articulators
TRANSCRIPT
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RATIONALE OF USE OF DENTAL ARTICULATORS IN COMPLETE DENTURE TREATMENT
PRESENTED BY :DR. SAKSHI SHARMAM.D.S. 1ST YEAR
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CONTENTS Introduction Definition of an articulator Historical review Advantages of an articulator Classification systems Requirements of articulators Parts of an articulator Parts of Hanau articulator and its functions Types of Hanau articulators Whip Mix articulator Dentatus articulator Summary Bibliography.
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INTRODUCTION
The primary function of the articulator is to
act as the patient in the absence of the
patient. An articulator is used to simulate
the patient’s temporomandibular joints,
mandible and maxilla, and the complex
neuromuscular mechanism that programs
mandibular movements.
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Other purposes for which an articulator is used
are:
1. Mounting of dental casts for diagnosis, treatment
planning, and patient presentation.
2. Fabrication of occlusal surfaces for dental
restorations.
3. Arrangement of artificial teeth for complete and
removable partial dentures.
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In 1858 Bonwill developed the first articulator with a serious effort to imitate the movements of the mandible in eccentric positions.
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DEFINITION
An articulator may be 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-8).
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HISTORICAL REVIEW The plaster articulator was first described by PHILLIP
PFAFF in 1756
Also known as SLAB ARTICULATORS
GARIOT designed the hinge joint articulator about 1805.
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In 1899, Richmond S. Hayes received a patent for an articulator that was the first to incorporate a fixed descending condylar path.
In the same year, Hayes introduced the first example of a functional face-bow like device .He named this device as “articulating caliper”.
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The New Century articulator was manufactured by the Snow Dental Co., Buffalo, New York, In 1906.
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The Acme articulator, which also was made by George B. Snow.
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The Gysi Adaptable articulator was introduced in 1910.
Gysi Simplex was introduced in 1914 as a mean value articulator.
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The maxillomandibular instrument designed in 1918 by George Monsoon, was based on the spherical theory.
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The Stephan articulator, developed in 1921.
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The Hagman Balancer, developed in the 1920s.
Opens and closes on a hinge
Requires no face-bow or interocclusal records for mounting.
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Rudolph L. Hanau,In 1921 developed a research model called Hanau Model C Articulator.
In 1923 he developed another research instrument, the Hanau Model M Kinoscope articulator.
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In the Wardsworth articulator, developed in 1924.
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The Hanau Model H110 manufactured in 1922 and 1923.
It has individual condylar guidance adjustments.
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The Hanau Model H110 Modified was introduced in 1927.
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In 1926, GYSI TRUBYTE ARTICULATOR was introduced. It is a non arcon instrument with a fixed intercondylar distance.
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The Stansbery articulator was developed by C. J. Stansbery Of Los Angeles in 1929.
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The HOUSE articulator was developed by M. M. HOUSE in the early 1930s
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The PRECISION COORDINATOR was developed by W. H. TERRELL, in the early 1930s.
It is an ARCON type of instrument that has curvilinear condylar guides.
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In 1944, DENTATUS was designed in SWEDEN.
This articulator is unique in that the relationship between the upper and lower members can be standardized with a gauge block, so that casts can be transferred from one articulator to another and still maintain the same relation.
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BERGSTORM designed an instrument in 1950 called the ARCON, which is similar to HANAU H, except that the condyles are on the lower member of the instrument, and the condylar guides are curved and on the upper member.
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The TRANSOGRAPH presented in 1952, is a split axis instrument designed to allow each condylar axis to function independently of the other .
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The GNATHOSCOPE, designed by CHARLES STUART in 1955.
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The NEY articulator was designed by DE PIETRO in 1960 and was an arcon instrument.
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The HANAU 130 – 21 was designed by RICHARD BEU and JAMES JANIK IN 1964.
It has a split horizontal axis that can be adjusted vertically and horizontally, adjustable intercondylar distance, adjustable bennet guides, and adjustable horizontal condylar path guides.
It is utilised with protrusive and lateral interocclusal records.
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The DUPLI-FUNCTIONAL articulator was designed by IRISH and presented in 1965.
It was primarily for use in complete denture construction.
It records each patient’s mandibular movements
It serves as a three dimensional tripod type of dental articulator on which denture may be constructed and their occlusion balanced.
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In 1968, NILES GUICHET designed the DENAR fully adjustable articulator (D4A).
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The TELEDYNE articulator was designed by RICHARD BEU IN 1975.
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The HANAU ARCON H2 was introduced by HANAU in 1977.
It is quite similar to HANAU H2, except that it is an ARCON instrument.
The next articulator to be introduced in HANAU series was HANAU RADIAL SHIFT ARTICULATOR
The HANAU WIDE VUE and WIDE VUE II are the newest to be introduced by HANAU.
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ADVANTAGES OF USING AN ARTICULATOR
Properly mounted casts allow the operator to better visualize the patients occlusion, especially from the lingual view. This is essential if a proper occlusal scheme is to be developed for complete dentures.
Patient cooperation is not a factor when using an articulator once the appropriate interocclusal records have been obtained.
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Considerable more chair time and patient appointment is required when utilizing the mouth as an articulator.
More procedures can be delegated to auxiliary personnel when utilizing an articulator for development of the patients occlusion.
The patient’s saliva, tongue and cheeks are not factors when using an articulator.
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MINIMAL REQUIREMENTS OF ARTICULATORS
It should hold casts in the correct horizontal and vertical relationships.
It should provide a positive anterior vertical stop.
It should accept a face- bow transfer record.
It should open and close in hinge movement.
It should allow protrusive and lateral motion.
The moving parts should move freely and be accurately machined.
The non moving parts should be a rigid construction.
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ADDITIONAL REQUIREMENTS
Adjustable horizontal and lateral condylar
guide elements.
The condylar elements as a part of the lower
frame and the condylar guides as a part of the
upper frame.
A mechanism to accept a third reference point
from a face-bow transfer record.
A terminal hinge position locking device.
Immovable mounting plates that can be
repositioned accurately.
