Solid Free-Form Fabrication Methods For The Production Of Dental Restorations

Abstract

Solid free form fabrication techniques can be utilized indirectly to manufacture substrates, dies, models, near-net shapes, shells, and wax-ups that are then used in the manufacture of dental articles. Digital light processing is the most preferred indirect method for the production of substrates. After the substrates are produced, various coating or deposition techniques such as gel casting, slip casting, slurry casting, pressure infiltration, dipping, colloidal spray deposition or electrophoretic deposition are used to manufacture the dental article.

1 . A process for the mass production dental articles comprising:
 obtaining digital data of a number of patients' tooth or teeth;   designing enlarged substrates, dies or molds based on the digital data of the patients' tooth or teeth;   concurrently rapid-prototyping a multiplicity of the enlarged substrates, dies or molds;   simultaneously applying ceramic particulate material onto a multiplicity of the substrates or into a multiplicity of the enlarged dies or molds;   sintering a multiplicity of green bodies to form the dental articles.   
   
   
       2 . The process of  claim 1  wherein simultaneously applying ceramic particulate onto a multiplicity of the substrates or into a multiplicity of the enlarged dies or molds comprises casting, pressing, molding or investing. 
   
   
       3 . The process of  claim 1  wherein the step of obtaining digital data of a patient's tooth or teeth comprises scanning a master die, a working die, or a wax-up of a dental article, or intraorally scanning the patient's teeth. 
   
   
       4 . The process of  claim 1  wherein the enlarged substrates, dies or molds are enlarged according to an amount the ceramic particulate will shrink during the sintering step. 
   
   
       5 . The process of  claim 1  wherein the step of designing enlarged substrates, dies or molds comprises creating virtual substrates, dies or molds with the use of a computer having software and memory. 
   
   
       6 . The process of  claim 1  further comprising preparing the enlarged substrates, dies or molds after the step of rapid-prototyping the enlarged substrates, dies or molds. 
   
   
       7 . The process of  claim 6  wherein the step of preparing the enlarged substrates, dies or molds comprises trimming the substrates, dies or molds or coating the substrates, dies or molds with conductive paint. 
   
   
       8 . The process of  claim 1  wherein the step of applying ceramic particulate material onto the enlarged substrates, dies or molds comprises gel casting, slip casting, slurry casting, pressure infiltration, pressure casting, direct coagulation, dipping, colloidal spray deposition, electrophoretic deposition. 
   
   
       9 . The process of  claim 1  wherein the step of applying ceramic particulate material into the enlarged substrates, dies or molds comprises filling the mold by injection molding, extrusion, heat pressing, hot pressing, hot casting, centrifugal casting, gravity casting, pressure casting, gel casting, slip casting, slurry casting and slip pressing. 
   
   
       10 . The process of  claim 1  wherein the ceramic particulate material is in the form of a suspension, slurry, slip, gel, pellet or feedstock. 
   
   
       11 . The process of  claim 1  further comprising heat-treating the ceramic particulate material prior to sintering to release the substrates, dies or molds and to eliminate organic ingredients from the ceramic particulate. 
   
   
       12 . The process of  claim 1  wherein the step of sintering the ceramic particulate material comprises sintering to full density. 
   
   
       13 . The process of  claim 1  further comprising finishing the dental article after the step of sintering the ceramic particulate material. 
   
   
       14 . The process of  claim 13  wherein finishing the dental article after the step of sintering the ceramic particulate comprises applying one or more layers of porcelain, glass, or glass-ceramic having a coefficient of thermal expansion (CTE) up to about ±2×10 −6 /° C. of the CTE of the sintered ceramic particulate material. 
   
   
       15 . The process of  claim 1  wherein the step of rapid-prototyping the multiplicity of the enlarged substrates, dies or molds comprises rapid-prototyping by stereolithography, photo-stereolithography, digital light processing (DLP), selective area laser deposition, selective laser sintering (SLS), electrophoretic deposition (EPD), robocasting, fused deposition modeling (FDM), laminated object manufacturing (LOM), or 3D printing. 
   
   
       16 . The process of  claim 1  wherein the ceramic particulate material is selected from the group consisting of zirconia, ytrria, hafnia, alumina, ceria, magnesia, titania, silicon nitride, silicon carbide, silica-alumina-nitride, mullite, garnets, porcelain, or combination thereof. 
   
   
       17 . The process of  claim 16  wherein the ceramic particulate material comprises a solid solution, agglomerates, complexes or mixtures thereof. 
   
   
       18 . The process of  claim 16  wherein the porcelain comprises glass, leucite, lithium disilicate, mullite or mica. 
   
   
       19 . The process of  claim 16  wherein the zirconia comprises tetragonal zirconia. 
   
   
       20 . The process of  claim 1  wherein the enlarged substrates, dies or molds are fabricated of die stone, clay, plaster of paris, gypsum, silica, leucite, zirconia, hafnia, zirconia, alumina, magnesia, zircon, aluminosilicate, cordierite, mica, silicon nitride, silicon carbide, silica-alumina-nitrides, mullite, garnet, or combination thereof. 
   
   
       21 . The process of  claim 20  wherein the silica comprises crystalline silica, amorphous silica, colloidal silica, or combination thereof. 
   
   
       22 . The process of  claim 1  wherein the substrates, dies or molds thermally decompose during the sintering step. 
   
   
       23 . The process of  claim 1  wherein the enlarged substrates, dies or molds are fabricated of a wax, paraffin, rubber, plastic, polymeric material, thermoplastic material, thermosetting material or light curable resin or combination thereof. 
   
   
       24 . The process of  claim 23  wherein the light curable resin is curable by visible or UV light. 
   
   
       25 . The process of  claim 23  wherein the light curable resin comprises acrylic, epoxy, silicone resins, or monomers or combination thereof. 
   
   
       26 . The process of  claim 1  wherein the dental article is in the shape of a coping, framework, pontic, denture teeth, a bridge, crown, space maintainers, tooth replacement appliance, orthodontic retainer, denture, post, jacket, inlay, onlay, facing, veneer, facet, implant, abutment, splint, partial crown, cylinder, pin, or connector.