DENTAL INSTRUMENTATION

The History of Articulators: A CriticalReview of Articulators Based on GeometricTheories of Mandibular Movement, Part II:Rupert Hall’s Conical TheoryEdgar N. Starcke, DDS

IN PART I of this series on “geometric” theoriesof mandibular movement,1 it was suggested that

William Bonwill and Francis Balkwill were the firstinvestigators to apply geometric principles to man-dibular movement and occlusion. Although theirhistoric work was in the 1850s and 1860s, it was notuntil much later, in the first decade of the 20th

century, that Carl Christensen and GeorgeMonsonindependently described their applications of the“spherical” theory of mandibular movement andarticulator design. While the dental profession hadtaken little notice of these events, nevertheless,Monson’s work was to have considerable influenceon the profession’s understanding of mandibularmovement and on the development of articulatordesign.

Some scholars, however, have held that it wasRupert E. Hall, a young dentist practicing in Hous-ton, Texas, who first reported on the principles ofthe geometric school of mandibular movement andocclusion when he introduced his “conical” theoryin 1915.2,3 AlthoughHall was not the first to explorethe relatively uncharted territory of geometric so-lutions for mandibular movement, he certainly wasthe first to wake up the profession to a new andprovocative concept.

Rupert Hall was always enthusiastic about what-ever issue he was promoting, and this one was noexception. From 1915 to 1920, Hall conducted re-search, made numerous presentations, publishedpapers and patented 4 articulators,4 all relating tohis new conical theory. When Hall first presentedhis geometric solution to mandibular movement in

1914, he had not yet established all of the basicprinciples for his conical theory.

Dr. Hall Unveils His FirstArticulator

The hardest and most important problem that has everconfronted the dental profession has been the movements ofthe human mandible. So complex have they been viewedthat some investigators have concluded a solution [is] be-yond the power of man . . . . Believing that I have solved themovements of the human mandible, I herewith submit foryour consideration and approval the following claims to-gether with the different experiments I have conducted,which have all, without exception, proven in the fullestdetail that such are the true movements.5

With these opening remarks, on January 19,1914, Rupert Hall began his presentation at ameeting of the Houston Dental Society in Houston,Texas, introducing his “first endeavors in articula-tor building,”6 the “Dental Occluding Frame,”* and anovel geometric explanation for mandibular move-ment. It may seem incongruous for Hall to haveassociated a geometric concept with this instru-ment; however, a closer examination of his descrip-tion7 reveals a relationship.

At the time of the Houston meeting, Hall stilladvocated reproducing condylar movement in ar-ticulators. He described the mandible as having theability to move in “four distinct directions: forward,

Correspondence to: Edgar N. Starcke, DDS, Clinical Professor, De-partment of Prosthodontics, The University of Texas Health Science Centerat Houston Dental Branch, 6516 John Freeman Avenue, P.O. Box 20068,Houston, TX 77225. E-mail: estarcke@mail.db.uth.tmc.edu.

Copyright © 2002 by The American College of Prosthodontists1059-941X/02/1103-0010$35.00/0doi:10.1053/jpro.2002.127767

*Rupert Hall applied for a patent for the “DentalOccluding Frame” on January 28, 1914, the same monththat he introduced it at the Houston Dental Societymeeting, but the patent was not granted until April 10,1917. It was an adjustable condyle instrument, but Hallwas already beginning to develop a “geometric” approachto explain mandibular movement. Within a year, he hadabandoned this articulator design and was promoting the“Hall Articulator,” also known as the “Alligator,” an artic-ulator based on his conical theory.

