US2819525A - Artificial tooth - Google Patents

Description

Jan. 14, 1958 H. SPIRO ET AL 2,819,?25

ARTIFICIAL TOOTH Filed July 19, 1955 30b 56; INVENTOIL, ai 227 0 ig mmigrmnfgwm 2,819,525 Ice P atented Jan. 14, 1958 to the point where it becomes useless before it can be told for certain that a pontic will not fit. In this case, the ground pontic must be discarded, and a facing must be 2,819,525 selected and ground to fit.

5 In the so called sanitary pontic there is. usually only ARTIFICIAL TOOTH a thin slab of porcelain between the metal backing and Harry Spiro and Alvin Piermont Spiro, Chieago, ill. t the {natal bacfkmg forms chewmg i' Y tace, no facing being provided. The sanitary pontic is Apllhcatloll y 1955, 581131 5229949 used in cases where there is extremely restricted vertical 17 Claims. (CL space and in inconspicuous locations, such as lower posterior bridges. The porcelain slab must be sufficiently thick, especially adjacent the keyway of prior art construction, to prevent cracking thereof from flexure of metal, and yet the metal must be sufliciently massive to T lhventlofl is concerned generally With artificial resist flexing of the span, which flexure also causes loss-of teelthiahd t Particularly withimpmvemeflts in intefthe supporting natural teeth from undue strain. Unforchangeable bridge teeth and backings. tunately, in accordance with the prior art construction a In modern dehtlstl'y 1t 18 the Preferred Practice to utlllZfl relatively thick porcelain slab and a massive backing of iiliitegfiliilngeablebtegth wlien ontle1 ctr rzihore teeth ituust be 20 metall are inl Imanly instanclesb 1antithetical when only a s p i in a ri ge. n suc oo cons UCIOII, an sma verti a eig t is avaia e. artificial tooth of porcelain or plastic is provided with a At the present time, a display of metal at the biting keyhole Shaped Slot y f y Whhfh a complementary edges of bridge teeth is considered to be anaesthetic. Acy Of a metal hacklhg 1S fecelyed, dental Cemfint cordingly, it has become the custom to utilize the lower 8, utlllled t0 holtlthe Parts 111 morcflr less Pfifmw porcelain edge of the facing, either when used by itself nently assembled relation. There are mainly two classes as a part of a pontic, as a biting edge Unfortunately, 0f .lhterchahgeahle t ly, taclngs a the porcelain is friable, and the supporting means of the l'l There l 1h addltloh, an occaslonttlrly used prior art is such that facings readily chip or crack cfi. In a a hlldge tooth khowh a sahlttlly P the case of a damaged pontic this involves a rather comg hi c lf 21656 l g d i p f t g l l l plicated job to refit and replace the broken tooth or tooth c n e so ere r o erwise suia y secure' 0 t fithegmetal R t h hfldge, example, g fillings It has been proposed heretofore to provide a two piece 111 a Jaceht P teet pontic, including a facing member and a transverse mem- A f g Consists essentially of a f y y thin Slab ber. However, in the prior art the facing member is not P Bottle other tooth S1ml1lat1hg Sllhstahce fitted to the gum ridge but is backed against the transverse $11ChaS P Whlch ly covers hacklhg Oh t member so that considerable biting thrust is imparted front side thereof so as to hide the backlng- T t g from the facing member predisposing the transverse meniot have the hg pt to Saddle the gtllh Tldgeher to fracture. Also, among other disadvantages, its l fk l g p agalllllst the t l 0t h g i gf i and minimum length is in excess of the vertical space usually m ere 9 Over ahgs t e gum e in t 6 acing available in a reat portion of bridge cases.

llhgllally overhanging metal must either Saddle the 40 It is an obje ct of this invention to provide a two piece 211111 f he SlOPed out of Contact Wlth the gtlth- Th6 metal, pontic artificial tooth wherein the facing is fitted to the yV Saddles t g tends to become accreted and gum independently of the pontic forming element, and the lflfltatmg t0 t gum tlsstle- When h metal 13 l p out pontic forming element is then additionally fitted if there tf t Wlth the a f pp p f formed is sufiicient vertical height, the fitted facing being usable h h 1S extremely uhdesll'ahle from hygieh1c Stahdwithout the addition of the pontic forming element it point. there is insuflicient height.