An adjustable incisal guide table.
Adjustable intercondylar width of the condylar
elements when graphic tracings to be used to
set and select condylar guidances.
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LIMITATIONS OF AN ARTICULATOR
An articulator can simulate but not duplicate jaw movements.
An articulator made of metal may show error due to tooling or resulting
from metal fatigue and wear.
The articulator may not exactly simulate the intraborder and functional
movements of the mandible.
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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.
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CLASSIFICATION OF ARTICULATORS
BASED ON INSTRUMENT FUNCTIONS
ABILITY TO SIMULATE JAW MOVEMENTS
ADJUSTABILITY OF THE
ARTICULATOR
THEORIES OF OCCLUSION
TYPE OF INTER- OCCLUSAL
RECORD USED
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BASED ON INSTRUMENT FUNCTION At the International Prosthodontic Workshop on
Complete Denture Occlusion at the University
of Michigan in 1972, an articulator classification
was developed based on the instrument’s
function, instrument capability, intent,
registration procedure, and registration
acceptance were considered in developing the
classification. The classification is as follows-
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BASED ON INSTRUMENT FUNCTION
CLASS I
CLASS II
CLASS IV
CLASS III
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CLASS I:
Simple holding instruments capable of accepting a single
static registration. Vertical motion may or may not be
possible.
The first articulators were called “slab articulators” and
were formed by extending plaster indices from the rear of
the casts.
The hinge- joint articulator is representative of this class.
J.B. Gariot reportedly designed the first hinge articulator
about 1805.
The “barn- door” hinge with an anterior vertical stop
qualifies for this classification.
• CLASS II :Instruments that permit horizontal as well as vertical motion but do not orient the motion to the temporomandibular joint via a face-bow transfer.
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CLASS II
CLASS II-A
CLASS II-B
CLASS II-C
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CLASS II-A : Eccentric motion permitted is based on average or arbitrary values. Example :
a) Articulator by GRITTMAN (1899) ; condylar path inclined at 15 degree
b) GYSI SIMPLEX articulator (1924) ; condylar path inclined at 30 degree and the incisal guidance is fixed at 60 degree.
CLASS II-B : Eccentric motion permitted is based on theories of arbitrary motion. Example :
MONSOON’s articulator (1914)
CLASS II-C : Eccentric motion permitted is determined by the patient using engraving methods. Examples :
HOUSE articulator (1927)
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•CLASS III :Instruments that simulate condylar pathways by using average or mechanical equivalents for all or part of the motion. These instruments allow for joint orientation of the casts via a facebow transfer.
CLASS III
CLASS III-A
CLASS III-B
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CLASS III-A : Instruments that accept a static protrusive registration
and use equivalents for the rest of the motion. EXAMPLE :
A) Hanau Model H (1923)
B) Dentatus (1944)
C) Arcon (1950)
CLASS III-B : Instruments that accept a static lateral protrusive
registrations and use equivalents for the rest of the motion. EXAMPLE:
A) Gysi’s trubyte Articulator (1926)
B) Kinoscope (1927)
C) Tripod Type Articulator (1928)
D) Ney Articulator (1960)
E) Hanau 130-21 (1964)
F) Teledyne Articulator (1975)
G) Panadent Articulator
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CLASS IV : Instruments that will accept three – dimensional dynamic registrations. These instruments allow for joint orientation of casts via a face – bow transfer.
CLASS IV
CLASS IV-A
CLASS IV-B
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CLASS IV –A : The cams representing the condylar paths are formed by the registrations engraved by the patient. These instruments do not allow for discrminating capability.
EXAMPLE : TMJ Instrument (1965)
CLASS IV-B : Instruments that have condylar paths that can be angled and customized either by selection from a variety of curvatures, by modification, or both.
EXAMPLES : Gnathoscope (1955) Denar Fully Adjustable Simulator
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BASED ON THE ABILITY TO SIMULATE JAW MOVEMENTS
CLASS I:
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.
They are capable of reproducing the timing of the side
shift of the balancing side and its direction on the
working side.
Examples: Mc Collum Gnathoscope, Hanau Kinescope,
Ney articulator, Denar D5A.
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CLASS II:
Instruments that will not receive stereograms.
Some of the instruments have fixed controls
while others are adjustable, but usually in no more
than two planes.
This class is divided into four types:
1) Hinge
2) Arbitrary
3) Average
4) special
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Type 1: HINGE: This type is capable of
opening and closing in a hinge
movement. Examples: Barn Door Hinge,
Gariot, Hageman Balancer, Gysi, Acme.
Type 2: ARBITRARY: This is designed to
adapt to specific theories of occlusion or
is oriented to a specific technique.
Examples: Monson, Transgraph, Gnathic
Relator.
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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 type of facebow can be
used in maxillary cast orientation. Examples:
Dentatus, Whip- Mix, Denar, Panadent.
Type 4: SPECIAL: This type is designed and used
primarily for complete dentures. Example: Stansbery
Tripod, Kile Dentograph, Irish Dupli- Functional.
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BASED ON THE ADJUSTABILITY OF THE ARTICULATOR
1. NON- ADJUSTABLE2. SEMI- ADJUSTABLE3. FULLY- ADJUSTABLE
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Non- adjustable articulators:
They can open and close in a fixed horizontal axis.
They have a fixed condylar path along which the condylar ball can be moved to simulate lateral and protrusive jaw movement.
The incisal guide pins ride on an inclined plate in a fixed inclination.
The distance between the teeth and the axis of rotation on this small instrument is considerably shorter than it is in the skull, with a resultant loss of accuracy.
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Advantages
Inexpensive
Less time required to
mount the casts on the articulator
Disadvantages
It reproduces only one contact
position
It demands increased intraoral
adjustment time.
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Semi adjustable articulators:
They have :
adjustable horizontal condylar paths
adjustable lateral condylar paths
adjustable incisal guide tables
adjustable intercondylar distances.
