A method for teeth restoration and a teeth matrix

[001] Related applications

[002] This patent application claims priority from US provisional applications serial number 60/916,814, filing date May 9 2007 and US provisional applications serial number 60/948,466, filing date 8 July 2007 , which are incorporated herein by reference.

[003] Field of the invention [004] This application related to methods for tooth restoration.

[005] Background of the invention

[006] In dental restoration, a prosthetic is prepared to replace one or more missing, damaged, or unaesthetic looking teeth. Such dental prosthetics include bridges, full crowns and partial crowns. Full and partial crowns are supported by remaining portions of the original tooth or teeth and/or by an abutment and/or dental implants extending from the jaw bone. Bridges are supported by two or more teeth structures adjacent to the missing teeth or solely by implants that replaces the missing tooth root. [007] The dental prosthesis is generally for functional and aesthetic purpose is made of porcelain, the porcelain is a brittle material and to withstand the ocullusal forces it need reinforcing. The reinforcing is generally obtained from a core structure of a hard material such as metals, aluminas (al2o3) zirconium, lava and more core material known to the art. The core structure is then incrementally covered with increments of porcelain slurry made of liquid and porcelain powder to provide outer surface of a tooth that is shaped according to the location in the mouth of the one tooth or more teeth. The surface of restoration is than tooled to provide the outer surface of the restoration in accordance with the appearance of a tooth. Since the preparation of the prosthesis, including the tooling of the prosthesis is performed at a dental laboratory; neither the recipient nor the dentist has any control on the final appearance of the restoration. Due to this situation, the recipient and the dentist expectations often do not adhere with the final appearance of the prosthesis, this lead to dissatisfaction and redo of the restoration to please the patient anticipations. [008] One prior art method involved building a wax model of the proposed restoration and receive the recipient approval. The drawbacks of this method are: (I)

The dentist usually can propose very limited options that are in the boundaries of his artistic capabilities expertise and cost; (ii) The method is a time consuming; (iii) The shade of the teeth are not included in this method, the wax do not demonstrate the shade of the porcelain; (iv) the success of this method depends on the technician's capabilities to copy the teeth structure that was approved by the recipient and the dentist.

[009] However, also in this case, the preparation of the prosthesis, including the tinting of the prosthesis material, is performed at a dental laboratory and neither the recipient nor the dentist has any control on the final appearance of the prosthesis. Thus, also in this method of dental restoration, the recipient is often is not satisfied with the final appearance of the prosthesis.

[0010] There is a growing need to improve the restoration process and especially to increase the predictability of the restoration process.

[001 1] Summary of the invention

[0012] A method for preparing a dental prosthesis, the method includes: selecting a tooth matrix out of a group of tooth matrices that differ from each other, the tooth matrixes differs by at shape, size and/or shade, wherein each tooth matrix comprises an inner cavity; wherein the outer surface of the tooth matrix has an appearance of a tooth; and attaching at least a wall of the inner cavity of the tooth matrix to an intermediate element that is connected to the remaining tooth structure, core material or to the implant.

[0013] A method for preparing a dental prosthesis, the method comprising: selecting a tooth matrix out of a group of tooth matrices that differ from each other, wherein each tooth matrix comprises an inner cavity; wherein a tooth matrix is has an appearance of a tooth; attaching at least a wall of the inner cavity of the tooth matrix to an intermediate element that is connected to the prosthesis core, remaining tooth structure or to the implant. [0014] Conveniently, the method includes attaching the at least wall of the inner cavity by a bonding material that is selected based upon a desired color of the prosthesis.

[0015] Conveniently, the method includes illustrating to a patient an expected result of a restoration process by temporarily placing in a mouth of the patient a tooth replacement element that resembles a selected tooth matrix.

[0016] Conveniently, the method includes providing digital tooth matrix information to a computerized process that generates the intermediate element so that the intermediate element will be designed such as to fit in the inner cavity.

[0017] Conveniently, the method includes shaping the remaining tooth structure in response to a shape and size of an inner cavity of the selected tooth matrix, spacing porcelain and core structure and to a shape and a restoration area within the mouth of the patient.

[0018] Conveniently, the method includes shaping the remaining tooth structure in response to a shape and size of a tooth grinding guide that is shaped so as to fit within the inner cavity of a tooth matrix.

