Title:
Refractory die with pin and sleeve for teeth restoration
Kind Code:
A1


Abstract:
A refractory die removably mountable to a base with a model die for use in producing a crown or veneer to be attached to a tooth to be restored. The model die, produced from die stone, is removably mounted to the base with a portion of the model die corresponding to the tooth to be restored being separable therefrom and used to produce the refractory die. Porcelain is placed on the refractory die to produce the crown or veneer.



Inventors:
Pawlus, John G. (Columbus, IN, US)
Application Number:
11/113736
Publication Date:
11/10/2005
Filing Date:
04/25/2005
Primary Class:
International Classes:
A61C9/00; A61C13/34; (IPC1-7): A61C19/00
View Patent Images:



Primary Examiner:
WILSON, JOHN J
Attorney, Agent or Firm:
David W. Carrithers (Louisville, KY, US)
Claims:
1. A pin and sleeve combination for mounting a refractory tooth die comprising: a main body including a top end, a bottom end, a front and a back, said main body having a longitudinal axis extending from said bottom end to said top end, said main body further having a pair of opposite sides extending from said bottom end to said top end and diverging as said sides extend in a direction from said bottom end to said top end, said main body having a first intermediate portion between said bottom end and said top end, said sides diverge outwardly at a first included angle as said sides extend from said bottom end to said intermediate portion and then at a second included angle as said sides extend from said intermediate portion to said top end with said second included angle being greater than said first included angle, wherein said pair of opposite sides extending from said back to said front which diverge as said sides extend from said back to said front, said front being rounded as it extends between said opposite sides, said bottom end includes an extension projecting outwardly therefrom; and a sleeve to mount onto and in spaced apart relation to said main body.

2. The pin of claim 1 wherein: said top end is substantially flat.

3. The pin of claim 1 wherein: said main body includes a second intermediate portion between said first intermediate portion and said top end.

4. The pin of claim 3 wherein: said opposite sides diverge at a third included angle as said sides extend from said second intermediate portion to said top end with said third included angle being less than said second included angle.

5. The pin of claim 1 wherein: said back is rounded as it extends between said opposite sides.

6. The pin of claim 5 wherein: said opposite sides diverge as said sides extend from said bottom end toward said first intermediate portion, said front and back diverge as said front and back extend from said bottom end toward said first intermediate portion.

7. The sleeve of claim 1 wherein: said sleeve fits loosely around said main body and said extension of said bottom end extends outwardly of said sleeve.

8. A combination for use in producing a crown or veneer for a damaged tooth within a set of teeth comprising: a base; a multi part model die of a set of teeth removably mounted to said base, said model die including a damaged tooth portion separable from said model die and corresponding to a damaged tooth within said set of teeth, said portion removably mounted independently of said model die to said base; a pin mounted with adhesive to said portion of said model die with said pin having a main body extending outwardly from said portion; a sleeve to be placed around said main body when forming said base with said sleeve oversized relative to said main body forming an expansion space located between said sleeve and said main body; and, a refractory die removably mounted independently from said model die to said base, said refractory die replicating and replacing said portion with said pin.

9. The combination of claim 8 wherein: said sleeve fits loosely around said main body with said pin having a leg extending outwardly of said sleeve.

10. The combination of claim 9 wherein: said pin having said main body including a top end, a bottom end, a front and a back, said main body having a longitudinal axis extending from said bottom end to said top end, said main body further having a pair of opposite sides extending from said bottom end to said top end and diverging as said sides extend in a direction from said bottom end to said top end, said main body having a first intermediate portion between said bottom end and said top end, said sides diverge outwardly at a first included angle as said sides extend from said bottom end to said intermediate portion and then at a second included angle as said sides extend from said intermediate portion to said top end with said second included angle being greater than said first included angle, wherein said pair of opposite sides extending from said back to said front which diverge as said sides extend from said back to said front, said front being rounded as it extends between said opposite sides, said leg extends down from said bottom end.