There are two types of semi- adjustable
articulators:
1. Arcon articulators
2. Non- arcon articulators.
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Comparison between ARCON and NON ARCON articulators
Arcon instrument has its condyles on the lower member and the condylar guides on the upper member.
e.g. Whipmix articulator, hanau university series.
Non arcon or condylar instruments are those that have the condyles on the upper member and condylar guides on the lower member.
e.g. Hanau Model H, dentatus, gysi.
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Advantages of Arcon articulators:
The face- bow transfer, occlusal plane and the
relationship of the opposing casts are preserved when the
articulator is opened and closed.
Condyles move in a relationship to their condylar housing that is similar to the
way the condyles move in the relationship to the
glenoid fossa in the skull. This makes visualization and understanding of condylar
movements easier.
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Fully adjustable articulators: It accepts three dimensional dynamic
registrations. They are capable of being adjusted to
follow the mandibular movement in all directions.
The articulator is capable of repeating most of the precise condylar movements depicted in any individual patient. These adjustments include:
a) Adjustable horizontal condylar guidanceb) Adjustable lateral condylar guidancec) Adjustable incisal guide tabled) Adjustable intercondylar distance.
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Condylar inclination:- As on the semiadjustable articulator , the
angle at which the condyle descends on the fully adjustable articulator during protrusive & laterotrusive movements can be altered.
Although the semi adjustable articulator can usually provide a condylar movement only in a straight pathway , the fully adjustable articulator is capable of adjusting the condylar pathway to duplicate the angle & curvature of the patient’s condylar movement.
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Bennett angle & lateral translation movement:-
The fully adjustable articulator has adjustments that permit duplication of both the patient’s bennett angle & the immediate lateral translation movement of the patient condyle .
Many semiadjustable articulator cannot duplicate this exact pathway because only flat surfaces are available to guide the condyle.
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Rotating condylar movements
During a laterotrusive movemement ,the rotating (i.e ., working) condyle does not purely rotate around a fixed point ; however it can move slightly laterally .
This lateral shift can also have a superior , inferior, forward , or backward component , which can influence the fossa depth & cusp height , as well as the ridge & groove direction developed in the posterior teeth.
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The rotating condylar movements affects both the working & non working sides but has its greatest effect on the working side.
Semiadjustable articulators do not have the ability to compensate for this movement.
The fully adjustable articulators can be set so that the pathway of the rotating condyle on the articulator will duplicate that of the patient.
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Intercondylar distance The distance between the rotating
centers of the condyle on the fully adjustable articulator can be modified to match that in the patient .
Often three general settings are available on the semiadjustable articulator:› Small › Medium › large
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With the fully adjustable articulator , a complete range of intercondylar distance can be selected .
Therefore the intercondylar adjustment is set at the precise milimeter distance as determined from the patient.
This then allows more accurate duplication of intercondylar distance & thus minimize errors .
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Advantages
Most accurate instrument to
reproduce restorations that precisely fit the
occlusal requirements of the patient.
Disadvantages
Demands high degree of skill
Expensive
Time consuming
its ability to duplicate mandibular movement.
its ability to duplicate mandibular movement.
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ARTICULATORS BASED ON THEORIES OF OCCLUSION
THE BONWILL THEORY OF OCCLUSION proposed that the teeth move in relation to each
other as guided by the condylar controls and the incisal point.
It was known as the theory of the equilateral triangle, in which there
was a 4-inch (10 cm) distance between the condyles and
between each condyle and the incisor point.
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The articulator designed by W.G.A. Bonwill allows
lateral movement, but since the condylar guidances
are not adjustable, they permit movement only in the
horizontal plane.
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THE CONICAL THEORY OF OCCLUSION proposed that the lower teeth move over the surfaces of upper teeth as over the
surface of a cone, generating an angle of 45 degrees with the central axis of the cone tipped 45 degrees to the occlusal
plane.
The Hall Automatic articulator, designed by R.E.Hall confirms to conical theory of
occlusion.
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THE SPHERICAL THEORY OF OCCLUSION showed the lower teeth
moving over the surface of the upper teeth as
over the surface of a sphere with a diameter of 8 inches (20 cm).
The center of the sphere was located in the
region of glabella, and the surface of
the sphere passed through
the glenoid fossae along or concentric with the articulating
eminences.
The theory was
proposed by G.S. Monson
in 1918.
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The articulators that function on theories
of occlusion have one common fault:
they make no provision for variations
from the theoretical relationships that
occur in different persons. When the
varying inclinations of condylar paths of
the two sides of many patients are
recognized, the need for modification
becomes apparent.
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ARTICULATORS BASED ON TYPE OF RECORD USED FOR THEIR ADJUSTMENT
- Interocclusal records
- Graphic records
- Hinge- axis records.
The general classes of records are used for transferring maxillomandibular relationships from the patient to the articulator:
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Interocclusal record adjustment-
Interocclusal records may be made in wax,
plaster of Paris, ZOE paste, or cold- cure
acrylic resin.
Each record is of only one positional
relationship of the lower jaw to the upper jaw.
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• Individually adjustable horizontal condylar guidances
• Variable controls for the Bennett shift
• Variable intercondylar distances• Split-axis condylar guidance
controls • Adjustable incisal guidance
controls.
The mechanical features that determine whether an articulator can be adjusted to accommodate interocclusal records include:
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Graphic record adjustment-
Articulators designed for use with graphic records
are generally more complicated than those designed
for interocclusal records.
Since graphic records consist of records of the
extreme border positions of mandibular movements,
the articulators must be capable of producing at
least the equivalent of curved movements. The
reason is that the border movements of the mandible
are in curves.
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Hinge- axis location for adjusting
articulators-
All the instruments that can be adjusted
to graphic records have one feature in
common: the necessity for correct
location of the opening axis of the
mandible.
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CLASSIFICATION ACCORDING TO VARIOUS AUTHORS
According to Gillis (J Am Dent Assoc 13:3, 1926)
Adjustable Fixed
According to Boucher (J Dent Res 14:39, 1934) Non- adjustable Adjustable a) A Two- dimensional instrument.
b) A Three- dimensional instrument.