p l q is designed to Stay 616311 the It is another object of this invention to provide a two zyh ltl g l f h o r 't i m ia l l hm liar t 51 2 h piece pontic artificial tooth having a natural appearing e acin on i i o in t hereio fiire desc ilfed, and in add iti on has a hgrizoiita l 5O fi f g i z gfi ig i gg5 21 2 2222 3; Lo the puma Slab, h y 0f p t i Wh extends lihgtlally h Another object of this invention is to provide an interh? P l 0f the ftlclng Portloh Saddle, h changeable artificial tooth having a natural appearing :g P t I YE t h the tilh h tldgefof a l g l- 2 biting edge stronger than any heretofore known in the ansverse por ion 0 e pon c is pre' era y s ape 0 art Conform to the gum ridge, usually y grinding, Shine" 55 More specifically, it is an object of this invention to times hyhuildlhg D w a Porcelain l g at 21 lower provide improved means for mounting artificial tooth tgf g tss i g gyil he zlc oi gg bx l fiq i thB faginglsj arlild pontilcbfoirlning ellliments lianfmetal backings In? 0 110 m H y 1 I 8 6011- w ere yt emeta ac 'ng rei orcest e acing or pontic. t e 111 i g h c l y tWO ahgularly dlsposed A further object of this invention is to provide an P 1 0 0 t e ape pohtlcartificial tooth of the interchangeable type wherein no P I to use the Porcelain Saddle pohtlc Whfih' grinding of offsets or slopes is necessary for additional ever Posslhle Inasmuch as no other suhstahcfi 15 as Will metal at the connectors to provide requisite strength and tolhtated y the gum tissue as a Wall fitted hlghly glflzhd rigidity, specifically on the transverse or pontic forming porcelain surface. Furthermore, the glazed porcelain surl t fhh stFtys l in the mouth-i lh addltwh, the POHtiC Yet another object of this invention is to provide means Permits natural tooth form lh the bridge leading t0 hettfif for utilizing plastic in interchangeable teeth having nat- Phhhetlcs and normal feel in the mouth- Accordingly, in ural appearing biting edges Where plastic previously was modern dentistry 23. facing l5 llSfid only when thfilfi i8 110i; not Successfully used due to the flexibility and oo resufficient vertical space to accommodate a pontic. Unsi tan e to abrasion thereof.

fortunately, in many cases where there is very little Another object of this invention is toprovide an artivertical height available, is necessary to grind a pontic ficial tooth wherein the backing lends greater support to the additional parts such as a facing or a pontic by a tenon joint with the metal backing largely embracing and thereby reinforcing the remaining part or parts.

Other and further objects and advantages of the present invention will be apparent from the following descriptron when taken in connection with the accompanying drawing wherein:

Fig. 1 is a perspective view of a two piece pontic artificial tooth constructed in accordance with the principles of the invention;

Fig. 2 is a vertical sectional view taken substantially along the line 22 of Fig. 1;

Fig. 3 is a vertical sectional view at right angles to Fig. 2 and taken substantially along the line 33 in Fig. 2;

Fig. 4 is an exploded perspective view of the tooth of Figs. 1-3;

Fig. 5 is a perspective view similar to Fig. l, but of a posterior tooth;

Fig. 6 is a vertical sectional view taken substantially along the line 6-6 of Fig. 5;

Fig. 7 is an exploded perspective view of the tooth of Figs. 5 and 6;

Fig. 8 is a perspective view of a tooth;

Fig. 9 is a vertical sectional view through the tooth of Fig. 8 and taken along the line 99 of Fig. 8; and

Fig. 10 is an exploded perspective view of the tooth of Figs. 8 and 9.

Referring now to the drawings in greater detail, and first to Figs. 14, there Will be seen an artificial tooth of the pontic type identified generally by the numeral and shown as it might fit against a gum 22. The tooth includes a generally L-shaped backing 24 including a rather substantial mass of metal which will not fiex. The backing is provided with a vertical front face 26 having lateral retaining ribs or ridges 28 thereon and undercut at 30. A base 32 projects forwardly from the vertical front face 26 and extends horizontally between the upper ends of the retaining ribs or ridges 23.