[0019] Conveniently, the method includes selecting a light transparent tooth matrix and a color of an adhesive that bonds the tooth matrix to the element.

[0020] Conveniently, the method includes determining a relative gap between a selected tooth matrix and an intermediate element, and associating a gap filling material with the tooth matrix.

[0021] Conveniently, the method includes sintering the gap filling material.

[0022] Conveniently, the method includes generating the tooth matrix.

[0023] Conveniently, the method includes generating a multi-layered tooth matrix.

[0024] Conveniently the method includes taking an impression for an index. [0025] Conveniently the method includes making an index to secure relative position between the prosthetic core and tooth matrix.

[0026] A method for generating a tooth matrix, the method includes: determining a shape of a tooth matrix out of a group of tooth matrices that comprises multiple tooth matrices that differ from each other, wherein each tooth matrix comprises an inner cavity; wherein a tooth matrix has an appearance of a tooth; and manufacturing, in response to the determination, the tooth matrix; wherein the inner cavity is shaped so as to include an intermediate element that is connected to a remaining tooth structure or an implant.

[0027] Conveniently, the method includes manufacturing a tooth matrix that comprises multiple layers, wherein an outer layer is light transparent.

[0028] Conveniently, the method includes applying a manufacturing process selected from a group consisting of: pressing, melt drawing, injection molding, hot pressing, extrusion processing, die pressing, slip casting, extrusion, injection molding, tape casting, green machining, and sintering.

[0029] Conveniently, the method includes manufacturing multiple layers of the teeth matrix by and molding the multiple layers to form a teeth matrix.

[0030] Conveniently, the method includes manufacturing multiple layers of the teeth that differ from each other by a level of light transmission. [0031] Conveniently the inner cavity is shaped to include the core and wherein a space for fill-in material is formed between the inner cavity and the core.

[0032] A method for generating a core, the method includes: receiving tooth matrix digital information and restoration area information; and applying a computerized process to design and manufacture the core so that the core substantially fits to a gap between an inner cavity of the tooth matrix and a remaining tooth structure or an implant located in the restoration area.

[0033] Conveniently, the method includes generating a multi-layered tooth matrix.

[0034] A tooth matrix, that includes: an outer surface, that resembles an outer surface of a tooth; an intermediate portion that is at least partially light transmissive; wherein the intermediate portion defines an inner cavity that is shaped such as to fit an intermediate element that is connected to a remaining tooth structure or to an implant.

[0035] Conveniently, the tooth matrix includes a light transmissive outer surface; and wherein the intermediate portion comprises multiple layers that differ from each other by their transmission level. [0036] Conveniently, the tooth matrix includes an enamel layer, a dentino layer, an enamel junction dentin layer and a pulp matter layer.

[0037] A kit, that includes: a group of teeth matrices that differ from each other, each tooth matrix comprises an inner cavity; wherein a tooth matrix is has an appearance of a tooth; and tooth grinding guides; wherein an upper portion of a tooth grinding guide is shaped according to an inner cavity of a corresponding tooth matrix.

[0038] Conveniently, an upper portion of a tooth grinding guide is smaller than the inner cavity of the teeth matrix and wherein a gap between the upper portion of the tooth grinding guide and a inner space is large enough to include binding material core material. [0039] Conveniently the kit includes temporary teeth, each temporary teeth having an outer surface that is substantially equal to an outer surface of teeth matrix and has an inner cavity that is larger than a unsewn remaining teeth structure.

[0040] Conveniently the kit includes measurement equipment for measuring the restoration area.

[0041] Brief description of the drawings

[0042] The foregoing and other objects, features, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, similar reference characters denote similar elements throughout the different views, in which:

[0043] Figure 1 illustrates various shapes of a tooth that resemble tooth matrices, according to an embodiment of the invention; Figure 1A-I represent the different shapes of the tooth matrix [0044] Figures 2A- 2D illustrate a tooth root, grinding guides and a handle according to an embodiment of the invention;

[0045] Figures 3a-3b illustrate by way of example only a cast used for multi layer during a molding process of a tooth matrix, according to an embodiment of the invention; [0046] Figure 4 illustrates various stages of a sequence for generating a tooth matrix according to an embodiment of the invention;