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According to Kingery (The American Textbook of
prosthetic Dentistry, ed 7. Philadelphia, 1942)
Simple articulatorsAdjustable or adaptable articulators
According to Beck (J Am Dent Assoc 64:468, 1962)
Suspension instrument Axis instrument Tripod instrument
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According to Weinberg (J Prosthet Dent 13:645, 1963)
Arbitrary – e.g. – Monson articulator, Hageman balancer
Positional – e.g. – Stansbery Tripod articulator
Semi adjustable – e.g. – Hanau Model H Fully adjustable – e.g. – Hanau kinescope,
Gysi Trubyte
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According to Posselt (Posselt, U: Physiology of occlusion, 1968)
Plain line Mean value Adjustable
According to Thomas (J Prosthet Dent 30:11, 1973)
Arbitrary Positional Functional
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According to Heartwell and Rahn (1974)
Instruments that will receive and reproduce pantographs and graphic tracings
Instruments that will not receive pantographs, which are sub divided into four types:
a) hinge type b) arbitrary c) adjustable d) instruments designed and used for complete
denture construction.
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According to Sharry (Sharry, J.J.: Complete Denture Prosthodontics, ed 3, 1974)
Simple Hinge type Fixed guide type Adjustable
According to Bergstrom Arcon - e.g. – Whipmix articulator Non arcon - e.g. – Hanau model H
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According to Rihani (1980)
Fully adjustable-
examples: Hanau Kinescope, Mc Collum Gnathoscope,
Simulator, Denar D4-A
Semi adjustable-
examples: Snow Acme, Gysi Adaptable, Gysi trubyte,
Dentatus, Hanau 130-28, Whipmix.
Non adjustable- examples: Gariot, Barn door hinge, Walker, Gritman, Snow,
Transograph
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FULLY ADJUSTABLECan accept the following five records:Face bow recordCentric jaw relation recordProtrusive recordLateral recordIntercondylar distance record
SEMI-ADJUSTABLECan accept the following three records:Face bow recordCentric jaw relation recordProtrusive record
NON-ADJUSTABLECan accept one or two of following three records:Face bow recordCentric jaw relation recordProtrusive record
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ADJUSTABLE VS. SEMIADJUSTABLE ARTICULATORS
(J Prosthet Dent 1973; 29(3): 269-75)
The semi-adjustable articulator guides only the lateral component of the rotating condylar movement, whereas the fully adjustable articulator may be set to simulate all components of mandibular movement.
The purpose of this study was to measure the discrepancies that may exist in articulator capability due to incomplete movement simulation.
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The effects of following on cusp positions were ascertained:
a) Intercondylar widthb) The shape of the condylar housingc) The timing and direction of the side shift.
To preclude the necessity of transferring the casts from one articulator to the other, only the fully adjustable articulator was used.
The capabilities of semi- adjustable articulator was used as control, while the capabilities of fully adjustble articulator was used as experimental.
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A semiadjustable articulator was compared with a fully adjustable articulator to determine the discrepancy of eccentric pathways of cusp motion.
The effects of intercondylar width, mediotrusion timing, superior wall shape, laterotrusion direction, and immediate side shift were measured.
All produced a significant variation.
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PARTS OF AN ARTICULATORIt consists of an upper member and a lower member. The upper member represents the
maxilla and the lower member represents the mandible.
The upper member is a triangular metal plate and the lower member is a L -shaped frame. The upper and lower members articulate around the condylar
guidance. The condylar guidance represents the glenoid fossa of the temporomandibular joint.
A vertical rod (incisal pin) separates the upper and lower triangular components in the anterior end. The vertical rod rests on the incisal table of the lower member also known as the incisal guide
table.
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PARTS OF HANAU ARTICULATOR AND THEIR FUNCTIONS
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CONDYLAR GUIDANCE
The condylar guidances are the control
centers of the Articulator and they
adjustably assimilate the multiple
function of the glenoid fossa.
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The condylar Track may be adjustibly inclined on the horizontal transverse axis from a “zero” to a plus 60 degree or to a minus 20 degree. These inclinations are
termed the protrusive inclination and simulate the patients superior
wall of the fossa.
The condylar track may also be adjusted on the vertical axis from a “zero” sagittal to 30 degree. This angle is termed the progressive
Bennett angle and corresponds to the medial wall of the patients
fossa.
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CLOSED CONDYLAR TRACK
The closed condylar guidance track
rotates in an enclosed housing which
stops the Condylar Element ,preventing
the accidental disengagement of the
upper member.
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FIXED CENTRIC STOP
Some products have a centric stop at
the posterior end of the Track to limit
anterior movement of the Condylar
Element. When the Element rests
against the Stop it is at centric, the
point from which the protrusive or
Bennett angles both emanate.
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ADJUSTABLE PROTRUSIVE-RETRUSIVE
This micrometer adjustment permits the Condylar Element to be protruded 6mm from centric or to be retruded 3mm from centric.
An axial reference line transcribes the one mm. spaced lines on the P-R Screw and a like line appears on the Sleeve of the Guidance.
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Loosen the Thumbscrew at the medial side of the Guidance and rotate the P-R screw to abut the wide “zero” centric line with the Sleeve end .
Protrusion or retrusion of the Condylar Element can be adjusted by rotation of the P-r Screw. One full turn of the Screw equals 1mm protrusion or retrusion .
96
CENTRIC LOCK
Engagement of a centric lock depresses a Centric Pin, causing it to arrest the Condylar Element at the centric position.
When locked, the Upper Member is restricted to an opening and closing movement only.
Releasing the Centric Lock two full turns will disengage the Centric Pin and return the Elements freedom of movement in the Condylar track.
97
CONDYLAR SHAFTS
The Condylar Shafts adjustibly slide in the “wings” of the Lower Member.
They have been factory fixed by Setscrews.
A resilient Bumper will protectively stop the Upper Member and against the “wing” of the Lower member when fully opening the Articulator.
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DUAL-END INCISAL PIN
Coinciding with these Condylar Shaft adjustments is an alignment of the chisel edge of the incisal pin with the central table of the incisal guide.
