ARTICULATORS THROUGH THE YEARS

5

A pictorial history of the articulators at the National Naval Dental Center is presented. All articulators

will be listed with a unique attribute noted.

The Plaster Articulator: Plaster extensions of the distal portions of the cast articulated the cast

together. Credited to Philip Pfaff of Berlin who was the dentist of Frederick the Great.

The Barn Door Hinge: Heavy-duty hinge modified by bending each arm 90 degrees to form a L-

shaped upper and lower member.

The Adaptable Barn Door Hinge: Has an anterior vertical stop and it is Usually a machine bolt.

The Kerr Articulator: Hinge is on the same plane as the occlusal plane. Allows fixed protrusive and

lateral movement.

The New Century Articulators (Snow in 1906): Rotational centers placed 4 inches apart.

The Acme Articulator: Elaboration of the New Century articulators. Three different models were

made to allow for three ranges of intercondylar distance.

The Gysi Adaptable and Simplex: The adaptable was introduced in 1906 but was too technical and

cost too much so the simplex was introduced in 1914. The condylar guidance was fixed at 33° and

has a S-shaped curve in profile.

The Bixby Attachment (1894): A forerunner of the face bow in attempt to regulate the

anteroposterior position of the cast on the articulator.

The Maxillomandibular Instrument: Designed by Monson in 1918; based on , the spherical theory.

Average radius of the sphere was 4 inches but could be changed.

The Stephan Articulator (Developed in 1921): Has a fixed condylar inclination and allows for an

arbitrary lateral movement.

The Hanau Model M Kinoscope (Early 1921): The Bennett angle is adjusted by changing the

eccentric cone on the outboard post.

The Hcfiher Relator: Developed in 1923 by Joseph Homer.

6

The Wadsworth Articulator: An adjustable intercondylar distance.

The Hanau Model H110: Designed to encompass mechanical averages (L= H/8 + 12).

The Hanau Model H110 Modified: Introduced the incisal guide table.

The Hageman Balancer (in 1920's): Based on the spherical theory of occlusion. Mandibular teeth

constructed first.

The Phillips Student Articulator (Model C) (Developed around 1929): Its developer claimed it

could follow any graphic record.

The Stansberry Tripod Instrument: Reproduces positions but not movements.

The House Articulator (Developed in the 1920's): It has a rotary milling device.

The Precision Coordinator: Developed in the early 1930's by Terrell. It has a Curvilinear condylar

guides.

The Hanau Crown and bridge Articulator: Small articulator that can simulate working and

balancing side excursions of 15° and protrusive of 30°.

The Phillips Occlusoscope: Phillips believed in only two (condylar) determinants of occlusion

therefore the incisal pin rested on a flat plane.

The Stephan Articulator (Modified) in 1940: Simple hinge joint with longer -'Upper and lower

members than the 1921 model and a fixed condylar path of 30°.

The Stephan Articulator Model P: An incisal pin and fixed 10° incisal guidance.

The Fournet Articulator: No lateral movement.

The Johnson - Oglesby and Moyer Articulators: The Johnson - Oglesby instrument is a small,

nonadjustable, flexible articulator developed around 1950. The upper member of the Moyer has

a ball and socket adjustment. It is a mean value articulator.

The Coble Articulator: A hinge articulator that maintains vertical dimension and

centric relation but does not allow for functional movements.

The Galetti Articulator: The casts are held mechanically without plaster.

7

The Pankey-Mann Articulator: Occlusal plane of the mandibular teeth are based on the Spherical

theory.

The Stuart Articulator: The settings are programmed by using pantographic tracings from the

patient.

The Hanau Model H2 Series: Increased the distance between the upper and lower member from

95mm to 110mm and added an orbital indicator to the upper member.

The Dentatus ARL Articulator: Allows for the transfer of cast from one articulator to another

while the same relationship is maintained.

The Improved New Simplex Articulator: Measures Average movements. It has a Condylar

inclination of 30°, Bennett movement of 7.5°. The incisal guide table adjusts from 0° to 30°.

The Verticulator: Developed to be used with the functionally generated path technique and

quadrant trays.

The Ney Articulator: No locking device between upper and lower members. It has varying

intercondylar distances. Custom ground plastic inserts can be used in the condylar elements.

The Hanau Model 130-21 Articulator: One of the models of Hanau university series. It was

introduced in 1963.

The Whip-Mix Articulator: A simplified version of Stuart's fully adjustable articulator. It cannot

be set to all positional records.

The Simulator: A fully adjustable articulator that can be set from pantographic tracings,

positional records, and other tracings.

The Denar D4A Articulator: it is a fully adjustable articulator. Programmed from tracings made

with a pneumatically controlled pantograph.

The Dentatus ARO Articulator: A moveable arm that holds the mandibular cast for repositioning

the mandibular cast without remounting.

8

REVIEW OF LITERATURE

9

The Early Years

Before the 1840s, a time that coincided with the development of dentistry as a profession in the United

States, Europe was our principal source of dental knowledge and practices. Investigating the infancy of

American dentistry is itself a challenge. Anecdotal information, inadequate historical records, and little

early scientific research have obscured much of what we know. It is not surprising that there are very few

references to articulators in the early literature; however, since 1900, the distinction of "inventing the

articulator' has been given to two prominent European dentists of the 18th and 19th centuries, Phillip

Pfaff and Jean Baptistc Gariot. In 1756, Phillip Pfaff, dentist to the court of Frederick the Great, : King

of Prussia, first described his method of making plaster casts. He described a £ way of making impressions

with sealing wax, one half of the mouth at a time, t removing the sections individually, and reassembling

them outside of the mouth. I He then poured plaster into the impression. If natural teeth were present, Pfaff

had I the patient bite into the wax so that the relationship of the teeth could be considered. For this reason,

it has been assumed that he used a device to preserve the relationship of the casts. Some scholars

therefore believe that he was the first to use a dental articulator,3 Even though this would seem logical,

it can only be considered conjecture, because Pfaff never mentioned such a device. In 1805, Jean ;

Baptiste Gariot described his method of making plaster casts and extending them | posteriorly to provide

an indexing mechanism for preserving the relationship of the I casts. Gariot was indeed the first to describe

a "plaster articulator

Note: Based on their function, "plaster articulators" would be appropriately classified as Class I articulators

or as Cast Relators. The Glossary of : Prosthodontic Terms (7th edition) defines a class I articulator as "a

simple holding instruments capable of accepting a single static registration." A cast relator is defined as a

"mechanical device that orients opposing cast to each other without t: reference to anatomic landmark."

The concern is not how a "plaster articulator" is classified, but whether it should "be described as an

articulator at all. The use of the terms "instrument" and mechanical device in the above definitions

clearly indicates that there is a distinction between appliances designed specifically for mounting

opposing casts and casts that are mounted by extending the plaster bases posteriorly for indexing. The

term planter articulator is familiar and is widely understood for what it represents. However it should be

recognized that plaster articulator is a misnomer because it actually refers to a product or method for

mounting cast with a plaster index and not to an instrument appliance or a device terms that are more

descriptive of mechanical articulator.

10

It was a simple plaster indexing procedure, which came to be known as the "oiled board" articulator (Fig

1). "Plaster articulators" were popular well into the 20th century, and through the years, many designs

have been reported in the literature. An early variation on the Gariot design was called the "slab"

articulator4 (Fig 2). Authors who described and used "plaster articulators" were Richardson, 1860, Coles,

1876, Peezo, 1916: and Essig, 1937." It is also noteworthy that three U.S. patents for "plaster articulators"

were granted between 1857 and 1888:

(a) A. A. Blandy of Baltimore, MD. Patent #16,708, March, 1857

(b) G. F. Schaffer of New York, NY. Patent #99,698, February, 1870

(c) J. L. P. Leman of Middlesex, England. Patent #386,711, July, 1888

Figure 1: A stylized model of Gariot's "oiled board" articulator. Posterior

extensions to the casts were poured on.an oiled board. Gariot made the indexing

holes with his little finger.

Figure 2: The casts, which have been extended toward the back and that portion

painted with a separating placed in a mass of soft plaster. The plaster is allowed to

set to become the indexing device.

The Gariot Articolator Mvth:

A misconception regarding the contributions of J. B. Gariot to the development of

articulators has persisted for nearly a century. Early authors, including Prothro,

Wilson, Gillis, Hall, and Turner, when reviewing the history of articulators, gave

credit to Gariot for inventing the fist mechanical hinge-type instrument. Even

recent aubors, including Heartwell and Rahn, Scandrett, Celenza, Mitchell and

11

Wilkie, and Becker and Kaiser, by merely repeating statements of early authorities, have

contributed io 'he perpetuation of this " Gariot articulator myth" Today, it continues to be

found in the literature and in school manuals and program study guides as well. It is now

clear that the origin of the myth is Vincento Guerini's paper, "The Historical Development

of Dental Art," read before the 3rd International Dental Congress in 1900. Guerini stated

that, "An eminent French dentist, Jean Baptiste Gariot, contemporary of Gardette, invented

the articulator about 1805." The paper was published in English in Dental Cosmos in

1901.These facts and others were covered superbly by George B. Denton in 1933, but have

been largely overlooked. Denton suggested that because Guerini did not elaborate on his

statement, dentists of the early 1900s incorrectly assumed that he was referring to the

mechanical hinge-type articulator that was very commonplace by that time. Very little is known

about the origins of dental articulators. All that can be said with assurance is two documented facts:

1) Phillip Pfaff was the first to describe a wax impression procedure and a method for making plaster casts;

and 2) Jean Baptiste Gariot was the first to describe a method for mounting casts and preserving their

relationship with a plaster index ("plaster articulator"). However, it must be Cognized that because Gariot

never claimed the procedure as an innovation, it may not have been original with him. Even though "plaster

articulators" were the first methods to be used for preserving the relationships

Of casts, sometime before 1840, the mechanical hinge articulators emerged to become a new and widely

used device for this purpose. The history of the origins of hinge articulator is even more of a mystery than

that of the plaster articulator.

It may never be known when, where, or from whose imagination the first mechanical hinge articulator

emerged. It is likely that early hinge articulators were handmade

Contrivances, constructed from materials at hand. Even though well into the 20th century plaster was

commonly used to relate casts, some time before 1840 mechanical hinge articulators seem to have become

the preferred type. According to the literature, there were three primary reasons expressed for their use and

popularity; these mechanical hinge articulators were more convenient and easier to use, allowed

modifications of the cast position when inaccuracies were suspected, and saved plaster of Paris.' From the

beginning, the term "articulator" was not popularly ascribed to the hinge-type devices.

