WO2012115623A1

WO2012115623A1 - Dental crowns with improved retention system

Info

Publication number: WO2012115623A1
Application number: PCT/US2011/025677
Authority: WO
Inventors: Frank PETTINATO
Original assignee: Tuff Kid Crowns Llc
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2012-08-30

Abstract

Dental crowns with a retention system and methods for installing the dental crowns are described. The dental crowns are formed of zirconia. The dental crowns have an open interior cavity with an exposed surface into which the retention system which includes one or more shaped grooves is integrated. The open interior cavity is sized to be mated to a prepared oral surface and the exposed surface of the open interior cavity with the integrated retention system is used to bond the dental crown to the prepared oral surface. Kits including various crown shapes in multiple sizes as well as methods for installing the crowns are also described.

Description

Dental Crowns With Improved Retention System

BACKGROUND

When a crown is needed for an adult tooth, the crown is created based on the shape of the existing tooth. As an example, an impression of the existing tooth can be created then dimensions can be taken from the impression. A crown is then custom fabricated in a lab, e.g., using CAD/CAM technology, to match the existing tooth. This process, as described for an adult, requires multiple dental office visits. In children's dentistry, this approach is neither well received by the patient nor economical. Typically, visiting a dentist for dental work is not an enjoyable experience for a child, so a process requiring multiple visits, e.g., a first visit to create an impression so that a custom crown can be created then another visit to install the crown, is not psychologically desirable. Additionally, the child's baby tooth will be lost as the child's permanent tooth comes in, thus an expensive custom created crown is uneconomical.

To overcome these drawbacks related to children's crowns, stock sets of crowns with multiple sizes of each tooth have been created. These sets have been created using various materials such as stainless steel and veneered stainless steel. As can be imagined, a stainless steel crown is quite visible in a child's mouth and many parents prefer to avoid such an obvious crown. Veneered stainless steel crowns, e.g., porcelain veneers, are designed to avoid being obvious, but the veneers are susceptible to cracking and being otherwise damaged due to the normal forces exerted during chewing. Adult crowns have also been made from these materials, but the dental industry has evolved to use different materials. For example, adult crowns are often made from porcelain or other hard, but millable, materials such as zirconia.

SUMMARY

Dental crowns formed substantially of zirconia are described. The dental crowns include an outer surface and an open interior cavity with an exposed surface for use in bonding to an oral surface. The dental crowns include a retention system integrated into the exposed surface of the open interior cavity of the dental crown. The retention system includes a shaped groove formed on the exposed surface of the open interior cavity of the dental crown. The crowns can be used in pediatric and veterinary applications. The crowns can be provided in kits including multiple sizes of molars, canines, lateral incisors, and/or central incisors.

Methods for providing a dental crown for a natural tooth are also described. The methods include preparing an oral surface to receive a dental crown. The dental crown is selected from a set of pre-fabricated crowns comprising dental crowns of various sizes. The pre-fabricated dental crowns are formed substantially of zirconia and include an outer surface and an open interior cavity with an exposed surface for use in bonding to the prepared tooth. The prefabricated dental crowns include a retention system integrated into the exposed surface of the open cavity of the dental crown. The retention system includes a shaped groove formed on the exposed surface of the open interior cavity of the dental crown. Once a dental crown in selected, an adhesive is applied to the exposed surface of the open interior cavity of the selected dental crown and the dental crown is seated on the prepared oral surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a cross-sectional view of a crown.

Figs. 2A-G show various shaped grooves that can be formed in the exposed surface of the interior cavity of the dental crown. Fig. 2A shows an s-shape, Fig. 2B shows a linear shape, Fig. 2C shows a rotated s-shape, Fig. 2D shows a combination of an s-shape and a linear shape, Fig. 2E shows a combination of two s-shapes and a linear shape, Fig. 2F shoes a combination of twos-shapes and a rotated s-shape, and Fig. 2G shows an interlocking system of s-shapes.