The incisal pin serves as the forward control of the Aticulator.
It cooperatively maintains a vertical stop.
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It provides a stylus contact for the excursive movements of the Articulator.
A midline groove is cut in the Incisal Pin about one inch from the spherical tip. Five additional lines calibrated in mm extend on either side thereof. These lines are used for recording or altering the vertical dimension.
100
Two annular grooves appear on the Incisal Pin at 37 and 54mm below the Frankfort Horizontal Plane. These grooves form arbitrary vertical landmarks for alignment of the incisal edge of the maxillary centrals when making a Facebow transfer.
101
The incisal pin extends beyond the top of the Upper Member and provides a third point of stability when inverting the Articulator for mandibular cast mounting.
The spherical tip of this incisal pin serves as the Dual-End and is useful for fabricating customized acrylic anterior guide tables.
102
ADJUSTABLE INCISAL GUIDE
The Adjustable Incisal Guide provides an independent adjustment of anterior guidance. It cooperates with the Incisal Pin and Condylar Guidances to present a stable ,three dimensional programmed guide pattern for the mounted casts.
103
The Incisal Guide rotates antero posteriorly from a horizontal “zero” degree to a 60 degree positive inclination of protrusion which is then secured by the small Locknut. The central guiding table is 5.56mm wide and forms the inclined surface for the protrusive guidance of the incisal pin.
104
Seperately adjustable Lateral Wings
elevate by a Thumbscrew from a “zero’
horizontal to a 45degree inclined and
are fixed by a Thumbnut. The
calibrations are very small and serve
only as a reference
105
An anterior slot in the lower member allows repositioning of the incisal guide. Adjust and lock the Guide at “zero” horizontal and slightly loosen the platform Lockscrew.
This adjustment will place the incisal pin contact on the rotational center of the guide, thereby maintaining the vertical dimension when adjusting the inclination for protrusion.
106
ORBITALE INDICATOR
This crescent represents the patient’s infra- orbitale notch and is the anterior reference landmark of the Frankfort horizontal plane.
When used with an Orbitale Pointer on a face bow, it provides an anatomical vertical orientation for the upper arch, obviating the use of any average reference lines on the incisal pin.
107
MOUNTING PLATES
Mounting plates are used to lute the upper and lower casts to the upper and lower members of articulator by means of a gypsum material.
108
OPERATORY PROCEDURE
INTEROCCLUSAL RELATION RECORDS:
The maxillary and mandibular occlusal rims have been prepared and patient adjusted to the correct vertical dimension, the occlusal plane and the desired horizontal overlap.
The top of the Bitefork or Biteplane, the stern at the patient’s left, is covered with a triple layer of base plate wax. Heat seal the periphery and soften the wax throughout in a water bath.
109
The softened wax impression
material on the Bitefork is
seated against the occlusal
surface of the upper rim and is
hand molded into and around
the notches.
Chill the Bitefork index and
check to assure removal and
accurate replacement of the
bite rim.
The Bitefork may alternately
be attached directly to the
upper occlusal rim by heating
the forks and piercing them
fully into the wax rim.
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Two interocclusal positional records of a terminal relation are required:
1. A centric interocclusal relation record is patient recorded at the vertical dimension of occlusion.
2. A protrusive interocclusal relation record is patient recorded at approximately 6 mm anterior of centric. Closure is made to a near anterior, non- piercing occlusal contact, being certain that the bite rims remain securely seated on their ridges.
111
LABORATORY PROCEDURE ARTICULATOR PREPARATION: Adjust the protrusive inclination of both condylar
guidances to 30 degrees and tighten the Thumbnuts.
Adjust the Bennett angles of both condylar guidances at 30 degrees.
Adjust the incisal pin to align the midline calibration to the top edge of the upper member.
Adjust the incisal guide to a “zero” degree.
112
Slide the platform to align the incisal pin contact over the “zero” indicating line on guidance.
Adjust both the P-R screws to about “zero” centric line.
Secure the “zero” centric adjustment by tightening the thumbscrews at the medial side.
Apply a thin coating of petroleum jelly to all surfaces of the articulator that will be exposed to the stone mounting media.
Firmly attach a mounting plate to the upper member.
113
MOUNTING MAXILLARY CAST Swing the upper member
of the articulator open to the centric bumper. Securely attach the mounting platform to the lower member.
Insert the lower end of the Transfer Rod/ Bitefork index assembly into the socket of the mounting guide.
Raise the pivot to contact the underside of the Bitefork index and lock in position by the thumbscrew.
114
Securely seat and accurately lute the upper
occlusal rim into the occlusal wax index on the
bitefork.
Mixture of stone is placed on the wetted mounting surface of the cast. The upper member is then
swung forward to embed the mounting plate and to bring the incisal pin into contact with the incisal
guide.
Upon complete set of mounting, the sticky wax luting is carefully broken
from the occlusal rim. The mounting guide and transfer record are
removed from the lower member.
115
MOUNTING MANDIBULAR CAST
Invert the articulator and swing the lower member back to the bench.
Apply a thin coating of petroleum jelly to all surfaces of lower member that may be contacted by the gypsum material.
Firmly attach a mounting plate to the lower member.
116
Securely seat the mandibular cast in the bite rim and lute together with sticky wax.
A mix of stone is placed on the wetted mounting surface of the lower cast and mounting is completed, securing the central locks.
117
ADJUSTMENT OF HORIZONTAL CONDYLAR GUIDANCE
Upon complete set of the mount, the Articulator is placed into an upright position
Carefully cut the tacking at the occlusal surface and remove the centric interocclusal relation record
118
Loosen the centric locks and the Thumbnuts for horizontal inclination of the condylar guidances. Raise the Incisal Pin to remove the possibility of mechanical interference with the Incisal Guide
Seat the protrusive interocclusal relation record onto the lower occlusal rim. Carefully guide the Upper Member into the imprint of the protrusive relation record
119
Grasp the upper cast to maintain a
tactile feel of the casts at the protrusive
record and-
Rotate the Right and Left Guidances
back and forth toaccurately seat the
upper and lower rims into the protrusive
relation record
Tighten the Thumbnuts for horizontal
inclination. The protrusive relation
record is then removed.
