• Whip-Mix: According to their design of their ear bow, in
anteroposterior direction at anterior wall of external auditory
meatus and in superior–inferior direction approximately at level of
most prominent point of posterior border of tragus.
• Brandrup-Wognsen: About 12 mm anterior to the most prominent
point of posterior border of tragus on line from it to the outer
• Weinberg’s Point: A point 11–13 mm anterior on a reference line
drawn from the middle and posterior border of tragus of the ear to
• Gysi: About 13 mm anterior to anterior margin of external auditory
meatus on line from superior margin of external auditory meatus
and the outer canthus of the eye.
FIGURE 5-9 Beyron’s point (P).
Hinge axis or transverse horizontal axis is defined as ‘an imaginary line
around which the mandible may rotate within the sagittal axis’. (GPT 8th
Hinge axis is also called horizontal axis, intercondylar axis, terminal
hinge axis, transverse horizontal axis.
Transverse horizontal axis (THA)
Authors who advocated that THA exists are B.B. McCollum, C.E.
Stuart, R.B. Sloane, H. Sicher and Allil.
• The THA is the most retruded hinge position and is significant
because it is learnable, repeatable and recordable and coincides with
CR. The limits of the hinge movement in this position are about 12–
15° at condyles or 19–21 mm in the incisal region.
• The THA plus one other anterior point serves to locate the maxillae in
space and to record the static starting point for functional
• The recording and reproduction of the opening axis of the mandible
enables a given occlusal relation to be reproduced on the articulator at any
vertical height without the necessity of making a new interocclusal
(IO)–centric relation (CR) record at new VDO.
The proponents (McCollum, Stuart, Sloane, Allil) of gnathology claim
that there is one THA common to both condyles.
• The condyles are in a definite position in the fossa during the
• Snow recognized the importance of this axis and to transfer this axis
to the articulator led to the development of facebow. In 1921,
McCollum, Stuart and others reported the first method of
The proponents (Page, Trapozzanno, Lazzari) of transographics claim
that each condyle has a different THA.
• He was the first one to state the theory of split
hinge axis. He also stated that:
• There were at least 12 hinge axes in every head.
• Three in each mandibular angle
• These, he said, were responsible for movements in
V.R. Tropazzono and J.B. Lazzari (1957):
• They found the presence of multiple hinge axes.
• Relaxation of the patient, during the making of THA
Because of the presence of multiple hinge axes points, increase or
decrease of the VD on the articulator is contraindicated unless a new
interocclusal record is made on the patient at the desired VDO.
• He refuted the transographic concept.
• He said that because it was mechanically impossible
for a solid object to have two axial centres of
rotation in the same plane for one direction of
Schools of thought regarding the transverse axis
• Absolute location of the axis: The absolute location of the hinge axis school,
as practised by V. Lucia (1953), B.B. McCollum (1939, 1943), E.R.
• Arbitrary location of the axis: The arbitrary axis school as practised by
• Nonbelievers in the transverse axis location: Nonbelievers such as H.A.
Collett (1955), R. Levao (1955), L.E. Kurlh and I.K. Feitistein (1951),
F.W. Craddock and H.F. Symmons (1952) and H.O. Beck (1959)
expressed doubts about the presence of THA.
• They thought that the axis is theoretically possible
but not practically acceptable.
• Split axis rotation: Page, V.R. Trapozzanno, J.B. Lazzari, F.R. Slavens
(1961) believed in the transographic theory.
• They believe in the split axis with which each
condyle rotates independently of the other, as the
mandible is not bilaterally symmetrical.
• There must be two axes parallel to each other with
both axes at right angles to the opening and closing
Articulator is defined as ‘a mechanical instrument that represents the
temporomandibular joints and jaws, to which maxillary and mandibular
casts may be attached to simulate some or all mandibular movements’. (GPT
• To diagnose the state of occlusion in both the natural and artificial
• To plan dental procedures based on the relationship between
opposing natural and artificial teeth.
• To aid in the fabrication of restorations and prosthodontics
• To correct and modify completed restorations.