Fig. 3A-C show cross-sectional views of a central incisor crown showing a useful retention system. Fig. 3A shows a cross-sectional lingual view of a first s-shaped groove on the inner side of the exposed surface of the interior cavity of the dental crown, Fig. 3B shows a cross-sectional buccal view of a second s-shaped groove on the outer side of the exposed surface of the interior cavity of the dental crown, and Fig. 3C shows a cross-sectional interproximal view of a first linear groove on one side of the exposed surface of the interior cavity of the dental crown (a second linear groove is also located on the opposite interproximal side).

Figs. 4A-C show cross-sectional views of a lateral incisor crown showing a useful retention system. Fig. 4A shows a cross-sectional lingual view of a first s-shaped groove on the inner side of the exposed surface of the interior cavity of the lateral incisor dental crown, Fig. 4B shows a cross-sectional buccal view of a second s-shaped groove on the outer side of the exposed surface of the interior cavity of the lateral incisor dental crown, and Fig. 4C shows a cross- sectional interproximal view of a first linear groove on one side of the exposed surface of the interior cavity of the lateral incisor dental crown (a second linear groove is also located on the opposite interproximal side).

Figs. 5A-C show cross-sectional views of a canine crown showing a useful retention system. Fig. 5A shows a cross-sectional lingual view of a first s-shaped groove on the inner side of the exposed surface of the interior cavity of the canine dental crown, Fig. 5B shows a cross- sectional buccal view of a second s-shaped groove on the outer side of the exposed surface of the interior cavity of the canine dental crown, Fig. 5C shows a cross-sectional interproximal view of a first linear groove on one side of the exposed surface of the interior cavity of the canine dental crown (a second linear groove is also located on the opposite interproximal side).

Figs. 6A-C show cross-sectional views of a molar crown showing a useful retention system. Fig. 6A shows a cross-sectional lingual view of first and second s-shaped grooves on the inner side of the exposed surface of the interior cavity of the molar crown, Fig. 6B shows a cross-sectional buccal view of third and fourth s-shaped grooves on the outer side of the exposed surface of the interior cavity of the molar crown, Fig. 6C shows a cross-sectional interproximal view of a first sideways s-shaped groove on one side of the exposed surface of the interior cavity of the molar crown (a second sideways s-shaped groove is also located on the opposite interproximal side)

DETAILED DESCRIPTION

Dental crowns, for example, for use in pediatric dentistry, and methods for installing the dental crowns are described. The dental crowns are formed substantially of zirconia. The dental crowns have an outer tooth shaped surface and an open interior cavity with an exposed surface. The open interior cavity is sized to be mated to a prepared oral surface and the exposed surface of the open interior cavity is used to bond the dental crown to the prepared oral surface. The dental crowns as described herein include a retention system integrated into the exposed surface of the open interior cavity. The retention system includes one or more shaped grooves created in the exposed surface of the open interior cavity of the dental crown.

The methods for installing the dental crowns as described herein include preparing an oral surface, such as a tooth, to receive a dental crown. Next a dental crown is selected from a set of pre-fabricated crowns comprising dental crowns as described herein of various sizes.

Once a dental crown is selected, an adhesive is applied to the exposed surface of the open interior cavity of the selected dental crown which includes the integrated retention system. Then the dental crown is seated onto the oral surface. The integrated retention system increases the stability of the bonded dental crown by improving the crowns ability to resist movement in multiple directions, e.g., from pushing, pulling, twisting, compressing, grinding, or rotating.

The dental crowns as described herein are formed substantially of zirconia. As used herein, the term zirconia is intended to mean a zirconia that contains no purposefully added stabilizers, such as yttria, ceria, india, or similar well known stabilizers. Zirconia crowns can be formed in various ways including placing substantially pure zirconia in a mold to form the specific shape desired for a crown, then the crown can be hardened by sintering. Additionally, a crown can be milled from a pre-formed solid piece of zirconia. Various pre-formed zirconia milling blanks as well as computer controlled milling machines are commercially available. One example of pre-made zirconia milling blanks is called BRUXZIR^® milling blanks. BRUXZIR^® milling blanks are available in various sizes from Glidewell Laboratories (Newport Beach, CA). BRUXZIR^® milling blanks are formed of solid monolithic zirconia that is prepared using a colloidal process (without mechanical pressing) and contains no organic binders. Prior to milling into crown shapes, the BRUXZIR^® milling blanks are hardened by sintering, e.g., for 6.5 hours at 1,530 degrees Celsius. After sintering, the crowns can be colored and glazed. An example of a commercially available computer controlled milling machine is the Dental Mill available from Digital Dental Lab (Laguna Hills, CA).

