ARTICULATORS
INTRODUCTION
In the fabrication of indirect dental prosthesis a
mechanical device is used to relate opposing casts called
an articulator
DEFINITION
An articulator is mechanical device which represents TMJ
and jaw members to which maxillary and mandibular casts
may be attached
Primary function of articulator is to simulate patient
in the absence of patient.
An articulator can simulate but they can not
duplicate all mandibular movement
Articulators: Minimal Requirements
It should hold casts in the correct horizontal and vertical relationship
It should provide positive anterior vertical stop
It should accept a face bow record
It should open and close in a hinge movement
The moving parts should move freely and be machined accurately
The non-moving parts should be a rigid construction
It should allow protrusive and lateral jaw motion
Articulator : uses.To open and close in a hinge manner
Hold opposing casts in a predetermined manner
To produce border and intra border movements like in
the mouth
To diagnose dental occlusal conditions in natural and
artificial conditions
To plan dental procedures
To aid in the fabrication of the prostheses
To correct and modify complete restorations
As a teaching aid to study occlusion and mandibular
movements
Articulators: Advantages over mouth
On patients co-operation
To rely No need Allow operator to view patients occlusion from
the lingual side
Refinement of patients occlusion can be easily be done on the
articulator than in the patients mouth
Saves a lot of chair side time
More procedures can be delegated to auxiliary personals when
using an articulator
The patients saliva, tongue and cheek are not factors when using
an articulator.
Articulators : Classification
Based on theories of occlusion
Based on type of inter occlusal records
Based on ability to simulate jaw movements
(IPWS classification)
(Heartwell and rahn classification)
Based on the adjustability of articulators
Bonwill theory articulators
Designed by WGA Bonwill
The teeth moves in relation to each
other as guided by condylar and incisal
guidance
Also known as theory of equilateral
triangle
Distance between the two condyles
is equal to the distance between
midpoint of the mandibular incisors
and condyle
Conical theory articulatorLower teeth move over the surface of the upper teeth as over the
surface of the cone generating an angle of 45° with the central axis
of the cone tipped 45° to the Proposed by RE Hall
occlusal plane.
Spherical theory articulatorLower teeth move over the surface of the upper teeth as over the
surface of the sphere with a diameter of 8“ with the center located
at the glabella
The surface of the sphere moved over the glenoid fossa &
articulating eminences.
Disadvantages of articulators based on the theory of occlusion
These are based on theoretical concepts
There is no provision for variations from the theoretical relationships
that occur in different persons
Articulators based on the type of record used for their adjustment.
Inter occlusal record adjustment
Made of base plate wax, zinc oxide eugenol, POP & acrylic resin
Graphic record adjustment.
Records of extreme border positions of mandibular movements.
Face bow pantograph can be attached
Hinge axis location for adjusting articulators
HEARTWELL AND RAHN CLASSIFICATION
Class I
These are instruments that receive and reproduce stereogram
These articulators can be adjusted to permit individual
condylar movement in each of the three planes they are capable
of reproducing the timing of the side shift of the orbiting
(balancing) side and its direction on the rotating side
Hence these articulators are called as four dimensional
instruments.
Eg: McCollum gnathoscope, Granger gnathoscope, Hanau
kinoscope, Cosmax, Aderer simulator, Ney articulator, Stuart
gnathoscopic computer, TMJ streographer, Denar D5A
CLASS IIThese instruments will not receive stereogram
Some have fixed controls, others are adjustable but usually in no more
than two planes a close approximation of condylar movements patterns
can be determined quickly and the information permits better
adjustments to the condylar control or the selection of a guidance fossa
that will closely match the condylar element movement gained from
stereograms
Gnathology is defined as the science which deals with the masticatory
apparatus as a whole including morphology anatomy histology
physiology pathology and therapeutics
Referred as `gnathalogic’ instruments
o Stuart Articulator - Charles Stuart 1955
o Denar D4A - Denar D5A
o Simulator
Has four types
TYPE I (HINGE)
Capable of opening and closing in hinge movement
Some permits limited non adjustable excursive like movements
eg: The barn door hinge, Trubite, Gariot, Twinstage occluder, Hageman
balancer, Bonwill, Gysi simplex and adaptable, The centric relator
Stephens models, Crescent models, Gysi, Acme
TYPE II (ARBITRARY)
Depends on specific theories of occlusion
eg: Monson, Handy II, The correlator, Transgraph, The gnathic relator,
Verticulator
TYPE III (AVERAGE)
Designed to provide condylar element guidance by means of
average positional records or mini recorder system
Horizontal or lateral guidance can be adjusted
Accepts face bow transfer
eg: House, Dentatus, Hanau, Whip mix ,Denar mark II and omni
TMJ, Panadent
TYPE IV ( SPECIAL)
Designed primarily for complete denture
eg : Stansberry tripod, Kile Dentograph, Irish Duplifunctional.
