Claims:CLAIMS:

We Claim:

1. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) consisting of:
a thermoplastic or bio polymer material layer configured to define a tooth shaped top occlusal surface (1); and
flexible axial wall surfaces (2) extending continuously towards the bottom portion with feather edge margin (3) with axial wall flexing (4), enabling the crown (10) to be directly mounted on a tooth.

2. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein the thermoplastic material layer can be selected from polyacetal, polyacrylate, polymethylmethacrylate (PMMA), polyamide, polyaryletherketone (PAEK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide (PEI), polyethersulfone (PES), polysulfone (PSU), and mixtures thereof or nano-reinforced bio polymer.

3. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein said polymer is a homo- or co-polymer of acetal resin, polyetheretherketone (PEEK) or polymethylmethacrylate (PMMA) or Graphene nano-reinforced bio polymer.

4. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein said thermoplastic or bio polymer material comprises at least one of the following: fibers, fillers, pigments and reinforcements.

5. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein the crown (10) is characterized by
i. Top Occlusal surface (1) with a preferable thickness of 0.7 mm
ii. Axial wall surfaces (2) with a preferable thickness of 0.3 mm
iii. Margins (3) with a preferable thickness of 0.2 mm.

6. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein to improve retention, the crown (10) is treated with either
sand-blasting with 45 ?m particles of Aluminum oxide, Pressure of 2.8 bar, distance of 1 cm for time period of 15 seconds or
silicatization of Alumina particles of 110 ?m coated with silica, Pressure of 2.8 bar, distance of 1 cm for time period of 15 seconds.

7. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein the process of mass-production is hot-mould injection moulding method, comprising of:
A top cavity mould (5), a bottom cavity mould (6), stage 1 push rod (7), stage 2 push rod (8), a crown cavity (9) to mould a dental crown (10).

8. A self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated crown (10) as claimed in Claim 1, wherein the stage 1 push rod (7) moves to remove the crown (10) from the bottom cavity mould (6) and stage 2 push rod (8) moves upwardly to remove the crown (10) from the Stage 1 push rod (7) and pushes the crown (10) out of crown mould cavity (9).

Dated this 15th day of March 2022

Vishakha Rekhi
Agent for the Applicant
, Description:TECHNICAL FIELD

The present invention relates to a Self-adaptable and semi-adjustable, tooth-coloured pre-fabricated dental crown.

The present invention particularly relates to self-adaptable, semi-adjustable, mass-produced, tooth-coloured pre-fabricated crown, particularly useful in dentistry for treatment of teeth having extensive carious lesions or cavities.

BACKGROUND AND PRIOR ART OF THE INVENTION

A dental crown is a very effective treatment used to restore a tooth that has been damaged in some way. Dental crowns provide an adequate solution to a range of dental problems. They are able to:
• Support a tooth that has been significantly damaged by decay
• Protect a tooth that has worn away from being damaged further
• Protect a tooth after a root canal procedure
• Hold a severely cracked or broken tooth together
• Cover a dental implant
• Improve the appearance of a tooth by changing its shape or colour

Dental crowns are a good long-term option because they are durable and usually last for at least 5-15 years, which increases patient satisfaction with the treatment. Treatment with dental crowns has a high success rate with respect to either other dental restoration methods or no treatment at all. This has been supported by various scientific studies which researched their use.

Dentists today use five main types of crowns: resin-veneered, zirconia ceramic, stainless steel, composite strip, and polycarbonate. Each of these crown types has advantages and disadvantages that dictate its suitability for different applications. Some of the most important factors considered by dentists when choosing a crown type are durability, aesthetics, retentiveness, adaptability, placement time, allergenicity, and cost.

Most common disadvantages of these types of crowns are:
• High Cost
• Inability to contour
• Increased operational time
• Poor aesthetics
• Low durability

Therefore, when there is a threat of losing the teeth before time, it is necessary to take measures to prevent that from happening. Tooth decay has been established to be the leading cause of tooth loss. If a tooth is too damaged by cavities to the point it cannot support a filling, a dentist may recommend dental crowns. This not only helps save a decayed tooth, but it also helps prevent spreading of the decay and infection to other parts of the mouth.

Primary teeth are usually thinner compared to permanent teeth and without the crowns, the decay can spread fast and easily between teeth. Crowns also help reduce the risk of cavities. Dental crown procedure for tooth restoration in all age groups plays an important role in oral health.