The outer surfaces of the dental crowns are shaped like teeth, e.g., children's baby teeth. Examples of the outer surface shapes of the dental crowns described herein include, but are not limited to, maxillary right central incisor, maxillary left central incisor, maxillary right lateral incisor, maxillary left lateral incisor, maxillary right canine, maxillary left canine, maxillary right first molar, maxillary left first molar, maxillary right second molar, maxillary left second molar, mandibular right central incisor, mandibular left central incisor, mandibular right lateral incisor, mandibular left lateral incisor, mandibular right canine, mandibular left canine, mandibular right first molar, mandibular left first molar, mandibular right second molar, and mandibular left second molar. As teeth are naturally formed in a variety of sizes, dental crowns of a variety of sizes of each outer surface shape are also included. The variation in sizes can reflect a simple proportional relationship, e.g., a second tooth is ten percent larger than a first tooth, or more sophisticated criteria can be used to establish the relationships between different sized dental crowns, e.g., a second crown is fifteen percent taller, but only eight percent wider, than a first crown to account for human tooth spacing variations. A set of pre-fabricated crowns of a specific tooth, e.g., a maxillary right central incisor, as contemplated herein can include two or more crowns of different sizes, three or more crowns of different sizes, four or more crowns of different sizes, five or more crowns of different sizes, six or more crowns of different sizes, seven or more crowns of different sizes, eight or more crowns of different sizes, nine or more crowns of different sizes, or ten or more crowns of different sizes. The variation in sizes provides a dentist with a range of options such that one of the sizes is similar enough to a patient's natural tooth size that a custom crown will not need to be formed. This range of sizes and the concomitant adaptability of the crowns to various situations will enable pediatric or veterinary dentists, for example, to fit a crown in a single office visit.

In addition to different sizes of each crown tooth type, sets of dental crowns as described herein including different sizes of different combinations of crowns are also contemplated. For example, a complete set of dental crowns can include different sizes of each of a maxillary right central incisor, a maxillary left central incisor, a maxillary right lateral incisor, a maxillary left lateral incisor, a maxillary right canine, a maxillary left canine, a maxillary right first molar, a maxillary left first molar, a maxillary right second molar, a maxillary left second molar, a mandibular right canine, a mandibular left canine, a mandibular right first molar, a mandibular left first molar, a mandibular right second molar, and a mandibular left second molar. Different sub-combinations of dental crowns in multiple sizes are also possible. For example, a posterior dental crown set could include different sizes of a maxillary right first molar, a maxillary left first molar, a maxillary right second molar, a maxillary left second molar, a mandibular right first molar, a mandibular left first molar, a mandibular right second molar, and a mandibular left second molar. For further example, an anterior dental crown set could include different sizes of a maxillary right central incisor, a maxillary left central incisor, a maxillary right lateral incisor, a maxillary left lateral incisor, a maxillary right canine, a maxillary left canine, a mandibular right central incisor, a mandibular left central incisor, a mandibular right lateral incisor, a mandibular left lateral incisor, a mandibular right canine, and a mandibular left canine. Having one or more sets of crowns available will enable a dentist to quickly find a crown useful in almost every situation and will enable pediatric and veterinary dentists to complete crown installations in a single office visit.

Fig. 1 shows a cross-sectional view of a crown 10. The crown has an outer surface 20 as described above and an open interior cavity 30. The open interior cavity 30 is sized and shaped such that it will be complimentary to an oral surface that has been prepared to receive the crown 10. The size and shape of the oral surface, e.g., a tooth, prepared to receive a crown 10 will be at the discretion of the dentist according to procedures well known to those of skill in the art. The size and shape of the open interior cavity 30 will vary depending on the overall size of the crown 10 and the size of the oral surface to which it will be bonded.