[0047] Figure 5 illustrates a tooth, enamel veneers matrixes, adhesive material that connects the tooth matrixes and prepared tooth, a tray and impression material according to an embodiment of the invention; [0048] Figure 6 illustrates a tooth, enamel veneers matrixes, adhesive material that connects the tooth matrixes and prepared tooth, a tray and impression material according to an embodiment of the invention;

[0049] Figure 7 illustrates an adhesive material, a core and an tooth matrix according to an embodiment of the invention; [0050] Figure 8 illustrates a kit according to an embodiment of the invention;

[0051] Figure 9 illustrates a method according to an embodiment of the invention;

[0052] Figure 10 illustrates a method according to an embodiment of the invention;

[0053] Figure 11 illustrates a method according to an embodiment of the invention and [0054] Figure 12 illustrates a method according to an embodiment of the invention.

[0055] Detailed description of the drawings

[0056] Conveniently, the predictability of restoration process is increased by utilizing tooth matrices that have a known shape.

[0057] In a sense the restoration process begins by defining the external shape (selecting a tooth matrix out of multiple prefabricated tooth matrices) of the prosthesis and ends by binding a tooth matrix to a core or other intermediate element that [0058] It is noted that multiple teeth can be reconstructed using the suggested method. Any tooth can be reconstructed.

[0059] Conveniently, a tooth matrix is provided. It is an element that includes an outer surface, that resembles an outer surface of a tooth and an intermediate portion that is at least partially light transmissive. The intermediate portion defines an inner cavity that is shaped such as to fit an intermediate element that is connected to a remaining tooth structure or to an implant.

[0060] Multiple tooth matrices are provided to a dentist and/or to a dental laboratory. They can differ from each other by shape, size and even color. There are shaped and sized in order to replace different teeth (for example - incisor, bicuspid premolar, canine, , molar, , and the like upper and/or lower jaws) of different patients. The patients can differ by the size of their tooth, the shape of their face and other parameters.

[0061] Conveniently, the different tooth matrices are designed in order to provide an adequate solution for most of the population, selected parts of the population or all the population.

[0062] Conveniently, the tooth matrix resembles the tooth it replaces. It can include a light transmissive outer surface and the intermediate portion.

[0063] The intermediate portion can include multiple layers that differ from each other by their transmission level.

[0064] Conveniently, the tooth matrix can include an enamel layer, a dentino enamel junction layer, an dentin layer and a pulp matter layer. Between layers and/or within layers can include reinforcing material to increase strength and/or dye material to improve the aesthetic of the restoration. [0065] A kit is provided, it include: a group of teeth matrices that differ from each other, each tooth matrix comprises an inner cavity; wherein a tooth matrix is has an appearance of a tooth; and tooth grinding guides; wherein an upper portion of a tooth grinding guide is shaped according to an inner cavity of a corresponding tooth matrix. [0066] The upper portion of a tooth grinding guide is smaller than the inner cavity of the teeth matrix and wherein a gap between the upper portion of the tooth grinding

guide and a inner space is large enough to include binding material, and optionally core material .

[0067] The kit can include temporary teeth, each temporary tooth having an outer surface that is substantially equal to an outer surface of teeth matrix and has an inner cavity that is larger than a unsewn remaining teeth structure.

[0068] The kit can include measurement equipment for measuring the restoration area to facilitate selection of the tooth matrixes.

[0069] Figure 8 illustrates a sample of such a kit.

[0070] The tooth matrix can be selected by the mentioned below process. [0071] Once the patient (recipient) needs to replace a one or more tooth with dental prosthesis, a sequence of stages can be followed in order to insure that an exact form and shade of teeth are provided.

[0072] These stages can start by a diagnostic stage - at this stage the dentist offers and suggest to the patient, and with the patient, the general form, shape size and shade of the restoration final result.

