INTRODUCTION Articulating anything is like carving statue. On building a statue, a sculptor does not keep on adding clay to his subjects, actually he keeps chiselling among at the unessential until the truth is revealed without obstructions. That is the articulator, though an important mechanical entity in itself, is meaningless unless that, occlusion functions in the mouth in harmony with biologic factors that regulate the mandibular activity of the patient. If it were practical to do so, the patient’s mouth would be the best articulator. I would like to say, “Begin with, the end in mind:. As is glossary of prosthodontic terms, articulator is defined as a mechanical instrument that represents the TMJ and jaws to which maxillary and mandibular casts may be attached to simulate some or all mandibular movements. HISTORY : There have been a series of articulators that have been introduced if we glance at the past; the numbers are many and the dentist becomes confused as to which one to choose. Philip pfaff was the person who introduced the earliest known
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INTRODUCTION
Articulating anything is like carving statue. On building a statue, a
sculptor does not keep on adding clay to his subjects, actually he keeps
chiselling among at the unessential until the truth is revealed without
obstructions. That is the articulator, though an important mechanical entity
in itself, is meaningless unless that, occlusion functions in the mouth in
harmony with biologic factors that regulate the mandibular activity of the
patient. If it were practical to do so, the patient’s mouth would be the best
articulator.
I would like to say, “Begin with, the end in mind:. As is glossary of
prosthodontic terms, articulator is defined as a mechanical instrument that
represents the TMJ and jaws to which maxillary and mandibular casts may
be attached to simulate some or all mandibular movements.
HISTORY :
There have been a series of articulators that have been introduced if
we glance at the past; the numbers are many and the dentist becomes
confused as to which one to choose. Philip pfaff was the person who
introduced the earliest known articulators. In 1756, he introduced the ‘ Slab
articulator’. In this, the distal end of the mandibular cast was extended and
grooved, into these extensions, maxillary casts were fitted.
The first mechanical articulator was introduced by J.B. Garriot. In
1805, he introduced ‘Garriot Hinge Joint Articulator’. It consisted of hinges
with a set screw in the posterior, against a metal plate to serve as a vertical
stop.
In 1830, Howarth & Ladmore, produced a most common method for
relating casts with the help of plaster index. (also called as “Plaster
articulators”). It consisted of two nested metal boxes which were held in
position and the hinge movement was controlled with elastics. The casts
were secured in place, with twins or elastics.
Another similar device was the spring field articulators, consisted of
two hinged metal boxes with each box having metal mounting pins for
securing the casts with plaster. The first improvement made to the simple
hinge articulator was a tongue-in-groove (sliding) mechanism for changing
the antero-posterior position of the upper member.
The planeline articulator and the Moffitt represent devices with lower
members designed to imitate the condyle, coronoid process and ramus of
mandible.
Initially, liberal amounts of soft crude wax was used to make
impressions and, at the same time, record a bite which was known as “mush
bite” and the centric relation record with this procedure was just plain luck.
In 1840, James Cameron of Philadelphia, produced his unique “Pole stand”
design. This articulator had features that allowed both the upper and lower
members to be arbitrarely adjusted. “Springs” have been incorporated in to
articulators since 1850’s. The most highly adjustable hinge articulator award
could be given to two devices, the Oehlecker, 1878, and the Moffitt, 1898.
Henrich Oehlecker of Hamburg, Germany, designed an articulator much
like that of microscope stage with fine adjustment controls for 3 planes of
movement. On the other hand John W. Moffitt, of Philadelphia, included
numerous closely spaced vertical and horizontal holes for making small
adjustments.
In 1876, George Davidson of Lambeth, England added a new
dimension to the term “adaptable” when he patented a articulator with a ball
and socket (universal) joint on the upper member, it also had rod and sleeve
mechanism for both vertical and horizontal adjustments.
Bonwill, was the first to use springs as a mechanism for holding the
individual condylar elements in centric position while allowing protrusive
and lateral movements to occur.