A retention system is integrated into the exposed surface of the interior cavity of the dental crown. The retention system consists of one or more shaped grooves formed in the exposed surface of the interior cavity of the dental crown (see Fig. 2A-G). The shaped grooves can be, for example, curved, s-shaped 40 (see Fig. 2A) or linear 50 (see Fig. 2B). The shaped grooves can be in a variety of orientations, e.g., a rotated s-shape 60 (see Fig. 2C), combinations (see Figs. 2D-2F), interlocking designs, e.g., interlocking s-shapes 70 (see Fig. 2G), numbers, and sizes. Additionally, the dimensions of the grooves, i.e., height, width, and depth, can vary. Shaped grooves useful with the crowns described herein can be, for example, from 0.05 mm to 1 mm deep, 0.07 mm to 0.9 mm deep, 0.08 mm to 0.7 mm deep, 0.09 mm to 0.6 mm deep, 0.1 mm to 0.5 mm deep, 0.2 mm to 0.4 mm deep, or 0.25 to 0.35 mm deep. The height and/or width of shaped grooves useful with the crowns described herein can be, for example, from 2 mm to 8 mm, 3 mm to 7 mm, 3 mm to 6 mm, or 4 mm to 5 mm. For specific example, an s-shaped groove useful with the crowns described herein can be 0.3 mm deep, 6 mm high, and 3 mm wide. The linear grooves provide the greatest benefit in prevention of motion related to forces applied at a right angle to its length, i.e., a vertical linear groove would help prevent twisting motion around the axis of a bonded tooth surface. The s-shaped groves help prevent motion in effectively every direction as vector lines applied at a right angle to the s-shape occur at almost every angle. Additional shapes, e.g., circles, triangles, curves, and other letter-shapes, and combinations thereof are also useful for shaped grooves.

Specific examples of retention systems useful with the dental crowns described herein are shown in Figs. 3-6. Figs. 3A-C are cross-sectional views of a central incisor crown 300 showing a useful retention system. Fig. 3 A is a cross-sectional lingual view of a first s-shaped groove 310 on the inner side of the exposed surface of the interior cavity 320 of the central incisor crown 300. Fig. 3B is a cross-sectional buccal view of a second s-shaped groove 330 on the outer side of the exposed surface of the interior cavity 320 of the central incisor crown 300. Fig. 3C is a cross-sectional interproximal view of a first linear groove 340 on one side of the exposed surface of the interior cavity 320 of the central incisor crown 300 (a second linear groove is also located on the opposite interproximal side). Thus, a useful retention system for central incisor crowns as described herein includes two s-shaped grooves and two linear grooves. Figs. 4A-C are cross- sectional views of a lateral incisor crown 400 showing a useful retention system. Fig. 4A is a cross-sectional lingual view of a first s-shaped groove 410 on the inner side of the exposed surface of the interior cavity 420 of the lateral incisor crown 400. Fig. 4B is a cross-sectional buccal view of a second s-shaped groove 430 on the outer side of the exposed surface of the interior cavity 420 of the lateral incisor crown 400. Fig. 4C is a cross-sectional interproximal view of a first linear groove 440 on one side of the exposed surface of the interior cavity 420 of the lateral incisor crown 400 (a second linear groove is also located on the opposite

interproximal side). Thus, a useful retention system for lateral incisor crowns as described herein includes two s-shaped grooves and two linear grooves. Figs. 5A-C are cross-sectional views of a canine crown 500 showing a useful retention system. Fig. 5A is a cross-sectional lingual view of a first s-shaped groove 510 on the inner side of the exposed surface of the interior cavity 520 of the canine crown 500. Fig. 5B is a cross-sectional buccal view of a second s- shaped groove 530 on the outer side of the exposed surface of the interior cavity 520 of the canine crown 500. Fig. 5C is a cross-sectional interproximal view of a first linear groove 540 on one side of the exposed surface of the interior cavity 520 of the canine crown 500 (a second linear groove is also located on the opposite interproximal side). Thus, a useful retention system for canine crowns as described herein includes two s-shaped grooves and two linear grooves.