Among the more common terms were "antagonizing frames", "occluding frames," "occlusion frames," and

"antagonizors."1' In 1914, Wilson emphatically expressed his opposition to the widely used designation,

articulator," arguing that it was a misnomer because, in the anatomic sense, the

12

term means "a joint.'" Similarly, he considered "articulation of the teeth" incorrect because teeth can

only articulate upon their proximal surfaces and not upon their occlusal surfaces. Wilson stated that

such instruments were intended to occlude and antagonize the teeth, not articulate them. Wilson

suggested the instruments are used to arrange artificial teeth in occlusion and "they should be in

'antagonization." In his textbook, Wilson referred to a simple hinge articulator as an "Occlusion Frame'

and to all others as "Antagonizors." This controversy concerning terms was quite evident in the literature

for years, but with the passage of time, "articulation" and "articulator" have become the accepted terms.

In the Glossary of Prosthodontic Terms (seventh edition): "articulation" is defined as, "in dentistry, the

static and dynamic contact relationship between the occlusal surfaces of the teeth during function. "6 The

term "articulator" is defined as "a mechanical instrument that represents the temporomandibular joints

and jaws, to whick. maxillary and mandibular casts may be attached to simulate some or all mandibular

movements." In contrast, the Glossary describes- "occluding frame" as an obsolete term, while omitting

the terms, antagonizing frame" and "antagonizors" altogether.

Early References to Mechanical Hinge Articulators

The first published reference to the earliest mechanical hinge articulators is probably Fairhurst's

discussion of Hovarth's articulator and Ladmore's articulator of the 1830s. Fairhurst described these

and other early examples as instruments consisting of two wooden or metal blocks or slabs hinged together

with a simple hinge. These articulators and others of the day must certainly have resembled what is now

commonly referred to as the "barn door hinge". Note:

The history of articulators would be incomplete with out mentioning the "barn door hinge". It is practically

a part of dental folklore. Today the term means different things to different people. For some, it represents

a hinge articulator. For Others, it may reflect dentistry's antiquity. For still others, it is simply an inside

joke. In reality, the "barn door hinge" represents more fact than fiction. Articulators literally fashioned

from barn door (or other similar) hinges have been commonly used through the years, and a few may be

found in use today. The "barn door hinge" did manage to make it into the vernacular and into the literature

as well.

13

Figure 3:

A Barn Door hinges Articularor

About 40 hinges type articulators were

Fig 4: Standard articulator

One of the earliest mechanical hinge articulators illustrated and discussed in some

detail in the literature is attributed to Thomas W. Evans.

Note:

Thomas W. Evans. Was known primarily as an American dentist and has described as "American's Dentist

to European Royalty". Evans was the first person to study and develop the use of vulcanite rubber for

denture bases.1 He has been credited with the introduction in Europe of both vulcanite rubber as a denture

base material (1848) and of nitrous oxide as a general anesthetic (1868). It is not know exactly when Evans

invented his articulator, but it is believed to have been about 1848-1849

The T.W. Evans articulator is a "very simple instrument by means of which the extension of the plaster

back of the plates and wax is rendered unnecessary. '"S He emphasized that the most important feature was

that vertical dimension could be preserved or altered as required.

14

Harris was initially introduced to this device in 1849 when Evans sent a sample of one to

the editors of The American Journal of 'Dental Science for evaluation. As a co-editor, Harris

noted that, "With the exception of a plaster antagonizing model, i t is superior to any of

the articulator." In April J850, .John D. Chevalier of Mew York submitted, with a letter to the

editor, a woodcut of the Evans instrument and a description of its use.

Fig 5: Thomas W.Evans Articulator (woodcut)

Cameron's It is not known if Thomas Evans patented his articulator, and this illustrates one of the obstacle

encountered by investigators seeking early patent data: according to House, the records of the US patent

office before 1870 may be incomplete.

The First US Articulator Patent: The first US patent for articulator was issued to James Cameron on

April 30, 1840 (Fig 6A and B).9

Cameron's articulator was unique in its departure in design from other hinge-type devices, and it is not clear

why that design was made. However, the inclusion of the anterior-posterior and vertical adjustment features

does show his concern for the pervasive problems related to the wax impression and "mush-bite" techniques

of the day and the necessity to make corrections using articulators. Cameron's

15

articulator also displayed a mistaken concent thai ha.-* neen, with son e persistence, repeated

in articulator design-that is, the idea that the mandibular member of the articulator must move.

The second articulator to be patented was thai T. Evens, exemplifies this problem, but also represents

advancement in the understanding of mandibular movement.

The Cameron Articulator, primarily a hinge-type device, is notable both because it was the

first articulator to be patented and because of its unusual poie stand design. The Evens

Articulator, however, represented an important advancement in concept.

The Evens Articulator: ("Dentist's Guide")10

The first recorded attempt to imitate mandibular movement, the Daniel T. Evens articulator patent

showed that Evens (and likely other dentists of his day) .recognized the forward and lateral movements of

the mandible. Evens named his "improved apparatus' the ''Dentist's Guide,' although it is not clear to

what improvements he referred. He believed that his articulator simulated the motion of the human

mandible and, as he expressed in his patent specifications, "a provision is made for adjusting the lower

plate allowing a motion at the joints similar to that which is admitted by the condyloid processes of the

living subject." This and similar statements in the literature, Evens' name has often been incorrectly

spelled as 'Evans,' These occurrences were likely a result of the uncommon spelling of his name and

because of name similarities with at least 2 other early articulator inventors. The patent letter suggests that

Evens, like his contemporaries, may have understood little of the fundamental nature about mandibular

movement beyond that of the hinge motion. Evens described movement of the mandibular assembly as

guided by the action of the joint controls in the following manner: Bar (K), 'upon the ends of which are

joint pins (H, H) extend through the horizontal slots (a, a) and attach in fixed positions to (ramus) plates

(I, I), that are part of (mandible) plate (G)'. 'Bar (K) has some lateral play upon the adjusting screw (L),"

allowing both protrusive and lateral movement. 1 Realistically, it seems more plausible that the

mandibular assembly pivoted at the center of the bar (at adjusting screw L) rather than near the horizontal

slots, as Evens seemed to suggest. Even with thumbscrews (b, b) to hold the bar in its "proper position," it

would have required a diligent effort to avoid rotation around adjusting screw L when hand- manipulating

the instrument into a lateral position. Daniel Evens was also the second articulator inventor to record the

misconception that, for an articulator to accurately imitate human jaw movements, only the lower member

should move. Over the years, this error has been repeated in later articulators and has generally

16

complicated the functional designs. Two examples of such articulators are John YV. Moffitt's,

patented in 1890i\nt\ B. L. Keeney's, patented in 1935

Figure 7: The Daniel T. Evens articulator, 1840.

The Evens articulator represented an important advance, it was met with little appreciation; and

consequently, disappeared early. In fact, so little information had been available on the Evens that for many

years it was believed that the original

17

US patent letter might be the only evidence that it ever existed. However, it is now apparent that dental

scholars of the day appreciated its merit, and, that for a period of time, it was manufactured and sold in

the Philadelphia area. „SV;, u7;v was the Evens articulator unsuccessful? It is assumed that although

most dentists of the 1840s failed to understand its 'pioneering' feature, the Evens was unsuccessful simply

because it was inconvenient and difficult to use and not because it was 'ahead of its time.' In fact, as an

examination of Paul B. Goddard's 1844 text suggests, it may never have reached the dental marketplace in

its original patented form. A drawing that appears in Paul B. Goddard's 1844 book may be the earliest

illustration of an articulator in the literature. The drawing, by illustrator W. E. Smith, is of an Evens

articulator that had been loaned to Goddard by Horatio G. Kern, a prominent manufacturer of dental

instruments in Philadelphia. By 1844, after obtaining the patent rights, Kern had put it on the market.

Goddard emphasized that the illustrations in his book were accurate representations of the objects depicted.

If this is true, it is apparent that the Evens articulator no longer had the precedent-setting joint mechanism

(horizontal slot). However, the device still retained its basic, yet least appealing design element, the

movable lower member. A ">new" feature (holes, d) had been added to allow for altering ramus plate

length (c) to satisfy individual vertical space requirements. It is tempting to speculate that Kern was

pressured to adopt the simple hinge and the vertical adjustment feature as design changes in response to

dentists' market demands. This may or may not be so; nevertheless, as a result of these changes in design,

the Evens articulator had little or no influence on the advancement of knowledge in the field of mandibular

movement. It would be W. G. A. Bonwill who, in 1864, inspired other investigations into this field when he

introduced to the profession his articulator and his theories on articulation and ' 'anatomic'' (balanced)

occlusion.n

18

Figure 10: The Evens Articulator, 1844

19

Figure 13: The Bonwill Articulator, 1858

Early Attempts to Reproduce Mandibular Movement:

In 1889, RICHMOND S. HAYES of East Bloomfield, NY received a patent for an articulator that was

the first to incorporate a fixed descending condylar path. Hayes introduced this new feature nearly 50 years

after the Daniel T. Evens articulator pioneered a provision for the lateral and protrusive movements of

the mandible.

By the 1890s, dental investigators, notably F.H. Balkwill (1866) and C.E. Luce (1889), had conducted

studies on mandibular movement, and both reported observing downward movement of the condyles

during mandibular excursions. Regrettably, these landmark studies were not widely publicized, and they

remained generally unknown to the dental profession for many years. So it is probable that Hayes

independently discovered the importance of the downward condylar motion 'and deserves recognition for

first applying this principle to articulator design. Although it is not well known, there were 2 distinct

articulator designs or versions described in the Hayes patent. The version of the Hayes articulator

ordinarily shown and discussed in the literature is one with familiar and often-copied design features.

Unfortunately, the illustration of this articulator most commonly published through the years does not

present a clear view of the condylar apparatus, and dentists of the day may not have fully understood its

function. On the other hand, the rarely seen version of the Hayes articulator was more innovative in

condylar design and probably reflected Hayes' concept of condylar movement more accurately. Its features

included fixed curved condylar paths and individual condylar tension springs.

20

Note:

It is important to note that the Hayes design is likely the first example of an articulator that can be easily

identified with what is now known as an "Arcon" articulator. Coined by Bergstrom in 1950, the term '

'Arcon" is a contraction of the words "articulator"and "condyle" (Ar =Arcon and Con = Condyle) and

describes an articulator containing the condylar path elements within its upper

13

member and the condylar elements within the lower member. Fixed Condylar Guide Articulators:

The Hayes articulator can also be classified as a "fixed condylar guide" articulator, having

nonadjustable condylar elements. Other articulators in this category that are well worth mentioning because

of their impact on the profession are the Gritman, Gysi Simplex, and the Stephan series. The Gritman

articulator Was patented and introduced with the Snow facebow by George B. Snow and A.D. Gritman

in 1899. The Gritman articulator featured descending condylar paths of 15 degrees, an average

determined by measurements taken from a large number of patients. The condylar paths also included a

slight Balkwill-Bennett angle "to represent the average oblique descent of the condyle"

21

Figure 14: Richmond Simmons Hayes, 1823-1890. Inset: The Hayes articulator with the "articulating

caliper."