Based on the adjustability of the articulator.
Arbitrary articulators
Can open and close only about a fixed horizontal axis
Fixed condylar paths
Incisal guide pin glide on an inclined plate on a fixed inclination
Semi adjustable articulators
They have adjustable horizontal and lateral condylar and incisal
paths, inter condylar distances. 2 types: Arcon and Non arcon
Fully adjustable articulators
Capable of adjustment in all directional movements of mandible.
Do not have condylar guidances; receptacles are present to becontoured into customized condylar and incisal guidances.
Eg.Stuart instrument, Gnathoscope, Simulator
Based on plane of orientation
The Articulators which are based on the
Camper's line.
Kavo, Stratos,
The Articulators which are based on the
Frankfort horizontal plane.
Hanau, Dentatus, Whip-Mix,
Denar Mark II, Stuart
Based on the ability to simulate jaw movement
The INTERNATIONAL PROSTHODONTIC WORKSHOP
on Complete Denture occlusion at the University of Michigan in 1972,
an articulator classification was developed.
This classification was based on articulator’s function, capability, intent and
registration acceptance
Class I simple holding instrument capable of accepting a single
Interocclusal record eg. Garriot’s Hinge, Barn hinge door.
Class II Instrument that permit horizontal as well as vertical
motion but don’t accept face bow transfer
Type A- eccentric motion is based on average or arbitrary values
eg.Grittman’s articulator, Gysi’s Simplex
Type B- Eccentric motion permitted is based on theories of arbitrary motions
eg. Maxillomandibular instrument
Type C- eccentric motion permitted is determined by patient’s engraving methods
eg. House’s articulator
Class III permit horizontal and vertical movements, do accept face
bow transfer but facility is limited. Simulate condylar pathways using
average or mechanical equivalent for the whole or part of condylar
motion but cannot allow total customization
Type A - they accept a static protrusive record and they use
equivalents for other types of motion
eg . Hanau articulators, Bergstrom articulator
Type B - accept static lateral protrusive record, use other
equivalents for other types of motion
eg. Trubyte articulator, Hanau kinescope, Stansberry tripod,
Neys articulator, Teledyne articulator, Whipmix articulator,
Denar Mark II, Bergstrom’s arcon articulator.
Class IV accept three dimensional dynamic registration they
allow point orientation of the cast using face bow transfer
type A-the condylar path is determined by engraving registrations
produced by the patient this path can not be modified
eg. TMJ articulator by Kenneth Swanson
type B-similar to type A but they allow angulations and
customization of the condylar path
eg. Stuart articulator, Denar D4A, Denar D5A, Simulator
Class ISimple holding instrument capable of accepting a single
interocclusal record vertical movements may or may not be possible
Slab articulator
A plaster extension on distal portion of mandibular cast was
grooved to serve as guide for a plaster extension on the maxillary
cast this constitutes an articulator called slab articulator
Class IIInstrument that permit horizontal as well as vertical motion but
don’t accept face bow transfer
Type A- eccentric motion is based on average or arbitrary
values
eg.GRITTMAN’S ARTICULATOR,
Condyles are on the lower member
and there paths are inclined 15
degree casts are mounted according
to the Bonwill's triangle
eg.Gysi’s Simplex
Condyles are on the lower member and there paths are
inclined 30 degree Incisal guidance fixed at 60 degree
Average value articulator
30° 25°
5°
CLASS II TYPE B
Permits eccentric motion based on arbitrary theories of
motion won’t accept face bow transfer
eg. Monson’s maxillomandibular instrument
Designed by Monson based on spherical theory of occlusion
Lower teeth move over the surface of the upper teeth as over
the surface of the sphere with a diameter of 8” with the center
located at the glabella
The surface of the sphere moved over the glenoid fossae &
articulating eminences.
Upper member of the articulator moves according to Monson’s
spherical theory
CLASS II TYPE CPermits eccentric motion determined by patients engraving methods eg. House’s articulator
A Needle House “chew in” record
4 metal studs in the upper rim against lower compound occlusal rim.
Diamond shaped pathways are generated the instrument.
