Blank for dental cutting and method for producing same

A dental mill blank, comprising a milling target portion comprising a resin-based material,

• the resin-based material comprising at least one composite material comprising a resin matrix and inorganic particles dispersed in the resin matrix,
• the inorganic particles comprising:
• at least one group of identical diameter spherical particles (G-PID) comprising spherical inorganic particles with a specific average primary particle diameter in a range of 100 nm to 1,000 nm and having a number-size distribution in which 90% or more of all particles have particle diameters falling within a range of the average primary particle diameter-5% of the average primary particle diameter to the average primary particle diameter+5% of the average primary particle diameter;
• and
• a group of superfine particles (G-SFP) comprising inorganic particles with an average primary particle diameter of less than 100 nm,
• the at least one group including one or more groups of identical diameter spherical particles, wherein
• the one or more groups of identical diameter spherical particles are A groups each represented by G-PIDm, wherein A is the number of the groups, m is 1 where A is 1 or m is a positive integer of 1 to A where A is 2 or more, and the average primary particle diameter of the group increases with increasing m,
• the groups represented by G-PIDm have average primary particle diameters differing by 25 nm or more from each other,
• the group of superfine particles has an average primary particle diameter 25 nm or more smaller than that of the group represented by G-PID1,
• the at least one composite material satisfies the relation n(Mx)<n(G-PIDm), wherein n(Mx) is a refractive index of the resin matrix for light with a wavelength of 589 nm at 25° C., n(G-PIDm) is a refractive index of the spherical inorganic particles of each group represented by G-PIDm for light with a wavelength of 589 nm at 25° C., and the relation is satisfied for each n(G-PIDm), and
• the at least one composite material has a short-range order structure in which the spherical inorganic particles of all the groups of identical diameter spherical particles in the resin matrix have an arrangement structure satisfying:
• Condition 1 where a radial distribution function graph plotted with r/r0 on an x axis and a radial distribution function g(r) on a y axis and showing a relationship between r/r0 and the g(r) for r, wherein r/r0 is a normalized dimensionless number calculated by dividing a distance r from a center of any spherical inorganic particle in the composite material by an average particle diameter r0 of all spherical inorganic particles dispersed in the composite material and the g(r) represents a probability of existence of any other spherical inorganic particle at a point apart by the distance r from the center of the any spherical inorganic particle, has peaks among which a peak closest to an origin provides a distance r1 between nearest neighbor particles as the r value corresponding to a top of the peak, and the distance r1 between nearest neighbor particles is 1 to 2 times the average particle diameter r0 of all spherical inorganic particles dispersed in the composite material;
• and
• Condition 2 where the radial distribution function graph has peaks among which a peak second closest to the origin provides a distance r2 between second nearest neighbor particles as the r value corresponding to a top of the peak, and the radial distribution function g(r) has a local minimum value of 0.56 to 1.10 between the distance r1 between nearest neighbor particles and the distance r2 between second nearest neighbor particles.