Figure 16: (A) The Gritman Articulator, 1899. The Grit-man had 15 degree descending condylar paths.

A heavy horizontal spring kept the upper member in position. There was a posterior "vertical stop" feature.)

(B) The Gritman Articulator, 1899. This view shows that the condylar paths had what Snow described as

a ' 'slight inward slant which represented the average oblique descent of the condyle only.

Alfred Gysi, of Zurich, Switzerland, introduced the Simplex articulator in 1912 in response to the

unwillingness of the profession to accept his Adaptable (fully adjustable) articulator, perceived as too

complicated and expensive for the average dentist. Gysi said that he "felt the need of a simple articulator

that was scientifically accurate.

figure 17: The Gysi Simplex Articulator, 1912: Gysi claimed that this articulator Was based on the "law

of averages" determined by scientific methods. Note that the rotation points (A) are posterior to the

condylar controls (B). In this later model, provision has been made for facebow transfer.

The Simplex had condylar paths of 33 degrees and lateral paths of 16 degrees. The incisal guide had

''the most practical upward slant." The Simplex was probably the first of this type of articulator to have

an incisal pin and guide assembly. Gysi claimed that the Simplex articulator was scientifically constructed

on the law of averages."14 However, not all dental scholars of the day accepted .this concept. A version of

the Gysi Simplex was manufactured until the mid-1990s.

22

Fredrick W. Stephan, of Chicago, IL, patented another early example of a "fixed condylar guide" articulator

in 1906. To Stephan belongs the kudos of L>stciblishing the oldest articulator line presently in common use.

Today, they are known as

By the turn of the 20th century, several investigators had examined the nature of mandibular movement. In

some instances, their endeavors had led to the development of articulators and other devices reflecting

newly discovered or rediscovered principles. Most of these studies were performed independently, with the

investigators unaware that others were working on the same problems. No generally known practical clinical

method existed for recording the direction of the patient's condylar paths and accurately transferring the

casts with the measurements to an articulator capable of accepting those records. The First "Adjustable

Condylar Guide" Articulator:

After Richmond S. Hayes' introduction of the first articulator with fixed descending condylar guides in 1889,

the next important breakthrough in articulator design occurred in 1896, when William E. Walker of Pass

Christian, MS obtained 2 patents for articulators with adjustable condylar guides.16

Although Walker was the first inventor to call attention to the considerable Variation in the downward

movement of the condyles and to construct an articulator based on this principle, the earliest version of his

articulator, constructed about 1895, had fixed condylar guides. It was called the "Walker- Bonwill" because

he had simply modified the Bonwill articulator by bending the condylar rods with the spiral springs to a 35-

degree angle.17 Although the second model, featured adjustable condylar controls, they could not be set

individually.

23

Figure 19: The Walker Articulator. This is the first patented version of Walker's articulator that he

called the" Walker Physiological Articulator." The adjustable condylar guides could not be set

individually.

Figure 20: The Walker Physiological Articulator. This is the second patented Version. The condylar

controls could be set individually.

The third model of the Walker articulator was the first to include individually adjustable condylar guides as

well as adjustable rotation centers for lateral movement. Walker patented these last 2 models sequentially,

calling them "Walker's Physiological Articulators." To measure the path of each condyle individually,

Walker devised an apparatus that he called the "facial clinometer" and a procedure for its use (Fig 21).

24

Figure 21: Walker's Facial Clinometer, a device for measuring the angle of the individual condylar paths.

Walker would then set the articulator according to these measurements.

The device was not intended for active transfer to the articulator.

Because it was designed to determine the angle of the condylar paths on the face, it can be considered to be

the origin of the extraoral method for recording mandibular movement, although the paths were not actually

scribed. The facial clinometer was never patented. Walker conducted a detailed study of mandibular

movement and reported his findings and descriptions of his articulators and other devices in the Dental

Cosmos in 1896 and 1897.18 Despite his efforts, Walker lost sight of one of the pieces to the puzzle: the

correct location of the casts in the articulator. The facial clinometer, designed to measure the downward and

forward condylar paths, did not allow for active transfer of the casts to the articulator. Although he did not

refer to Bonwill's instructions, Walker probably was following them in placing the incisor point at 10 cm

from the condylar axis. Walker's efforts were more far- reaching and valuable than he or the profession

realized. Unfortunately, his articulator was considered too complicated and expensive, and the use of the

facial clinometer by dentists of ordinary ability was regarded as out of the question.

Note:

William Walker was unaware of the observations of Luce and Balkwill concerning the descending motion

of the condyles. E.C. Kirk, editor of the Dental Cosmos, brought Luce's research to Walker's attention a few

weeks after he submitted his

25

first paper for publication. Walker had asked Kirk lor any information he had on the subject. Even

though l uce's work antedated his own by several years, Walker Stated that he was gratified to learn

that Luce had reached similar conclusions using entirely different methods. This is the second

patented version. The condylar controls could be set individually.

Christensen's Phenomenon": Another Rediscovery

Figure 22: Prof. Carl Christens en of Copenhagen, Denmark, 1857-1921.

"In 1901 and 1905, Carl Christensen of Copenhagen (Fig 22) contributed what was considered to be

the solution to the puzzle when he reported his observations of the space that occurs between the

maxilla and mandible during protrusion. Christensen introduced an adjustable articulator, similar to

Walker's but simpler in ■ design. He suggested the use of a protrusive interocclusal wax record to

measure the angle of the condylar paths that he believed corresponded to the observed space, and to

use this record to set the condylar controls of an adjustable [articulator (Fig 23 A and B). Christensen

recognized the importance of placing the .casts in the correct location in the articulator, but did not

acknowledge the use of a -facebow. As Walker likely believed, Christensen considered the correct

placement of the casts to be as close as possible to the "natural relative distance" from the joint

mechanism, a distance Bonwill placed at 10 cm. The space that Christensen brought to the attention

of the profession is called "Christensen's Phenomenon," a term coined by Ulf Posselt.19 Actually, it

would have been more aptly named "Balkw ill's Phenomenon," because it had been previously

described by Balkwill in 1866 (Fig 24A and B). Nevertheless, Christensen's procedure was a major

contribution and is likely the origin of the intraoral (check bite) method for recording mandibular

movement.

26

Figure 23: Christensen's Articulator and "Phenomenon. These illustrations show Christensen's articulator

with mounted casts and occlusion rims in (A) centric occlusion and (B) in protrusion, demonstrating the

space that occurs between the maxilla and mandible when a protrusive movement is made. The articulator

has been adjusted to this Position.

Figure 24: Balkwillpointed out that (A) when "the jaws are closed and at rest. . . the condyle lies at the back

of the glenoid fossa. " But, (B) with the lower jaw bought forward "so that the edges of the front teeth meet,"

the condyle is lepressed and "the space between the back teeth increases. "

in 1907, George Snow reported on the status of articulator development and what to believed to be the

essential requirements of a method for achieving "accurate articulation of artificial dentures." Snow was the

first to report what was generally recognized to be the solution to the puzzle: a practical and easily applied

clinical method for using an adjustable articulator in denture construction. In doing so, he described the use

of the Snow facebow, Christensen's procedure, and introduced snow "NewCentury" adjustable articulator.20

 

27

the New Century" and Other Early "Adj ustable Condylar Guide" Articulators:

The original 1907 patent shows new the Snow New Century articulator was essentially an improved version

of the Gritman articulator (1899) with adjustable rather than fixed descending condylar guides. The second

version of the New Century articulator (1909) included a more efficient central retaining spring and Other

improvements."1 For example, the posterior elbow extensions on the lower bow of later models improved its

stability while being handled on the laboratory bench. Earlier models without this feature tended to fall over

backwards. This and ; subsequent models were simple in design and easy to use and proved to be popular,

With respect to the chronology of US patents, Snow's patent of his New Century articulator did not directly

follow that of Walker's patent. In fact, Snow was issued the fourth patent for an articulator with adjustable

condylar guides. The second patent was issued to Clemens Huberty of Chicago, 1L, in 1901. In his patent

letter, Huberty claims that his articulator is of simple and efficient construction and provides "independent

movements of the respective jaw members of the articulatorHowever, the illustrations and instructions

clearly show that this model was a complicated device requiring several adjustments for it to function as

intended. It is not known if any of these devices were manufactured. The third patent was issued to Matthew

M. Kerr of Detroit, MI, in 1902. For many years, it was believed that the Kerr articulator was the first

patented with adjustable condylar guides. We now know that Walker's was the first. Like the Snow New

Century, the Kerr articulator was widely accepted by the profession for many years. It was the first one of

this type with a simple and practical design, and was quickly assigned to the Kerr Dental Manufacturing

Company who manufactured and aggressively promoted it. Matthew Kerr made one common but significant

error in design; he did not include calibration (unit) markings on the condylar Controls so that the settings

could not be preserved. Inventors learned very early the wisdom of placing calibration markings on all

articulator controls.

28

Figure 25: The Hubert Articulator, 1901. This was actually the second articulator to be patented with the

adjustable condylar guide feature. It was very complex, and it is doubtful if any were manufactured.

The Next Innovation: The Incisal Pin and Guide Feature:

Figure 26: The Snow New Century articulator, 1909. This is the second- generation model of this articulator.

This and subsequent models were widely faccepted by the profession.

Figure 27: The Kerr Articulator, 1902. This articulator was the third to be patented with the adjustable

condylar guide feature, and was popular for many years. It is interesting to note that the condylar controls

are approximately at the level of the occlusal plane.

There is no denying that a milestone had been reached by the first decade of the ,20th century. However, by

the beginning of the next decade, another innovation was well on its way to becoming an integral part of

articulator design, the incisal pin and guide feature.

29

Evolution of the Incisal-Pin and Guide

Alfred Gysi began his study of mandibular movement and articulator design in the early

1890s. He frequently collaborated with colleagues who shared his interests. Among some of his

most notable associates were Eugene Muller, Hermann Schroder, Carl Rumpel, R. Fischer, and

George Wood Clapp. Through his investigations, Gysi eventually became interested in

producing articulators with incisal guide mechanisms designed to function as the primary

control The Trubyte Articulator: Gysi's "Improved Adaptable"

In 1928, Gysi received a US patent for the Trubyte Articulator." This instrument featured an

incisal table with guiding lateral edges that could be set to follow the

incisor point "gothic arch" tracings. The incisal table included a provision for adjusting the

inclination of the protrusive path. Dentists who studied jaw

movement generally assumed that the condyles were the rotation centers of the

- mandible. Gysi believed, however, that the vertical (opening) and lateral "rotation points" of the

mandible existed only as "theoretical rotation centers" and not as actual anatomic structures.

figure 28: ( A ) The Gysi Trubyte Articulator, 1928. (B) The Gysi Trubyte Articulator, 1928.