• To arrange artificial teeth.
Requirements of an Articulator
• It should hold cast in correct horizontal and vertical relationship.
• The cast should be easily removable and re-attachable.
• It should provide a positive anterior vertical stop (incisal pin).
• It should accept facebow transfer record using an anterior reference
• It should open and close in a hinge movement.
• It should be made of noncorrosive and rigid materials that resist
• It should not be bulky or heavy.
• There should be adequate space present between the upper and
• The moving parts should move freely without any friction.
• The nonmoving parts should be of rigid construction.
Additional requirements are as follows:
• The condylar guides should allow protrusive and lateral jaw
• The condylar guides should be adjustable to accept and alter the
• The incisal guide table should be customizable.
• It should have adjustable intercondylar distance.
• These allow the operator to visualize the patient’s occlusion,
especially from the lingual aspect.
• Patient’s cooperation is not a factor when using an articulator once
the appropriate interocclusal records are obtained from the patient.
• The refinement of complete denture occlusion in the mouth is
difficult. This is eliminated by the use of articulators.
• These reduce the chairside time.
• The patient’s saliva, tongue and cheeks do not interfere when using
• An articulator can simulate but not duplicate jaw movements.
• Articulators made of metal may show error due to tooling or error
resulting from metal fatigue and wear.
• The articulator may not exactly simulate the intraborder and
functional movements of the mandible.
• Thus, 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 visually detect the finer
• Making accurate marks in the presence of saliva
• Exact location of the condyles
• The resiliency of the supporting structures
• The dentures are movable on slippery base
Articulators have evolved from simple hinge axis device to more
sophisticated instruments simulating the movements of the jaws
accurately. The objective of evolution was to reproduce the occlusal
1756: Plaster articulator was first described by Phillip Pfaff. It is also
1805: First mechanical articulator described by JB Gariot.
1800s: Barn door hinge articulators.
1800s: Adaptable barn door hinge was capable of opening and closing
only in a hinge movement. It has anterior vertical stop between the
upper and lower members. It is also known as Dayton Dunbar
1840: J. Cameron and T.W. Evans made attempt to device plane line
1858: W.G.A. Bonwill developed an articulator based on the theory of
equilateral triangle (Bonwill triangle). It was the first of the kind of
articulator that imitated the movements of mandible in eccentric
1896: P.M. Walker devised a clinometer which had provision for Gothic
1902: M.M. Kerr articulator developed by Kerr brothers had fixed
protrusive and lateral movements. Hinge was located at
approximately the same place as the occlusal plane of the mounted
1906: New century articulator developed by George B. Snow.
1910: Acme articulator was also developed by George B Snow. It had
three models of different widths with three ranges of intercondylar
1910: Gysi’s adaptable articulator developed by Gysi.
1914: Gysi simplex articulator was introduced. Condylar guidance of
this articulator was fixed at 33° and was shaped like ‘ogee path’.
This path is an S-shaped curve in profile.
1918: Maxillomandibular instrument developed by George Monson.
This articulator was based on the spherical theory of occlusion.
1923: Rudolph L. Hanau developed Hanau model M Kinescope
articulator. This articulator has two condylar posts on each side.
Bennett angle was adjusted here.
1923: Homer Relator was introduced by Joseph Homer. Plastic
material was used to preserve the articulator positions.
1927: Hanau model H110 modified introduced incisal guide table.
1929: Stansberry tripod instrument was developed without hinge to
reproduce any functional relationship.
1938: Phillips occlusoscope did not use facebow. The articulator was
adjusted by either intraoral or extraoral records.
1950s: Coble articulator maintained CR and vertical dimension (VD)
but did not allow functional movements.
1955: Pankey–Mann articulator was developed by L.D. Pankey and
1956: Stuart articulator was developed by Charles E. Stuart. It is a fully
adjustable arcon-type articulator.
1963: Hanau model H2 Series. It had increased distance between the
upper and lower members from 95 to 110 mm.
1958: Dentatus ARL articulator. It is a semi-adjustable articulator with
straight condylar path and fixed intercondylar distance.