In 1864, Bonwill introduced the dental profession to theory of tooth
guided (balanced ) occlusion along with the anatomical articulators. This
articulator could not guide but it could follow. In 1889, Luce of Germany
described the forward and downward movements. in 1895, Kelly R.Bragg,
of Shelbenia invented a device which combined the articulator and
vulcanizing flasks, and by using special impression trays to transfer the
casts directly to the flasks made it unnecessary to remove the casts from
articulator until processing.
Evens, Hayes, and Bonwill (1899) are the early examples of
articulator with “Vertical stop”. In 1899, Grittman introduced an articulator
with :
1) Fixed condylar paths : this was modified by George B.Snow as the
“New century articulator” in 1906 which was later modified.
2) Incisal pin.
3) Posterior extension to prevent tipping were included in it.
In 1902, Kerr Brothers introduced the KERR Articulator with :
1) Fixed protrusive and lateral movements.
2) Hinge in the same plane as occlusal planes
In 1910, ACME articulator was introduced which was elaboration of
George. B. Snow.
1) It is available in 3 models to accommodate 3 ranges of intercondylar
distance.
2) The condylar paths are adjustable straight paths.
3) The incisal guide pins rests on changeable guide.
4) Benett movement is provided.
Gysi introduced “Adaptable” articulator in 1912. It had only fixed 45-
degree incisal guide table.
Gysi continued the exact incisal guide design in his “Simplex”
articulator, an “average value” version of the “Adaptable”. He suggested
that the slope of “Simplex” incisal table could be altered with use of metal
plate and modelling plastic.
In 1916, Rupert E. Hall deviced “Alligator”. It had a “Single rotation
centre”. It was the first articulator which included an incisal guide table with
adjustable lateral wings.
In 1917, Hall deviced “Dental Occluding Frame” which had
adjustable, curved condylar paths, including settings for Balkwill-Bennett
angle, and a mechanism for adjusting the intercondylar distance. It also
included a horizontal incisal table with adjustable lateral wings and a
triangular guiding edge on each lateral wing that could be set to follow
“Gothic arch” tracing.
In 1918, Hall patented the “Automatic anatomic” articulator based on
his “Conical” theory of occlusion.
It has been generally accepted that Gysi coined the term “Gothic
arch” to describe the character of incisor point movement in horizontal
plane. Gysi was the first investigator to design and study the incisal pin and
guide assembly and to report its significance for reproducing mandibular
movements.
The BERGSTROM articulator is an arcon instrument. This term has
been coined by Bergstrom, the term comes from first two letters of
articulator and the first three letters of condyle, the original Hanau had many
similar features.
The STEPHAN Articulator :
Developed in 1921 and was similar in design to Garriot Hinge
articulator except that it has :
1) Fixed condylar inclination.
2) Allows for arbitrary lateral movement. Useful in fabrication of small
restorations and for prosthesis repair. They can be used for complete
dentures when non-cusp teeth are indicated.
Hanan Model M. Kinoscope :
Rudolf L. Hanau, in 1923 developed Kinoscope which has double
condylar posts on each sides, each one for horizontal and lateral condylar
guidance.
Hanau model H110 and modified H110 was later developed in 1922
and 1927 respectively. In 1928, Gysi patented “Trubyte” articulator which
had incisal table with guiding lateral edges that could be set to follow
incisor point “gothic arch” tracings. It was the first articulator with an
adjustable incisal guide assembly. It had 100 lateral wings called as
“FISCHER ANGLE”.
Between 1922 and 1927, Needles and Milus .M. House developed
House-Needles incisal guidance system for dental articulators.
Stansberry tripod :
Before 1929, articulators could not accept all the positional records.
In this instrument, maxillary cast is mounted in an arbitrary position, later
the mandibular cast is mounted with centric relation in plaster. The
articulator reproduce positions, not movements.