11. A method of producing replacement material to restore a first tooth within a set of teeth comprising the steps of: creating a first impression of a set of teeth with a first tooth; creating from said impression a model die of said set of teeth with said model die having a first portion corresponding to said first tooth to be restored; providing mounting pins; providing a pin having a main body; mounting said mounting pins to said model die; mounting said pin having said main body to said first portion with an adhesive so said main body projects therefrom; creating a base adjacent said model die enclosing said pins and said enlarged section of said pin; removing said model die with said pins and said pin having said main body from said base; severing said model die into multiple portions including at least said first portion with said main body projecting therefrom and a second portion; creating a second impression of said first portion with said main body projecting therefrom; creating a first refractory die from said second impression providing a replica from refractory material of said tooth and said main body projecting therefrom; mounting said refractory die and said second portion onto said base by inserting said pins and said replica of said tooth and enlarged section into said base; and, placing material onto said refractory die to enable said first tooth to be restored.

12. The method of claim 11 wherein said set of teeth includes a second tooth to be restored that is spaced apart from said first tooth by teeth from said set and further comprising the steps of: said first impression and said model die are created of said set of teeth with said first tooth and said second tooth, said model die having a third portion corresponding to said second tooth and said second portion corresponding to teeth of said set between said first tooth and said second tooth; providing an additional pin having a main body and mounting said additional pin to said third portion with an adhesive so said main body of said additional pin projects therefrom; said base is created so it also encloses said main body of said additional pin; severing said model die into multiple portions including said third portion with said additional pin having said main body projecting therefrom; creating a third impression of said third portion with said additional pin having said main body projecting therefrom; creating a second refractory die from said third impression providing a replica of said second tooth and main body projecting therefrom; mounting said first refractory die, said second refractory die, and said second portion onto said base; and, placing material onto said second refractory die to finally configure said second tooth.

13. A pin and sleeve combination comprising: a main body including a top end, a bottom end, a front and a back, said main body having a longitudinal axis extending from said bottom end to said top end, said main body further having a pair of opposite sides extending from said bottom end to said top end and diverging as said sides extend in a direction from said bottom end to said top end, said main body having a beveled top end with a downwardly facing beveled surface diverging greater than said opposite sides; wherein said front being rounded as it extends between said opposite sides, said bottom end includes an extension projecting outwardly therefrom; and a sleeve to mount onto and in spaced apart relation to said main body.

14. The pin of claim 13 wherein: said pair of opposite sides extend from said back to said front and said sides diverge as said sides extend from said back to said front.

Description:

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of prior U.S. patent application Ser. No. 10/339,037, filed Jan. 9, 2003, and a continuation-in-part of International Application No. PCT/US2004/020933, filed Jun. 29, 2004.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of teeth restoration and more particularly to the use of refractory dies.

Description of the Prior Art

In order to add a veneer or a crown to a damaged tooth, the dentist makes a single impression of the entire set of teeth including the damaged tooth. For example, if the damaged tooth is an upper tooth then a yieldable material such as plastic, rubber and the like is used to make an impression of the entire upper set of teeth including the damaged tooth. As discussed in “Preparation and Fabrication of Ceramic Veneerley” by Paul Sturridge and Irfan Ahmad in QDT, Quintessence of Dental Technology, Volume 22, page 169 (1999), a working cast is then prepared from the impression. Typically, the working cast will be produced by pouring die stone into the impression and then allowing the die stone to harden. Small cylindrical pins are then mounted to the bottom of the working cast to enable the working cast to be mounted to a base and to allow for individual removable dies to be repositioned correctly in the base. The dies are subsequently sectioned, trimmed and repositioned back on the base. An impression of this trimmed model in the base is taken with silicon impression material and the base is removed with the individual dies retained in the impression. The dies corresponding to any teeth that are to be restored utilizing refractory dies are then removed from the impression and these voids are then filled with refractory material. A special refractory pin is placed in each die and a new base is poured.

An alternate prior art method used to create a working model with refractory dies is to trim the dies that will be used to make the refractory dies and to then reposition the dies back into the original impression. The remaining portion of the model is then poured up in dental stone. The individual dies are subsequently removed and duplicated in silicone. The dies are removed from the silicone impression and refractory material is poured into the impression to produce the refractory dies. The resulting product is then placed into the working model.

The first method requires the additional step of pouring of a second base. Further, the method has the disadvantage of having to redo the entire model should an individual die be damaged. The second method introduces possible positioning error by having to be replaced in the original impression. The second method also requires increased time to prepare the individual dies prior to duplicating.

The refractory die includes a pair of small pins extending outwardly in the same direction as the remaining cylindrical pins extending from the working cast. When the refractory die along with the working cast is within the mold, a plaster base is poured resulting in a final cast mounted to a base.