1960: Verticulator developed by William Windish.
1962: Ney articulator is an arcon-type articulator with no locking
device between the upper and lower members in CR.
1964: Whip-Mix articulator was developed by Charles E. Stuart. It is a
semi-adjustable articulator which has three intercondylar
1968: Denar D4A articulator developed by Niles Guichet. It is a fully
adjustable articulator which is programmed by tracings made with
pneumatically controlled pantographs.
1971: Simulator evolved from Granger Gnathoscope. It is a fully
adjustable articulator that is set from pantographic tracings,
positional records and other tracings.
1975: Denar Mark II by S. Hobo and F.V. Celanza.
1978: Penadent articulator – based on the work of Robert Lee.
1981: Panahoby articulator – Arcon-type semi-adjustable articulator
devised by S. Hobo. It had provisions of adjustment of sagittal
inclination of condylar path between 0° and 60°, immediate
mandibular lateral translation between 0 and 4 mm, progressive
lateral translation between 0° and 25°.
1982: Cyberhoby articulator – Fully adjustable articulator devised by
FIGURE 5-10 Whip-Mix articulator.
The articulators have evolved over the period of time and the
present generation of articulators such as KaVo Protar, Denar Mark II,
Panadent, Hanau radial shift incorporate the Bennett movement in
order to simulate the mandibular movements as closely as possible.
Classification of articulators
• Based on instrument functions
• Based on the ability to simulate jaw movements
• Based on the adjustability of the articulator
• Based on the theories of occlusion
• Based on the type of interocclusal record used
According to the International Prosthodontic Workshop on Complete
Denture Occlusion at University of Michigan in 1972, articulators are
• Simple holding instruments capable of accepting a
• The first articulators were known as ‘slab
articulators’. Plaster indices extended from the
posterior portion of the casts and were keyed to
each other by means of these indices (e.g. JB
Gariot’s hinge articulator [1805]).
Instruments that permit horizontal as well as vertical
motion but do not orient the motion to TMJ with
• It permits eccentric motion based on average or
• In this type, the condyles are on the lower member
and their paths are inclined at 15°. Casts are
mounted to this articulator according to Bonwill’s
theory (e.g. Gritmann articulator [1899]).
Gysi simplex articulator (1914) has the condylar path
inclined at 30° and the incisal fixed at 60°.
• Permits eccentric motion based on arbitrary theories
of motion (e.g. maxillomandibular instrument
designed by Monson in 1918 based on his spherical
• Permits eccentric motion based on engraved records
obtained from the patient and does not accept a
facebow transfer (e.g. House articulator designed
• Instruments that simulate condylar pathways by
average or mechanical equivalents for all or part of
the motion and allow for joint orientation of the
casts with a facebow transfer.
• Accepts facebow transfer and a protrusive
interocclusal record (e.g. Hanau model H designed
by Rudolph Hanau in 1923, Dentatus articulator
• Accepts facebow transfer, protrusive interocclusal
records and some lateral interocclusal records.
• For example, A. Gysi (1926) introduced the Trubyte
articulator. It is a nonarcon instrument with a fixed
intercondylar distance. The horizontal condylar
inclinations are individually adjustable and the
individual Bennett adjustments are located near the
centre of the intercondylar axis. The incisal guide
• Instrument accepts three-dimensional dynamic
registrations and utilizes a facebow transfer.
• The condylar pathways are formed by registrations
engraved by the patient (e.g. TMJ instruments
designed by Kenneth Swanson in 1965).
• Condylar pathways are selectively angled and
For example, 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 both
immediate and progressive side shift Bennett
Based on the ability to simulate jaw movements
• These are instruments that receive and reproduce
stereograms (pantograms). These articulators can
be adjusted to permit individual condylar
movement in each of the three planes. These are
capable of reproducing the timing of the side shift
of the orbiting (balancing) side and its direction on
• Instruments that will not receive stereograms. Some
of the instruments have fixed controls whereas
others are adjustable, but usually in no more than
two planes. Most are set to anatomical averages or
with some type of positional records.