211Journal of Prosthodontics, Vol 11, No 3 (September), 2002: pp 211-222

laterally (to either side) and backward.” He alsobelieved that all previous inventors had failed toreproduce the backward movement, or what hecalled the “fourth movement,” in their articula-tors.5

Hall’s “Dental Occluding Frame” was an “adjust-able condylar guide” articulator with advanced fea-tures, including controls for the Bennett movementand for adjusting the intercondylar distance andthe innovative gothic arch controlling feature of theincisal guide mechanism (Fig 1). With this instru-ment, Hall believed that he had produced an artic-ulator “capable of reproducing all of the move-ments of the human jaw in incising and

masticating.”5 The “fourth movement” was accom-plished by placing the condyles (pin 28) in theglenoid fossa (cam 36) so that as 1 condyle movesforward, downward, and inward, the other condylemoves backward, upward, and outward. That is, theupper member of the articulator will pivot aroundcentral rod 31 in bearing box 29 when it is hand-manipulated to guide 1 condyle (pin 28) to followthe Bennett guide (rib 46 on cam 36) in a downwarddirection. The corresponding pin 28 will follow thecorresponding Bennett guide (rib 46 on cam 36)upward. Hall contended that the jaw pivots at apoint in the center of and below the condylar line.Consequently, the upper member would have an

Figure 1. Hall’s “Dental Oc-cluding Frame.” (A) Frontalview. This drawing diagramsthe oscillatory (rocking) move-ment of the upper memberthat Hall claimed repre-sents natural jaw move-ment. The movement iscontrolled by the right andleft condyles (pins 28) bear-ing on the fossae (cams 36)and the incisal pin (48)bearing on incisal guides(plates 51). (Reprinted withpermission from Hall RE: Asolution of the mandibularmovements. Texas Dent J1914;32:5.5) (B) Cross-sec-tional lateral view showingthe central pivoting pin (31)in bearing box 29. Pin 31usually rests only againstthe anterior wall of bearingbox 29 that is large enoughfor the pin to move freelywithin it. This mechanismdid not serve as a verticalstop. (Reprinted from USpatent.7)

212

oscillating (rocking) motion in both the horizontaland vertical planes. Hall held that these move-ments mimicked the natural movements of themandible.5

Figure 2 is a schematic representation of themovements of the “Dental Occluding Frame” in thehorizontal plane. Point A corresponds to pivot pin31 in bearing box 29 (see Fig 1) around whichtriangle B-C-D oscillates. Point B is the front of theinstrument designated by incisal pin 48. Hall musthave assumed that the condyles moved equallyforward and backward and that the incisor pointmoved laterally and in a straight horizontal direc-tion.5 However, contrary to Hall’s explanation, it isapparent that point B, corresponding to pin 48,would move on an arc with point A as the center,and that points C and D, corresponding to cam 46,would move in arcs with point A as their center aswell.

Curiously, Hall did not include a true “centricstop” with pivoting pin 31 in the “Dental OccludingFrame” and, more interestingly, he did not provide ahinge mechanism. Its absence would have surelycompelled many dentists of the day to ask: “Nohinge? What else are these articulators for?”

Hall’s Initial Geometrical Solutionto Mandibular Movement

To explain his theory of mandibular movement,Hall envisioned that if 2 equilateral triangles (con-

structed on Bonwill’s principles) were placed backto back, they would share a common base thatrepresented the condylar axis. The vertex of theanterior triangle would be located at the incisorpoint, and the posterior vertex would be located inthe region of the external occipital protuberance.

Figure 3 diagrammatically demonstrates Hall’sinitial geometric solution to mandibular move-ment. Viewed on the horizontal plane, this drawingrepresents a double-Bonwill equilateral trianglewith a common base. Points L and R connecting thebase of the anterior triangle are located at the rightand left condyles with the vertex M at the medianline (incisor point). Points L and R, connecting thebase of the posterior triangle, are located atthe right and left fossae, with the vertex P at theexternal occipital protuberance. Point P was con-ceived as the anatomic rotation center of the man-dible. Hall also believed that the mandible openedand closed on arcs concentric to a point at theexternal occipital protuberance (Fig 4).

