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John G.

Knapp DDS MS Page 1 March 5, 2007


CLASSIFICATION OF DENTAL RELATERS AS
OCCLUDERS AND ARTICULATORS
COURSE #40600 :: Supplement

John G. Knapp DDS MS

Introduction:
Classifications should facilitate the use or understanding of
the classified items. This applies to the classification of
articulators and related instruments as well. The purpose
of this supplement is to bring clarity and simplicity to
understanding and selection of these instruments.

Goal: Gysi adaptable instrument:


This represents an early adjustable
In this course one simple classification of articulators is articulator (1912)
introduced. This is a new approach based on symmetry
and simplicity. The Dental Relater Classification System is
introduced as a new term

Objectives:
We will show various classification methods. The student
may then select the classification of choice as they all have
advantages. It is hoped that the student will be able to use
the classifications in understanding their use, subtleties,
the selection and have the vocabulary for discussion with
others.

Method:
Classifications are presented to show by example that
there are various interpretations of the array of CEREC in-office direct milling system:
instruments which have been developed. Descriptive text, This represents an adjustable occluder
with virtual reality capability and
images and videos are used to emphasize the nuances. CAD/CAM machining
John G. Knapp DDS MS Page 2 March 5, 2007

STANDARD CLASSIFICATION:
The standard approach for articulator classification is based
on the Glossary of Prosthodontic Terms, which classifies
articulators into four types: Class I through Class IV.

Class I
This is a simple holding instrument capable of accepting a
single static registration. Vertical motion is possible.

Class II. Class I: Simple hinge cast


holder
This is an instrument that permits horizontal as well as
vertical motion but does not relate the motion to the
temporomandibular joints.

Class III.
This is an instrument that simulates condylar pathways by
using averages or mechanical equivalents for all or part of
the motion. These instruments allow for orientation of the
cast relative to the joints and may be arcon or non-arcon Class II: Monson
instruments. Maxillomandibular instrument
based on geometry
• Arcon articulator - An articulator that maintains
anatomic guidelines by the use of condylar analogs in
the mandibular element and fossa assemblies in the
maxillary element.

Class IV.
This is an instrument that will accept three-dimensional
dynamic registrations. These instruments allow for
orientation of the cast to the temporomandibular joints and Class III: Hanau non
replication of all mandibular movements. adjustable condyle
movement instrument

Fully adjustable condylar


simulating instrument which
will accept dynamic
registrations
John G. Knapp DDS MS Page 3 March 5, 2007

OPEN-END DENTAL RELATER CLASSIFICATION:


This is an alternative classification system. It is
comprehensive but complex. For our discussion here is an
alternative classification of articulators. Advantages of this
system allows for organization of instruments based on a
historical and heuristic relationship. It is open-ended and
further allows for development of methods beyond today’s
current technology. This includes cast relaters as
articulators.

Class A
This is a holding device for relating casts with a fixed
intermaxillary relationship with the possibility of a hinge
opening only function. Frequently there was a hinge stop
to enable the operator to see and use the intermaxillary
space if no teeth were available to stop further closure of
the intermaxillary space. There was no orientation of the
motion to the TM joints and there was no relation to
excursive function of the mandible Simple hinge with vertical stop from
the Whip Mix Co. historical
collection

Class B
These instruments relate one working cast and two
opposing casts. The opposing casts have an anatomical Hanau Twin Stage Occluder
representation and the other is a functional representation
of chewing.
This is a holding device with a fixed relationship. They had
either a vertical or hinge opening only function. They had a
vertical stop similar to the class A instrument. There was
no correlation to the motion to the TM joints.

Jelenco Verticulator
John G. Knapp DDS MS Page 4 March 5, 2007

Class C
This is an instrument, similar to a Class A, which also
permits horizontal motion to match tooth facets during cast
articulation. Occasionally they have vertical stops but that
is the exception rather than the norm.
Some of the original instruments are of this type and date
back to the 19th Century.
This type of instrument is widely used today for fabrication
of simple restorations like single crowns. The disposable
plastic instrument is very low in cost and provides a Bonwill 1858

credible value.