A further problem with the prior art methods is the breakage of refractory material surrounding the small cylindrical pins that project from the portion of the refractory die representing the tooth to be restored. Disclosed herein is a new large pin used in combination with the portion of the model die representing the tooth to be restored to produce a refractory die with a refractory pin extending therefrom with an enlarged external body.

SUMMARY OF THE INVENTION

One embodiment of the present invention is a method of restoring a first tooth within a set of teeth comprising the first step of creating a first impression of a set of teeth with the tooth to be restored. A model die is created from the impression with the model die having a first portion corresponding to the tooth to be restored. The first portion is provided with a mounting pin having an enlarged section that is then mounted to a base. An oversized sleeve is mounted to the enlarged section of the pin prior to forming the base. Next, the model die is removed from the base and severed into multiple portions including at least the first portion with the enlarged section projecting therefrom and a second portion. A second impression of the first portion with the enlarged section is produced allowing creation of a first refractory die providing a replica of the tooth and the enlarged section projecting therefrom. The refractory die and the second portion are mounted onto the base by inserting the pins and the replica of the enlarged section into the base. Replacement material is then applied to the refractory die to allow for the final configuration of the tooth to be restored.

It is an object of the present invention to provide a new and improved method for restoring teeth.

A further object of the present invention is to provide a mold of a set of teeth including a refractory die of a tooth to be restored removably mounted to a base with separable portions to allow replacement of any one portion without the necessity of reproducing the entire model.

A further object of the present invention is to provide a mounting pin to removably mount a refractory die within a model die set of teeth.

Yet another object of the present invention is to provide a sleeve for initially accommodating a model die of the damaged tooth and subsequently accommodating a relatively larger refractory die for the damaged tooth.

A further object of the present invention is to provide a mounting pin to adhesively mount to a base thereby eliminating hole-drilling of a first portion corresponding to the tooth to be restored.

Yet another object of the present invention is to provide a mounting pin having a bevel to guide a sleeve onto the mounting pin and positively seat the pin within the sleeve.

Related objects and advantages of the present invention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a grouping or arch of teeth including a tooth to be restored.

FIG. 2 is a perspective view of a model die replica of the teeth of FIG. 1.

FIG. 3 is a perspective view of a cylindrical pin used to mount portions of the model die of FIG. 2 to a base.

FIG. 4 is front view of an alternate embodiment of a refractory die-mounting pin.

FIG. 5 is a side view of the pin of FIG. 4.

FIG. 6 is a top view of the pin of FIG. 4.

FIG. 7 is a bottom view of the die of FIG. 2 with the pins of FIGS. 3 and 4 mounted thereto.

FIG. 8 is a top view of the model die of FIG. 7 mounted to a base with the portion of the model die representing the tooth to be restored removable therefrom.

FIG. 9 is a perspective view of the model die portion removed from FIG. 8 positioned within a container to produce an impression.

FIG. 10 is a perspective view of a refractory die of the tooth to be restored.

FIG. 11 is the same view as FIG. 8 only showing a model die corresponding to multiple teeth to be restored.

FIG. 12 is a perspective view of a sleeve for mounting to the pin of FIG. 4.

FIG. 13 is a side view of the sleeve of FIG. 12.

FIG. 14 is a top view of the preferred embodiment of a sleeve for mounting to the pin of FIG. 4.

FIG. 15 is a front view of the sleeve of FIG. 14.

FIG. 16 is a cross-sectional view illustrating the positioning of the pin of FIG. 4 in the sleeve of FIG. 14.

FIG. 17 is a perspective view of the replica tooth and replica pin produced from the use of the sleeve of FIG. 15.

FIG. 18 is a front view of an alternate embodiment of a refractory die-mounting pin.

FIG. 19 is a side view of the pin of FIG. 18.

FIG. 20 is a top view of the pin of FIG. 18.

FIG. 21 is a perspective view of the preferred embodiment of a sleeve for mounting to the pin of FIG. 18.

FIG. 22 is a perspective view illustrating the positioning of the pin of FIG. 18 in the sleeve of FIG. 21.

