Dental composition based on silicone crosslinkable by cation process

A process for the preparation of a dental prosthesis or dental restoration, comprising the step of shaping and curing a low shrinking polymerizable or crosslinkable dental composition comprising a mixture of:

• (1) at least one crosslinkable and/or polymerizable silicone oligomer or polymer which is liquid at room temperature or which is heat-meltable at a temperature of less than 100° C., and which comprises:
• at least one unit of formula (FS):
• wherein:
• a=0.1 or 2,
• R0, identical or different, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogeno or alkoxy radical,
• Z, identical or different, is an organic substituent comprising at least one reactive epoxy, or alkenyl ether or oxetane or dioxolane or carbonate functional group,
• and at least two silicon atoms,
• (2) at least one aromatic hydrocarbon photosensitizer, having a residual light absorption of between 200 and 500 nm, and selected from the group consisting of the following formulae (VIII), (X). (XII) and (XXII):
• thioxanthones of formula (VIII):
• wherein:
• m=0 to 8,
• R17, identical or different substituent(s) on the aromatic nucleus (nuclei), represent a linear C1-C12 alkyl radical, a branched C1-C12 alkyl radical, a C6-C12 cycloalkyl radical, a radical Ar1, a halogen atom, an —OH, —CN, —NO2, —COOR6, —CHO, Ophenyl, —CF3, —SR6, —Sphenyl, —SO2phenyl, Oalkenyl, or —SiR63 group;
• xanthones of formula (X):
• wherein p=0 to 8
• anthracene of formula (XII):
• wherein=0 to 10, and
• biscoumarins of formula (XXII):
• wherein:
• R18, identical or different, has the same meaning as R17 above or represents a group:
• —NR62, wherein R6 represents a linear C1-C12 alkyl radical,
• (3) at least one dental filler present in a proportion of at least 10% by weight relative to the total weight of the composition, and
• (4) an effective quantity of at least one borate-type photoinitiator, whose borate residue is:
• 1′:
• [B(C6F5)4]−
• 2′:
• [(C6F5)2BF2]−
• 3′:
• [B(C6H4CF3)4]−
• 4′:
• [B(C6F4OCF3)4]−
• 5′:
• [B(C6H3(CF3)2)4]−
• 6′:
• [B(C6H3F2)4]−
• 7′:
• [C6F5BF3]−
• wherein the cationic entity of the borate is:
• [(Φ)2I]+
• [C8H17—O-Φ-I-Φ]+
• [(Φ-CH3)2I]+
• [C12H25-Φ-I-Φ]+
• [(C8H17—O-Φ)2I]+
• [(C8H17—O-Φ-I-Φ)]+
• [(Φ)3S]+
• [(Φ)2-S-Φ-O—C8H17]+[(CH3-Φ-I-Φ-CH(CH3)2]+
• [(Φ-S-Φ-S-(Φ)2]+
• [(C12H25- Φ)2I]+
• [(CH3-Φ-I-Φ-OC2H5]+;
• and
• wherein the composition has a volumetric polymerization and/or crosslinking shrinkage of less than 1.5% v/v.