120
ADJUSTMENT OF LATERAL CONDYLAR GUIDANCE (BENNETT ANGLE) HANAU Formula
L = H/8 + 12
is used for adjusting the lateral condylar guidance
In this formula, ”H” is the Horizontal Condylar (Protrusive) inclination and
“L” is the Lateral Condylar Guidance (Bennett Angle)
121
ARRANGEMENT OF ANTERIOR TEETH
The six upper and six lower teeth are
set up in the arrangement dictated by
the patient’s esthetic and phonetic
requirements.
122
INCISAL GUIDE PREPARATION
Lock the Articulator into centric. The occlusal rims are then seated onto their casts at the established vertical and centric relation
Lower the incisal pin into contact with the “zero” horizontal incisal guide, the chisel end of the pin resting crosswise on the center table and lock in the position by the Thumbscrew
123
ADJUSTMENT OF INCISAL GUIDE Gently guide the upper
cast into a straight protrusion
The lingual edges of the upper central incisors are brought into contact with the incisal edges of the lower incisors
The incisal guide is then rotated antero- posteriorly to make contact with incisal pin, tightening the small locknut to maintain the angulation
124
The upper cast is then guided into a right lateral cuspid to cuspid guidance relation by thumb pressure at the right side of the upper cast to assure the Bennett Shift
The Lateral wing is then elevated to contact the corner of the incisal pin and the Locknut is tightend to maintain this adjustment
125
Apply thumb pressure at the left side of the upper cast and guide it into a left lateral cuspid to cuspid excursion
Adjust the remaining Lateral Wing to contact the incisal pin and secure the adjustment by tightening the Locknut.
126
ARRANGEMENT OF POSTERIOR TEETH
The remaining teeth are set into centric occlusion and checked in working, balancing in protrusive excursions.
The incisal pin acts as the vertical stop and must remain in contact with the incisal guide surfaces from centric throughout all excusive movements
The waxed occlusal rims may be tried in the patient for esthetics, occlusal function.
127
Reset the completed occlusal rims onto their master casts. Seal the rims to the casts to preserve the tissue surface from plaster or stone seepage during the Flasking procedure.
128
PROCESSING
Before removing the master cast/waxed dentures, record the articulator calibrations for later use
Record the –Serial Number, R & L Horizontal Inclination, R& L Bennett Angle and Vertical of incisal pin
129
THE HANAU ARTICULATOR
HANAU H2
HANAU ARCON H2
HANAU WIDE VUE HANAU RADIAL SHIFT
HANAU ARTICULATOR
130
THE HANAU H2 ARTICULATOR
The Hanau model H was designed by Rudolf
Hanau a mechanical engineer in 1923. This
articulator is the forerunner of the present-day
Hanau H2.
Non- arcon type.
Hanau felt that as the “realeff” (resiliency and like
effect” of the denture supporting tissues)
decreased, the instrument would more closely
simulate mandibular movement.
131
The maxillary cast may be mounted on the
Hanau H2 articulator by means of a face-
bow transfer.
The following face-bows can be utilized
with the Hanau H2. These are:
1. Facia face bow
2. Earpiece face bow
3. Twirl bow
132
When transferring the ear piece face bow to the
articulator, the earpieces are seated on the
auditory pins of the centric locks.
The facia and earpiece face bows may use either
the orbitale or the incisal plane as the anterior
reference point for making the face bow transfer.
The anterior reference point along with the two
posterior reference points form the axis orbital
plane, which is transferred to the articulator
along with the maxillary cast.
133
The axis-orbital plane transfer allows the maxillary cast to be transferred to the
articulator so that the occlusal plane has a relationship in the
articulator that is similar to that in the patients skull.
When the orbitale is used, the face bow should be
equipped with an orbitale pointer that is related to the orbitale indicator on the upper member of the
articulator.
Without the orbitale pointer, the incisal plane is adjusted so that it is level with the upper notch on
the incisal pin when making the face bow
transfer.
134
Following the relationship of the mandibular casts to the maxillary cast by means of a centric relation interocclusal record, the horizontal condylar inclinations must be determined.
This is accomplished by means of a protrusive interocclusal record. The patient should protrude approx. 6 mm.
135
The horizontal condylar guidances are adjusted until the maxillary cast seats into the protrusive interocclusal record.
136
The amount of Bennett
movement is calculated from
the horizontal condylar
settings by Hanau’s
equation. Bennett angle L = H + 12 8
H= Horizontal condylar
inclination determined by
protrusive interocclusal
record
137
The incisal guide table is
adjustable in both sagittal and
frontal planes.
There is a single sagittal and
right and left frontal
adjustments.
The adjustments are made to
compensate the amount of
horizontal and vertical overlap
incorporated in the anterior
arrangement of denture teeth.
138
ARCON PRINCIPLE IN THE CONDYLAR MECHANISM OF ADJUSTABLE ARTICULATORS
(J Prosthet Dent 1963; 13(2): 263-68)
An articulator of the Arcon type has the condylar slot fixed to the upper member and the ball attached to the lower member. This positioning of the condylar elements is the reverse of the usual arrangement. Many articulators, including the Gnathologic type, use the arcon principle.
139
It is claimed that this principle truly represents the condition found physiologically where the temporomandibular fossae are located in the skull and condyles are a part of mandible.
140
MECHANISM OF THE ARTICULATORS
The mechanism of the articulators are reversed in function. In the condylar type of articulator , the angulation of the condylar slot is constant to the lower member.
During protrusive movements, the angulation changes between the upper member and the condylar slot of the articulator.
In the Arcon articulator, reverse is true.
141
PROTRUSIVE CONDYLAR READINGS The protrusive condylar
inclinations were measured in relation to the horizontal plane of the instrument.
When the condylar instrument (Hanau) returned to the centric position, the condylar slot remained at 40 degree angulation to that plane.