FIG. 23 is a perspective view illustrating the positive seating of the pin of FIG. 18 into the sleeve of FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now more particularly to FIG. 1, there is shown an arch of teeth 20 positioned within a person's mouth and illustrating a front tooth 21 to be restored positioned between and adjacent teeth 22 and 23. In order to restore tooth 21, either porcelain or other suitable material may be used to build up the tooth to a final configuration.

Prior to pouring an impression of teeth 20, the tooth 21 to be restored is prepared by removing decay, old fillings, etc. In the preferred embodiment, a conventional impression is then produced of teeth 20 by pouring impression material, such as polyvinyl siloxane into a mold or tray and placing the tray into the mouth allowing the impression to set up. The tray is then removed with the impression material having in it cavities corresponding to the teeth and providing a female die. The model die is then prepared by pouring a mixture of material into the impression. A conventional mixture includes for example, 20 ml of water along with 100 grams of die stone which is a gypsum with a resin. The mixture is stirred under a vacuum to eliminate air bubbles. The mixture is hardened producing a male model replica 25 (FIG. 2). Die model 25 is trimmed and the bottom is ground to produce a flat even surface.

Two different types of mounting pins are mounted to the bottom of replica 25. The pins include conventional cylindrical pins 26 (FIG. 3) and a unique refractory die pin 27 (FIGS. 4-6). Holes are drilled in the bottom surface of replica 25 with pins 26 and the cylindrical top end 28 of pin 27 then being inserted into the cylindrical holes. A standard glue, such as cyanoacrylate is first placed into the holes to securely hold the pins therein.

Pin 27 has a main body 29 with a top end 30, a bottom end 31, a pair of opposite side surfaces 32 and 33, a front surface 35 and rear surface 36. A pair of cylindrical pins 28 and 34 project outwardly respectively from top end 30 and bottom end 31 of main body 29. The main body is tapered both in a horizontal direction and a vertical direction as viewed in FIGS. 4 and 5. That is, surfaces 32 and 33 diverge as the surfaces extend from bottom end 31 to intermediate area 37 located between ends 30 and 31. Likewise, surfaces 35 and 36 diverge as they extend upwardly from bottom end 31 to an intermediate area 37 located between ends 30 and 31. Surfaces 32 and 33 extend vertically from area 37 to top end 30 along lines parallel to longitudinal axis 38 extending centrally through the pin. Front surface 35 and rear surface 36 are rounded being convex and cooperatively with side surfaces 32 and 33 providing a larger width 39 at the front end of the pin as compared to the width 40 at the rear of the pin. Surfaces 32 and 33 extend convergingly toward end 36 forming an included angle 16. The rounded front surface 35 and rounded rear surface 36 extend vertically along lines parallel to axis 38 between area 37 and top end 30. Main body portion 29 has an oblong horizontal cross-section from end 30 to end 31.

The cylindrical pins 26 (FIG. 3) are inserted into the holes previously drilled in the bottom of model 25 (FIG. 7) with the exception of the portion 44 of the model upon which is formed the tooth 21 to be restored. Instead of mounting pins 26 to portion 44, the refractory die pin 27 is mounted by inserting cylindrical top end 28 into a cylindrical hole drilled in the bottom of portion 44 thereby positioning the enlarged main body 29 beneath the model. For a relatively small sized tooth, such as, a front tooth, the rear surface 36 of pin 27 is located aft of the tooth to be restored whereas the front surface 35 faces outwardly and in a forward direction from the row of teeth. Once the adhesive within the pinholes has set up, plastic sleeves are installed on pins 26 and pin 27 in order to keep a base from sticking onto the pins. Commercially available sleeves are mounted to pins 26 whereas a special new sleeve 100 (FIGS. 12 & 13) is mounted to pin 27. Sleeve 100 has a hollow interior 101 to receive the main body of pin 27. The bottom wall 102 of the sleeve is closed. Hole 103 extends through wall 102 enabling end 34 of the pin to extend through the wall. Likewise, a stone separator is painted onto the bottom of model 25 to keep the model from sticking to the plaster base. Commercially available stone separators are available, such as an acrylic liquid.

The plaster base is produced by pouring a plaster liquid mix into a mold. For example, 100 grams of plaster with 23 ml of water may be poured into a mold and mixed under a vacuum. Die model 25 is then inserted into the mold with the model teeth facing upwardly. Once the plaster has hardened, the model with plaster base is removed from the mold. A plaster base 48 (FIG. 8) is therefore provided with a plurality of upwardly opening pinholes formed therein that receive the downwardly extending pins of model 25.