Spring hinge, reusable, metal

Spring hinge, disposable plastic


John G. Knapp DDS MS Page 5 March 5, 2007

Class D
This is an instrument, similar to a Class A, which also
permits horizontal and vertical motion based on classical
geometry. They are completely unrelated to the
movements of the mandible in the envelope of motion
except for simple opening and closing. These movements
are not at all related to the TM joints.

Balancer Jr, Hagman

Mandibulomaxillary instrument,
Monson, 1925
John G. Knapp DDS MS Page 6 March 5, 2007

Class E
This is an instrument, similar to a Class A, which also
permits horizontal motion. This motion is based on a
simulation of the function of the TM joints. Class E
articulators simulate condylar pathways by using average
mechanical equivalents for all or part of the motion.

Gysi, Simplex

Hanau, 147-I

Stephan

Denture tripod,
Stansberry

Phillips, Student

Steele’s
John G. Knapp DDS MS Page 7 March 5, 2007

Class F
This is an instrument, similar to a Class E, which also
permits horizontal motion. This action simulates condylar
pathways movement by using adjustable mechanical
equivalents for all or part of the motion.
Orientation of the cast relative to the joints and may be
arcon or non-arcon instruments. An arcon articulator is an
instrument which maintains anatomic guidelines by the use
of condylar analogs in the mandibular element and fossa
assemblies in the maxillary element. Non arcon
instruments simulate mandibular movement where the
condyle analog is attached to the mandibular member of
the instrument.

Non-Arcon Articulators

Hanau, University

Hanau, 96H2O

Dentatus, ARL
Gysi, Adjustable

Hanau, Kinscope
House, Rotary Grinder
John G. Knapp DDS MS Page 8 March 5, 2007

Class F:
Arcon
These illustrations show a variety of articulators. Other
instruments are shown in the class G group which have
similar condyle analog relationships.

Whip Mix, 8500

Hanau, H2 Arcon

Dentatus, ARA
John G. Knapp DDS MS Page 9 March 5, 2007

Class G
This is an instrument, similar to a Class F. These
instruments allow for orientation of the cast to the
temporomandibular joints and replication of all mandibular
movements. They permit:
Acceptance of three-dimensional dynamic registrations

Hanau, Adjustable Ney

TMJ

Denar, D5A

Stewart, Gnathological
Computer

Granger, Gnatholater
John G. Knapp DDS MS Page 10 March 5, 2007
Digitally adjusting
the anatomy
Class H
These are not analog instruments. These
representations do not permit the mounting of casts. A
virtual representation permits:
• CAD/CAM fabrication of dental restorations
without analogs
There are two sub-classifications to this type including:
Sub-class 1 (H1)
This is a digital representation similar to a class G. This Optical Milling Digital
permits CAD diagnosis of malocclusions and Scanne Tool Interphase

representations of TM joints.
Sub-class 2 (H2)
This is a digital representation similar to a class C.

Class I
This is like no other articulator system. The potential for
this concept lies in the future but it should now be
considered. This is a biologic representation of the
functional demands of a given stomatognathic system. The
purpose of this would be to replace all or part of the
dentition using agents to promote or retard the the
metabolism of the individual. Directing the replacement of
missing structures will be based on cellular engineering.
This representation would allow for development of the
“True Determinants of Occlusion”. These would include the
genetic coding of RNA for protein synthesis. Additionally it
would include mapping of the growth centers and the
functional matrix. Humeral agents, not yet discovered,
would be the activators of this development.
A developmental plan would include replacement of the
dental complex of bone, periodontium, teeth innervation
and vascularization. This plan would direct the “True
Determinants of Occlusion” to design of replacement
anatomy including the coordination of development within
the “Functional Matrix”. It would incorporate a stimulation
of growth center control and introduction of genetically
engineered cells strategically implanted to permit
functional unit system generation or regeneration. RNA
could be guided in selective protein synthesis creating a
biologic matrix. As yet unknown media would cause
selective differentiation of a stem cell like complex with
selective mineralization within a biologic matrix. This
system also generates a response in the form of
biologically compatible remodeled or replaced exact tissue
types, functioning in a normal fashion.
John G. Knapp DDS MS Page 11 March 5, 2007

CONSEQUENCES OF THE OPEN-END


ARTICULATOR CLASSIFICATION SYSTEM
Historical value
In this system there is an apparent sequential
development in the design of these instruments. This
apparent sequential development is a false interpretation
as there is no real historic merit to this interpretation.