The backing 24 also is provided with an upper generally horizontal face 36 having lateral retaining ribs or ridges 38 thereon undercut at 40. A base 42 extends across the front of the face 36 between the retaining ribs or ridges 38. It will be apparent that a large mass of metal is presented by the backing, thereby providing wide and long sides for attachment by soldering or otherwise to other metal parts for anchoring to fillings in pier teeth or the like, also to resist flexure of the backing. The ribs 28 and face 26 present a tenon groove at the front of the backing, while the ribs 38 and face 36 similarly provide a horizontal tenon groove.

The tooth 20 includes also a facing 46 having a tenon 48 on the back thereof fitting into the tenon groove formed by the vertical front face 26 and the retaining ribs or ridges 28. The edges 50 of the tenon fit into the undercut portions of the ribs 28, being complementary thereto, and a tenon thereby securely fits into place. It will be apparent that the tenon and groove are preferably parallel and the facing tip is completely shoulderless so as to permit vertical adjustability of the pontic forming element on the facing by shortening the facing tenons length. The top surface 52 of the facing fits against the gum ridge 22, and is ground in order properly to fit. After the top surface 52 has been fitted, a part of the top of the tenon 48 may be ground off so that the backing can be moved downwardly for the accommodation of the pontic forming element in the available space. The rear face or surface 54 of the facing below the surface 52 and above the tenon 48 is flat for abutment against the base 32 and for abutment by a pontic forming element now to be described. It will be understood that dental cement is used to hold the parts firmly together upon final assembly.

The pontic forming element 56 is preferably made of porcelain, although the facing may be made of plastic or sanitary pontic artificial porcelain. The bottom of the pontic forming element 56 is provided with a tenon 58 complementary to the tenon groove formed by the face 36 and ribs 38. The top surface 60 of the pontic forming element preferably is ground to more or less saddle shape to rest on the gum ridge 22. Since a portion of the pontic forming element, specifically the tenon 58, depends below the facingtenons housing, it will be apparent that the pontic forming element need extend only an extremely short distance above the metal of the backing 24. Accordingly, the pontic forming element 56 can be placed in an extremely small vertical space. The front end of the pontic forming element 56 as is indicated at 62 is flat for abutting against the back surface 54 of the facing, while the underside of the pontic forming element at 64 is flat endwardly of the tenon to rest on top of the base 42.

it will be apparent from the foregoing that the facing 46 imposes no thrust on the pontic forming element 56. All of the vertical thrust on the facing is taken up by the base 32. Accordingly, the pontic forming element can be ground to an extremely low vertical height while still providing adequate strength therefor.

The ribs 28 which partially embrace the facing brace and rigidify the facing, while being practically hidden thereby. These ribs 28 extend to the bottom edge of the facing, and hence form a part of the biting surface, although being hidden from view. Since these metal ribs are part of the biting surface, they prevent undue force from being imposed on the porcelain or the like of the facing 46 and prevent breaking thereof. Such break ng further is limited or prevented by the ribs and the remforcement provided by the ribs. If, by some chance, the

facing should be broken, another facing can easily be substituted therefor without the necessity of removing the backing 24 and the difiicult-to-refit pontic forming element from the patients mouth. In many instances when there is a rather broad gum ridge as indicated in Fig. 2, the pontic forming element 56 also can be replaced, although it is thought that there practically never would be any necessity of replacing this element in the artificial tooth herein disclosed due to the lack of any strain imposed on the pontic forming element.

The artificial tooth 20 heretofore shown and described is a front tooth or incisor. However, the principles of the invention are applicable equally well to a back tooth or molar as may be seen in Figs. 5-7. In these figures similar parts are identified by the use of the same nu.- merals as used heretofore, with the addition of the suffix [1. Extended description is believed to be unnecessary in view of the similar numerals for similar parts. However, it will be noted that the backing 24a comprises a generally rectangular mass of metal, and that substantially lesser vertical height is available than in the previous embodiment of the invention. In spite of the decreased height, there is still a firm base or shelf 32a backing up,

the tenon 48a of the facing. Again it will be observed that the retaining ribs or ridges 28a extend substantially to the extreme bottom or biting edge of the facing, and in this instance the metal backing 24a also serves as a biting surface of the tooth 20a. The facing again is substantially independent of the pontic forming element, which is butted against it, and the facing therefore can be ground to fit the gum independently of the pontic forming element, so that it can be used alone if need be,

and the facing does not transmit any thrust to thepontic forming element.