• This class is divided into four types:
Type 1 (hinge): This type is capable of opening and
closing in a hinge movement. A few permit limited
nonadjustable excursive-like movements.
Type 2 (arbitrary): This is designed to adapt to specific
theories of occlusion or is oriented to a specific
Type 3 (average): This type is designed to provide
condylar element guidance by means of averages,
positional records or mini-recorder systems. Most
permit adjustments of both horizontal and lateral
guidance surfaces. Some types of facebow can be
used in maxillary cast orientation.
Type 4 (special): This type is designed and used
primarily for complete dentures.
• Denar: Mark II and Omni model
• TMJ: Mechanical fossa and moulded fossa models
Based on the adjustability of the articulator
Based on the types of records used for their
Interocclusal record adjustment
• Most articulators used for fabrication of complete dentures are
adjusted by some kind of interocclusal records.
• These records are made in wax, plaster of Paris, zinc oxide eugenol
paste or cold curing acrylic resin.
• Articulators designed for the use with graphic records are generally
more complicated than those designed for interocclusal records.
• As graphic records consist of records of extreme border positions of
the mandibular movements, the articulator must be capable of
producing at least the equivalent of curved movements.
Based on the theories of occlusion
• One of the early instruments that reproduced eccentric movement
• Although Bonwill invented his articulator in 1858, it was marketed
• According to the Bonwill’s theory of occlusion, the teeth move in
relation to each other as guided by the condylar and the incisal
• Bonwill’s theory is also known as the theory of equilateral triangle
according to which the distance between the condyles is equal to
the distance between the condyles and the midpoint of the
mandibular incisors (incisal point).
• An equilateral triangle is formed between the two condyles and the
incisal point. Theoretically, the dimension of the equilateral triangle
• Bonwill articulators allow lateral movement and permit the
movement of the mechanism (joint) only in the horizontal plane
FIGURE 5-11 Diagrammatic representation of Bonwill
Conical theory articulators (proposed by R. E. Hall).
The conical theory of occlusion proposed that the lower teeth move
over the surfaces of the upper teeth as over the surface of a cone,
generating an angle of 45° with the central axis of the cone tipped 45°
to the occlusal plane (Fig. 5-12).
FIGURE 5-12 Diagrammatic representation of the conical
• The articulator devised by G.S. Monson in 1918 operated on the
spherical theory of occlusion.
• The spherical theory of occlusion proposed that lower teeth move
over the surface of upper teeth as over a surface of sphere with a
• The centre of sphere was located in the region of glabella.
These have adjustable horizontal condylar paths, adjustable lateral
condylar paths, adjustable incisal guide tables and adjustable
intercondylar distances. The degree and ease of these adjustments
There are two types of semi-adjustable articulators:
• These articulators are used to simulate the patient’s condylar path
by using mechanical equivalents which has capacity to simulate all
• Casts mounted in this articulator have approximately the same
spatial relationship as the condyle to the teeth, thus discrepancies in
the difference in the radius of arc of closure is minimized.
• Therefore, the occlusal discrepancies in the finished restoration are
• Facebow transfer is necessary to use semi-adjustable articulators.
• It is useful in diagnostic evaluation of the study cast, occlusal
analysis, occlusion correction and rehabilitation.
• It is ideal to use a semi-adjustable articulator with facebow for
complete denture fabrication with minimal occlusal errors.
• It is the more preferred articulator for complete denture construction to
fully adjustable as it is comparatively easy to use and requires less
• It is the articulator of choice for denture remount procedures.
• Semi-adjustable articulator can accept centric, lateral and protrusive
• It can be arcon or nonarcon depending on the location of the
condylar guides and condylar elements.
Arcon and nonarcon articulators.
The term arcon was given by G. Bergstorm. ‘Ar’ means articulator and
‘con’ means condyle. The differences between arcon and nonarcon
articulators are given in Table 5-2.