According to George H. Wilson, Rupert Hallpresented his inventions and a practical demonstra-tion at the 1914 National Dental Association

Figure 2. Hall’s schematic representation of the move-ment of the “Dental Occluding Frame” in the horizontalplane. (A) The position of pivoting pin 31. (B, C, and D)Positions of the incisal pin 48 and the moving condyles(pins 28). (Reprinted from US patent.7)

Figure 3. A diagram of Hall’s geometric solution ofmandibular movement. This represents Hall’s double-Bonwill equilateral triangle with common base: L-R-Mdesignates the anterior triangle (right and left condylesand incisor point), and L-R-P designates the posteriortriangle (right and left glenoid fossae and the externaloccipital protuberance, identified as the lateral rotationcenter). (Reprinted from Hall, p 7.5)

213

(NDA) annual session in Rochester, New York.Wilson reported that the presentation made amarked impression on those who attended. Amongthose interested were representatives of the S. S.White Dental Manufacturing Co., which securedthe cooperation of Hall to perfect the instrumentand place it on the market. However, Wilsonclaimed that it did not reach the marketplace until1919 because of “various problems,” including thedemands of World War I.2

Wilson’s account of the events surroundingHall’s introduction of his new theory is noteworthy,because it contains discrepancies that cannot beignored. For example, Wilson may have been think-ing of another occasion—there is no record of Hall’sparticipation in the Transactions of the 1914 NDAmeeting.8 Moreover, there are indications that theS. S. White Co. produced an articulator designed byHall sometime before 1919; nevertheless, if this istrue, then the instrument undoubtedly had a verylimited distribution. By 1919, however, the S. S.White Co. featured a very different instrument intheir catalogue than that which Rupert Hall wouldhave demonstrated in 1914. Hall’s “Automatic Ana-tomic Articulator” was featured in the S. S. Whitecatalogue as the “Hall Articulator #12.”9

Evolution of Hall’s Conical Theoryof Mandibular Movement

In September 1915, Hall presented his new conicaltheory and an articulator designed to support thetheory at the Panama Pacific Dental Congress in

San Francisco, CA.10 Hall called his new instrumentsimply the “Hall Articulator,” but it was to becomebetter known as the “Alligator.” Actually, Hall re-ceived patents for 2 models of the “Alligator.” Theoriginal version was patented on June 20, 1916.11

Hall himself probably built it, and there may havebeen only 1 (Fig 5A). The second version, patentedon March 6, 1917,12 was the first of his articulatorsto be produced by the S. S. White Dental Manufac-turing Co. (Fig 5B). Regardless of which of thesearticulators Hall presented at the Panama-PacificDental Congress, on this occasion he likely firstintroduced his conical theory to an internationaldental audience.

Demonstrating the same conviction that he hadshowed when introducing the “Dental OccludingFrame,” Hall proclaimed that:

My articulator affords the means for reproducing me-chanically all the masticatory movements and their combi-nations. In an articulator, we must remember to reproduceonly the movements necessary to mastication—movementswhen the planes of one or more teeth are in contact—movements when the condyles are in the fossae and not onthe eminentia.10

When Hall described the conical theory at theSan Francisco meeting, he emphasized his basicpremise that the geometric solution to mandibularmovement involves conceiving the Bonwill equilat-eral triangle as folded back on its base as a hinge,with the posterior vertex in the region of the exter-nal occipital protuberance (see Fig 3). By 1915,however, Hall had developed his theory beyonduncomplicated lateral movements. He now believedthat the “simple movements of the mandible” (i.e.,the opening/closing and incisive, or protrusive,movements) were independent of, yet subordinateto, the lateral rotation center.10 Hall suggested thatthe dihedral angle (of the triangles) would be thesame as the dihedral angle between the lateralsurfaces of 2 triangular pyramids with a commonbase, thus forming a double pyramid. In the sagittalview of the double pyramids applied to the skullshown in Figure 6, Hall explains that the axis of theopening and closing movement is located at pointE, at the level of the occlusal plane, below the headof the condyle B. The axis of the incisive movement,one that is in combination with the opening/closingmovement, is located at point D, below and parallelto point E. The location of the axis of mandibularlateral movement is identified as in the region of

Figure 4. Hall conceived that the opening and closingmovements of the mandible were on arcs concentric to apoint in the area of the external occipital protuberance.(Reprinted from Hall, p 9.5)

214

point A, but in combination with the other move-ments was considered to be in the median planeposterior to the condyles and on a plane, K-L, 45degrees oblique to the occlusal plane.12

In the “Hall Articulator,” the external occipitalprotuberance was identified as the apex of a cone,and the mechanical reproduction of this lateralrotation center was the foundation for this instru-ment. As a result, the actual mechanism was lo-cated posterior on a level with the occlusal plane,placing the opening/closing axis equidistant fromthis posterior position and the incisor point (Fig 7).