However, as the Arcon articulator returned to centric position, there was a changed angulation of the condylar slot at 39 degrees.
The difference in readings occurs because of the mechanical method of producing motion.
142
HANAU ARCON H2
The Hanau Arcon H2 was introduced by Hanau in 1977. It is a semiadjustable arcon type of instrument.
It consists of an upper member containing the condylar guidance elements and a lower
member to which the condylar spheres are attached.
The upper and lower members are mechanically connected.
The Hanau articulator is classed as a modified two- dimensional instrument.
143
The upper cast is oriented to the upper member
( which represents the skull) by face- bow transfer
record. The arbitrary face- bow is routinely used for
complete dentures.
The Hanau face- bow consists of a U- shaped frame or
assembly that is large enough to extend from the
region of the TMJs to a position 2 to 3 inches (5 to 7.5
cm) in front of the face and wide enough to avoid
contact with the sides of the face.
144
The parts that contact the skin over the TMJs are the
condyle rods, and the part that attaches to the
occlusion rims is the fork.
The condyle rods are positioned on a line extending
from the outer canthus to the top of the tragus and
approximately 13 mm in front of the external auditory
meatus.
This placement of the rods will locate them within 2
mm of the true center of the opening axis of the jaws.
145
The lower cast is oriented to the lower member of the
articulator, representing the mandible, by relating the
lower to the upper cast through an interocclusal CR
record.
The fork of the face- bow is attached to the maxillary
occlusion rim, thus the record is a simple
measurement from the jaws to the approximate axis
of the jaws.
146
The horizontal condylar guidances are adjusted by
an interocclusal protrusive record. The lateral
condylar guidances may be set arbitrarily or may be
adjusted by right and left lateral interocclusal
records.
The lateral condylar guidances on this articulator do
not allow upward, downward, forward, or backward
movement of the working condylar sphere.
147
The articulator is provided with an adjustable incisal
guide table that is routinely used for removable
prosthodontic restorations.
It has a straight incisal guide pin with a flat end, which
permits movements on the guide table.
The pin on the Hanau articulator is adjustable and
allows for vertical changes without changes in pin
position relative to the middle of the incisal guide
table.
148
HANAU RADIAL SHIFT : It was first produced in 1981.
Arcon instrument with fixed intercondylar distance of 110 mm.
The condylar guidance of the articulator is designed to incorporate a curved immediate side shift (radial shift) with an adjustable progressive Bennett angle.
Three incisal guide tables are available :- A mechanical table- A flat table- A pantacrylic table
149
HANAU WIDE VUE : These are the newest articulators introduced by HANAU.
HANAU WIDE VUE and HANAU WIDE VUE II, both are arcon instruments with a fixed intercondylar distance of 110 mm.
The only difference between the two instruments :
HANAU WIDE VUE has a closed condylar track and WIDE VUE II has an open condylar track.
150
THE WHIP MIX ARTICULATOR
The basic whip-mix articulator was designed by Charles Stuart (1955) and manufactured by Whip-Mix Corp.
It is an arcon articulator as the condylar controls are attached to the upper member of the articulator.
151
The intercondylar distance is adjustable to three positions by means of removable condylar guidance spacers along the instruments horizontal axis. :
Small (S) - 96 mm
Medium (M)- 110 mm
Large (L) - 124 mm
152
A face bow transfer may be utilized for mounting the maxillary cast. The horizontal condylar inclinations are set by means of protrusive interocclusal records.
The amount of Bennett movement is set by means of a lateral interocclusal record.
153
Spring latch assembly
The upper and lower members are mechanically attached by means of a spring latch assembly.
154
There are two different face bows that can be
utilized with the Whip Mix articulator. They
are:
1. Quick mount or earpiece face bow and
2. Adjustable axis or kinematic face bow
155
The earpieces are placed in the
external auditory canals when
adjusting the face bow to the patient.
The patient’s approximate intercondylar
distance is determined from the scale on the front of the face bow as S, M or L indicating small, medium or large
intercondylar distance.
The earpieces are seated on pins on
the condylar housings.
The bridge of the nose is utilized as
the anterior reference point.
156
Whip mix earpiece facebow attached to skull
157
Following the relationship of the
mandibular cast to the maxillary cast by
means of a centric relation interocclusal record, the horizontal condylar inclinations must be determined.
This is accomplished by means of protrusive interocclusal records. These records should be made at approx. 6
mm of protrusion.
The casts are seated in the interocclusal records and the
horizontal condylar guidance adjusted until it contacts the condyle.
The Bennett angulation is set with lateral
interocclusal records. The casts are seated in the lateral interocclusal records and the medial walls of the condylar
housings adjusted until they contact the
condyles.
158
The Whip-Mix articulator is equipped either with a mechanical incisal guide table or a plastic incisal guide table that can be individually customized with autopolymerizing resin.
The incisal guide pin is straight and one end is flat and the other end rounded. The flat end is used with the mechanical incisal guide table, while the rounded end is used with the plastic table.
159
The basic whip mix has numerous modifications that are available.
Condylar thumb- lock screws may be added to assure proper seating of condyles when making hinge articulator movements.
160
Optional immediate side shift guides are available from 0.25mm to 1mm.
When using the shift guides, the articulator must be equipped with detent mechanism to return the upper member of articulator to centric position.
161
The Accumount mounting system for articulator interchangeability utilizes a special table that is precisely attached to the lower member with a low-fusing alloy during manufacturing. The mounting plate is attached to this table when mounting the mandibular cast.
162
THE DENTATUS ARTICULATOR
The Dentatus is similar to the other articulators
described.
It is employed quite extensively in European
dental schools, particularly the Scandinavian ones.
It too is a semi- adjustable instrument that, like the others, can be modified
according to several patient variables.
163
AN EVALUATION OF BASIC ARTICULATORS AND THEIR CONCEPTS
PART I : BASIC CONCEPTS
PART II : ARBITRARY, POSITIONAL, SEMIADJUSTABLE ARTICULATORS
(Lawrence A. Weinberg ;J Prosthet Dent, 1963, vol 13)
164
The objective of all articulators is to serve as a laboratory aid in imitating physiological motion by substituting mechanical equivalents for anatomic parts.