Figs. 6A-C are cross-sectional views of a molar crown 600 showing a useful retention system. Fig. 6A is a cross-sectional lingual view of first and second s-shaped grooves 610 on the inner side of the exposed surface of the interior cavity 620 of the molar crown 600. Fig. 6B is a cross- sectional buccal view of third and fourth s-shaped grooves 630 on the outer side of the exposed surface of the interior cavity 620 of the molar crown. Fig. 6C is a cross-sectional interproximal view of a first sideways (i.e., horizontal) s-shaped groove 640 on one side of the exposed surface of the interior cavity 620 of the molar crown 600 (a second sideways s-shaped groove is also located on the opposite interproximal side). Thus, a useful retention system for molar crowns as described herein includes two vertical s-shaped grooves and two sideways s-shaped grooves. The molar crown retention system as just described is equally useful in both first and second molars. Generally, the combinations of multiple s-shaped or s-shaped and linear grooves are equally useful in the maxillary, mandibular, right, and left side versions of the described central incisors, lateral incisors, canines, and first and second molars.

Methods for using the dental crowns described herein will be well known to those of skill in the art. Generally, the methods include preparing an oral surface, such as a tooth, to receive a dental crown. Next an appropriately sized dental crown as described above is selected from a kit including various sizes of the type of tooth the crown is to cover. Next an adhesive is applied to the exposed surface of the open interior cavity of the selected dental crown and the dental crown is seated on the oral surface. Adhesives useful with zirconia crowns are well known to those of skill in the art. The dental crowns described herein are generally useful in pediatric dentistry as they can be combined in kits with appropriate size variations to enable a dental practitioner to prepare a tooth and secure a crown in a single office visit. The same temporal and convenience issues are of concern in veterinary dentistry and the dental crowns, kits, and methods described herein would be equally useful in veterinary dentistry (with the appropriate tooth profiles for the animal at issue).

Examples

Example 1

A set of crowns will be created by programming a Dental Mill (Digital Dental Lab;

Laguna Hills, CA) to mill pre-sintered, e.g., 6.5 hours at 1,530 degrees Celsius, BRUXZIR^® milling blanks (Glidewell Laboratories; Newport Beach, CA) to produce seven sizes each of a maxillary right central incisor, a maxillary left central incisor, a maxillary right lateral incisor, a maxillary left lateral incisor, a maxillary right canine, a maxillary left canine, a maxillary right first molar, a maxillary left first molar, a maxillary right second molar, a maxillary left second molar, a mandibular right canine, a mandibular left canine, a mandibular right first molar, a mandibular left first molar, a mandibular right second molar, and a mandibular left second molar for a total of 112 crowns. After milling, the crowns will be colored and glazed to a smooth surface.

Example 2

An posterior set of molar crowns will be created by programming a Dental Mill (Digital Dental Lab; Laguna Hills, CA) to mill pre-sintered, e.g., 6.5 hours at 1,530 degrees Celsius, BRUXZIR^® milling blanks (Glidewell Laboratories; Newport Beach, CA) to produce seven sizes each of a maxillary right first molar, a maxillary left first molar, a maxillary right second molar, a maxillary left second molar, a mandibular right first molar, a mandibular left first molar, a mandibular right second molar, and a mandibular left second molar for a total of 56 crowns. After milling, the crowns will be colored and glazed to a smooth surface.

Example 3

An anterior set of crowns will be created by programming a Dental Mill (Digital Dental Lab; Laguna Hills, CA) to mill pre-sintered, e.g., 6.5 hours at 1,530 degrees Celsius, BRUXZIR^® milling blanks (Glidewell Laboratories; Newport Beach, CA) to produce seven sizes each of a maxillary right central incisor, a maxillary left central incisor, a maxillary right lateral incisor, a maxillary left lateral incisor, a maxillary right canine, a maxillary left canine, a mandibular right canine, and a mandibular left canine for a total of 56 crowns. After milling, the crowns will be colored and glazed to a smooth surface.