[0073] The diagnostic stage can include one of the following stages or a combination thereof: a. The dentist can choose from a variety of Teeth Like (Fig. 1) form design and shade on a catalog and instruction in the kit (Fig. 8) or computer files. The preferred form of teeth will be in harmony with the outer shape of the patient dentition, face and appearance. It is known to the art four different categories of face-teeth harmonies forms; rectangular, triangular, oval, and round. b. In the shape category there are different shapes of Teeth Like (Fig.1) between vigorous and soft teeth appearance depending on the patient gender, personality and appearance. c. The dentist then chooses the shade of the restoration from a range of bright to dark teeth according to the related (adjacent) teeth and the patient preferences. The shades will be chosen with the aid of shade guide in the kit (Fig.8). d. The dentist measures the accumulate size of the adjacent teeth to be restored from mesial to distal, and /or the separate size of each tooth with the aid of a ruler (Fig.8). The dentist also measures the length of the teeth from the cervical aspect of the one or more teeth to the incisal edge of the one or more teeth, this measurement is made also according to what

known to the art, like lip line, ocullusal limitations of the restoration and the well-known to the art of matching the teeth location and size in harmony of the persons appearance- smile- design rules for matching to patient appearance and teeth. e. When the information of all the above mentioned steps acquired, the dentist can pick the right Teeth Like Adhesive (Fig 8 - element c) of veneers that are able to be located in the patient mouth. The veneers contain the final shape; shade and position of the proposed prosthetic. The adhesive veneer teeth are placed it in the patient's mouth for demonstration of how the restoration will look like when completed. Once received the patient approval to the particular tooth matrix set (Fig.l , 8) a series of action and components that are design to serve for the purpose of consistent predictability. The Restoration set guides the labor to achieve it. The dentist and patient now have mutual knowledge how the restoration will look like and what to aim for in the next stages of the restoration construction.

[0074] After the dyagnostic stage is completed a tooth/teeth impression of the restoration and neighboring working area (fig. 5) is sent to a dental laboratory. [0075] In order to obtain the impressions for the lab the dentist has to go through several steps (also referred to as dentist tooth preparation stages): a. The final result has been set in the diagnostic and patient approval stage, the size of the teeth comprising the restoration and their position in the mouth is known and approved by the patient, as a result it is also known the amount of tooth reduction that should be made to make space for the aesthetic buildup of the core structure and the porcelain. b. The Restoration set (Fig 8) provides for the one or more teeth preparation a Tooth Grinding Guide (Fig 2a-c). The Tooth Grinding Guide is transparent matrixes that have the outer shape of the tooth (similar to the outer surface of the Tooth Matrix, the inner shape that can be seen from the outside of the matrix resembles the size and structure of optimal prepared tooth for the design chosen in the previous stage. It is advised that every tooth will have a corresponded matrix. The purpose of the preparation matrix is to provide a guided tooth preparation in respect of optimal tooth size reduction to allow the buildup components for the final result. The tooth

preparation matrix will be called in this paper Tooth Grinding Guide (Fig.2, 8d.) c. The preparation sequence will follow the described steps: general reduction, placing the Tooth Grinding Guide (Fig.2) until it is fully sited on the prepared tooth. Careful attention should be drawn to the outer surface of the matrix since this surface will represents the position of the final restoration. d. Once the dentist starts to grind the tooth using the Tooth Grinding Guide(Fig.2) he will be guided to set the correct amount of grinding from every site of the tooth, in a way of example only, a protruded tooth which is designed to be in its normal position, by using Tooth Grinding Guide(Fig.2) will direct the dentist to grind more from the bucal or labial side and less from the palatal side, this is done by showing the dentist the final size and position of the tooth from the outer side of the Tooth Grinding Guide(Fig.2) which resembles a tooth shape and from its inner side cavity that marks the size and shape of the prepared tooth. e. Once the teeth has been prepared according to the guidance of the Tooth Grinding Guide two possible options are: a. impression, known to the art, of the prepared teeth is being taken using a plastoelasto material, the impression material is in fully plastic stage and after the impression is inserted the material is set to a fully elastic stage, b. optional procedure will include the Enamel matrixes in the impression stage: The veneers or Tooth matrix (Fig 1) is placed on the prepared teeth they located to the desired position and temporarily secured (Fig.7) to the prepared teeth and impression is taken (Fig f. This will provide the dental technician with the relative position between the prepared teeth and the location and size of the final restoration.

[0076] The dental laboratory receives the impression and pour cast stone to receive the positive structure of the imprinted mouth. The lab then constructs from a selection of materials known to the art the core structure and sends it to the dentist for try on to assure fitness of the core to the teeth.