US 11045279 Patent discloses System and method for fabricating dental crowns and bridgework includes the steps of: selecting one or more model teeth; forming a mould around the model tooth using a soft flexible material; removing the model tooth from the mould; adding wet dental restoration material to the mould and vibrating the mould; pressing framework into the wet restoration material; vibrating the mould and removing moisture; allowing the restoration material to dry and removing the moulded crown or bridgework from the mould; trimming off excess restoration material and adding restoration material to the margin area as needed; baking the crown or bridgework in an oven without the mould and removing the crown or bridgework from the oven when the restoration material is at least partially cured.

Patent document US 10610330 discloses a hardened preformed dental composite crown, a kit of parts containing those crowns, process of production and use thereof. The pre-formed dental crowns are in particular useful for treatment of paediatric dental defects.

US 8845329 Patent document discloses a Dental retention system which facilitate the adjustment or removal of an oral appliance, e.g., a crown or bridge, from a reconfigurable abutment assembly are described. The adjustable abutment assembly may be secured to an anchoring implant bored into the bones within the mouth. The abutment assembly has a projecting abutment portion with one or more shape memory alloy compression plates or elements extending along the projecting abutment portion. Each of the plates has a length with one or more straightened portions and with at least one curved or arcuate portion. Energy may be applied to the elements such that the arcuate portion self-flattens to allow for the oral appliance to be placed thereupon while removal of the energy allows the elements to reconfigure into its curved configuration thereby locking the oral appliance to the abutment.

Another Indian Patent Application 201847043376 discloses a dental crown wherein the crown is made with a fiberglass or quartz fibre embedded with cosmetic resin composite.

To overcome these problems and disadvantages of the prior art, the present invention offers to provide a Self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown, particularly useful in dentistry for treatment of teeth having extensive carious lesions or cavities.

The present invention thus offers significant advantages with unique features like

• Self-adaptable
• Semi-adjustable and crimpable
• Contourable and trimmable
• Tooth-coloured look, close to natural colour
• Pre-fabricated
• Higher flexibility than most available methods
• Easy to set-up
• No maintenance
• Economical cost
• Mass production possible

SUMMARY OF THE INVENTION

Many shortcomings of the prior art are overcome by the present invention as disclosed. Additional features and advantages are disclosed through the techniques of the present invention. A specific embodimentand aspect of the invention is described in detail herein.

The present invention provides a Self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced, crown, particularly useful in dentistry for treatment of teeth having extensive carious lesions or cavities.

Thus, there is provided by the present invention a dental crown formed of a thermoplastic polymer material, said crown comprising:
a tooth-shaped occlusal top surface;
and self-adaptable axial surfaces, at least one of which includes inwardly directed bottom portion.

According to a preferred embodiment of the invention, the thermoplastic polymer material comprises a polymer selected from the following polymers: polyacetal, polyacrylate, polymethylmethacrylate (PMMA), polyamide, polyaryletherketone (PAEK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide (PEI), polyethersulfone (PES), polysulfone (PSU), and mixtures thereof or nano-reinforced biopolymer.

More preferably, the thermoplastic polymer is a homo- or co-polymer of acetal resin, polyetheretherketone (PEEK) or polymethylmethacrylate (PMMA) or Graphene nano-reinforced biopolymer.

According to another preferred embodiment of the invention, the thermoplastic polymer material further comprises at least one of the following: fibers, fillers, pigments and reinforcements. The fibers and fillers may be in their conventional or nano size.

A dental crown according to the present invention may be formed by several methods. Non-limiting examples of such methods includes hot mould injection moulding, compression moulding and machining.

According to a preferred embodiment of the invention, the dental crown is produced by hot mould injection moulding which comprises:
Top and bottom moulds; and
employing the top and bottom moulds to the injection mould to form a dental crown from a thermoplastic polymer or bio polymer material.

Preferably, the top and bottom moulds include a push rod, which is operated to eject the moulded crown following opening of the moulds.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative embodiments and features described above, further embodiments and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the invention are set forth in the appended description. The invention itself, as well as a preferred mode of use, objectives and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying figures.

The preferred embodiment is described, by way of example only, with reference to the accompanying figures wherein reference numerals represent the elements:

FIG.1 illustrates final presentation of the self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown.

FIG.2 illustrates cross-section of the self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown demonstrating the occlusal top surface, the axial walls and the adaptable bottom portion.

FIG. 3 illustrates axial- wall flexing and the final retaining shape of the crown.

FIG. 4 illustrates the hot mould injection moulding process of the crown.

The figures depict embodiments of the invention for purposes of illustration only.