HANAU CROWN AND BRIDGE ARTICULATORS :
Small articulator with a posterior pin and cam guidance mechanism
can be set to simulate working and balancing side excursion of 150. It can be
set for left & right quadrant or for anterior restorations. Fixed protrusive
movement is 300.
From 1940, Stephan Articulator :
Modified in 1940 with fixed condylar path of 300. It is same as 1921
model except the upper and lower mounting arms are longer.
Stephan articulator model P :
Additional features are incisal pin and a vertical height adjustment.
Another version includes a fixed 100 incisal guidance.
TRANSOGRAPH BY PAGE :
Presented in 1952. It is a split axis instrument designed to allow each
condylar axis to function independent of the other. He did not believe in the
common hinge axis, that is why he split it in to two.
THE DENTOGRAPH :
Designed by KILE in 1955 was primarily used for complete denture
construction. The vertical dimension of occlusion is established by use of
carborandum and plaster occlusal rims developed in a generated path by the
Patterson method.
THE DUPLIFUNCTIONAL ARTICULATOR :
Designed by Irish & presented in 1965.
Primarily for use in complete denture construction. It has 2 main
purposes, first it records each patient mandibular movements and then
without further convertive procedures serves a 3D tripod type of articulator
upon which dentures may be constructed and then occlusion balanced.
McCollum developed a mandibular movement records and an
articulator Gnathoscope in 1939.
THE STUART ARTICULATOR :
The stuart gnathologic computers was designed by C.E Stuart in 1955
(GNATHOSCOPE) Gnathology is defined as a science that deals with
masticatory apparatus as a whole including morphology, anatomy,
histology, physiology, pathology and therapeutics.
Features :
1. The upper frame carries all cams that direct the rotations and slidings
of the condylar elements and the fossae.
2. The lower frame carries the condylar elements and simulate
mandible.
3. The intercondylar distances is adjustable to each patient.
4. The fossa cup can be adjusted.
5. The plastic eminence can be altered according to that of the patient if
the protrusive and lateral path difference is there.
6. The operating parts are devoid of set screws.
7. The side shift (Bennett) and its timings is cut in to lateral wings.
The instrument will receive pantograms made in the 3 planes. It also
records the amount and character of movements in one plane and relation to
other planes.
TRUBYTE SIMPLEX :
The new simplex uses average movements :
1) The condylar guides are inclined at 300.
2) Bennett movement of 7.50.
3) The incisal guide table adjusts from 0-300
A mounting jig which doubles to level the occlusal plane is used for
arbitrary mounting of upper cast. Alternatively a plane orientation jig
positions the lower cast first and it is used for positioning the gothic arch
transfer – useful in complete denture construction.
NEY ARTICULATOR :
It was designed by Dr. D. Pietro in 1960 and was an arcon instrument.
1. This is the first articulator to have condylar housings that contained
adjustable rear, medial and top walls in one assembly.
2. Intercondylar distance is adjustable.
HANAU H2 :
Discussed later in detail
DENTATUS:
This is another adjustable articulator designed in 1944 in Sweden.
The condylar elements are attached to upper member and the condylar path
is straight.
Bennett angle is calibrated to 400.
Inter condylar distance is fixed.
This recieves hinge axis face bow transfer.
Its features are similar to Hanau Model H.
MODIFIED DENTATUS ARO :
With movable arms that holds the cast.
HANAU 130-21 : Discussed later
WHIP MIX : Discussed later
THE SIMULATOR ARTICULATOR :
It was designed by Ernest Granger.
It was set with a conventional pantograph. A minigraph could be used
when full mouth pantographic tracings is not feasible.
It consisted of only two anterior recording plates which were related
to casts mounted to the hinge axis. Tracings of protrusive and lateral
movements were made.
Its Bennett guide can be set by adjustment only and cannot be
customized.
PANADENT ARTICULATORS
DENAR D4A
DENAR D5A
DENAR MARK II
TMJ ARTICULATORS
CYBERHOBY ARTICULATOR.