DIFFERENCES BETWEEN ARCON AND NONARCON
Arcon Articulator Nonarcon Articulator
The condylar element is attached to the lower member
of the articulator and the condylar guidance is attached
Condylar guidance is attached to the lower
member and the condylar elements are attached
Simulates TMJ Does not simulate TMJ
The facebow transfer, occlusal plane and the
relationship of the opposing casts are preserved when
the articulator is opened and closed
Angulation between the condylar inclination and
the occlusal plane changes when the articulator is
Upper member is rigid and the lower member is
Upper member is movable and lower member is
Examples are Hanau Wide Vu and Whip-Mix Examples are Hanau H series, Dentatus and Gysi
• These are capable of being adjusted to follow the mandibular
• By virtue of numerous adjustments available on it, the articulator is
capable of repeating most of the precise condylar movements
depicted in any individual patient. The adjustments include the
• Adjustable horizontal condylar guidance
• Adjustable lateral condylar guidance
• Adjustable incisal guide table
Adjustable intercondylar distance, i.e. the fully adjustable
articulator can accept the following records:
Stuart instrument gnathoscope is an example of fully adjustable
• Most accurate instrument to reproduce restorations that precisely fit
the occlusal requirements of the patient.
• Demands high degree of skill
• Primarily for extensive treatment requiring the reconstruction of an
Split cast method and its importance
Split cast method is defined as ‘method of mounting casts wherein the
dental cast’s base is sharply grooved and keyed to the mounting ring’s base.
The procedure allows verifying the accuracy of the mounting, ease of removal
and replacement of the casts’. (GPT 8th Ed)
• This technique was first introduced by A.G. Lauritzen.
• It is an useful method of relating upper and lower cast to each other
in the articulator for the purpose of occlusal rehabilitation.
• It is used to compare the interocclusal records.
• It is used in mounting casts for multiple restorations or full mouth
• To verify plaster records in centric and to adjust the horizontal
condylar inclination in the articulator.
• To verify centric records during full mouth rehabilitation.
• To check the accuracy of hinge axis transfer.
• To observe processing errors during clinical remount procedure.
• To simplify waxing and carving procedure, as the master cast can be
easily removed from the articulator and replaced back.
• Custom cut notches (Lauritzen)
• Split cast formers – diagonal grooves
Preparation of the primary cast
• Impression is poured with stone conventionally.
• Sides and base of the cast is trimmed to form a primary cast.
Preparation of the secondary cast
• V-shaped notches are made on the base of the cast with cylindrical
• Two notches are made in the area of lateral incisor, two at the buccal
border and one at the posterior border of the cast.
• Box the cast after applying separating medium around the cast.
• Stone is poured in the boxed cast with different colour to form the
• Secondary cast is separated from the primary cast and its fit into the
• The separated secondary cast is assembled back on the primary cast.
• Split cast consists of a primary cast with five notches and a
secondary cast with five ridges corresponding to the notches.
Articulation of the split cast
• Split cast is mounted on the articulator with the help of facebow
• Split cast technique allows separation of the primary cast from the
secondary cast which is mounted on the upper member of the
Mounting lower cast to articulator with centric
Centric interocclusal record is used to mount the lower cast with the
Verification of several interocclusal centric
• After mounting, the interocclusal record is removed and the second
record is placed in its position over the lower cast.
• Upper split cast is removed from the mounting and positioned over
• The upper member of the articulator which has the secondary cast is
lowered into the base of the upper primary cast until the notches
• If the notches engage accurately, the interocclusal centric record is
• If the notches do not engage accurately, another interocclusal record
• At least two interocclusal centric records should fit the cast
accurately in order to verify the record.
• This shows consistency and accuracy of the interocclusal centric
• Only then it is accepted as the true centric record.
Bennett movement or laterotrusion is defined as ‘condylar movement on
the working side in the horizontal plane. This term may be used in
combination with terms describing condylar movement in other planes, for
example, laterodetrusion, lateroprotrusion, lateroretrusion and
laterosurtrusion’. (GPT 8th Ed)
‘the direct lateral side shift of the mandible that occurs simultaneously with a
lateral mandibular excursion’. (Bouchers)
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