One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing has broadly outlined the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other arrangement for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the invention. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.

To overcome one or more drawbacks mentioned in the background, the present invention provides a self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown, particularly useful in dentistry for treatment of teeth having extensive carious lesions or cavities.

FIG.1 an exemplary embodiment of the disclosure which illustrates final presentation of the self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown.

With reference to FIG.2, this is an exemplary embodiment of the present invention illustrating cross-section of the self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown (10) demonstrating the occlusal top surface (1), the axial walls (2) and the flexible, adaptable bottom portion (4).

FIG. 3 an exemplary embodiment of the disclosure which illustrates the axial- wall flexing (4) and the final retaining shape of the crown (10).

As can be readily seen in Figures 2 and 3, the self-adaptable and semi-adjustable, tooth-coloured, pre-fabricated, mass-produced crown (10) is formed with an occlusal tooth-shaped top surface (1), which is thickened to absorb biting force; thin uniform axial surfaces (2) where biting forces are minimum and a feather edge margin (3) for ease of placement of crown (10).

Preferably, the thin axial surfaces (2) are adaptable. The crown (10) may readily be mounted, such as through the use of dental cement in the mouth of a patient, as part of treatment of teeth having extensive carious lesions or cavities.

It is a particular feature of the invention that the crown (10) is of a colour which generally matches that of the patient’s teeth. (tooth-coloured).

The crown (10) of the embodiment of the present invention is characterized by high tensile strength, high impact resistance and stiffness, excellent fatigue endurance and resistance to moisture, excellent dimensional stability and sufficient resilience and resistance to creep. It has the natural appearance of a vital tooth.

Further the exemplary embodiment of the present invention is characterized by
- Occlusal top surface with a preferable thickness of 0.7 mm
- Margins with a preferable thickness of 0.2 mm
- Uniform Axial walls with a preferable thickness of 0.3 mm
- Axial Walls are semi-flexible and semi-adjustable.
- The Occlusal top surface is self-adaptable.

In an exemplary embodiment of the present invention, to improve retention of the crown (10), it is treated with either
a. sand-blasting with 45 ?m particles of Aluminum oxide, Pressure of 2.8 bar, distance of 1 cm for time period of 15 seconds or
b. silicatization of Alumina particles of 110 ?m coated with silica, Pressure of 2.8 bar, distance of 1 cm for time period of 15 seconds.

Figure 3 demonstrates the Axial wall flexing (4) and final retaining shape once the crown (10) is fitted.

As can be seen in the Figure 3, the axial wall flexing (4) is semi-flexible and self-adaptable to take the shape of the tooth and make a perfect fit.

FIG. 4 illustrates the hot mould injection moulding process of the crown, particularly the operation of the manufacturing of the crown (10) from the thermoplastic polymer or bio polymer in accordance with the preferred embodiment of the present invention.

As seen in Figure 4, the crown (10) is moulded in a mould cavity which is defined by a top mould cavity (5), a bottom mould cavity (6), a stage 1 push rod (7) to remove the crown (10) from the bottom mould (6) and a stage 2 push rod to remove the crown (10) from the stage 1 push rod (7).

FIG. 4 elucidates the stage of moulding when the top cavity mould (5) lies in tight engagement with the bottom cavity mould (6) and the push rods (7 and 8).

The dental crown (10), which is fabricated in the Crown cavity mould (9) between the top cavity mould (5) and the bottom cavity mould (6) and the push rods (7 and 8), is formed by the injection of thermoplastic polymer or bio polymer material into the crown cavity (9).

FIG. 4 shows the release stage wherein the bottom cavity mould (6) is separated from the top cavity mould (5), thus permitting removal of the crown (10) from crown cavity (9).

FIG. 4 also illustrates an ejection stage wherein the stage 1 push rod (7) moves to remove the crown (10) from the bottom cavity mould (6) and stage 2 push rod (8) moves upwardly to remove the crown (10) from the Stage 1 push rod (7) and pushes the crown (10) out of crown mould cavity (9).

It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the spirit of the invention. Thus, it should be understood that although the present invention has been specifically disclosed by the preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and such modifications and variations are considered to be falling within the scope of the invention.

It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural references unless the context clearly dictates otherwise.

Reference Numerals for the Figures:

1. Occlusal surface of crown
2. Axial wall surface
3. Feather edge margin
4. Axial wall flexing
5. Top cavity mould
6. Bottom cavity mould
7. Stage 1 push rod
8. Stage 2 push rod
9. Crown cavity
10. Crown