Also employs a rotatory grinder on the upper member for milling in a 40/1000 inch elliptical areas so as to free the occlusion in centric occlusion
CLASS IIIPermit horizontal and vertical movements, do accept face bow transfer
but facility is limited. Simulate condylar pathways using average or
mechanical equivalent for the whole or part of condylar motion but
cannot allow total customization
HANAU MATE ARTICULATOR
It is an arcon instrument accept a
face bow transfer it has average
condylar guidance of 30°
Bennett angle 15° incisal guide table
is 10° in both protrusive and lateral
movement
They won’t accept a static
protrusive record
Class III TYPE AType A -they accept a static protrusive record and they use
equivalents for other types of motion
eg. Dentatus, Hanau articulators,
DENTATUS
• It is Designed in Sweden 1944
•Similar to Hanau but it is unique
in that the relationship between
upper and lower can be
standardized with a gauge block
so that cast can be transferred
one to another articulator without
changing the relationship
Mounting procedureMounting the maxillary cast
Attach face bow to the articulator
Maxillary cast is attached to the articulator using orientation jaw relation record .
Support the bite plane with a cast support to carry the additional
weight..
Maxillary cast is made flat and v-shaped notches are prepared on the
mounting surface at the periphery. This surface is lubricated with thin
coating of petroleum jelly.
The cast is then securely seated in the denture base with the occlusal
rim firmly resting in bite fork imprint.
Mixture of stone is placed on the cast, the upper member is swung
back to embed the mounting plate and to bring the incisal pin into
contact with the incisal guide.
Mounting the mandibular cast
Mandibular cast is mounted after recording tentative and centric jaw
relations.
Articulator with mounted maxillary cast is inverted to aid in mounting
the Mandibular cast.
Maxillary occlusal rim is placed on the cast, mandibular occlusal rim is
positioned over the maxillary occlusal rim without using the centric
relation record and mandibular cast is placed in the lower rim measure
and note the X dimension.
Now centric relation record is interposed and maxillary and mandibular
occlusal rims with there casts are luted.
Adjust the pin so the X dimension us same.
Stone is placed on the cast and lower member is swung back to embed
the mounting plate and incisal pin touching incisal guide.
Adjustment of lateral condylar guidanceCan be adjusted according to the Hanau’s equation for lateral
condylar guidance or with lateral relation record.
Hanau`s equation L=H/8+12
L=Lateral condylar guidance
H=Horizontal Condylar guidances
Mathematical Study of Hanau Articulators
Average anatomic location of hinge axis
For average anatomic location of hinge axis a Max error of 5 mm is
considered .If the relation of the jaws to the hinge axis of the patient
differ from relation of the casts to the hinge axis of the instrument,
when a 3mm wax centric record is removed and articulator is closed
an anteroposterior error of approximately 0.2mm would be produced
.
Arbitrary location of anterior point of reference
An elevation of anterior part of the face bow decreases the protrusive
condylar reading & vice versa.
Any of the commonly used arbitrary point of reference can change
vertical height of the face bow mounting not more than + 16 mm .
When the face bow mounting is oriented 16mm high , there is reduction
of 9°in condylar reading making it 31° from the lower member.
The effect of change in condylar inclination
on occlusion
Working cusp inclines
The working condylar motion of Hanau is built into the
machine & is dependent on the balancing condylar motion.
A difference of 10 degree in the working condylar inclination
produces approximately a 1.3° change in the Bennett angle the
net effect is practically immeasurable at the working condyle
and half again as much at the 2nd molar working cusp inclines
BALANCING CUSP INCLINES
The hypothetical patient
has a 40° cuspal inclines .
The 9° reduction in the
protrusive reading due to
elevation of the face bow
decreases the second molar
balancing cusp inclination
to 35.5°, this error is of 0.2
mm for 3 mm cusp.
STRAIGHT CONDYLAR PATH
The average Hanau articulator has a straight condylar slot
rather than a curved path.
condylar path follows a curvature of ¾ inch radius. With
static records , only the centric relation & eccentric positions
are recorded.
The midpoint of the
excursion produces the
maximum error with a
straight condylar slot.
The maximum difference
between a straight condylar
path & one that is having
½ inch radius is 0.4 mm a
maximum error of 0.4 mm
produces 0.2 mm error at
second molar. This is for a
3mm cusp height with a
constant incisal guidance.