PARTS OF ARTICULATOR
The articulator is programmed to produce a motion that is
determinant of the occlusal anatomy being developed. The motion produced
by the instrument is dictated by the settings of these control areas, the two
condylar and incisal guide control.
This is clinically significant in that it encourages the treatment
sequences to be accomplished according to the dentist or patient desires
rather than be dictated by instrument limitations.
1. Posterior control areas ( condylar controls) : These control areas are
adjusted according to patient’s TMJ characteristics and can be identified by
a pantograph.
2. Anterior control areas (incisal guide control) : This control area is of
equal importance as the posterior control area. In existing occlusions it is
adjusted in consideration of the vertical and horizontal overlap of anterior
teeth. In edentulous mouth, the vertical and horizontal overlap of anterior
teeth is determined by esthetic and phonetic measurements.
3. Centric occlusal position of the mounted casts in proper orientation of the
control areas is a must.
CLASSIFICATION OF ARTICULATORS
I. Articulators based on theories of occlusion :
1) BONWILL’S THEORY OF OCCLUSION :
It proposed that the teeth move in relation to each other as guided by the
condylar controls and the incisal point.
It was also known as the theory of the equilateral triangle in which there
was a 4 inch (10cm) distance between condyle and between each condyle
and the incisal point.
It was designed by W.G.A. Bonwill
Since condylar guidances were not adjustable, movement in horizontal
plane is only permitted (eccentric position)
2) CONICAL THEORY OF OCCLUSION :
This proposed that the lower teeth move over the surfaces of the
upper teeth as over the surface of cone, with a generating angle of 450 and
with the central axis of cone tipped at 450 angle to the occlusal plane eg.
Hall automatic articulator designed by R.E. Hall.
Teeth with 450 cusps were necessary for constructing dentures on this
articulator.
3) SPHERICAL THEORY OF OCCLUSION :
It proposes that the lower teeth moves over the surface of the upper
teeth as over the surface of sphere with a diameter of 8 inches (20cm). The
center of the sphere is located in the region of the glabella, and the surface
of the sphere passes through the glenoid fossae along the articular
eminences or concentric with them.
Proposed by G.S. MONSON in 1918.
The draw back of this classification is that provision was not made for
variation from the theoretical relationship that occur in different persons.
II. Articulators based on the types of records used for their adjustment:
Three general classes of records are used for transferring maxillo-
mandibular relationship from the patient to the articulator.
1. Inter occlusal records
2. Graphic records
3. Hinge axis recods.
Some articulators are designed for use with only one record where as
others can use two or three types of records in combination.
1. Inter Occlusal Record Adjustment :
These records can be made in wax, pop, zinc oxide eugenol paste or
cold-curing acrylic resin. These records is of only one positional
relationship of the lower jaw to upper jaw.
2. Graphic record adjustment :
Since the graphic records consists of records of the extreme border
positions of mandibular movement, the articulator must be capable of
producing these curved movements provided the graphic records are correct.
These records are difficult and unreliable in edentulous patients.
3. Hinge Axis location for adjusting articulator :
The correct location of the opening and closing axis of the mandible
should be made, if not the correct adjustment of these instrument is not
possible.
III. Articulator classification based on the instruments function :
(At International Prosthodontic workshop on complete denture
occlusion at the University of Michigan in 1972).
Class I :
Simple holding instruments capable of accepting a single static
relationship.
Vertical motion is possible, only for convenience. Eg. Slab
articulator, hinge joint articulator, barn door hinge.
Class II :
Instruments that permit horizontal as well as vertical motion but do
not orient the motion to TMJ via a face bow transfer.
A) Eccentric motion permitted is based on average or arbitrary value e.g.
Gysi simplex articulator, Grittman.
B) Eccentric motion permitted is based on theories of arbitrary motion.
Eg. Monson maxillomandibular articulator.
C) Eccentric motion permitted is determined by the patient using