On October 18, 1919, Rupert Hall introducedthe “Automatic Anatomic Articulator” (Fig 8A) and his

conical theory in a paper read before the NationalSociety of Denture Prosthetists at their first annualmeeting in New Orleans, LA.13 Supporters of Hall’sphilosophy welcomed the “Automatic Anatomic Artic-ulator”14 because it was a departure from the “alli-gator” design, representing a more complete em-bodiment of the conical principles. Among hissupporters was Milus M. House, who suggested anadditional feature. The lower arm B (jaw castholder) can be protruded or retruded by an adjust-ing screw E. This movement is used to grind theteeth to accommodate the retrusive movement ofthe mandible. To retrude the arm, it is necessary towithdraw the stop screw as shown in Figure 8B.

Figure 5. (A) An original model of the first patented version of the Hall articulator, also known as the “alligator,” 1916.(From the collection of the author.) (B) The second patented version of the Hall articulator, 1917. The S. S. WhiteDental Manufacturing Company produced this model for Hall in 1916. (Inset) Both versions of this articulator had aprovision for the use of a facebow. (Reprinted from the collection of the University of Texas Health Science Center atHouston Dental Branch.)

215

Hall’s description of his conical theory and itsapplication to the automatic anatomic articulator isillustrated in Figures 9 and 10. Building on Hall’sbasic tenets as illustrated in the detail of Figure 6shown in Figure 9A through D represent Hall’sdouble pyramid as viewed on the sagittal plane,with B as the position of the condylar line (joiningthe bases of the triangles in the horizontal plane)and E as the center of the opening/closing move-ment. If cone apex A is the center of mandibularlateral movement and is scribing the arc of a circlein the horizontal plane, then line A-C (the plane ofocclusion) is deflected vertically by the guiding cuspplanes of the teeth.

It should be noted that Hall believed that anangle of 45 degrees would produce cusps of the

highest efficiency in mastication. In natural teeth,this is found predominantly in the maxillary firstbicuspids. Hall chose the 45-degree angle as the“generating” angle (anterior guidance C) for thecone.

The inclination of the cusp plane of the keytooth, the maxillary first bicuspid, is projected lineI-J. Line K-L projected from apex A intersecting theprolongation of line I-J at right angles determinesthe axis of the oscillatory (rocking) movement ofthe mandible as guided by the laterally inclinedplanes of the teeth.

The mechanical centers for movement intendedto represent mandibular movements based on thegeometric centers in Figure 9A are shown in sche-matic form in Figure 9B. This shows a diagram ofthe “Automatic Anatomic Articulator” for imitatingmandibular movement intended for use in practice.Geometrically, line A-C, the plane of the teeth,becomes an element of a cone A-M-C, and thus thesurface of a cone should present curves character-istic of the curves found in the teeth of the maxil-lary arch.

In the construction of complete dentures, forexample, the maxillary teeth would be set to con-form to the inner surface of an 8-inch cone, thelength having been determined by the 2 Bonwill4-inch equilateral triangles placed back to back (seeFig 10).

Variations on the Same Theme:Changes in the “Automatic

Anatomic Articulator”Rupert Hall made several changes in the design ofthe “Automatic Anatomic Articulator,” some significantand some minor. The basic principles of his conicaltheory never really changed, but he altered thefeatures of the device, moving from a very rigidinterpretation of the conical theory to a more flex-ible interpretation. For example, in the initial mod-els he included a provision for a mounting jig todetermine the vertex of the maxillary (Bonwill’s)triangle. Later, he provided for the use of a facebowas he had for his earlier articulators. Obviously,using a facebow would have changed not only thesize, but also the orientation of the maxillary trian-gle. Hall implied that he had altered some articu-lator designs to correct errors. It is also quite ap-parent that some changes were made due tomarketplace pressures for a more practical instru-ment. Nevertheless, Hall claimed that each suc-