Schematic drawing illustrating the influence of the Rumple [sic] incisal guide on the position of the

lateral rotation centers.

figure 29: The Gysi Trubyte Articulator, 1928. The incisal guide assembly is also known as the

"Rumpel guide. " It is a controlling mechanism and Gysi's first adjustable incisal guide.

30

He emphasized, however, that these rotation points must be precisely calculated to use full capabilities of

his adjustable articulator. Gysi theorized that the distance of" the lateral rotation points of the mandible

from the sagittal plane could be determined by measuring and tracing the paths of the incisor point.

Ironically, Gysi had studied this relationship

as early as 1901, but the Trubyte was the first articulator with an adjustable incisal guide assembly for

which he held a patent and that was a commercial success. (Gysi had produced earlier articulator

models with this type of incisal guide feature in Europe as early as 1913.) Gysi also maintained that the

vertical and lateral (condylar) rotation points were not located in the same position. Gysi supported this

contention by citing the recent discoveries of Norman Bennett, and a research report by Richard Breuer

(1908). Breuer showed that the vertical rotation point was located posterior and inferior to the lateral

(condyle) rotation point. Gysi also pbinted out that W.E. Walker's articulator (1896) was designed with

adjustable Vertical rotation points and that it was in the same relative position to the condylar elements

that Breuer would later suggest. Subsequently, Gysi designed the Adaptable and the Simplex

articulators with this type of lateral and vertical rotation point relationship.

Figure 30: A composite drawing by Gysi of Breuer's illustrations showing the most logical position of the

vertical "rotation point" to be at (R).

• Figure 31: A drawing by Gysi of a portion of Walker's Physiological Articulator,

showing the vertical rotation point to be at (F), below and posterior to condylar slot

(C).

31

Figure 32: A sectional view of one "rotation point" was used in the Adaptable (adjustable) and Simplex

(fixed) articulators. Vertical rotation point R is located horizontally posterior to the condyle K and

vertically one half the distance between the head of the condyle and the level of the occlusal plane N.

However, Gysi abandoned this design in the Trubyte articulator for a horizontal

condylar axle that could move laterally to accommodate variable rotation points, especially for those that

were found to be located at a point outside of the fixed condylar guide assemblies.

Note: Gysi was the first inventor to recognize Bennett's work and the importance of the Balkwill-Bennett

movement in articulator construction. Gysi's Adaptable articulator was the first to embody the

adjustable Balkwill-Bennett movement feature.

Other Gothic Arch Incisal Guide Control Articulators The Gysi Trubyte was not the only articulator with

a Gothic arch incisal guiding system available to US dentists in 1928. In 1921, John W. Needles

produced an articulator with this type of incisal guide as the primary control.

Figure 33: The Needles Articulator, 1921. The design of this articulator incorporated many elements of

Monson's theory. Its primary control was the incisal guide assembly.

32

needles developed a hybrid design that incorporated elements of Monson 's "single rotation center" idea

as well as the controlling incisal guide assembly, hi addition, between 1922 and 1927, Needles and

Milus M. House developed the liousc- Needles incisal guidance system for dental articulators'4

igure 34: The Needles and House Articulators, 1926. House modified John Needles' original incisal guide

assembly design (see Fig 33). This illustration Shows (A) the House (left) and Needles articulators and

(B) a close-up of the House and Needles improved incisal guides that were used in later articulator

models. House's innovation was the offset incisal pin. The lower section of the pin Was set at an angle

of 55 degrees tangent to the arch of closure of the articulator to facilitate smooth movement of the pin

past the gothic arch guiding edges to contact the lower protrusive guide plate.

John Needles was on the original 15-member research team and worked closely ith House on several

projects. One such project produced a new mandibular movement registration procedure now known as

the "House-Needles Chew-in." in 1925, John A. Lentz of Phoenix, AZ was issued a patent for a Gothic

arch incisal guide control device with adjustable lateral wings, a feature originally suggested by Rupert

Hall in 1917. It also featured an adjustable guide for rotrusive movements (Fig 35).

33

' Figure 35: The Lentz Incisal Guide, 1925. This incisal guide assembly included

' the Gothic arch controlling edges on each of 2 adjustable lateral wings along with

yian adjustable protrusive path, iis

Rupert Hall and Alfred Gysi: Clash of the Titans

The second meeting of the National Society of Denture Prosthetists was held in 'Boston, MA on August

11-21, 1920. The meeting had provided Dr. Rupert Hall ' (Fig 36) and Professor Alfred Gysi (Fig 37)

with an opportunity to meet and ^discuss their beliefs.

36: Rupert E. Hall (1884-1963). Dr. Hall produced at least 5 articulators unknown number of

experimental designs during his career.

34

gure 37: Professor Alfred Gysi (1865-1958). This photograph was taken about the time of Gysi's

first trip to the United States in 1913.

Besides holding widely divergent views on the principles of mandibular movement, occlusion, and

articulator design, Gysi and Hall accused each other of claiming the other's inventions. In addition,

they criticized each other for failing to have credit to other inventors who rightfully deserved

recognition for their contributions. One of the first disputed issues raised the question: Who was the

Ventor of the incisal-pin and guide feature as an improvement of articulators? It indisputable that

C.E. Luce of Stuttgart, Germany applied for the patent on september 28, 1910 and was granted the

first patent for this feature on November 28;.'1911.25 Is this important? In general, application dates

do provide useful information when attempting to determine at what point an idea emerged or an ent

occurred. In this particular case, it is less significant because in January 10, Gysi's article in the

Dental Cosmos described his use of an incisal-pin and guide as early as 1908 in Europe. Hall

remarked that even if this is true, Gysi had not claimed the incisal pin in his patent of the 1912

Adaptable articulator. Gysi's response was surprising: he stated that although he was indeed the first

to claim yipatent rights to the incisal pin, the patent was not granted because the US Patent Office

contended that the Kerr Articulator26 (Fig 38) included a support pin behind the plaster models, and

that to place this support in front of the plaster models did not constitute a new invention.

35

Figure 38: The Kerr Articulator, 1902. This articulator has a posterior vertical Stop much like many other

articulators of the day. It can only be speculated as to why the Patent Office would regard this feature

as comparable to an incisal guide.

' The incisal guidance issue that created the most contention between Gysi and Hall , was Gysi's

introduction of the controlling Gothic arch incisal guide in the Trubyte. r* Hall believed that this

feature belonged to him by virtue of the patent granted for his Dental Occluding Frame in 1917.

Because Hall applied for the patent on r' January 28, 1914, and Gysi had not applied for the Trubyte

patent until November

r 2. 1926, Hall believed that Gysi had no right to claim this feature as his own. The

if * *

Dental Occluding Frame was Hall's first attempt at articulator design. He did not place any special

emphasis on its features at the time. In fact, it took over 3 years w-'for the patent to be granted, and

during this time, Hall directed his efforts toward ^building articulators that reflected his "conical

theory." As a result, Hall did not ^'promote the Dental Occluding Frame. By 1928, Hall had been

granted 3 patents Ljf^and had designed at least 5 articulators, the latest one being a "tripod"-type v

instrument. With several other articulators with Gothic arch incisal controls already ^pn the US market,

the Lentz, the House, and the Needles, for example, it is not clear why Gysi's introduction of the

Trubyte elicited such a strong response from ^all. To whom, then, should be given credit for the

innovation of the Gothic arch incisal guide control feature? Gysi said: "(Carl) Rumpel first suggested

changing [the] rotation centers on the condyle chord to an adjustable guidance for the incisal pin" (Fig

39).

36

Gysi's early collaborations and close working relationships with other inventors is apparent through

examples of articulators that these men produced. In 1914, Hermann Schroder and Carl Rumpel

produced an articulator with Rumpel's , "gothic arch" incisal guide control and condylar controls after

Gysi's design for his 1908 adjustable articulator (Fig 41).

figure 41: (A) The Schroder-Rumpel Articulator, 1914. This instrument embodied both the Rumpel

incisal guide and (B) condylar controls similar to Gysi's 1908 model adjustable articulator. (C) The Gysi

Adjustable Articulator,

§1908 and (D) a close-up of an interchangeable condylar control. A comparison of illustrations B and D

shows the similarities between the 2 condylar control designs.

In 1924, Gysi worked with his assistant, R. Fischer, to produce an early version of the Trubyte

articulator. It featured a modification of the Rumpel guide by including Fixed 10-degree lateral wings.

This feature reflects Fischer's description Of the lateral path of condyles, now known as the "Fischer

angle" (Fig 42).

37

Figure 40: The original Gysi-Rumpel Articulator, 1914. This drawing illustrates (Jysi's first articulator

design with Rumpel's "gothic arch" incisal controls. Gysi would not patent this feature until 1928.

Figure 42: The Gysi-Fisher Articulator, 1924. This is an early model of the Trubyte articulator. The 10-

degree fixed lateral wings on the adjustable incisal guide were not retained on the model granted a US

patent.

And, in about 1929, Gysi and Rumpel produced an articulator that was essentially a Simplex with

Rumpel's incisal guide(Fig 43).

Figure 43: The Gysi-Rumpel Articulator, c. 1920. This instrument was a modification of the Gysi

Simplex with Rumpel's guide.

-r '

■The history of the incisal-pin and guide would be incomplete without at least mentioning the custom

incisal guide table. It can be considered either the most primitive or the most sophisticated of the

incisal guide systems, depending on one's viewpoint.

Jt,is one of the earliest and clearly an important and particularly useful tool for ; today's restorative

dentist. To find its origin, one needs only to look back at Luce's $4,911 patent. Perhaps, for this feature

of articulators, dentistry is back where it started.

to.

The Appearance and Early Use of the Incisal-pin and Guide27 "As early as the 1840s, some form of

"vertical stop" was a common component of ^mechanical articulators. Clearly, some early inventors

recognized the importance of preserving the vertical relationship of the casts in the articulator and

provided ; this feature. A notable "holdout" was William G.A. Bonwill, who believed that "SUch a

device wjould interfere with the accurate function of an articulator (Fig 44).

38

Figure 44: William G.A. Bonwill (1838-1899).