Working condylar movements
This The effective condylar
movements in Hanau articulator is
upward backward and lateral
movement contains lateral
Bennett shift of 0°
The working cusp inclines at the
2nd molar would be average between
the extreme guidance namely 15°,
hence the articulator would produce
working cusp inclines at the 2nd
molar of 15° while the patient
would require 30°
Hanau Arcon H2 Introduced by Hanau in 1977
IGT is same as H2 mechanical table
in addition to this has ‘’ Pentacrylic”
incisal guide table and pin provided
for customization with acrylic resin
Upper and lower members are
attached to each other by condyles
and their guidances
Accepts face bow transfer primarily
earpiece face bow
For kinematic face bow it condylar
should be equipped with extendible
shaft
Quite simIntrodilar to H2 except it is an Arcon instrument
Hanau radial shiftArcon instrument with fixed
inter condylar distance
The condylar guidance of the
articulator is designed to
incorporate a curved immediate
side shift with an adjustable
progressive Bennett angle. the
radial shift adjustment has a 3mm
radius and allow up to 3mm of
radial shift before intercepting the
pre adjusted progressive Bennett
angle
The condylar guidance is
adjustable horizontally and curved
superior wall with a 0.75” radius
Hanau wide vue articulator
CLASS III TYPE BAccept face transfer Protrusive interocclusal records and some interocclusal record.
Eg. Trubite articulator,
Whipmix articulator
TRUBITE ARTICULATOR
Designed by Gysi in 1926
It is an nonarcon instrument wih a
fixed intercondylar distance
Horizontal condylar inclinations are individually adjustable
Individual bennette adjustments are near the center of intercondylar distance
Incisal guide table is adjusted acoording to the gothic arch angle can accept lateral interocclusal records not all
WHIPMIX ARTICULATORIt is semi adjustable Arcon type of articulator
It is designed by Charles Stuart in 1955
Its intercondylar distance is adjustable at three positions small(S)
96mm medium(M) 110mm, large(L) 124mm by means of removable
condylar guidance spacers along the instruments horizontal axis
Accepts face bow transfer
Horizontal condylar inclinations are set by means of lateral or
protrusive intercondylar record
It is available with either mechanical guide table adjustable in both
frontal and sagittal plane
Or with plastic incisal guide table that can be individually customized
Bennett angulation is set with lateral interocclusal record
the casts are seated in the LI record and medial wall of the condylar
housing is adjusted until they contact the condyles
Incisal guide table
Provided with either with mechanical incisal guide table or plastic
incisal guide table that can be individually customized with auto
polymerizing resin the mechanical guide table has single sagittal table
adjustment right and left frontal adjustment
Incisal guide pin is straight has a one flat end used with mechanical
guide table and one rounded end used with plastic IGT
MODIFICATIONS OF WHIPMIX ARTICULATOR
Condylar thumb lock screw
For stabilization of condyles during hinge movement
Optional immediate side shift guides available from 0.25 mm to 1mm
size is determined by amount of Bennett movement
Curved condylar guides horizontal or medial are designed to reflect
average relationship between condyles and fossa
CLASS IVAccept three dimensional dynamic registration and allow
point orientation of the cast using face bow transfer
Type A-The condylar path is determined by engraving
registrations produced by the patient, this path can not be
modified
Eg. TMJ articulator
Designed by Kenneth Swanson in 1965
Intraoral registration is generated by Studs in auto polymerizing
resin called as stereographic recording this record is placed on the
articulator and used to mold the fossa in auto polymerizing resin
which produces accurate analog of patients TMJ
CLASS IV TYBE B
These instruments will accept three dimensional dynamic records
and utilize face bow transfer. The condylar pathways can be
selectively angled and customized
Arcon vs non arconCondylar articulator or non arcon articulator has
Condylar element attached to the upper member of the
articulator & condylar guidance attached to the lower member
of the articulator. Eg. Hanau H series, Dentatus, Gysi
.
Term coined by Bergstrom in 1950
Arcon means ARticulator and CONdyle
An Arcon articulator has Condylar
element attached to the lower element of the
articulator and condylar guidance attached to
the upper member of the articulator
Resembles the TMJ eg. Hanau University
series, Whip mix
Arcon provides greater accuracy in the
transfer of angle of condyle descent by the
protrusive positional record But in non arcon
instrument the condyle will move distally in
protrusion so this distance will be doubled
SUMMARYThe frequently asked question is which articulator to be used can be
best answered vaguely that how much do you know about it…..
Amount of information required from your patient
Amount and type of restoration planned
Availability of equipments
Late Carl O Boucher stated that it must be recognized that the
person operating the instrument is more important than the
instrument used.
Success or failure of a final restoration us more depends on dentist
rather than the articulator used