[0077] In case option b is selected then the dental laboratory worker can make an index (Fig 6) of the position relation between the Tooth matrix and the prepared teeth. [0078] The dentist can receive from the dental laboratory the core and place the core on the prepared teeth. If there is a good enough fit between the chosen Tooth

matrix set and the core then the tooth matrix is placed on the core using a light sensitive adhesive (Fig 7). The patient approves the setup and an impression is taken for the lab.

[0079] This stage is followed by a dental laboratory final preparation stage. During this stage the dental technician makes an index of the relative position between the core and the tooth matrix (Fig. 6A) as designed by the dentist with the approval of the patient. The index serves for positioning the Tooth matrix while the porcelain slurry (made of liquid and powder porcelain) is poured between the core and the Tooth matrix (Fig.6E). When the excess of the liquid is drained from the slurry the index is removed and the new structure (Fig 6B ₁ E) is being sintered in temperature that is lower than the Tooth matrix production sintering temperature.

[0080] At this stage particular demands like special tooth shade effects and structural effects like different component inserts can be made to enhance and individualize the prosthesis. [0081] According to another embodiment of the invention the dentist can use the tooth matrix system to obtain an immediate aesthetic makeover. [0082] The dentist can employ stages a-e of the diagnostic stage, stage a-d of the dentist tooth preparation stages, and then have an approved set of teeth matrixes which answer patient aesthetic and functional anticipations (steps a-e of the diagnostic stage).

[0083] The dentist should use composite material or other means that are known to the art to lute and secure the selected teeth in their corresponded preparations. [0084] Following all or part of the procedures described above will secure a method that enable the dentist and patient to visualize and determent the final result at the beginning of the process, this method will insure the Prosthesis predictability.

[0085] Conveniently, the Tooth matrix can be applied to computer aided design (CAD) processes that manufacture cores. Computer automated equipment can fabricate a one or more core material from metals like titanium for implants and aesthetically oriented like Aluminas and zirconiums. This is frequently referred to as digital dentistry, where computer automation is combined with optics, digitizing equipment, CAD/CAM (computer-aided design/ computer aided machining) and mechanical milling tools. Examples of such a computer-aided milling machine include the CEREC 2TM machine supplied by Siemens (available from Sirona Dental Systems; Bensheim, Germany); VITA CELAYTM (available from Vita Zahnfabrik; Bad Sackingen, Germany); PRO-CAMT ¹ (intra-Tech Dental Products, Dallas, TX); and

PROCERA ALLCERAMTM (available from Nobel Biocare USA, Inc.; Westmont, IL). U. S. Patent Nos. 4,837,732 and 4,575,805 also disclose the technology of computer- aided milling machines for making dental prostheses.

[0086] The tooth matrix when it has fewer walls and/or path of insertion can be used for the following stages.

[0087] The digital computer files that describe the inner shape of the Tooth matrix can be integrated into the Cad-Cam core designing files, so that they leave optimal space for adaptation with the inner surface of the Tooth matrix. [0088] A typical space will be 0.1 mm-2.5mm. This space will be filled with the appropriate glass ceramic to adjust thermal coefficient and strength. The Tooth matrix will be filled with the slurry porcelain and secure to the bad on the core material. Another possible application is filling the space between the core and the tooth matrix with material that can be set without the aid of a laboratory machining to be managed chairside. [0089] This feature can facilitate more the labor of the dental technician; he will have to fill-in just the exact glass ceramic powder slurry, as a result there would be less build up that would save a substantial amount of time laboring material saving and reduced costs. [0090] The tooth matrix can be manufactured by applying one or more methods of making dental tooth matrix (Enamel Shell) such as but not limited to: pressing, melt drawing, injection mold, hot pressing and extrusion processes, die pressing, slip casting and extrusion, injection molding and tape casting. Hot pressing, hot isostatic pressing, cold isostatic pressure, and pressure casting. With the aid of additives or without. [0091] Sintering for processing ceramic of the tooth matrix (Enamel Shell) is performed, it is preferred that the material be fully sintered to achieve greater than about 98% of the theoretical density of the ceramic material. More preferably, fully sintering achieves greater than about 99.0% theoretical density, and most preferably greater than 99.5% of the theoretical density. The Tooth matrix (Enamel Shell) can be fabricated by pressing powder to a desired shape and sintering the pressed compact at temperatures close enough to the material's melting point so that the ceramic coalesces and densifies. In one such manufacturing technique, high purity aluminum oxide powder is placed in the die cavity of a high-pressure press. Submicron size particles can be used. Hot pressing accelerates the sintering process and allows one to achieve substantially greater density in the sintered compact. Methods that are

known to the art like powder injection molding may also utilize to produce the tooth matrix.