Model 25 is then removed from base 48 with portion 44 then being cut from the model by sawing along dashed lines 49 and 50. Line 49 (FIG. 7) extends between model tooth 54 (FIG. 2) corresponding to the tooth 21 (FIG. 1) and adjacent model tooth 51 corresponding to tooth 22 whereas line 50 extends between model tooth 54 and adjacent model tooth 52. Model die is therefore broken into a portion 73, a middle portion 74 corresponding to the tooth 21 to be restored, and a portion 75 (FIG. 8). The poured base encloses pins 26 and pin 27 including the enlarged main body 29 and bottom pin 34.

Die model portion 74 (FIG. 9) consisting of the portion of the model representing the tooth 21 to be restored along with a pin 27 is inserted into container 55 subsequently filled with a liquid soft silicone with the tooth facing upwardly. Container 55 has a removable base 80 with a soft-top surface 81 through which pin end 34 may be inserted to mount pin 27 to the removable base. Shell 82 is removably mounted to base 81 and encloses portion 74. The silicone is poured into shell 81 covering portion 74. Once the soft silicone has set up, base 81 is removed from shell 82 and portion 74 is removed forming a female hole or mold of portion 74. A release agent is sprayed into the hole and refractory material is poured into the hole formed within container 55. The refractory material has a co-efficient of thermal expansion approximately equal to porcelain subsequently applied thereto. Thus, the refractory material can be heated to a high temperature in order to fuse the porcelain without the refractory material breaking. Once the refractory material has set for an hour, the resulting replica 76 (FIG. 10) consisting of a replica of model portion 74 may be removed from container 55 and mounted to base 48 in place of portion 74.

Base 48 and refractory die 76 are fired to an initial temperature of, for example, of approximately 700 degrees centigrade and then inserted into a porcelain oven, for example, at 1000 degrees centigrade for five minutes in the conventional manner. Once the refractory die 76 has cooled, the porcelain may be stacked on die 76 or a veneer is added, configured, and fired in a high temperature oven to the final tooth configuration in the conventional manner. The resulting crown may then be removed and mounted in the patient's mouth.

Several advantages result from utilizing a model die consisting of the die stone portions 73 and 75 whereas the tooth to be restored consists of a refractory die 76. An advantage is in the event the die 76 breaks during the heat application and porcelain addition, then a new refractory die can be produced by repeating the procedure of pouring a new refractory die in container 55 utilizing the hole formed by portion 74 without the need of producing new die stone portions 73 and 75 along with base 48. Further, in the event it is desired to have better access to the sides of refractory die 76 when mounted to the base, portions 73 and 75 may be removed during the porcelain addition. Most importantly, the present invention does not require either the model die to be re-inserted into the mold when the refractory die is poured or the taking of a second impression of the entire model die since the refractory die is poured by itself. In addition, only a single base 48 is poured in the present invention unlike the prior methods.

In many cases, multiple teeth are to be restored within the same set of teeth with the teeth to be restored not being located in adjacent fashion. The teeth to be restored may correspond to the positions occupied by die portions 74 and 91 mounted to base 48 in FIG. 11. Portions 91 and 74 are separated by die stone portion 92. Individual refractory dies may be produced from portions 91 and 74 in a manner identical to the production of refractory die 76. In the event the refractory die breaks corresponding to portion 91 whereas the refractory is successfully produced corresponding to portion 74, then the process must be repeated only for the refractory die corresponding to portion 91 thereby providing exceptional savings in both cost and time. Both portions 74 and 91 include a pin 27.

The method of producing a crown or veneer for attachment to tooth to be restored includes the first step of creating a first impression of the set of teeth. A model die of die stone material is then created from the first impression. A portion of the model die is severed that corresponds to the tooth to be restored. The severed portion of the model die is used to make a further impression that is used to produce the refractory die. The refractory die and the remaining portion of the model die is removably mounted to a base. Cylindrical pins mount the model die to the base and a pin with an enlarged section mounts to the base the portion of the model die corresponding to the tooth to be restored. Porcelain is then formed and fired on the refractory die and subsequently attached to the tooth to be restored.