Figure 6. A lateral elevation of Hall’s double pyramidapplied to the human skull. This illustration indicates theapproximate locations of the axes of the simple mastica-tory movements of the mandible as determined by Hall.E is the opening/closing axis, and D is the axis of theincisive or protrusive movement. The axis of the mandib-ular lateral movement lies on line K-L, 45 degrees to theocclusal plane. On line K-L is the apex A of the posteriortriangle. (Reprinted from Hall, p 682.13)

216

Figure 7. (A) Patent draw-ings of the original version ofthe “Hall Articulator,” 1916.Note that the mechanism forlateral movement is pivotingpin 20 in bearing box 18 pro-jecting the lateral motion toapproximately the level ofthe occlusal plane. In this in-strument (and continued inthe second version), provisionis made for the use of a face-bow. Because of the “differ-ence in length of the skulland jawbone of various per-sons,” to maintain equiva-lency of the anterior and pos-terior triangles, longitudinaladjusting mechanisms areprovided (slot 22 for arm 21and rods 25 for cast holders32 and 33). (Reprinted fromUS patent.11) (B) Patentdrawings of the second ver-sion of the “Hall Articulator,”1917. The S. S. White DentalManufacturing Company pro-duced this model for Hall. Itcontains the same featuresas the first model, but unlikethe first model, it has all theattributes of a commerciallymanufactured product. (Re-printed from US patent.12)

217

ceeding version of his articulator was capable ofmechanically reproducing all masticatory move-ments more accurately than the last. And so it waswith all of the articulators that Hall produced dur-ing his long career. Students of dental history knowthat during the late 1920s, Hall abandoned hisgeometric ideas and embraced the “tripod” or

“three-dimensional” concept of articulator design,defending this philosophy with the same ardentdedication.

Originally, Hall had received a patent for thisversion of his “Automatic Anatomic Articulator” alongwith his first manufactured model in 1918 (Fig11).14 He applied for a division of the originalpatent in 1918 and received an individual patent forthis articulator in 1920.15 This is an example of adesign for accommodation. In the patent letter,Hall claimed that his principle objective, in additionto the reproduction of accurate masticatory move-ments, was to provide an articulator that

may be so adjusted as to accurately coincide with themeasurements and conditions that may be found in eachindividual patient. . .to provide means for relatively shift-ing the jaw model holders longitudinally to produce anydegree of overbite. . .the models may be moved on a hingetoward and from each other on an adjustable axis.14

Other claims included adjustments for varyingthe size of the articulator to accommodate denturesof different sizes and a provision for the use of afacebow.

In the early 1920s, M. M. House improvedmechanically on the original “Automatic AnatomicArticulator” design, but kept its general principlesunaltered. This instrument was produced as the“Hall–House Precision Articulator”; it was not patented(Fig 12).16

In 1924, at the annual meetings of the NationalSociety of Denture Prosthetists and the AmericanDental Association in Dallas, Texas, Hall intro-duced an instrument that he considered a greatlyimproved version of his “Automatic Anatomic Articu-lator” (Fig 13). Now calling this instrument the“Hall Arbitrary Articulator,” Hall stated that he be-lieved that the mistake in the development of his1918 articulator was the adoption of a horizontalmovement for the protrusive motion:

This, as in Bonwill’s articulator, was wrong. That hadI adopted average downward or oblique movement insteadof a horizontal movement, this instrument would have beenfundamentally correct. This [arbitrary] instrument is thefinest, most complete and most nearly accurate arbitraryarticulator ever built. . .and such an instrument is indi-cated in preference to the use of adjustable two-dimensionalarticulators so constructed and limited in their movements,which includes every articulator in our analysis past and tobe analyzed except the Luce, Lentz, and Hall three-dimen-sional articulator.6