[0092] The Tooth matrix may be provided at near full density (>95% of theoretical). [0093] Alternatively, it may be provided with sufficient porosity partially sintered as to facilitate machining and final sintering with the fill-porcelain. Theoretical density for a crystalline ceramic is calculated from the atomic weights of the constituents and the volume of the crystallographic unit cell.

[0094] If desired, the inventive Tooth matrix can be hot isostatic pressed (HIP) to accelerate the sintering process. In a press, isostatic pressure is applied while the material is heated to the sintering temperature. The combination of high temperature and high pressure compact the HIPed part to have substantially zero porosity. U. S. Patent No. 4,954,080 provides further discussion as to hot isostatic pressing aluminum oxide, the disclosure of which is incorporated by reference. [0095] Yet another method for producing a rod of crystalline ceramic material is described in U. S Patent No. 4,639,218, which refers to an EFG (Edge-defined, Film- fed, Growth) modification of the Czochralski process for growing crystalline alpha- alumina. Alternatively, hot forging of ceramic can be employed to form the tooth matrix. [0096] Tooth matrix ceramic powder is mixed with a viscous material to enable the powder flow to form a designed shape of a tooth. The powder mix includes of a fine ceramic powder with the appropriate additions of binder(s) and plasticiser(s) to give the desired flow properties (rheology), either cold or when heated prior to being forced through the die. filling of a mould, a negative of the Tooth matrix , a plastic mix is prepared and heated in the barrel of the moulding machine until it is at the correct temperature at which the mix has a sufficiently low viscosity to allow flow if pressure is applied to form the Tooth matrix by low to high pressure.

[0097] A plunger is pressed against the heated mixture forcing it through an orifice and on into the Tooth matrix tool cavity. The molded Tooth matrix is removed from the die and the organic binder is slowly burnt out in a controlled atmosphere by means of a carefully controlled heating schedule, prior to sintering. [0098] The mentioned above phase of manufacturing is illustrated in figures 2A- 2B.

[0099] The Tooth matrix can be manufacturing with one or more layers. The outer layer would be preferably from clear transparent material designed to represent the enamel of a natural tooth, the clear layer preferably will vary in width from 0.2mm to 1.2mm. The use of a light transmissive material for a Tooth matrix allows internal

tailoring of the appearance of the restoration by modifying both the color of the ceramic slurry in the dental laboratory, or by lutting or bonding agent for immediate aesthetic makeover by the dentist.

[00100] In case of the production of more then one layer, the production will include more stages. The second layer from enamel powder will employ certain areas of the Tooth matrix to provide shade of natural tooth. The third layer will include dentin ceramic material to provide more shade to the Tooth matrix. On the cervical aspect of the Tooth matrix a darker material preferably is added. In multiple layers, depends on the manufacturing technique chosen on or more stages are employed. In a way of example only, in molding, the part of the mould that configure the inner part of the Tooth matrix will be replaced with a hemi-mould part that will provide space for a second layer to be added to the Tooth matrix cavity in all manufacturing procedures. By way of example only in press procedure different powders are employ to regulate the layers in the designed order to achieve aesthetic pleasing and natural Tooth matrix.

[00101] Alternate way for the added layers to Tooth matrix would be by means of separate molding procedure for each layer as described above. The separate layers that will be finely adjusted in terms of shape, color, thermal coefficient expansion, and other thermal properties that are needed for combined sintering. [00102] The layers will be added together to comply a form of a Tooth matrix and will be sintered together to become one piece of Tooth matrix. [00103] The surface treatment of the Tooth matrix can be in the range of: as sintered to 1 N in the scale of New ISO scale numbers for the outer surface of the Tooth matrix. The higher scales of surface finish from as sintered will be achieved by machine polishing.