Selection value
Understanding the influence of the determinants of
occlusion and articulation in biomechanics can direct the
operator in the selection of the appropriate instrument. As
the articulator classification increases the end control
adjustment sophistication increases. This may signal a
challenging learning curve. With increasing sophistication
in instruments and the related jaw relation records there is
a concomitant demand on the operator in understanding,
using, supplying and maintaining the instrument.

As the classification increases, the relative effectiveness of


the TM joint interpretation in the instrument increases.
When there are few anatomic landmarks available from the
patient, understanding and appropriately using the
instruments will help in designing the appropriate occlusal
and articulation scheme. This understanding can also allow
the operator to alter the settings of the variable elements
to gain a restorative or prosthodontic result that is beyond
a simple reproduction of functionally generated occlusions.

A higher classification may suggest a benefit / value


gradation however without understanding of the
consequences of the end control factors this is a false
indicator. The possibility of peer pressure in instrument use
is a dangerous interpretation.

While we are still in the age of industrialization and


modernism, understanding of biomechanics of the
stomatognathic system, will allow us to develop future
systems beyond a mechanical approach to articulation.
John G. Knapp DDS MS Page 12 March 5, 2007

Grouping of the Dental Relater classifications via bio-


mechanical interpretation
Instruments can also be grouped on the basis of their
biomechanical functions. There is basis for three groups.
These include geometry, tm joint analog and functionally
generated pattern instruments. This can be grouped from
the open ended system of classification.

The Geometry basis includes instruments from Class A, D.


These instruments are derived from Classical geometric
shapes which are used as references for orientation of the
plaster casts in these instruments.

The TM joint analog basis includes instruments from Class


C, E, F, G, H1. They all have intra-cast relationships based
on a centric position. The design components have upper
plate that holds the maxillary cast and a lower plate that
holds the mandibular cast. They have a vertical stop that
delimits closure progress. The posterior frame supports the
vertical dimension of occlusion through a tm joint analog
and together with the anterior vertical stop relates the
upper and lower plates in the three dimensional
framework.

Functionally generated pathways of articulation include


instruments/representations which match the wear facets
of teeth opposing a working cast of tooth analogs. These
include instruments of Class B, C, H2. This instrument
group is designed to facilitate a relationship of a working
cast to an opposing functionally generated surface.

Type H1:
This is a digital representation similar to a class G. These
are not analog instruments. These representations do not
permit the mounting of casts. This virtual representation is
based on matching facetted occlusal anatomy of existing
teeth and possible combination of occlusal shapes to act in
harmony without consideration of joint function

DENTAL RELATER CLASSIFICATION SYSTEM


John G. Knapp DDS MS Page 13 March 5, 2007
The classification of instruments in the remainder of the
courses is based on the very simplest of terminology.
There is a four terminology that defines all instruments.
These terms include:

Relater
This is an instrument which simulates an analogy of oral
dental anatomy.

Occluder
Is a mechanical instrument designed to relate analogs of
dental occlusal anatomy in a specific position. Usually this
position is maximum intercuspation or centric relation
occlusion.

Articulator
Articulators are mechanical designed to relate the position
of the maxillary and mandibular opposing plaster casts of
teeth to one another and to other determinants of
occlusion.

Adjustable
The term suggests that some aspects of these instruments
are adaptable or modifiable. The end control factors may
represent either positional check bite positions or
adjustable end control factors such as the determinants of
occlusion.

Fixed
These instruments are very simple and rigid. They capture
an unchangeable relationship.

We will base this classification on the simple term


“Relater”. All relaters are a combination of occluders or
articulators which may be either fixed or adjustable.

The term Fixed Occluder incorporates all standard


classification instruments of Class I. For example simple
hinge, Verticulators, Twin Stage hinges, and even denture
duplicators.

