Method for producing a blank and dental restoration

Abstract

The invention relates to a blank from a ceramic material, wherein at least two layers of ceramic material of different compositions are filled into a die layer-by-layer and after filling of the layers they are then pressed and sintered, wherein after filling of a first layer this is structured on its surface in such a way that the first layer, viewed across its surface, differs in its height from region to region, and then a layer with a composition that differs from the first layer is filled as a second layer into the mold.

1 . A pre-sintered or fully-sintered blank for use for the production of a dental restoration, comprising of a ceramic material which includes zirconium dioxide doped with yttrium oxide (Y 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO) and/or cerium oxide (CeO 2 ), when viewed across its height has layers of different compositions, wherein material of a first layer differs from material of a second layer in terms of color and proportions of stabilized crystal forms present at room temperature, and wherein the blank has at least three layers, of which one is a middle layer that extends over at least 1/10 H to ⅕ H of the total height H of the blank, and which is formed from a material of the first layer and the second layer. 
     
     
         2 . The method according to  claim 1 , wherein the surface of the first layer is structured in such a way that result in elevations, with depressions that are demarcated from the elevations. 
     
     
         3 . The method according to  claim 1 , wherein a ring structure is formed in the surface when viewed from above, which shows concentrical elevations and depressions. 
     
     
         4 . The method according to  claim 1 , wherein the structure is produced by an element that moves in relative to the first layer and which structures the first layer in its surface region by means of a section which has a wave-like, comb-like or saw-tooth-like shape. 
     
     
         5 . The method according to  claim 1 , wherein the structure is generated by a pressure element that acts in the direction of the surface of the first layer. 
     
     
         6 . The method according to  claim 1 , wherein the pressure element used is such that elevations extending concentrically or parallel are pressed into the surface of the first layer with depressions extending between them. 
     
     
         7 . The method according to  claim 1 , wherein the structure is formed such that the volume of the elevations is equal to, or approximately equal to, the volume of the depressions. 
     
     
         8 . The method according to  claim 1 , wherein the material of the further layer is mixed with that of the first layer commencing from the free surface of the further layer over a height that corresponds to at least twice the height of the further layer. 
     
     
         9 . The method according to  claim 8 , wherein the material used for the further layer is the same as that used for the second layer. 
     
     
         10 . The method according to  claim 1 , wherein the materials used as ceramic materials include zirconium dioxide doped with yttrium oxide (Y 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO) and/or cerium oxide (CeO 2 ), wherein the material of the first layer differs from the material of the second layer in terms of color and/or the proportions of stabilized crystal forms present at room temperature. 
     
     
         11 . The method according to  claim 1 , wherein the material of the first and/or second layer and/or the intermediate layer is colored with at least one coloring oxide of elements of the group Pr, Er, Fe, Co, Ni, Ti, V, Cr, Cu, Mn, Th. 
     
     
         12 . The method according to  claim 1 , wherein the first layer is mixed with the second layer in those regions which lie one on top of the other over a height that is ⅕ H to ¼ H, where H is the total height of the first and second layers. 
     
     
         13 . The method according to  claim 1 , wherein the first layer in an unstructured state has a height that is half, or approximately half the total height H of the first and second layers. 
     
     
         14 . The method according to  claim 1 , wherein the material used as the first and/or second ceramic material is one in which the percentage of yttrium oxide in the first layer is 4.5 wt % to 7.0 wt % and/or the percentage in the second layer is 7.0 wt % to 9.5 wt %, wherein the percentage of yttrium oxide in the first layer is lower than in the second layer. 
     
     
         15 . The method according to  claim 1 , wherein the ceramic material used for the first layer and the second layer is one in which the ratio of tetragonal crystal phase to cubic crystal phase of the zirconium dioxide both in the first layer and in the second layer after pre-sintering is ≥1. 
     
     
         16 . The blank according to  claim 1 , wherein in the middle layer the percentage of the material of the first layer starting therefrom in the direction of the second layer decreases continuously or substantially continuously. 
     
     
         17 . The blank according to  claim 1 , wherein the zirconium dioxide is doped with yttrium oxide, wherein the percentage of yttrium oxide in the first layer is between 4.5 wt % and 7.0 wt % and in the second layer is between 7.0 wt % and 9.5 wt %, that the percentage of yttrium oxide in the first layer is lower than in the second layer. 
     
     
         18 . The blank according to  claim 1 , wherein the percentage of yttrium oxide in the middle layer from the first layer commencing in the direction of the second layer increases continuously or substantially continuously. 
     
     
         19 . The blank according to  claim 1 , wherein the first layer is different from that of the second layer. 
     
     
         20 . The blank according to  claim 1 , wherein a restoration derived from the blank, when viewed in a tooth axis direction on the root side has a higher translucency than on the incisal side and/or on the incisal side has a higher translucency than on the root side, after complete sintering. 
     
     
         21 . A dental restoration produced from a blank according to  claim 1 , wherein the restoration when viewed in a tooth axis direction includes at least one first layer extending on the root side, a second layer extending on the incisal side and a middle layer or intermediate layer extending between them, which decreases in strength continuously or substantially continuously commencing from the first layer in the direction of the second layer and/or increases continuously or substantially continuously in its translucency, wherein the layers contain or consists of ceramic material, which contains zirconium dioxide doped with yttrium oxide (Y 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO) and/or cerium oxide (CeO 2 ), and wherein material of the first layer differs from material of the second layer in terms of color and proportions of stabilized crystal forms present at room temperature. 
     
     
         22 . The dental restoration according to  claim 21 , the dental restoration is a bridge having a connector with basal side extending in the region of the first layer.