[00104] The inner portion of the Tooth matrix can be designed to be rough as possible in the range from as sintered to etched by means that are known to the art. [00105] Green machining can also be applied. This technique can be applied to as- pressed of the tooth matrix which is still in a chalky condition. Common metal working machines are used to machine the Tooth matrix for individual appearance in this soft condition as greater material removal rates are possible than by post sintering. [00106] Tolerance of the teeth matrix can be about 0.05 to 0.2 mm. [00107] Once the Tooth matrix ceramic powder has been compacted and green machined (if required) the powder compact. Densification is achieved by sintering at temperatures up to 1800°C.

[00108] The sintering or firing process provides the energy to encourage the individual powder particles to bond or sinter together to remove the porosity present from the compaction stages.

[00109] During the sintering process the green compact shrinks. However, this shrinkage is predictable and can be accommodated.

[001 10] Hot Pressing can be applied during the manufacturing process. It can include simultaneous application of external pressure and temperature to enhance the Tooth matrix densification. It is conducted by placing either Tooth matrix powder or a compacted preform into a suitable die, typically graphite, and applying uniaxial pressure while the entire system is held at an elevated temperature, up to 2000 ⁰ C.

[001 1 1] Hot lsostatic Pressing can be applied during the manufacturing process.

The Tooth matrix hot isostatic pressing casting technique involves sintering a compact at high temperature in a pressurized gas atmosphere. The compact must either be impermeable to the pressurizing gas or be encapsulated in a gas-tight container. Hot

Pressing is especially suited to relatively simple shapes, with the components usually requiring diamond grinding to achieve the finished tolerances

[001 12] In the former case, powder compacts are first sintered to remove surface connected porosity. [001 13] The use of hot isostatic pressing leads to additional densification and increased strength.

[001 14] The teeth matrix can be made of various materials such as dental glass ceramic is in correlation with the core material.

[001 15] Material orientation: the material to be used with physical properties to comply with such core material that are known to the art of making dental porcelain restoration i.e.; metals Aluminas Zirconiums

[001 16] Teeth matrices of various shapes, color and size can be provided. These different shapes can be provided to a dentist to be selected of. They can be represented in a catalog or in computer files. [001 17] The tooth matrix can also serve to build a coreless crown (a dental prosthesis without a core) or bridge, the tooth matrix when achieve strength greater then 250Mpa can support the occlusal forces, therefore the prosthesis does not need internal reinforcement of a core. The following steps will be taken to make the coreless prosthesis. A. selection of the appropriate tooth matrix. B. isolating the tooth stamp (chairside) or the representation tooth stamp from the stone cast (dental laboratory). C.

filling the gap with light cure composite (chairside), or porcelain and sintering (dental laboratory).

[001 18] The tooth matrix includes one or more layers and at least one layer can be made of light transmissive material to provide aesthetically pleasing dental prostheses. [001 19] The outer structural appearance of a tooth matrix can resembles of the outer surface of a tooth.

[00120] The inner surface of the tooth matrix is rough and can include undercuts.

[00121] The tooth matrix can include one or more layers of different light transmission properties. [00122] The tooth matrix can include the layers generally will be arranged as resembles a natural tooth layers e.g. Enamel, dentino enamel junction dentin and pulp matter.

[00123] The layers can be modified to achieve aesthetic results

[00124] The Tooth matrix will be produced by method and process which are known to the art for handling production of powder and molted ceramic material, The tooth matrix can be produce from a layer which will be clear (transparent) of color and receive the color from the layer under the inner surface of the matrix.

[00125] Figure 9 illustrates method 200 for preparing a dental prosthesis, according to an embodiment of the invention. [00126] Method 200 starts by stage 210 of selecting a tooth matrix out of a group of tooth matrices that differ from each other, wherein each tooth matrix includes an inner cavity; wherein a tooth matrix is has an appearance of a tooth. Stage 210 can include selecting between tooth matrices that differ by their size, shape, color. It is noted that the color can be determined by the color of adhesive material and/or fill-in (porcelain) that connects the tooth matrix to the intermediate element - especially when the tooth matrix is transparent or partially transparent.

[00127] Stage 210 can include illustrating to a patient an expected result of a restoration process by temporarily placing in a mouth of the patient a tooth replacement element that resembles a selected tooth matrix. This tooth replacement element can be a temporary element.

[00128] Stage 210 can include selecting a light transparent tooth matrix and a color of an adhesive that bonds the tooth matrix to the element.

