Gc Corporation

Koichi Mamada

Kimihiko Sato

Masaaki Kaneko

Keisuke Ikushima

Kenichi Iiyama

A dental diamond bur having grains of diamond attached to a head of the bur body with a plated metal layer containing grains of a fluorine compound that are almost uniformly dispersed and have an average diameter smaller than that of the diamond.

Dental diamond bur

A dental gypsum bonded investment composition comprising 100 parts by weight of a mixture comprising (a) .alpha.-hemihydrate gypsum as a binder and (b) quartz and/or cristobalite as a refractory material, and optionally, (c) one or more aggregates selected from the group consisting of metallic oxides, metallic carbides, and metallic nitrides, which can substitute a part of the refractory material, having from 0.01 to 1.0 part by weight of a poly-tetrafluoroethylene resin and optionally, from 0.001 to 0.05 part by weight of one or more anionic surfactants selected from the group consisting of alkylbenzenesulfonates and alkylsulfates mixed therewith, is disclosed. The dental gypsum bonded investment composition of the invention keeps the fine particles to have a stable performance without being removed by the pneumatic transportation at the time of production, has superior heat resistance, and can be used for casting of alloys having a high melting point such as casting alloys for metalceramic restorations.

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Tokyo, Japan

Koichi Mamada