Human motion of the mandible are 3-D curved motions because the skeletal framework is moved by muscles and hinged at TMJ.
165
Reproduction of any such motion requires the establishment of 3 fixed points on or attached to the object.
Recording the starting position, the path , and the end position of these 3 points is obtained to reproduce mandibular motion.
2 of the required guidances of mandibular motion are the condylar paths, the third point is measured at incisors known as incisal guidance.
166
Establishment of fixed base
Maxilla is fixed base from which mandibular motion is measured.
Face bow serve to transfer this relationship b/w maxilla and starting position of paths of mandibular movement.
167
Basic elements of mandibular motion
Described as pure or border movements of protrusive and right and left lateral excursions.
Protrusive excursion. Incisal guidance. Balancing condylar path. Balancing cusp inclines Working condylar motion bennett lateral shift.
168
ARBITRARY, POSITIONAL, SEMIADJUSTABLE ARTICULATORS
Articulators have been classified as arbitrary, positional, semi- adjustable, and fully adjustable.
ARBITRARY (Based on Monson Spherical Theory)
Examples: Monson Articulator, Hagman Balancer.
POSITIONAL ARTICULATOR ( Stansbery Tripod Concept)
169
The Stansbery tripod is a “positional” articulator. The objective of this concept is to obtain the static, or positional relationships of the mandible in centric relation, protrusive, and each lateral position
170
SEMIADJUSTABLE ARTICULATOR (Hanau Model H Concept)
The Hanau model H is one of the most commonly used semi- adjustable articulators. It was primarily designed for complete denture construction.
The objective of the technique is to closely produce mechanical equivalents of mandibular movements on the instrument.
171
RATIONALE FOR MATHEMATICAL STUDY:
The conditions of the evaluation are such that the occlusal errors produced by the clinical procedure identified with each articulator are cumulative rather than self- correcting.
An error can be defined as “deviation from the truth”, and truth as “agreement with reality”.
When applied to the study of articulators, an error produced in the occlusion will be considered as deviation from the known hypothetical
The second molar cusp height has been selected for the calculations because variations in condylar movement have a greater effect on the posterior teeth than on the anterior teeth.
172
When applied to the study of articulators, an error produced in the occlusion will be considered as deviation from the known hypothetical
The second molar cusp height has been selected for the calculations because variations in condylar movement have a greater effect on the posterior teeth than on the anterior teeth.
173
THE EFFECT OF THE CHANGE IN CONDYLAR INCLINATION ON OCCLUSION
Approximate error at the second molarBalancing cusp height (mm)
Approximate error at the second molarWorking cusp height (mm)
Average anatomic location of the hinge axis
0.2 0.2
Arbitrary location of the anterior point of orientation
0.2 No error
Straight condylar path 0.2 0.2
Fischer angle 0.1 No error
Individual working condylar motion
No error 0.8
Maximum total error 0.7 1.2
174
SELECTION OF AN ARTICULATOR
If occlusal contacts are to be perfected in centric occlusion only, a simple, sturdy, hinge-
type articulator without provision for lateral or
protrusive movements can be selected.
This type of instrument has been called one- dimensional
because only one interocclusal record is necessary for its
adjustment and use.
175
If denture teeth are to have a cross-arch and cross-tooth
balanced occlusion, the minimum requirement is a semi-adjustable
articulator.
This may be an instrument with individually adjustable condylar
guidances in both the vertical and horizontal plane, such as the
simple instruments in the hanau university series, the whip mix
articulator, or the dentatus articulator.
176
If more control of the occlusion is desired, a completely adjustable
three dimensional articulator is of value.
A three dimensional articulator requires a CR
record, at least two lateral records, and
some means for controlling the height and inclinations of the
cusps.
The means for their adjustment may be
interocclusal records or three-dimensional
graphic tracings made by a kinematic face-bow
apparatus.
177
The more complicated articulators pose some
problems in making complete dentures because of
the resiliency of the soft tissues of the basal seat
on which the recording bases must rest. Because
this resiliency permits some movement of the
bases in relation to the bone, the records made are
not necessarily records of the true path of
movement of the bone.
178
SUMMARY
The trend in articulators is being influenced primarily by prosthodontists working in the fields of fixed restorations and full mouth rehabilitation. They have suggested and devised instruments that are much more complicated than those traditionally used by dentists providing removable prosthodontic service.
There are a number of very fine and fully adjustable articulators, but most of these are not easily adapted for use for complete denture patients.
179
The reason for this lack of practical application for complete denture patients is the soft tissue foundation upon which the recording bases must rest. As long as the recording bases that support the recording instruments can move in relation to the underlying bone, the highly sensitive articulators cannot be accurately adjusted.
180
REFERENCES
PROSTHODONTIC TREATMENTFOR EDENTULOUS PATIENTS; TENTH EDITION
SHELDON WINKLER; ESSENTIALS OF COMPLETE DENTURE PROSTHODONTICS; SECOND EDITION
L.A. WEINBERG; AN EVALUATION OF BASIC ARTICULATORS AND THEIR CONCEPTS PART 1;JPD 1963; 13(4)
L.A. WEINBERG; AN EVALUATION OF BASIC ARTICULATORS AND THEIR CONCEPTS PART 2; JPD 1963; 13(4)
181
MITCHELL; ARTICULATORS THROUGH THE YEARS. PART 1. UPTO 1940; JPD; 1978; 39(3)
A. RAHINI; CLASSIFICATION OF ARTICULATORS;JPD 1980; 43(3)
LAWRENCE A WEINBERG: ARCON PRINCIPLE IN CONDYLAR MECHANISM OF ADJUSTABLE ARTIVULATORS; JPD 1963; 13(2)
NEAL D BELLANTI: SIGNIFICANCE OF ARTICULATOR CAPABILITIES; JPD 1973; 29(3).