Preform for the production of a dental prosthesis

A preform intended for the production of a dental prosthesis, said preform comprising a group of agglomerated ceramic, glass-ceramic or glass particles, such that, as volume percents:

• more than 40% and less than 90% of the agglomerated ceramic, glass-ceramic or glass particles of said group have a size greater than 0.5 μm and less than 3.5 μm, said agglomerated ceramic, glass-ceramic or glass particles hereinafter being denoted “enamel particles”, and
• more than 10% and less than 60% of the agglomerated ceramic, glass-ceramic or glass particles of said group have a size greater than 3.5 μm and less than 5.5 μm, said agglomerated ceramic, glass-ceramic or glass particles hereinafter being denoted “dentine particles”,
• a microstructure of the preform being such that there is an axis X, termed “axis of variation,” along which the Ve/(Ve+Vd) ratio changes continuously, Ve and Vd denoting the volume percents of enamel particles and of dentine particles, respectively,
• the enamel and dentine particles representing, together, more than 90% of the volume of the agglomerated ceramic, glass-ceramic or glass particles,
• the agglomerated ceramic, glass-ceramic or glass particle size distribution of said group of particles being bimodal and comprising first and second principle modes,
• the first principle mode being greater than 1.5 μm and less than 3.5 μm, the second mode being greater than 3.5 μm and less than 5.5 μm,
• wherein the preform has a first region, termed “enamel region”, in which the Ve/(Ve+Vd) ratio is greater than 0.9 and a second region, termed “dentine region”, in which the Ve/(Ve+Vd) ratio is less than 0.1,
• the enamel and dentine regions being in the form of layers and extending from opposite enamel (Fe) and dentine (Fd) faces of the preform, taking into consideration the axis of variation.