Abstract: Disclosed are of the protected photoinitiators of the formula: wherein Aryl1 is an aromatic or heteroaromatic ring; Aryl2 is an aromatic ring; each R1 is an alkyl, an aryl, an electron donating group or an electron withdrawing group, and subscript a is 0 to 3; each R2 is an alkyl, an aryl, an electron donating group or an electron withdrawing group, and subscript b is 0 to 3; Prot is a protected carbonyl group.

Abstract: Addition-fragmentation agents of the formula are disclosed: wherein R1, R2 and R3 are each independently Z-Q-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of R1, R2 and R3 is Zm-Q-, Q is a linking group have a valence of m+1; Z is an ethylenically unsaturated polymerizable group, m is 1 to 6; each X1 is independently —O— or —NR4—, where R4 is H or C1-C4 alkyl, and n is 0 or 1.

Abstract: Addition-fragmentation agents having the following functional groups: 1) a labile addition-fragmentation group that can cleave and reform to relieve strain, 2) at least one high refractive index group, and 3) at least one ethylenically unsaturated, polymerizable group are described.

Abstract: Dental compositions and methods of formulating a dental composition are described. In one embodiment, the dental composition comprises a polymerizable resin comprising one or more ethylenically unsaturated monomers or oligomers and nano-particles. The nanoparticles have a refractive index of at least 1.600 and an average discrete or aggregate particle size of no greater than 100 nm. The dental composition further comprises inorganic metal oxide filler having a discrete or aggregate average particle size of at least 200 nm. The nanoparticles are present at a concentration to provide a refractive index differential between the cured polymerizable resin and inorganic metal oxide filler such that the contrast ratio of the dental composition is at least 40.

Abstract: Addition-fragmentation agents having the following functional groups: 1) a labile addition-fragmentation group that can cleave and reform to relieve strain, 2) at least one high refractive index group, and 3) at least one ethylenically unsaturated, polymerizable group are described.

Abstract: A curable dental composition comprising an addition-fragmentation agent and a curable dental resin is disclosed.

Abstract: Novel stress-reducing crosslinking oligomers that have application in dental restoratives, thin films, hardcoats, composites, adhesives, and other uses subject to stress reduction are described. The addition-fragmentation process of crosslinking results in a chain-transfer event that provides novel polymers that may be further functionalized. In addition, the addition-fragmentation oligomer comprises pendent functional groups that bond to a substrate by forming an ionic or covalent bond, or etch the substrate by chemically removing some material from the substrate.

Abstract: A Addition-fragmentation oligomers containing allylic disulfide groups are described. The oligomers may be added to polymerizable compositions to provide labile crosslinks that can cleave and reform during the polymerization process.

Abstract: Addition-fragmentation agents of the formula are disclosed: wherein R1, R2 and R3 are each independently Z-Q-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of R1, R2 and R3 is Zm-Q-, Q is a linking group have a valence of m+1; Z is an ethylenically unsaturated polymerizable group, m is 1 to 6; each X1 is independently —O— or —NR4—, where R4 is H or C1-C4 alkyl, and n is 0 or 1.

Abstract: Provided are novel high refractive index monomers, and dental resins containing the same.

Abstract: The present disclosure provides addition-fragmentation oligomers of the general formula: The crosslinking oligomers of this disclosure provide stress relief by including labile crosslinks that can cleave and reform during the polymerization process.

Abstract: Addition-fragmentation oligomers of the general formula Z—By-A-(B-A)x-B-A-By—Z, where the A monomers units are derived from a diester or diacid, the B monomer units are derived from a difunctional monomer having functional groups co-reactive and at least one of the A or B monomers comprise a 1-methylene-3,3-dimethylpropyl group.

Abstract: Addition-fragmentation agents having the following functional groups: 1) a labile addition-fragmentation group that can cleave and reform to relieve strain, 2) at least one high refractive index group, and 3) at least one ethylenically unsaturated, polymerizable group are described.

Abstract: A curable dental composition comprising an addition-fragmentation agent and a curable dental resin is disclosed.

Abstract: A Addition-fragmentation oligomers containing allylic disulfide groups are described. The oligomers may be added to polymerizable compositions to provide labile crosslinks that can cleave and reform during the polymerization process.

Abstract: Addition-fragmentation agents of the formula are disclosed having the following functional groups: 1) a labile addition-fragmentation group that can cleave and reform to relieve strain, 2) at least two surface-binding functional groups that associate with the surface of a substrate.

Abstract: Addition-fragmentation agents of the formula are disclosed: wherein R1, R2 and R3 are each independently Z-Q-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of R1, R2 and R3 is Zm-Q-, Q is a linking group have a valence of m+1; Z is an ethylenically unsaturated polymerizable group, m is 1 to 6; each X1 is independently —O— or —NR4—, where R4 is H or C1-C4 alkyl, and n is 0 or 1.

Abstract: The present disclosure provides addition-fragmentation oligomers of the general formula: The crosslinking oligomers of this disclosure provide stress relief by including labile crosslinks that can cleave and reform during the polymerization process.

Abstract: Dental compositions are described comprising an addition-fragmentation agent of the formula: wherein R1, R2 and R3 are each independently Zm-Q-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of R1, R2 and R3 is Zm-Q-; Q is a linking group have a valence of m+1; Z is an ethylenically unsaturated polymerizable group; m is 1 to 6; each X1 is independently —O— or —NR4—, where R4 is H or C1-C4 alkyl; and n is 0 or 1. Also described are dental articles prepared from a dental composition comprising an addition-fragmentation agent and methods of treating a tooth surface.

Abstract: Provided are novel high refractive index monomers, and dental resins containing the same.