Just as in many present-day simple articulator designs, the "vertical stop" feature frequently involved a

short, vertical pin or screw contacting a fixed or adjustable horizontal plate and was centrally located

just anterior or posterior to the condylar axis. The Evens, Hayes, and Bonwill (post-1899) are early

examples of articulators j,with this type of "vertical stop" Not until the first decade of the 20th century,

however, did the incisal pin appear as an integral part of articulator design, functioning as a mechanism

for anterior guidance rather than simply as a means for ' preserving the vertical relationship of the

casts. In a paper published in the month of his death (Sept

1899), Bonwill remarked that his articulator "had never been changed in design [ since it was invented

in 1858." He believed that "a prop to keep the jaws apart" was unnecessary and would interfere with

lateral movements. Therefore, it can be Concluded that Bonwill articulator models with "vertical

stops," such as those ^modified by The S.S. White Dental Mfg Co and The Consolidated Dental Mfg

Co, '.were produced after 1899. The history of the incisal-pin and guide feature is not ^Without its

share of controversy and contradiction. Obviously, there was little [consensus among early inventors

regarding the concept of incisal guidance. It was ^generally held that the incisal guide could be

controlled and adjusted by the dentist. ^Because the character of the incisal guide table was largely

determined by the inventor's interpretation of its intent, it is not surprising that many variations in the ?

design of these tables came into use. A flat horizontal surface was the most Common, but incisal tables

were also designed with various protrusive inclinations, |Spme in combination with fixed or adjustable

lateral wings. Similarly, concave, Convex, paraboli'c, or cup-shaped incisal guide tables were used,

seemingly without regard for other features of the articulator

39

The First Articulators Patentee! With an Incisai-pin and Guide Assembly

Luce, or Sinft«art, Germany, received the first patent for an articulator with incisal-pin and guide assembly

on November 2H, 1911. Luce, formerly of Boston, MA, was also one of the first investigators to describe

the downward and forward movements of the condyles (1889).

Luce's articulator was the first "scribing" type; i.e., it had posterior and incisal path controls that were

functionally generated (in modeling plastic; Fig 45).

Figure45: The Luce Articulator, 1911. The first "scribing" type articulator will be discussed more fully in a

future article.

"[The second patent issued for an articulator with this feature was received by Ernest Eltner of Basel,

Switzerland in July 1912. Eltner's articulator featured a horizontal incisal guide table with an adjustable

posterior vertical flange that limited protrusive movements. The incisal pin had a chevron-shaped blade tip.

The ' purpose of this unusual design was not explained (Fig 46).

* Figure46: The Eltner Articulator, 1912. The second articulator patented with an Mcisal-pin and guide

table. Eltner's articulator was constructed on the theory that the temporomandibular joints have 2 horizontal

axes, one running through the Condyles and the other through the articulator eminences.

Alfred Gysi received a patent for his "Adaptable" articulator in October 1912. This ^Vas Gysi's first US

articulator patent (Fig 47A). Although the "Adaptable" was

40

highly advanced for the time, ii had only a fixed, 45-degree incisal guide table. Nevertheless, the

"Adaptable" was considered too complicated for the average practitioner and was not a commercial success.

Earlier, Gysi had produced 2 other adjustable articulators, neither of which he patented. His

"Wippunktarticulator" (Fig 47 C) was never introduced in the United States.

flgure47: (A) The Gysi "Adaptable" Articulator, 1912, the third articulator iiented with an incisal-pin and

guide table. This advanced design embodied the first adjustable

controls for the Balkwill-Bennett movement, but had a fixed incisal guide table. It estimated that only about

100 of these were manufactured. (B) This adjustable articulator featured interchangeable curved condylar

guide paths. It was prominently featured in Gysi's early work, but was quickly supplanted by the Adaptable."

(C) The Gysi "Wippunktartikulator"(c. 1908), a very early 'justable articulator, was not introduced in the

United States.

next articulator, produced just before the "Adaptable," had interchangeable ondylar controls (Fig 47B) and

was featured by Gysi in his early writings. By however, he had replaced this articulator with the "Adaptable"

in both his pings and in the courses

at he gave that year in the United States. Gysi continued the exact incisal guide sign in his "Simplex"

articulator, an "average value" version of the adaptable." Introduced to American dentists at essentially the

same time as the daptable," the "Simplex" articulator was a decided success (Fig 48A). Up to this Gysi

apparently had given

41

little thought to adjustable incisal guides. Possibly because of advice or criticism, Gysi suggested that the

slope of the '"Simp/ex" incisal table could be altered with The use of a metal plate and modeling plastic (Fig

48/V).

Figure 48: (A) The Gysi "Adaptable" and "Simplex" Articulators, 1912. The

incisal guide tables for both articulators are of the same design. (B) Gysi suggested that the inclination of the

incisal guide table for the "Simplex" could be modified with modeling plastic and sheet metal.

Ray W. Burch of Hart, MI received the fourth patent issued for an articulator ' ith an incisal pin, in

December 1913. Burch was the first to employ the ^ovation of converting maxillary and mandibular

facebow into an articulator, e facebow devices were connected by condylar slot assemblies and were

"adjusted while being worn by the patient. The incisal pin was used simply to maintain the anterior vertical

position (Fig49).

Figure49: The Birch Articulator, 1913. Rod 20 rests on plate 42 to maintain the ertical position of this

bimaxillary facebow device.

fter the Burch articulator, George B. Snow patented the "Acme" articulator ovember 1915), Snow's third

articulator patent and the first with an incisal-pin and guide.29

42

Figure50: The Snow "Acme" Articulator, 1915, the first patented version of this trument. The

protrusive angle of the incisal table was adjusted by heating the solder between rod 4 and plate 8.

Tr

n the earliest model (Fig 50), the protrusive angle of the incisal table was adjusted by heating the solder

between the components identified by the numbers 4 and 8, " d moving the table up or down. Later

models featured interchangeable tables

igureSl: Snow "Acme" Articulators. These later models had, among other improvements,

interchangeable incisal tables (A), and an adjustable table (B).

43

David M. Shaw of Eltham, England patented an articulator in February 1916 (Fig 52).

figure52: The Shaw Articulator, 1916. This is an early example of an articulator with an incisal pin

assembly, and an unusual design. It has adjustable condylar paths, but the function of the incisal pin is not

clearly stated in the patent letter. The Dental Manufacturing Company Limited produced the Shaw

articulator in

London, England.

This device has been largely overlooked, but deserves mention because of the notable design of the incisal

pin assembly, apparently intended to affect protrusive and lateral motion with the curved incisal chevron-

shaped tip functioning on the curved wire "guide." In November 1916, Rupert E. Hall received his first

patent for an articulator, a device that has been unceremoniously nicknamed the Alligator"

: The "Alligator" Articulator, Hall's first patented articulator, was not Well received. (A) Complete view

of articulator. (B) Anterior close-up of incisal- pin and guide table. The adjustable lateral wings

incorporated into the horizontal incisal guide table were an innovation.

According to House, "Alligator " was the least offensive of its nicknames. It was patented as a "single

rotation center" device, but Hall provided no instructions for its use. This instrument predated his later

model based on his "conical" theory of

44

occlusion. The "Alligator" was the first articulator to include an incisal guide table with adjustable lateral

Figure54: From the Hall patent, this is a conceptual drawing of an articulator that 'all used to explain the

theory on which the articulator in Fig 53 is based.

e illustration appearing in this patent (Fig 54) has been misinterpreted as the first jrsion of the "Alligator." In

fact, it is a "perspective view of an articulator. . Showing diagrammatically the principles upon which the

articulator is based." On llll's second articulator (March 1917), a revised version of the "Alligator, " the cisal

pin was designed to function within a 45-degree cup (Fig 55)30

1gure55: Hall's second articulator patent and the new and improved "Alligator. "

^e incisal guide is a 45-degree cup. 17 %

jail's "Dental Occluding Frame": The First Patented "Gothic Arch" Incisal

Guide Table:

f"

Jupert Hall's third articulator patent, issued for the "Dental Occluding Frame" ^pril 1917), was

groundbreaking. It was an Arcon instrument that featured adjustable, curved condylar paths, including

settings for the Balkwill-Bennett gle,

wines.

and a mechanism

45

figure57: Hall "Automatic Anatomic" Articulators, 1918. (A) The original

(patented version 19 had a horizontal incisal guide table with 45-degree fixed lateral wings. (B) The

updated version (not patented) had an adjustable incisal guide table with fixed lateral wings.

version of the "Automatic Anatomic" articulator was never patented. Gysi's Treipunkt" articulator,

patented in June 1917, was a departure in design (Fig A&B).

figure58: The Gysi "Dreipunkt" Articulator, 1917. (A) This illustration is from 1917 US patent. The

device had fixed cup-shaped condylar guides and a fixed iegree incisal guide. It resembles a "tripod"

articulator, but Gysi did not Wribe it as such. 20 (B) In this later version, the condylar guides have

been Wed, leaving its other features unchanged.

ljjar to the "tripod" or "positional" articulator, it had fixed 33-degree condylar to accommodate

mandibular styli. Gysi retained the same fixed 40- degree isive incisal guide table that he had used in

previous articulator designs.

fired Gysi: First Recognition of the Importance of the Incisal-pin and Guide been generally

accepted that Gysi coined the term "Gothic arch" to describe ^character of incisor point movements

in the horizontal plane. Gysi undoubtedly the first investigator to design and study the incisal-pin and

guide assembly to

report on its significance for reproducing mandibular movement. Gysi Med that he and Eugene

Muller of Zurich worked from 1896 to 1899 to Struct an articulator that "exactly imitated the form of

the condyle and glenoid

46

aspect of the history of articulators would require an undue a; Viount ol space. jilStead, this essay will be

limited to a discussion of some of the earlier, more ynusual articulators whose history reflects interesting

and sometimes amusing Concepts. The illustrations selected should make it apparent that "a picture

is/1 Indeed, "worth a thousand words." So, readers are invited to enjoy this affectionate look back at some

of the more intriguing ideas of the early inventors.

32

."gome Examples of the Earliest Mechanical Articulators"

" ' e December 1999 article in this series noted that Fairhurst had described 2 ^culators of the 1830s, the

Howarth and the Ladmore, produced at a time when e^most common method for relating casts was the

plaster index (also referred to "plaster articulators"). The Howarth and the Ladmore, however, were

ichanical devices that conformed to one of the definitions of an articulator, that Class I or "non-adjustable"

articulator.

ure 60: The Howarth Articulator, 1830s. This is one of the earliest known hanical articulators. It was

produced by the Dental Manufacturing Company mdon, and may have been patented in Europe.

$ Howarth articulator (Fig 60) consisted of 2 nested metal boxes designed to Ction as a simple hinge.