Figure 8. (A) Hall’s “Automatic Anatomic Articulator.”Note that the mechanism for the lateral rotation centerhas been placed at the level of upper arm C. However,this center is still located on a line 45 degrees oblique tothe occlusal plane. The hinge axis remains at the level ofthe occlusal plane, designated by “M” on the incisal pin.M. M. House’s feature for longitudinal adjustment of thelower cast holder is at E. (B) Diagram of House’s sugges-tion for an added feature to Hall’s articulator to accom-modate for retrusive movement of the mandible. (A andB reprinted from Hall, p 684.13)

218

Alfred Gysi’s Views on Hall’sConical Theory and Articulator

What did Hall’s old friend and rival Alfred Gysithink of all this? In 1930, Hall quoted from Gysi’s1919 article in a German journal,† in which Gysi setout his opinions about Hall’s conical theory and the“Automatic Anatomic Articulator.”6 Hall quoted fromthis paper to show that Gysi had always failed tounderstand and appreciate the principles embodiedin the “Hall Arbitrary Articulator” and how severelyhe ridiculed Hall’s theory of the arcuate movementof the mandible. Perusing this article carefully, onecan detect a slight indignation in Gysi’s tone:

It was believed, Gysi said, that finally the real motionof the human lower jaw was known since the most promi-nent scientists had arrived at unanimous results. . . . How-

ever, it is an old established truth that one may have adifferent opinion about everything. Even today, there are. . .people, even with an academic education, who do notbelieve that the moon revolves around the earth and bothrevolve around the sun. It is true that it takes a certain

Figure 10. In Hall’s conical theory, for occlusion incomplete denture construction, the teeth of the maxillarydenture would conform to a segment of the inner surfaceof an 8-inch cone. (Reprinted from Hall, p 685.13)

†Gysi A: Hall’s utomatic anatomic articulator.Schweizerische Vierteljahrsschrift fur Zahnheilkunde1919; 29: 90

Figure 9. (A) This detail of Figure 6 illustrates how Hall conceived the construction of the cone overlaying the doublepyramid. This figure should be related to B to visualize howHall applied the cone to his automatic anatomic articulator.(B) A diagram of the “Automatic Anatomic Articulator” illustrating Hall’s application of the elements of the cone and othergeometric rotation centers for calculating artificial reproduction of the movements of the mandible. (A and B reprintedfrom Hall, pp 682-683.13)

219

amount of intelligence, which should enable us to absorbsuch ideas so thoroughly as to be convinced of them.

Along comes now an American dentist, Dr. RupertHall, and teaches us that the motions of the lower jaw donot emanate from a left and right axis, but around an axislocated in the center plane of the head, running from theglabella to the external occipital protuberance.

From my observations, Hall’s articulator is by no meansa really normal anatomic articulator. . .its constructionshould be based on scientifically exact investigations thatrepresent the results of a large number of carefully recordedcases. These proofs have not been furnished by Dr. Hall. Ican easily understand that Hall’s articulator will findmany adherents, as it is produced by the S. S. WhiteManufacturing Company, which it is conceded has a worldreputation for new and practical instruments of first classquality. In the present case, the initials S. S. W. have thesame effect on many as the burning candle has on moths,which scorch their wings. It must be feared that thisinstrument will become one of the many illusions that have

swamped our profession at intervals. . . However, at a timewhen Bolshevism finds so many adherents, it is quitepossible that Hall’s articulator, too, will find a goodlynumber of adherents.6

Apparently, Gysi thought that the only goodfeatures in Hall’s articulator were those that Hallhad copied from Gysi. By adopting his methods,Gysi claimed that “very probably, Dr. Hall willsucceed in improving on his ‘automatic’ articulatorto such an extent that one need but insert a coin init, and it will place the teeth in proper position, justlike an automat.”6 Gysi ended his paper on thismore somber note:

In a great many recent articulators, parts of my artic-ulator have been copied, and I said nothing against it,because of the fact that this had been, more or less, done ina decent and fair way and because these articulators in

Figure 11. This version of the Hall automatic anatomic articulator was originally included in the 1918 patent with themodel shown in Figure 8A. In 1920, Hall received an individual patent for this model through a division application.(Reprinted from US patent.15)

220

Figure 12. The “Hall–House Precision Articulator.” This instrument embodies several structural improvements to the“Automatic Anatomic Articulator” offered by M. M. House, including an unobstructed posterior view of the mounted casts.However, none of the basic features reflecting the conical theory were altered. This device was manufactured in theearly 1920s but was not patented. (Inset) A detail of the mechanism for longitudinally adjusting the lower cast holder.This added feature was suggested by House for grinding teeth to compensate for retrusive movements of the mandible.(Reprinted from the collection of the University of Texas Health Science Center Houston Dental Branch.)