Application of the principles of the invention to the so-called sanitary pontic is illustrated in Figs. 8-10. Similar parts again have been identified by similar numerals, this time with the addition of the suffix b. In the sanitary pontic there is no facing. The tooth 20b consists only of the metal backing 24b and the pontic forining element 56b. The metal backing is provided with a biting or chewing surface 66. porcelain or the like pontic 56b is he function of the Q to provide engagement with the gum which will not irritate 'or injure the gum, and which will stay clean. It will be apparent that the metal of the backing 24b in this instance cannot be of very great height, and that the porcelain of the pontic forming element 56b also cannot be of very great height. However, the metal in the form of the retaining ribs or ridges 38b and the base 42b serves to reinforce the remainder of the backing so that the backing will not flex. At the same time the raisedtenon 58b on the porcelain pontic reinforces the pontic to prevent breaking thereof. In accordance with the prior art teachings, a keyhole shaped key or retaining rib would extend downwardly from the surface 36b, and the porcelain would have to be the full height of the pontic forming element 56b and tenon 58b, having a keyhole shaped slot or groove therein, This leaves a relatively weak metal backing which tends to flex, thereby leading to damage to the adjacent pier teeth. It will be apparent that if a prior art metal backing were made as thick as applicants backing including the ribs or ridges 38b thereon, then the porcelain could be only as thick as the main portion of the pontic forming element 56b, and the keyhole slot necessarily formed in this thin porcelain element would very likely lead to breaking of the pontic forming element.

v From the foregoing it will be apparent that the artificial tooth herein presented possesses many advantages over the prior art. The facing of the tooth is readily replaced in case of damage thereto. Furthermore, damage to the facing is extremely unlikely in view of the more or less wrapping of the metal base around a substantial part of the facing. Breakage further is minimized by the retaining ribs or ridges which project downwardly substantially as far as the biting tip or incisal, and by the solid and broad support provided for the facing by the transverse base 40. The tenon with wrap around or lateral or edge support is of extreme importance in the pontic forming element as well as in the facing. The wrap around or rib construction of the metal backing provides a rigid backing without requiring that the pontic forming element be so thin as readily to break. Damage to the pontic forming element further is minimized by the fact that the facing does not bear on the pontic forming element, but rather passes in front of it with a pontic formng element abutting against the facing, thrust of the facing being taken up by the transverse base 32.

In accordance with the present invention plastic can be used for a facing having a natural appearing biting edge, whereas it could not satisfactorily be so used in the past. In the present invention the projection of the backing including the retaining ribs thereon down to the biting or chewing portion of the tooth minimizes wear on the facing. Furthermore, the facing is readily replaced in accordance with the present invention.

The teeth herein shown and described can be produced readily with conventional tools, whereas the prior art requires the use of special grinding tools of very small size which quickly change significantly in dimensions.

Various changes in structure will no doubt occur to those skilled in the art, and are to be understood as forming a part of the invention in so far as they fall within the spirit and scope of the appended claims, the specific examples herein shown and described being by way of illustration only.

The invention is claimed as follows:

1. An artificial tooth comprising a backing and a facing made of tooth simulating material, said facing having a tenon extending laterally across a major portion of the width of said facing, said tenon extending substantially to the biting portion of the facing, and said backing having a pair of projections thereon providing a tenon groove opening downwardly at the bottom of said backing and complementary to said tenon, said projections extending substantially to said biting portion for absorbing biting or chewing thrust.

2. An artificial tooth as set forth'in claim 1 wherein the tenon extends less than the full 'length of the facing on a side confronting the metal backing, having a transverse terminating edge spaced from the upper edge of said side of the facing, and wherein the backing has a transverse projection between the aforesaid. pair of projections engaging the end of said tenon and limiting upward movement thereof in said groove, said projections bracing said backing and partially surrounding said facing to reinforce the same.