The boxes were held in position, and the hinge ement was controlled with elastics. The casts were

secured in place with twine lastics. Another similar device was the Springfield articulator, consisting of

2 ged metal boxes with each box having metal mounting pins for securing the J with plaster (Fig61).

Ure 61: The Springfield Articulator Frame, 1830s. This device used metal Wing pins and what appears

to be a standard door hinge mechanism, ngfield must have also recognized the importance of visual

access to the back the casts. The device is marked with the initials A5L5S, probably the tfacturer's logo.

47

Although bulky and probably cumbersome to use, these articulators were, alter all, the first of

their kind. The 2-hinged flat plates of the Ladmore articulator had projections for securing the

casts to the plates with plaster (Fig 62).

Figure 62: The E.J. Ladmore Articulator, 1830s. This early device was later patented in England and was

produced by Claudius Ash, Sons and Co, Limited. "" The hinge mechanism was quite rigid, and an

adjustable screw was used for a '{vertical stop. "

itThe novel idea for a simple hinge device originated in France in 1912 (Fig 63).

figure 63: The "Statum" Articulo-Monleur Universel Articulator, c.1912.

16 "Statum" Universel articulator featured its own built-in mounting cups, a fast id easy way to mount

casts. This device was equipped with 2 types of hinge lechanism: 1 for casts with occlusal contact and 1

with a vertical stop for casts jfithout contact. Obviously, this feature was not added to improve function,

but ifather to save time.

the First Improvements to the Simple Hinge Articulators

lost of the simple hinge articulators were unremarkable in design and, in fact, much like the familiar "barn

door hinge." Nevertheless, because they offered more than that basic function, they provided the basis for

innovators to |8|Velop a variety of new and useful features. It is likely that the first improvement

48

made to the simple hinge articulator was a tongue-in-groove (sliding) mechanism for changing

the anterior-posterior position of the upper member (Fig 64).

Figure 64: A planeline articulator Ithough it is unknown exactly in what sequence these ideas emerged,

other early changes included features to vary and to preserve the vertical space. Articulators jfoduced

before 1900, representing variations on these additional changes, were He Hoffstadt, 1871 (Fig 55), the

Smith, 1885 (Fig 56), the Moffitt, 1890 (Fig 57), d the Simpson, 1893 (Fig 58).

Figure 65: The Hoffstadt Articulator, 1871.5

ese innovations may have been added to hinge articulators simply to allow commodation of various jaw

relationships and cast sizes. However, after amining some of the complex and occasionally elaborate

designs for what were Sentially simple hinge articulators; it becomes obvious that there were other asons

for these changes. At this point, it is well worth mentioning an interesting enomenon that affected the

design of mechanical articulators almost from the beginning. The planeline articulator (Fig 64) and the

Moffitt (Fig 67) represent CVices with lower members designed to imitate the condyle, coronoid process,

4 ramus of the mandible. James House noted that some inventors must have lieved that simulating the

features of the mandible "was supposed to have some .agical' influence to articulator function."

49

Figure 67: The G.E. Smith Articulator, 1885. The Smith was quite intricate for an articulator that did not

perform many functions.

Figure 68: The J. W. Moffitt Articulator, 1890. This device had a rod and sleeve Vertical adjustment

mechanism. Moffitt designed the lower member to imitate the features of a mandible.

Figure 69: The G.W. Simpson Articulator, 1893. This instrument featured a tongue-in-groove horizontal

adjustment and a rod and sleeve vertical adjustment.

50

Figure 72: The Williams Articulator, 1904. the "Most Highly Adjustable Hinge Articulator" Award could

be given to 2 devices, the Oehlecker, 1878, and the Moffitt, 1898.33 Of course, each represents a different

category. Heinrich Oehlecker, of Hamburg, Germany, designed an articulator much like that of a microscope

stage with fine adjustment controls for 3 planes of movement (Fig 73). On the other hand, John W. Moffitt, of

Philadelphia, (Fig 74), included numerous closely spaced vertical and horizontal holes for making small

adjustments. The runner-up in this category would be the Hare articulator, 1907, based on a design similar to

the Moffitt, but with far fewer holes

51

(Fig 75). In 1876, George Davidson, of Lambeth, England, added a new dimension to the term ''adaptable" when he

patented an articulator with a ball and socket (universal) joint on the upper member. This device also had rod and sleeve

mechanisms for both vertical and horizontal adjustments (Fig 76). David M. Hitch of Laurel, DE included a similar ball

and socket joint in his more conventionally designed 1894 articulator (Fig 77). And, in 1927, Archie E. Brown of El

Paso, TX received a patent for a most unconventional, steam iron look-a-like device (Fig 78). Lewis Knight of Beloit,

KS would win in the "universal joint" category for his entry in 1904. This instrument featured 2 ball and socket joints,

located on the horizontal arms of both the upper and lower members (Fig 79).

Figure 73: The Oehlecker Articulator, 1878. For a simplehinge articulator, this instrument had more

adjustments than a precision microscope stage.

figure 74: The Moffitt Articidator, 1898. This little gem could be set to at least 36 sitions.

52

Figure 78: The Brown Articulator, 1927.

an arrangement probably compensated for the fact that this device had no iftical adjustment feature.

Designed to accommodate various cast sizes and jaw lation records, all of these "adaptable" articulators

could be adjusted arbitrarily to Sect the bite if required. The new bite could then be preserved with

setscrews or me similar device. Many of these instruments, however, had no calibration e, and if the

settings were lost, especially those of the "universal joint" nnections, the operator was simply out of luck.

'culator Springs Eternal

lgs have been incorporated into articulator design since the 1850s. The value Spring-enhanced articulator

controls had become more apparent, and many of articulators in the second half of the 19th century included

some type of coiled ig device. Such devices have generally been effective as a mechanism for Wg the

instrument in centric position. The posterior central spring was

53

preferred for this purpose by such inventors as Lewis, Hayes, Kerr, Snow, and Others. (Fig

80)

figure 80: Articulator with posterior springs, 1920s. The device is marked "CE' "LE," but the inventor is

not known

e articulator illustrated in is worth mentioning because of its interesting design the use of 2 posterior central

springs, neither of which was commonly seen, illiam Bonwill was likely the first to use springs as a

mechanism for holding the dividual condylar elements in centric position while allowing protrusive and

literal movement to occur. In 1864, Bonwill introduced the dental profession to the theory of tooth guided

(balanced) occlusion along with his Anatomical articulator eg81) .

Figure 81: The Bonwill Articulator, 1858. frictly speaking, this articulator was certainly not "anatomical," but

was well Suited for clinical demonstration of his theories. It is difficult to believe that Onwill did not recognize

the limitations of his articulator, but for over 40 years, ^.did not admit that his device had no true controls or

settings that could be -preserved. In 1900, shortly after Bonwill's death, Schwarze produced an ■^trument that

was essentially a Bonwill articulator with enhanced condylar ygftures (Fig 82).

54

ifigure 82: The Schwarze Articulator, 1900. Essentially a Bonwill, but may have ieett more easily

manipulated. Unfortunately, there was no way to preserve ettings.

condylar assembly, Schwarze added an extra rod and spring set ipendicular to the existing one.

This assembly was allowed to freely rotate in the igittal plane. Like the Bonwill articulator, there was no

provision to calibrate or to reserve jaw positions. It was a good idea as far as it went, but the result was

Simply a more highly adaptable version of the Bonwill articulator. For the sheer udicrous use of springs

in articulator construction, Ira R. Wheeler, of Brockton, II, deserves recognition (Fig 83).of. each

figure 83: The Wheeler Articulator, 1923. Realistically, there is no practical on for the use of springs in

this manner.

1923, Wheeler produced a simple hinge articulator with an anterior- posterior SJUstment feature for the

upper member and with the condylar posts constructed Vertical coiled springs. Would this articulator be

classified as "fully adjustable?" the 1930s, W. Baiters, of Leipzig, Germany, produced a hinge

articulator with cisal pin and table and with essentially the same type of posterior vertical constructed of

springs as is shown in this model from 1922 (Fig 84A).

55

gaiters, however, provided metal rods that could be placed within the springs so that the

instrument could function as a simple hhn?.e articulator (Fig 84/7).

figure 84: (A) The Baiters Articulator, 1922. (B) Baiters placed metal rods within the springs to stabilize

the vertical posts when mounting the casts. If the rod Remained in place, it was essentially a simple hinge

articulator.

This same type of device is still available to 21st century dentists. In 1897, Frank Fourt of Fairfield, IA

received a patent for an articulator designed much like a space-age Bonwill. The 2 posterior condylar

springs must have functioned primarily to hold the condyles in "centric" position, because this assembly

could not have allowed a correct lateral motion (Fig 85).

'en with its complex features, the Fourt was essentially a hinge articulator and ay be remembered only as a

"dead ringer " for the USS Enterprise. Although a €W manufacturers of modern articulators have returned

to "rubber band" chnology (mainly to keep the instrument from falling apart), some type of spring

Cchanism is used in many of today's articulators. It is likely that springs will )Vays be essential features of

some classes of articulators, if only to retain certain proponents in position.

.Jl Age-old Problem for Articulator Users P^eofthe design problems that has frustrated those who use

articulators but which apparently been frequently ignored or overlooked by inventors is that, when in

position, many articulators do not allow good visual and working access

56

to the lingual aspects of the mounted casts. Although efforts have been made in fecent years to

address thus problem by design improvements such as the "wide body" approach, a few

years ago some clever inventors had other ideas. In 1941, Ylctor Bloom and Benjamin Siegel of

New York, NY placed the posterior hinge Connection in a lateral offset position to provide

clear access to the back of the fcasts (Fig 86). And early in the 20th century, Popiel

produced a simple hinge ^articulator with a mechanism that allowed a 90-degree rotation

of the mounted (•casts to provide the operator with an unobstructed view (Fig 87).

*pril IS. IM1,

figure 86: The Bloom and Siegel Articulator, 1941. Might it have come in both kht- and left-handed

models?

* I J

fulti-purpose" Articulators34 Qth dentists' unending search for quality, accuracy, efficiency, and, of course,

jOther shortcut, it is not surprising that these devices were created nor that they fe eventually relegated to

some forgotten niche of the past. In 1902, Clarence \Stocks, of Greenville, TX, received a patent for his

Dental Occlusor (Fig 88).

57

tocks was serious about "getting a handle on" the "mush bite." His jjectives were to "find the proper 'shut' or

'bite' of the jaws," and to "enable the roduction of the anatomical movements of the lower jaw and the

stationary sition of the upper jaw." When the correct bite is located, the handles are locked position. Wax is

placed in the trays and impressions made at the exact bite sition. Presumably, plaster casts were poured and

then secured in position using jaster index. William Luxmore, of Chicago, IL, patented his "New and

Useful \provements in Dental Articulators" in 1908 (Fig 89).