When mounting the pin with an enlarged section for a small tooth, the enlarged section is positioned so that its enlarged front portion faces outwardly and forwardly with respect to the set of teeth. In the event that a second tooth is to be restored that is within the set, then the method described herein is repeated for the second tooth.

The preferred embodiment of the sleeve 140 (FIG. 14) is identical to sleeve 100 (FIG. 13) with the exception that the internal cavity 141 of sleeve 140 is sized larger with respect to the main body 29 of pin 27 as compared to the internal cavity 101 (FIG. 12) of sleeve 100 relative to the main body of pin 27. In addition, a plurality of ridges 144 extend inwardly from the continuous wall 143 of sleeve 140 surrounding cavity 141.

When pin 27 is inserted into sleeve 140 (FIG. 16), an expansion space or gap 160 surrounds the main body of pin 27. That is, the main body of pin 27 is sized inwardly of and apart from the internal surface of cavity 141 of sleeve 140. Gap 160 extends completely around the main body of pin 27 but is not present between either the main body 29 of pin 27 and ridges 144.

In the embodiment depicted in FIG. 14, two ridges 144 are provided on the opposite ends of wall 143 of the sleeve whereas four ridges 144 project inwardly from the pair of sides of wall 143 of the sleeve. A greater number or a lesser number than six ridges may be employed to space apart the interior surface of wall 143 from pin 27.

The bottom wall 145 of sleeve 140 includes an aperture through which the bottom end 34 of the pin projects. Likewise, the top end 28 of the pin projects outwardly from the sleeve.

When utilizing pin 27, the pin is mounted to portion 44 as previously discussed with the main body of the pin 27 projecting beneath portion 44. Sleeve 140 is mounted to pin 27 with model 25 along with pin 27 and sleeve 140 then being inserted onto a mold of plaster as previously disclosed. Once the plaster is hardened, model 25 with pin 27 is removed. Portion 44 is then cut from model 25 in the same fashion as previously disclosed creating die portion 74 (FIG. 8) having the pin 27 projecting therefrom. Die model portion 74 including pin 27 is inserted into container 55 (FIG. 9) with bottom end 34 projecting totally into base 81. Once the silicon has hardened and the cavity is formed, portion 74 including pin 27 is removed from the container and the cavity is filled with the refractory material extending from the bottom of the main body of pin 27 to the distal end of tooth 21 forming a refractory die 150 (FIG. 17). Die 150 consists of a replica 152 of tooth 21 plus a replica 151 of pin 27.

Die 150 is mounted to base 48 and inserted into a porcelain oven as previously described for die 76 and base 48. The cavity in base 48 that previously received the pin 27 having sleeve 140 mounted thereto is slightly larger than pin replica 151 due to the prior presence of sleeve 140 allowing the pin replica 151 to expand without interference of its surroundings.

The preferred embodiment of pin 167 (FIG. 18) is similar to pin 27 (FIG. 4). The pin 167 has a main body 169 with a top end 170, a bottom end 171, a pair of opposite side surfaces 172 and 173, a front surface 175 and a rear surface 176. The top end 170 is flat. A cylindrical pin 174 projects outwardly from bottom end 171 of main body 169. The upper portion of the main body 169 includes a first lower intermediate portion 177 and a second upper intermediate portion 178. The main body 169 is tapered both in a horizontal direction and a vertical direction as viewed in FIGS. 18 and 19. The main body 169 has a longitudinal axis that extends from the bottom end 171 to the top end 170. Surfaces 172 and 173 diverge at a different included angle through the first lower intermediate portion 177, through the second upper intermediate portion 178 and the remaining portion of the main body 169. That is, surfaces 172 and 173 diverge as the surfaces extend from bottom end 171 to first intermediate portion 177 located between ends 170 and 171 thereby forming an included angle 190. Surfaces 172 and 173 diverge at included angle 192 through the first lower intermediate portion 177 and further diverge at included angle 194 through the second upper intermediate portion 178. Likewise surfaces 175 and 176 diverge as they extend upwardly from bottom end 171 through the first intermediate portion 177 and through the second intermediate portion 178 located between ends 170 and 171. Surfaces 175 and 176 diverge at a different included angle through the first lower intermediate portion 177, through the second upper intermediate portion 178 and the remaining portion of the main body 169. That is, surfaces 175 and 176 diverge as the surfaces extend from bottom end 171 to first intermediate portion 177 located between ends 170 and 171 thereby forming an included angle 196. Surfaces 175 and 176 diverge at included angle 197 through the first lower intermediate portion 177 and further diverge at included angle 198 through the second upper intermediate portion 178. The included angle 192 is greater than the included angle 190. The included angle 197 is greater than the included angle 196. The included angle 194 is less than the included angle 192. The included angle 198 is less than the included angle 197. A bevel 180 is formed at the intersection of first intermediate portion 177 and second intermediate portion 178. Front surface 175 and rear surface 176 are rounded being convex and cooperatively with side surfaces 172 and 173 providing a larger width 181 at the front end of the pin as compared to the width 182 at the rear of the pin. Surfaces 172 and 173 extend convergingly toward end 176 forming an included angle 186. Main body portion 169 has an oblong horizontal cross-section from end 170 to end 171. Optionally, the pin 167 is made of polyvinyl chloride or PVC.