Figure 13. This model ofHall’s “Automatic AnatomicArticulator” was produced in1924. Hall contended thatthis instrument embodied afeature that corrected hisfundamental mistake ofadopting a horizontal protru-sive movement.6 This articu-lator included an adjustableincisal inclination featureand a mechanism for movingthe upper arm in a straightprotrusive motion. The lat-eral wings of the incisal guideremained at 45 degrees. (Re-printed from the collectionof the University of TexasHealth Science Center Hous-ton Dental Branch.)

221

question were more or less usable instruments. In Dr. Hall’scase, I deemed it necessary to warn my colleagues.6

Did Gysi really believe that there was a “more orless decent and fair way” to steal one’s ideas? Per-haps Gysi was simply piqued because he believedthat Hall was using his ideas to pursue what heconsidered a ludicrous endeavor.

In any case, Hall must have still been smartingfrom this 10-year old slap in the face, because afterthe conclusion of Gysi’s article, he commented: “Inall moderation, I think I may claim that Dr. Gysihas done himself little credit in writing this article.A careful study of the subject will show that he is asfar wrong in some of his criticisms and opinions ashe is intemperate and unreasonable in his attituderegarding my articulator and my opinions.”6

More on the history of articulators will be pre-sented in the next issue of the Journal of Prosthodon-tics.

References1. Starcke EN: The history of articulators: A critical history of

articulators based on “geometric” theories of mandibularmovement. Part I. J Prosthodont 2002;11:134-146

2. Wilson GH: Prostheses, then and now. Dent Cosmos 1920;62:6-13

3. Washburn HB: History and evolution of the study of occlu-sion. Dent Cosmos 1925;67:331-334

4. Starcke EN: The history of articulators: The appearance andearly use of the incisal-pin and guide. J Prosthodont 2001;10:52-60

5. Hall RE: A solution of the mandibular movements. TexasDent J 1914;32:3-9

6. Hall RE: An analysis of the development of the articulator.J Am Dent Assoc 1930;17:3-51

7. Hall RE: Dental Occluding Frame. US Patent No. 1,222,203.April 10, 1917

8. King OU (ed): Transactions of the National Dental Associ-ation’s 18th Annual Meeting, Rochester, NY, July 7-10, 1914.Huntington, IN, National Dental Association, 1914, pp 1-77

9. S. S. White Dental Manufacturing Company: Catalogue L.Philadelphia, PA, S. S. White Dental Manufacturing Com-pany, c1918, p 75

10. Hall RE: The Hall articulator, in Ottolengui R (ed): Trans-actions of the Panama-Pacific Dental Congress, Vol. II. SanFrancisco, CA, Panama-Pacific Dental Congress, 1915, pp520-521

11. Hall RE: Dental Articulator, US Patent No. 1,187,532. June20, 1916

12. Hall RE: Dental Articulator, US Patent No. 1,218,178.March 6, 1917

13. Hall RE: Movements of the mandible and approximatemechanical imitation of these movements for the arrange-ment and grinding of artificial teeth for the efficient resto-ration of lost masticatory function in edentulous cases. JNational Dent Assoc 1920;7:677-686

14. Hall RE: Dental Articulator, US Patent No. 1,271,161. July2, 1918

15. Hall RE: Dental Articulator, US Patent No. 1,338,918. May4, 1920

16. Turner CR, Anthony LP (eds): American Textbook of Pros-thetic Dentistry (ed 5). Philadelphia PA, Lea & Febiger,1928, p 176

222