58

'j]jS "especial object" was to provide to dentists "in the manufacture of bridge work" a device

for which . . . "waxing, investing and soldering can be performed • yyjthout the need for

removing the casts from the articulator. ' 1 For soldering "procedures, a Bunsen burner was

placed on the base. In 1895, Kelly R. Bragg, of Jjg^elbina, MO, received the first of 2 patents for

an articulator and a method "to ;greatly facilitate, both in time and convenience, the

manufacture of artificial i 'dentures." His device combined the articulator and vulcanizing

flasks (Fig 90), 'and by using special impression trays to transfer the casts directly to the

flasks, 'ade it unnecessary to remove the casts from the articulator until processing. In illustration from

the second patent (the "simplified and improved device"), ragg has added a "universal joint" to the upper

flask to readily accept the bite

ord.

ribing" Articulators—Those with Functionally Generated Custom Guide Btrols

'Patent Office records indicate that the first patent for a "Scribing" articulator jissued to Charles E. Luce of

Stuttgart, Germany, in 1911. Many "Scribing" iCulators have since appeared in the literature and in the

marketplace. Some have -?n relatively successful and some have not, and it appears that some, like that

of ,0. Boucher, of Columbus, Ohio, were developed primarily as research 'ments.

59

The Carl Bouchcr "Ora l Recorder" and "Tripod" Art i cu la tor I I I 1932, Carl O. Boucher

reported his method of registering and reproducing the anatomical movements of the mandible as

reflected by movement of ; ;k: complete denture record bases in function. Boucher believed that any

recording method must accurately register all paths of the denture bases during the various

excursions of the mandible while the teeth are in contact. Acknowledging, therefore, that complete

denture bases are not stable during function, Boucher suggested that "any changes in relationship of the

bases must be recorded regardless of the cause if balanced occlusion is to be perfected on an articulator."

For the purposes of his Study, Boucher devised an oral functional recorder with an Extraoral Gothic

arch ;ing assembly and a tripod-type "scribing" articulator.

^ . ...... . ..— m I I I — II——......Hill III III I

h "Oral Recorder" (Fig 91) consisted of upper and lower triangular metal bite- sates. The upper metal

plate (7) had a tracing cup (3) attached at each corner, a Central bearing post (6), and an extraoral tracing pin

(1). The lower metal plate (5) 4 three corresponding rounded tracing posts (4), a flat plug (9) screwed into

the ter of the plate [interchangeable with a "tooth form die" (10)], and an extraoral cing tray (2).35 Boucher

explained that the "Oral Recorder'' was used for two ses: first, by using the extraoral "Gothic arch"

assembly, to establish centric ation, second, by using the intraoral tracing cups and posts, and by applying

the ropriate "tooth form die," to record the movement of the denture bases in ction. Boucher's "Tripod"

articulator (Fig 92A) consisted of a maxillary tripod Imber (1), the legs of which terminating as articulating

pins (8)fit into three responding cup holders (9) in the mandibular base (6). A fitted and keyed steel with a

removable lid (10) for holding the tracing material was in each holder, centering device was placed in each

cup for mounting the casts in centric Ration. Boucher described the technique for the use of the "Oral

Recorder"in ll. Essentially, after the vertical dimension was determined with occlusion ;> the casts were

mounted in tentative centric relation "by means of interposed The maxillary cast was mounted in the

articulator to the hinged cast holder 3nd the mandibular cast directly to the base cast mounting (7). The wax

was

60

Kflioved and the hinge (3) closed "until the bite rims have approximately the same ' jelation as in the

mouth." The "Oral Recorder" was then attached to the occlusion 'rims (Fig 92B).

$ire 92: (A) The Boucher "Tripod" Articulator. This display of the various ^ of the articulator is

annotated by Dr. Boucher. (Reprinted from J Dental irch, Boucher CO, 1934, p. 42)4 (B) The

Boucher "TripodArticulator" with fOral Recorder" mounted on the occlusion rims in position. (1)

spacer; (2) iic arch tracer pin and tray assembly. ft..

^cer (1) was used to insure that the metal plates were exactly parallel. With the jlug in place in the

lower metal plate, centric relation was determined using the Soral Gothic arch tracing needle and

tray assembly (2). Centric relation was raed with a plaster check-bite. The plaster check-bite was

then removed and It plug in the lower metal plate was replaced with "the 'tooth form die' that ponds

to the mould of the posterior tooth [selected for the patient]." The Siups on the upper metal plate

were filled with modeling compound and while Mnpound was still soft, the "Oral Recorder" was

placed in the patient's kfor the patient to make all possible motions of the mandible while keeping

intral bearing post in contact with the "tooth form die." The records were fin the modeling compound

by the tracing posts. "The 'Oral Recorder' is then led to the 'Tripod' articulator [that] is adjusted by

means of the guides in the )Und cups of the recording apparatus." In order to adjust the articulator,

the [centering devices were removed from the cups on the articulator base. The fere filled with

modeling compound and placed in position in the cup holders ^base. The modeling compound was

resoftened and the tripod was brought JO position guided by the recording apparatus. The "Tripod"

articulator was into all relations permitted by the recorder tracings, resulting in ponding tracings

being made in the. articulator cups. The next procedure was 'ert the modeling compound tracings in

the cups to metal. Impressions were

61

made of the tracings with plaster in the cup lids. The modeling compound was removed from

the cups and filled with a molten eutectic alloy (Hooper's metal). The cup lids with the

plaster impressions in position were quickly replaced on the CUps, reproducing the tracings

in metal. The articulating pins of the tripod in contact with these tracings form the only

movable controls of the articulator. What did Boucher specifically say about the issue of

maintaining balance during complete denture function? "The [tracings] are entirely relative

as to the bases, showing only the end result, or the combined effects of all known and

unknown forces involved in jaw movements and occlusion in dentures.

The condyle paths, whether curved or straight, Bennett movement, compression of tissue, and shifting of

the denture bases on the ridges, are disregarded as such; but the effects of these, and any other forces, are

registered by the recording apparatus and reproduced on the articulator." So, what about the widely held

presumption •lhat "Enter bolus, exit balance" prevails as a problem common to all denture wearers with

balanced occlusion?

i^'Sf f- ,

'Boucher argued that "balanced occlusion may be so accurately adjusted that a [balancing contact is

maintained when a bolus of food is interposed on the working "side, within the limits of compression of the

tissues on the ridges and in the

condyle fossae.''

it"

tfhe Jaw Bone is connected to the Head Bone . . .

jane only "Scribing" articulator patented in the 1950s was that of Louis A. Fine of "La.Palisse, France. Fine

received a patent for his articulator on May 18, 1954.36 Rule's interpretation of the physiologic movements

of the mandible and how they translate into mechanical equivalency in an articulator seem a little peculiar,

to say :the least. No standard form of articulator is therefore physiological or productive of Jju[normal

functions."

Wine envisioned that for his articulator to "operate in conformity with anatomically and physiologically

correct principles," it should be constructed to conform to Juman anatomy (Fig 93A, B).

62

Wifjgure 93: (A) The Fine Articulator, disassembled view. Fine referred to the Wffinatomical structure of

the lower member (2) as an "exact" replica of the P? average" mandible and to the incisalpin (5), as the

"stylus. " The upper member Wmpid two sections. To the posterior section were attached parts 14 and 15

that mfcarried the glenoid fossae, and to the anterior section the adjustable incisal guide WBable or "box"

(9). The adjusting screw (7) and lug (6) of the locking device WrSosterior to the left condyle (23) worked

with cams (16 and 17) to provide a type of filltiding hinge device. (Reprinted from the 1954 US patent.) 5

(B) The Fine wmmiculator, open and closed views. Appearing very bizarre in profde, Fine's mmrticulatnr

did resemble a human skull, especially with the addition of naso-frontal Wm^t (12) that, he said, "allows

defining directly the facial angle and the 'Simon WmtMe.' that is, the perpendicular line at the point of the

greatest slope of the orbital HHWess. The subnasal (8) and chin reference marks [aids in determining]

Cuvier's Wjwgle, that is, the angle between the lines connecting the center point of the mffncisors with the

frontal point and the aural channel respectively.'' These BB||titrations show more clearly the supposed

function of the posterior hinge- UBflxking device showing that cams 16 and 17 were intended to place a

force on the WBBxk.of the condyle to depress the mandible against the rubber bands (21, 22) gagSwtf/

correspond to the constrictor and depressor muscles'', respectively.

BMKgMBpiirV * •.

Hre Fine described it, "My improved articulator comprises upper and lower Hgttftbers forming exact

replicas of the temporo-maxillary bones, the interengaging IfSftiaces of which are in exact conformity with

the average shape of a man's H£3Aium and said members are associated with bodies engaged between the

upper HE^ttlber and the parts of the lower member corresponding to the condyles, said HfiS&es

corresponding to the complete menisci of the temporo-maxillary jointing. BU&se menisci have a volume

corresponding to the actual cranial menisci and their

63

presence provides for relative movements between the two members of the articulators that are exactly

similar to the natural physiological relative movements between the upper and lower portions of the

skull." The menisci were fashioned of acrylic resin and Fine hinted that they may have had a flexible

component to them for "scribing" purposes. The "bony anatomical" structures were cast in brass or

bronze. In order to further maintain the anatomical components in their correct physiologic positions,

Fine used two pairs of rubber bands to correspond to the passeter and external pterygoid muscles.

Unfortunately, Fine did not discuss the other components of this device and their functions in any detail.

The incisal pin and guide, for example, was referred to only as the "front stylus and box while the

posterior hinge joint mechanism was described as a "rear clamping screw allowing a gradual adjustable

opening of the jaws." Similarly, he described the various reference points, but not the process with

which they were used. And in regard to his scribing method, his only reference was to "plaster

tracings." Fine's inverted •incisal pin and guide assembly deserves further mention because his

articulator is -,,c'the first to be patented with this feature.

-^Fl'ne suggested that as far as the "opening movement of the main lower member is concerned, the

operator should exert a stress to open the articulator through a -^lowering of the lower member in

which case the two members act as levers and transmit said stress to the menisci. Fine did indeed devise an

articulator, the major ^components of which resembled human anatomical structures. Furthermore, he

t^painted a detailed picture of how he believed the "anatomic" components of his ^'articulator would

imitate exactly the function of the corresponding structures in the inhuman skull. Unfortunately for Fine,

he apparently was not aware that function is ir/arely best achieved when a mechanical equivalent is

designed to imitate nature, perhaps he never even noticed that airplanes do not have feathers or flap their

Wings. So, as fascinating as Fine's device may be, it has been duly filed under .Curiosities in the historical

archives of dental articulators.

