfer
fixtures which have extendible condylar axis pins. The ear piece face-bow
utilizes the external auditory canal as posterior preference point. During the
face-bow transfer, the condylar part must be utilized depending upon whether
the patient condylar distance is S.M. OR L. The bridge of the nose is usee as
the anterior reference point. The horizontal condylar inclination is determined
by menas of either protrusive inter-occlusal record or lateral interocclusal
record. The benett angle is set with lateral interocclusal records. Optional
immediate side shift or immediate Benett movement condylar guides are
available from 0.25mm to 1.00 mm.
The whip-max articulator is equipped either with a mechanical or a
plastic incisal guide table. Plastic guide table can be customized individually
with auto polymerizing resin. The mechanical guide table has a single sagittal
adjustment and right and left frontal adjsutment.
The incisal guide pin is straight, of which one end is flat and is used
with mechanical incisal guide table and the other rounded end used to
customize the plastic table.
REVIEW OF LITERATURE:
According to Hisatoshi Tanaka 1,2, the primary purpose of an articulator
is to simulate mandibular movement and is also used as diagnostic and
treatment planning aid. The choice of articulator depends pon how well the
instrument is handled. The mechanism of an articulator must be precise, easy
to adjust and simple to understand.
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20. Wilson and Lang said that the evolution of an articulator closely
associates with the knowledge and understanding of the functional activity of
the chewing mechanism.
Closer the articulator simulates mandibular movements, more complex
they become in designing fully adjustable articulators simulate most accurately
but their usefulness is limited because of the complexity of recording and
adjusting.
Semi adjustable articulator can be used for individual static record. The
arcon type produces more constant condylar paths. This type of arrangement is
used during articulator construction. Semi-adjustable articulatoar guides only
the medial component of the balancing side, whereas, the fully adjustable can
guide bot balancing and working side.
Semi-adjustable articulators have either a fully or semi-adjustable
intercondylar distance mechanism. The latter type do not allow the change of
the patients vertical rotational centers, whereas , the former type allows the
change.
According to Neal D. Bellant 4 thesemi-adjsutable articulator guides
only the lateral component of the rotating condylar movmeent, whereas, all
component of mandibular movement are set to simulate in fully adjustable
articulator.
Accuracy of the simulation of the jaw movement controls the accuracy
of the fabricated prosthesis. Lack of accuracy results in parafunctional habits.
The intercondylar width in small and medium range is reproduced in
semi adjustable articulator.It is incapable of reproducing any variation in the
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21. timing of mediotrusion, but is capable of simple laterotrusion. When centric
and lateral positions are accurately transferred to the articulator, the paths
between these positionis interpolated as a stgraight line.
In patients with a backward and upward component in laterotrusion, the
rotating condyle contracts posterior or superior wall of the condylar fossa
before it reaches its final positon, but in patients with a forward or downward
component, the rotating condyle is anterior or inferior from the condylar fossa.
At some point, all articulators fall to represent the chewing mechanism.
Articulators have no inherent ability to do something for the operator. An
expert who knows the limitation of a simple instrumen in producing
mandibular movemens can achieve beter results with it than some one using a
more complex instrument that he did not fully understand.
DISCUSSION:
Evolution of articulators through the years ha given an insight of the
researchers trying to develop a mechanical device that simulates the jaw
members and its movements.
The purpose of using an atriculator is to develop a prosthesis that will be
harmonious in the oral cavity. Various articulators have been developed and
are being improved upon as and when the functions of the jaws are understood
better.
Accordingly, in the present day, the availability of articulators range
from simple hing type to fully adjustable articulators.
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22. Selection of articulators depends upon the clinical situation. In
complete dneture prosthesis, semi-adjustable articulators suffice the
requirements to develop a good denture. Fully adjustalbe araticulators is used
for fixed prosthesis.
It is difficult to manour fully the adjustable articulators in complete
denture patients because the clutches used ot obtain the hinge axis and
condylar movements are more cumbersome to be used in edentulous patients
which in turn does not provide accurate records.
REFERENCES:
1. HISATOSHI TANAKA, et.al., A new semi-adjustable articulator part-1.
Concept behind the new articulation J.P.D., 1975. 33. 10.
2. HISATOSHI TANAKA , et.al., part-2, Adjustment of a new concept
articulator J.P.D., 1975, 33, 158.
3. WILSON AND LANGE, Practical crown and bridge prosthodonics.
4. NEAL D. DELLANTI, J.P.D., 1974, 29, 269.
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