3. An artificial tooth as set forth in claim 1 wherein the opposite substantially vertical edges of the tenon are parallel.

4. An artificial tooth comprising a backing and a facing element made of tooth simulating material, saidelemerit having a vertical tenon on the back thereof having on the front thereof providing a vertical tenon groove opening downwardly at the bottom of said backing and complementary to said tenon, said projections extending substantially to said biting portion for absorbing biting. or chewing thrust, and a horizontal transverse projection between said pair of projections substantially at the top of said backing and engaging the upper end of said tenon below the top of the facing element for limiting movement of the tenon and facing element upwardly, said projections bracing said backing and partially surrounding said element to reinforce the same, said facing element and said backing being relatively vertically adjustable by removal of a portion of the top of said tenon.

5. An artificial tooth as set forth in claim 4 wherein the facing element extends above the backing and is provided with a gum engaging surface.

6. An artificial tooth as set forth in claim 5 wherein the tooth is further provided with a pontic forming element mounted on top of said backing and butting against the rear face of said facing element.

7. An artificial tooth as set forth in claim 4 and further including a pontic forming element mounted on top of said backing.

8. An artificial tooth comprising a backing and an additional element made of tooth simulating material, said element comprising a pontic forming element having a guru engaging surface on one of its horizontal sides and a tenon on its opposite side terminating short of an edge thereof, said tenon having undercut longitudinal grooves on its sides extending openly in both longitudinal directions, and said backing having a pair of projections providing a tenon groove complementary to said tenon.

9. An artificial tooth as set forth in claim 8 and further including a transverse projection between said pair of projections limiting tenon movement in said groove, said projections bracing said backing and partially surrounding said element to reinforce the same.

10. An artificial tooth as set forth in claim 9 wherein the tenon extends laterally across a major portion of the corersponding dimension of said pontic forming element.

11. An artificial tooth as set forth in claim 8 and further including a facing element, said facing element having a vertical tenon thereon terminating short of the upper edge thereof, and said backing further having a forward pair of projections forming a tenon groove complementary to the tenon on said facing element, and a horizontal projection extending transversely between said forward projections and forming a base receiving thrust from said facing element tenon.

12. An artificial tooth as set forth in claim 11 wherein the facing element is provided with a biting portion, and said forward projections extend substantially to said biting portion, said forward projections and horizontal base further bracing said backing and partially surrounding said facing element to reinforce the same, and also absorbing biting forces.

13. An artificial tooth as set forth in claim 12 wherein the facing element extends above said backing and is provided with a gum engaging surface forming a continuation of the gum engaging surface on the pontic forming element, said facing element having a substantially flat rear face adjacent the gum engaging surface thereof and said pontic forming element having a flat front face butting against said rear face.

14. An artificial tooth as set forth in claim 8 wherein the backing has a tenon groove on a substantially vertical face thereof, and further including a facing of tooth simulating material having a tenon thereon received in said last mentioned tenon groove, said facing element having a gum-engaging surface forming a continuation of the gumenga-ging base of the pontic-forming element.

'15. An artificial tooth comprising a backing, a pontic forming element mounted on said backing and having a gum engaging surface, and a facing of tooth simulating material mounted on said backing and projecting above said backing substantially into contact with said pontic forming element, said facing and pontic forming element together forming the gum ridge engaging base of said tooth.

16. An artificial tooth comprising a metal backing and an additional element made of tooth-simulating material, said element having a tenon extending less than the full length thereof on a side confronting the metal backing, said tenon extending to one edge of said element and terminating short of the opposite edge, said metal backing having a pair of projections thereon providing a tenon groove complementary to said tenon, and a transverse projection between said pair of projections engaging the end of said tenon and limiting movement thereof in said groove, said groove being open at the end opposite the projection for receiving said tenon with a sliding movement parallel to said tenon, said projections bracing said backing and partially surrounding said element to reinforce said element.

17. An artificial tooth as set forth in claim 11 wherein the bottom surface of the tenon on the pontic-forming element is on a horizontal plane situated below the top end of the tenon on the facing element, thereby making the pontic adaptable into close-bite vertically restricted spaces.

References Cited in the file of this patent UNITED STATES PATENTS

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