The TMJ Articulator * OhtjSeptember 21, 1965, Kenneth H. Swanson, of Glendale, California, received

^thefirst of three patents, the culmination being the development of an articulator k^JtWould be the first

to define a "scribing" articulator as a "fully adjustable" p,7as some may prefer, "highly adjustable")

articulator. Even though Swanson "Reived the

patents, the development of the TMJ Articulator and the methods for Use was due to the collaborative

efforts of Swanson and Harvey H. Wipf, of California, who worked together for well over a decade. The

first model ^M.the TMJ Articulator itself, designed with familiar contemporary features, (Fig actually

embodied several departures for a "scribing" articulator. Significant these were provisions for the

"arcon"feature, adjustable condylar posts,

64

and adjustable curved incisal guide pin that was concentric with the arc of closure. Furthermore,

Swanson advocated the use of a facebow; a feature that previous inventors suggested was unnecessary

with this type of articulator. The "centric" or "hinge axis" position of the condyles was verified by

palpation, and the position of the maxillary cast was determined with a conventional facebow with an

infraorbital pointer type rod to establish a third point of reference. The three functional controls of the

articulator were the two posterior condylar elements and the anterior incisal guide. The two posterior

controls consist of spherical condyle heads (29) on the condyle posts (25) of the lower frame, and on the

upper frame, "angle guides" (33) are positioned at an angle "that approximates the minimum angle between

a horizontal plane and the plane of the human socket and ball joint." Three-sided open boxes (34) are

mounted in the "angle guide" to accept a moldable material [wax] for generating the functional mandibular

^athways. Stone dies were then made of the pathways and were replicated in 'crylic resin. The incisal guide

table (45) had a "guide socket" in which "a ontoured socket (61) may be formed. . .to give the desired

mouth opening and ite characteristics."

gure 94: (A) The TMJ Articulator, 1965, from Swanson's first articulator patent, is model was improved

dramatically in the second model. (25) Condyle post; ^ condyle head; (34) three-sided open box; (44)

incisal pin; (45) incisal guide ■}e; (61) functionally contoured pocket. (Reprinted from the 1965 US

Patent.)6 iSwanson's functionally generated path ("chew-in") method included in the 'ent of his first

model. Similar to the Needles-House "Chew-in '' method, four Qngular studs (52) were placed in the

maxillary base plate to generate the Ctional pathways (54) in the mandibular base plate.

r.

65

The 4-stud functionally generated path ("chewin") procedure (Fig 94B) Swanson advocated was essentially

developed by Milus M. House in the mid- 1920s. Reportedly, Flouse's was an improvement over John

Needles' 3-stud system. Similarit^s of Swanson's method to the adopted Needles-House "chew-in"

procedure included constructing baseplates to fit the maxillary and mandibular teeth or alveolar ridges and

placing four triangular studs (52) in the maxillary baseplate for generating the mandibular functional

pathways (54) in the mandibular occlusal surface. A departure from the Needles-House method was the

suggestion by Swanson that " . . if an impression compound has been used in the surface of [the mandibular

plate], a hard plastic reproduction is made of this plate." On June 11, 1968, Swanson, then of thousand

Oaks, California, received a ...patent related to structural improvements to his articulator (Fig 95);

specifically to ^'the condylar posts and the addition of a centric guide and spring tension assembly post

(Patent Figs 91 and 92) mounted on the lower frame between the condylar Imposts (Patent Figs 91 and 94).

These changes were made to the existing articulator >;to permit free hinge movement and full support of

the upper frame in the open ^position without detachment of the upper ,and lower frames (Patent Fig 93).

The " ^nondetachable feature (Patent Fig 95) was designed to "not adversely affect or ^interfere with the

normal manipulation of the dental articulator for simulating the ij jaw movements.''

figure 95: The TMJ Articulator, 1968. Swanson's second articulator patent ""-Unbodied structural

improvements, many of which were retained in subsequent Models.

About 1968-1970, this improved model of the TMJ Articulator was introduced ife.the

profession. This articulator essentially embodied all the features of the final iSjtosion except the right and

left centric locking hooks had not yet been added. In deption to the improvements to the posterior structures

of the articulator as

66

indicated in the second patent letter, improvements were made to the upper and lower frames as well as to the incisal pin and guide assemblies. Accessories included a facebow, hinge axis locator, and an occlusal lane analyzer system consisting of an analyzing "flag" and use of the Hanau mechanical incisal table with the Schuyler pin. Plastic fossa boxes of 15° and 45° were also available. In September 1975, Swanson received a patent8 for a third model of the TMJ Articulator (Fig 96A). This model was essentially the same as the previous one, except that the right and left centric locking hooks were included (Patent Fig 93, No. 88). More significantly, however, this patent included mechanical condylar controls. The fundamental design of these controls included adjustable Bennett (62) and protrusive angles (74) (Patent Fig 94). It is assumed that these mechanical fossae were intended as an added accessory. In addition, plastic preformed fossae of 28°, .-35°, 40°, 45°, and 50° were offered; Figure 96B is a photograph of the third model "with functional condylar controls and right and left locking hooks.38

WPl

*he "Dupli-Functional" Articulator On January 20, 1969, Edwin F. Irish, of Richmond, Virginia,

received a patent Or the "Duplifunctional"Articulator. Irish characterized his instrument as an SXtraoral tracing device that records three-dimensional mandibular movements and . thout requiring the transfer of records, is converted into a "tripod-type of dental articulator upon which dentures may be constructed and their occlusion balanced."

pe recording apparatus (Fig 97A) was composed of two semicircular framework S^mblies. The upper assembly (A) ran approximately from one condylar region found the face to the other condylar region.

Passing through the upper assembly re three vertically adjustable rods, one each through the right terminal (C) and

67

Figure 97: (A) The "Dupli-Functional" Articulator: the recording apparatus. This shows the upper (B) and lower (C) recording assemblies with the bearing plates ,H) attached. The vertical recording rods (C-

E) are in the central position of the fjree lower receptacle cups (G). (Reprinted from Journal of Prosthetic Dentistry, sh EF Dupli-Functional Articulator, p. 643, Copyright (1965), with permission from the

Editorial Council of the Journal of Prosthetic Dentistry.) 15 (A) (Overlay), e anterior receptacle cup (35) and recording rod (2) serve as the incisal pin and ide assembly because of the function of the adjustable

plane guide (37) on bar 8). 'ie, anterior cup [Fig 97A (Overlay)] functioned as an incisal guide control and COrdingly, contained an adjustable plane guide (37) on bar (38) that was variable m 0° to ± 25° for rod (2). The plane guide was arbitrarily adjusted to be j§mpatible with the desired anterior vertical overlap when posterior teeth with "~ps were used. This was accomplished either before or during the functional gistration of mandibular movements. Corrected occlusion rims were then ched to the bearing plates of the upper and lower assemblies. When the casts ©[^mounted in the articulator using mounting plates, the conversion to the 'ripod" articulator was complete (Fig 98)

68

figure 98: The "Dupli-Functional" Articulator: conversion to the tripod-type articulator because the casts have been mounted on the recording apparatus. The occlusion rims were attached to bearing plates F and

H, the upper anterior extension (A) of which orients the occlusion rim and recording assembly. After the Afunctional recordings were made, the casts were attached to the upper (B) and Slower (C) mounting

plates.

|The central bearing recording device devised by Irish is noteworthy. Irish lained that "Pascal's laws of hydraulics have been utilized, and the central aring "point," with its unwanted concentration of forces has

been broadened so itflat the bearing surface includes the areas overlying the ridges." The bearing vice was a cellophane "pillow" filled with water interposed between the two flat ing plates. The fluid-filled

"pillow"was pliable but not elastic. It was bonded the upper bearing plate while the lower bearing plate was free to move against under side. An optional simple hinge device (Fig 99) could be attached to the Bpper

and lower assemblies to facilitate the early laboratory procedures of setting e denture teeth. It would then be removed for balancing the occlusion according the patient's recorded functional controls.

fete: Initially, the patient's vertical dimension of occlusion and a tentative centric were established using wax interocclusal records and mounting the casts a planeline articulator. The relationship of the occlusion rims was then ferred to the bearing plates of the recording assembly.

\Ure99: The "Dupli-Functional" Articulator, showing the optional removable This device was used for convenience for initially setting the denture teeth.

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le articulator is a rigid device with movement patterns determined by solid Ithways, whereas the mandible is guided by muscles, ligaments and non-rigid bint surfaces, by the teeth and by complex neuro-muscular

system. The mandible Uspended by the ligaments and muscles is resilient and flexes under normal iiologic stresses and the teeth are suspended in the membranes that respond to ssses in an elastic manner. The more

adjustable the articulator, the factors of ldibular movements can be reproduced with a greater degree of accuracy. At ?same time, more complicated the device, more the human errors involved.

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J. Classification based on the instruments funetion:-

It was given at the international Prosthodontic workshop on complete denture occlusion at the University of Michigan in 1972.

riassl:- punction:

-Simple holding instrument

-Accept single interocclusal record or single static registration -Vertical motion may or may not be possible.

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^Example:

rSlab articulator (first articulator)

PR?'-' V ,

iHinge joint articulator IJB. Gariot articulator (1805) 3arn door hinge articulator (with anterior vertical stop, will accept a CR record idiwill reproduce this position reliably if the hinge does not have any play.)

The "Barn-door" Hinge Articulator

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is II:-

lit horizontal & vertical motion but do not orient the motion to the TMJ via a

le- bow transfer.

it'jf

jce- Bow: According to G.P.T, Face- Bow is a caliper like device that is used to )rd the relationship of the jaws to the temporo-mandibular joints and to orient [casts on the articulator to the relationship of the opening axis of temporo- idibular joints.

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II-A:

it eccentric motion based on averages and will not accept a face bow ier.

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E.g.:- Grittman Articulator (By Grittnian in 1899) •Condyles are on lower member of the articulators and their ]3a;

-Casts are mounted on the articulator on the basis of Bonwill's triangle, which is a 4inch equilateral triangle from condyle to condyle and to the lower central incisor contact point.

4

Gysi simplex (by Alfred Gysi in 1914) (Most popular instrument of this class).

[Condyles on the lower member ^Condylar paths are inclined 30 incisal guidance is fixed at 60°.

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The Gysi Simplex articulator

The Grittman articulator

iSSjI-B:

pits eccerjfriiimotion, based on arbitrary theories of motion and will not accept l^ow transfer.

Monson maxillomandibular articulator (By Monson in 1918).

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> are inclined 15°.

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