The preferred embodiment of the sleeve 200 (FIG. 21) is identical to sleeve 140 (FIG. 14) with exception of a continuous wall 202 having a portion 204 that is tapered as compared to continuous wall 143 (FIG. 14) of sleeve 140. The continuous wall 202 correspondingly diverges with the surfaces 172, 173, 175, and 176. In addition, a plurality of ridges 206 of sleeve 200 is identical to the plurality of ridges 144 (FIG. 14) with the exception that a ridge portion 208 of each of the ridges 206 is tapered. The taper or slope of portion 204 is similar to the taper of each of the ridge portions 208. In one option, the slope of the portion 204 and ridge portions 208 corresponds with the surfaces 172, 173, 175, and 176 in the first intermediate portion 177. Like the bottom wall 145 of sleeve 140, the sleeve 200 also includes an aperture through which the cylindrical pin 174 projects. After the pin 167 is fully inserted into the sleeve 200, the top end 170 and the second intermediate portion 178 project outwardly from the sleeve 200 (FIG. 22). The sleeve 200 is made of a resilient material.

When utilizing pin 167, the top end 170 of the pin 167 is adhesively mounted to portion 44 leaving the entire body of pin 167 projecting beneath portion 44. With this embodiment, no holes need to be drilled into portion 44 as the pin 167 is mounted or glued to the bottom of portion 44. Since holes no longer need to be drilled in the portion 44 wherein pin 167 is glued, it is less likely that ends of pins 26 will overlap each other near portion 44. Sleeve 200 is mounted to pin 167 (FIG. 22), such that the surfaces 172, 173, 175, and 176 rest against the ridge portions 208 and the portion 204. Advantageously, the pin 167 will positively seat in the sleeve 200 (FIG. 23). The bevel 180 near the top end 170 of the pin 167 guides the sleeve 200 into the final contacting position of the pin 167 and the sleeve 200. Further, the bevel 180 guides the sleeve 200 to center the sleeve 200 over the pin 167. Additionally, the bevel 180 restrains the sleeve 200 from additional movement after the sleeve 200 is in its final position.

The pin 167 and sleeve 200 are inserted onto a mold of plaster as previously disclosed. Once the plaster is hardened, model 25 with the pin 167 is removed. Portion 44 is then cut from model 25 in the same fashion as previously disclosed creating a die portion 74 (FIG. 8) having the pin 167 projecting therefrom. Similarly to pin 27 (FIG. 9), die model portion 74 including pin 167 is inserted into container 55 with the cylindrical pin 174 projecting totally into base 81. Once the silicon has hardened and the cavity is formed, portion 74 including pin 167 is removed from the container 55 and the cavity is filled with refractory material extending from the bottom of the main body of pin 167 to the distal end of tooth 21 forming a refractory die 150 as disclosed for pin 27 in FIG. 17. The die consists of a replica of the tooth 21 plus a replica of the pin 167.

Similarly to die 150, the die is mounted to base 48 and inserted into a porcelain oven as previously described for die 76 and base 48. The cavity in the base 48 that previously received the pin 167 having sleeve 200 mounted thereto is slightly larger than the pin replica due to the prior presence of sleeve 200 allowing the pin replica to expand without interference of its surroundings. Advantageously, the plurality of ridges 144 of sleeve 200 enable the sleeve 200 to receive the pin replica made of refractory material without binding the sleeve 200 as the pin replica is inserted into the sleeve 200.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.