The term Adjustable Occluder incorporates open end


classification instruments Class H and I. For example the
CAD/CAM devices like the Cerec

The term Fixed Articulator incorporates most of the


instruments which are used today. In the standard
classification this would include Class II and III. For
John G. Knapp DDS MS Page 14 March 5, 2007
example this may vary from the Bonwill to the Steel’s or
the Monson to the disposable plastic.

The term Adjustable Articulator incorporates all of the fully


Click on the
adjustable articulators which are listed in the Standard
photograph of each of
Classification IV. Examples of this include the Gysi
the analog instruments
Adjustable, the Whip Mix, the Denar and the Stewart. This in the grid to see video
disregards the concept of arcon or non arcon instruments clips of instrument
or the idea of semi or fully adjustable. action only if you are
enrolled in course
The Dental Relater Classification could be pictured in this 40600
simple grid.

Occluder Articulator
Fixed

Twin stage Cresent/Stephan


Adjustable

Cerec Denar

The value of this classification is in its simplicity and ability


to include instruments which do not fit into any of the
previous classifications. It combines two aspects of
dentistry by implying TM joint related variables to
functionally related variables and the clinical need for
opposing casts of natural teeth.

Conclusion:
The classification system which this author believes
delivers the best value is the simplest. The historic
argument of geometric based instruments vs. TM joint
range of motion instrument suggests a lack of vision. The
real argument lies in the dichotomy of functionally based
interpretations of occlusion contrasted against the
biometrically derived schemes.
John G. Knapp DDS MS Page 15 March 5, 2007
References:
Bonwill, WGA., The Scientific Articulation of the Human
Teeth as Founded on Geometrical, Mathematical, and
Mechanical Laws. Dent. Items of Interest, pp. 617-643,
October 1899

Weinberg LA. An evaluation of basic articulators and their


concepts. Part I. Basic concepts. J Prosth Dent, 13, 622-
644, 1963

Weinberg L. A. An evaluation of basic articulators and their


concepts. Part II. Arbitrary, Positional, Semi adjustable
Articulators. J Prosth Dent, 13, 644-663, 1963

Celeza, FV, An analysis of articulators. DCNA 23: 305-326,


1979

Hall, RE, An analysis of the development of the articulator.


JADA 17:3-51, 1930. In Vol II

Mitchell DL and Wilkie ND. Articulators through the years.


Part I. Up to 1940. J Prosth Dent, 39:330-338, 1978

Mitchell DL and Wilkie ND, . Articulators through the years.


Part II. From 1940. J Prosth Dent, 39:451-458, 1978

Mohamed, S.E., Schmidt, J.R. and Harrison, J.D.


Articulators in Dental Education and Practice. J Prosth
Dent, 36:319-325, 1976

Smith, D. Does one articulator meet the needs of both


fixed and removable prosthodontics? J Prosth Dent,
54:296-302, 1985

Awni Rihani, Classification of articulator. J Prosth Dent,


43:344-347, 1980

Monson, GS. Occlusion as Applied to Crown and Bridge


Work. J Nat Dent Assoc 7:399-413, 1920

Alfred Gysi, Practical application of research results in


denture construction. JADA 16:199-223, 1929

Schweitzer, J.M. An evaluation of 50 years of


reconstructive dentistry. Part II: Effectiveness. J Prosth
Dent, 45: 492-498, 1981
John G. Knapp DDS MS Page 16 March 5, 2007
Becker C.M. and Kaiser D.A. Evolution of Occlusion and
Occlusal Instruments. J Prosthod 2:33-43, 1993

Schweitzer, J.M. An evaluation of 50 years of


reconstructive dentistry. Part II: Effectiveness. J Prosth
Dent, 45: 492-498, 1981

Becker C.M. and Kaiser D.A. Evolution of Occlusion and


Occlusal Instruments. J Prosthod 2:33-43, 1993

International Prosthodontic Workshop on Complete


Denture Occlusion, Lang, BR and Kelsey, C, coeds.
University of Michigan Press, 1972

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