[00129] Stage 210 can include determining a relative gap between a selected tooth matrix and an intermediate element.

[00130] Stage 210 can be followed by stage 215 of associating a gap filling material with the tooth matrix. Stage 215 is followed by stage 220.

[00131 ] Stage 215 can include sintering the gap filling material.

[00132] Stage 210 is followed by stage 220 of attaching at least a wall of the inner cavity of the tooth matrix to an intermediate element that is connected to the remaining tooth structure or to the implant.

[00133] Stage 220 can include attaching the at least wall of the inner cavity by a bonding material that is selected based upon a desired color of the prosthesis.

[00134] Stage 210 can also be followed by stage 230 of shaping the remaining tooth structure in response to a shape and size of an inner cavity of the selected tooth matrix and to a shape and a restoration area within the mouth of the patient.

[00135] Stage 230 can include shaping the remaining tooth structure in response to a shape and size of an tooth grinding guide that is shaped so as to fit within the inner cavity of a tooth matrix. [00136] Stage 230 is followed by stage 220.

[00137] Method 200 can also include stage 290 of providing tooth matrix information to a computerized process that generates the intermediate element (such as the core) so that the intermediate element will be designed such as to fit in the inner cavity. [00138] Method 200 can also includes stage 280 of generating the tooth matrix.

Stage 280 includes generating a multi-layered tooth matrix. It can include any stage of method 300 or a combination thereof.

[00139] Figure 10 illustrates method 300 for preparing a dental prosthesis, according to an embodiment of the invention. [00140] Method 300 starts by stage 310 of determining a shape of a tooth matrix out of a group of tooth matrices that includes multiple tooth matrices that differ from each other, wherein each tooth matrix comprises an inner cavity; wherein a tooth matrix has an appearance of a tooth. Wherein the inner cavity is shaped so as to include an intermediate element that is connected to a remaining tooth structure or an implant.

[00141 ] Stage 310 is followed by stage 320 of manufacturing, in response to the determination, the tooth matrix.

[00142] Stage 320 can include manufacturing a tooth matrix that comprises multiple layers, wherein an outer layer is light transparent.

[00143] Stage 320 can include applying at least one manufacturing process out of: pressing, melt drawing, injection molding, hot pressing, extrusion processing, die pressing, slip casting, extrusion, injection molding, tape casting, green machining, and sintering. [00144] Stage 320 can include manufacturing multiple layers of the teeth matrix by and molding the multiple layers to form a teeth matrix.

[00145] Stage 320 can include manufacturing multiple layers of the teeth that differ from each other by a level of light transmission.

[00146] Figure 1 1 illustrates method 400 for preparing a dental prosthesis, according to an embodiment of the invention.

[00147] Method 400 starts by stage 410 of receiving tooth matrix information and restoration area information.

[00148] Stage 410 is followed by stage 420 of applying a computerized process to design and manufacture the core so that the core substantially fits to a gap between an inner cavity of the tooth matrix and a remaining tooth structure or an implant located in the restoration area.

[00149] Figure 12 illustrates method 500 according to an embodiment of the invention.

[00150] Method 500 includes a sequence of stages 510- 520. The sequence can be executed one or more times.

[00151] Stage 510 includes performing a diagnostic stage and receiving the approval of the patient.

[00152] Stage 520 includes performing a guided grinding of the tooth.

[00153] Stage 530 includes performing an impression and finding the final location of the teeth matrix.

[00154] Stage 540 includes preparing the core material.

[00155] Stage 550 includes positioning the tooth matrix relative to the core at the patient restoration area.

[00156] Stage 560 includes taking an impression for an index. [00157] Stage 570 includes making an index to secure relative position between core and tooth matrix.

[00158] Stage 580 includes inserting porcelain slurry to the space between the core and the tooth matrix.

[00159] Stage 590 includes cementing one or more crowns or bridges.

[00160] Method 500 can include qa combination of the mentioned above methods. [00161] The present invention can be practiced by employing conventional tools, methodology, and components. Accordingly, the details of such tools, component, and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, in order to provide a thorough understanding of the present invention. However, it should be recognized that the present invention might be practiced without resorting to the details specifically set forth. [00162] Only exemplary embodiments of the present invention and but a few examples of its versatility are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.