The present invention is not limited in scope by the embodiments disclosed herein which are intended as illustrations of a few aspects of the invention and any embodiments which are functionally equivalent are within the scope of this invention. Various modifications of the dental crowns and methods for using the dental crowns in addition to those shown and described herein will become apparent to those skilled in the art and are intended to fall within the scope of the appended claims. Further, while only certain representative combinations of various aspects of the dental crowns and method steps disclosed herein are specifically discussed in the embodiments above, other combinations of the various aspects of the dental crowns and method steps will become apparent to those skilled in the art and also are intended to fall within the scope of the appended claims. Thus a combination of various aspects of the apparatus or steps may be explicitly mentioned herein; however, other combinations of various aspects of the dental crowns and steps are included, even though not explicitly stated. The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof and are open, non-limiting terms.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for use as a dental crown comprising:

a dental crown, the dental crown being formed substantially of zirconia and including an outer surface and an open interior cavity with an exposed surface for use in bonding to an oral surface; and

a retention system integrated into the exposed surface of the open interior cavity of the dental crown, the retention system including a shaped groove formed on the exposed surface of the open interior cavity of the dental crown.

2. The apparatus of claim 1, wherein the oral surface is a child's tooth.

3. The apparatus of claim 1, wherein the oral surface is an animal's tooth.

4. The apparatus of claim 1, wherein the shaped groove is curved.

5. The apparatus of claim 1, wherein the shaped groove is s-shaped.

6. The apparatus of claim 1, wherein the shaped groove is a plurality of grooves.

7. The apparatus of claim 6, wherein the plurality of grooves comprises s-shaped grooves.

8. The apparatus of claim 6, wherein the plurality of grooves comprises a combination of straight and s-shaped grooves.

9. The apparatus of claim 7, wherein the s-shaped grooves are oriented vertically.

10. The apparatus of claim 7, wherein the s-shaped grooves are oriented vertically and horizontally.

11. The apparatus of claim 1 , wherein the dental crown is in the shape of a molar and the shaped groove comprises a plurality of s-shaped grooves oriented vertically and horizontally.

12. The apparatus of claim 1, wherein the dental crown is in the shape of a canine, lateral incisor, or central incisor and the shaped groove comprises a plurality of s-shaped grooves and straight grooves.

13. A kit comprising multiple sizes of a dental crown according to claim 1 in the shape of one or more of a molar, canine, lateral incisor, or central incisor.

14. A kit comprising multiple sizes of a dental crown according to claim 1 in the shapes of canines, lateral incisors, and central incisors.

15. A method for providing a dental crown for a natural tooth:

preparing an oral surface to receive a dental crown;

selecting a dental crown from a set of pre-fabricated crowns comprising dental crowns of various sizes, the dental crowns being formed substantially of zirconia and including an outer surface and an open interior cavity with an exposed surface for use in bonding to the prepared tooth, the dental crowns including a retention system integrated into the exposed surface of the open cavity of the dental crown, the retention system including a shaped groove formed on the exposed surface of the open interior cavity of the dental crown;

applying an adhesive to the exposed surface of the open interior cavity of the selected dental crown; and

seating the dental crown on the oral surface.

16. The method of claim 15, wherein the oral surface is a child's tooth.

17. The method of claim 15, wherein the oral surface is an animal's tooth.

18. The method of claim 15, wherein the shaped groove is curved.

19. The method of claim 15, wherein the shaped groove is s-shaped.

20. The method of claim 15, wherein the shaped groove is a plurality of grooves.

21. The method of claim 20, wherein the plurality of grooves comprises s-shaped grooves.

22. The method of claim 20, wherein the plurality of grooves comprises a combination of straight and s-shaped grooves.

The method of claim 21, wherein the s-shaped grooves are oriented vertically.

24. The method of claim 21, wherein the s-shaped grooves are oriented vertically and horizontally.

25. The method of claim 15, wherein the dental crown is in the shape of a molar and the shaped groove comprises a plurality of s-shaped grooves oriented vertically and horizontally.

26. The method of claim 15, wherein the dental crown is in the shape of a canine, lateral incisor, or central incisor and the shaped groove comprises a plurality of s-shaped grooves and straight grooves.