The present invention relates to particles comprising a core, in particular a magnetic core, and a first coating of a first shell material, wherein a second coating of a second shell material is applied to the surface of the first coating facing away from the core, the second shell material is different from the first shell material and has a higher refractive index than the first shell material.

The present invention relates to particles comprising a core, in particular a magnetic core, and a first coating of a first shell material, wherein a second coating of a second shell material is applied to the surface of the first coating facing away from the core, the second shell material is different from the first shell material and has a higher refractive index than the first shell material.

Dental composition comprising (a) a homogeneous phase comprising monomer combinations (i) and (ii), (i) and (iii), (ii) and (iii), or (i), (ii) and (iii), or comprising monomer (iii), wherein (i) represents one or more compounds having one or more radically polymerizable carbon-carbon double bonds; (ii) represents one or more compounds having one or more cationically polymerizable groups; and (iii) represents one or more compounds having a combination of one or more radically polymerizable carbon-carbon double bonds and one or more cationically polymerizable groups; (b) an initiator system comprising (iv) one or more radical polymerization initiator of the following formula (I): ##STR00001##
wherein M is Ge or Si; R.sup.1, R.sup.2 and R.sup.3 may be the same or different, independently represent an organic group, and R.sup.4 represents a hydrogen atom, an organic or organometallic group; provided that when R.sup.4 is a hydrogen atom, the initiator system further comprises a sensitizer compound having a light absorption maximum in the range from 300 to 600 nm; (v) a cationic polymerization initiator, which is a compound selected from the following formula (II), (III) and (IV): ##STR00002##
wherein R.sup.5 and R.sup.6, which may be the same or different, independently represent an aryl group which may have a substituent; and Y.sup.− represents an anion; ##STR00003##
wherein R.sup.7, R.sup.8 and R.sup.9 which may be the same or different, independently represent an aryl group which may have a substituent; and Y.sup.− represents an anion; ##STR00004## R.sup.10, R.sup.11, R.sup.12, and R.sup.13 which may be the same or different, independently represent an alkyl or aryl group which may have a substituent; and Y.sup.− represents an anion.

The present invention provides a photocurable composition for use in stereolithography, the photocurable composition including: a (meth)acrylic monomer (X) that is at least one selected from the group consisting of di(meth)acrylic monomers containing, within one molecule, two aromatic rings and two (meth)acryloyloxy groups, and that has a weight average molecular weight of from 400 to 580; a (meth)acrylic monomer (D) that is at least one selected from the group consisting of (meth)acrylic monomers containing, within one molecule, at least one aromatic ring and one (meth)acryloyloxy group, and that has a weight average molecular weight of from 140 to 350; and a photopolymerization initiator.

The present invention relates to particles comprising a core, in particular a magnetic core, and a first coating of a first shell material, wherein a second coating of a second shell material is applied to the surface of the first coating facing away from the core, the second shell material is different from the first shell material and has a higher refractive index than the first shell material.

Provided is a photocurable composition including a monomer component including: a monomer (X) containing, within one molecule, two aromatic rings and two (meth)acryloyloxy groups, and having an Mw of from 400 to 580, and a monomer (H) containing, within one molecule, at least one of a hydroxyl group or a carboxy group, and a (meth)acryloyloxy group, and having an Mw of from 100 to 700; and a photopolymerization initiator. The composition has a functional group value (a) of from 0.510.sup.3 to 2.010.sup.3 mol/g.

Functional group value (a)=(n.sub.H/M.sub.H)P.sub.HFormula (a)

wherein n.sub.H represents the total number of hydroxyl groups and carboxy groups contained in one molecule of the (meth)acrylic monomer (H); M.sub.H represents the Mw of the (meth)acrylic monomer (H); and P.sub.H represents the mass ratio of the (meth)acrylic monomer (H) with respect to the total amount of the (meth)acrylic monomer component.

A fluoride treated medical implant, such as a dental component, is provided, the medical implant comprising fluorinated metal oxide on the substrate surface. A method for the preparation of such treated implants is also provided, the method involving exposure of the medical implant to a fluorine-containing reagent. A dental structure is also provided, which includes a first dental component comprising a fluorinated metal oxide layer on its surface, a silane coupling agent, a dental cement, and a second dental component having a surface bonded to the dental cement. An additional dental structure, which includes a first dental component comprising a fluorinated metal oxide layer on its surface, a dental cement, and a second dental component having a surface bonded to the dental cement is also provided.