Preparation method for dental material with transmittance and color gradients and product prepared thereby

A method for preparing a dental material with light transmittance and color gradients, comprising:

• (1) preparing at least three kinds of composite resin material precursor powders with different light transmittances, wherein each composite resin material precursor powder with a light transmittance is prepared by:
• weighing raw materials, including a resin monomer, a filler, an initiator and a colorant;
• and
• mixing the raw materials to obtain a composite resin material precursor powder,
• wherein the weight ratio of the filler to the resin monomer is 10:90 to 90:10, the initiator is present in an amount of 0.1 to 3% by weight of the resin monomer, the colorant is present in an amount of 0.001 to 0.2% by weight of the total resin monomer and the filler;
• and wherein the resin monomer includes olefinic unsaturated monomers and/or epoxy resins;
• (2) adding successively the at least three kinds of composite resin material precursor powders with different light transmittances to a mold in an ascending order of light transmittance or in an descending order of light transmittance, and molding by dry-pressing under a pressure of 3 to 20 MPa, to obtain a pre-molding green body of dental material with light transmittance and color gradients;
• wherein a top surface of the precursor powder is flattened after adding each composite resin material precursor powder into the mold;
• or
• (2′) among the at least three kinds of composite resin material precursor powders with different light transmittances, molding by dry-pressing a composite resin material precursor powder with a first light transmittance under a pressure of 3 to 20 MPa, to obtain a first green body;
• coating the first green body with a composite resin material precursor powder with a second light transmittance, molding by dry-pressing under a pressure of 3 to 20 MPa to obtain a second green body;
• and repeating the operations of coating and molding by dry-pressing until the at least three kinds of composite resin material precursor powders are molded by dry-pressing to obtain a pre-molding green body of dental material with light transmittance and color gradients, wherein the light transmittance of each layer of precursor powder in the pre-molding green body of dental material with light transmittance and color gradients is increased successively from inside to outside;
• and
• (3) subjecting the pre-molding green body of dental material with light transmittance and color gradients prepared in step (2) or step (2′) to a thermocuring treatment to obtain the dental material with light transmittance and color gradients, wherein the thermocuring treatment is performed at a temperature of 115 to 185° C. under a pressure of greater than 160 MPa for a time period of 0.5 to 4 h.