Patent ID: 7320596

Claim:
A method of extruding dental material from a cartridge, comprising: providing a cartridge having an elongated body, a nozzle, and a piston, said elongated body having an inner chamber wall and end wall portion, said elongated body enclosing dental material, and, said nozzle having a cylindrical nozzle channel with a substantially uniform diameter, an inner channel wall enclosing said nozzle channel, and a channel wall exit orifice rim, said nozzle extending from said end wall portion of said elongated body, said inner chamber wall having a chamber wall exit port rim, said chamber wall exit port rim having an opening and being connected to said inner chamber wall of said elongated body and said inner channel wall of said nozzle, said chamber wall exit port rim having a chamber wall exit port rim effective diameter D 1 , said nozzle channel having an effective diameter D 2 , said nozzle channel effective diameter D 2 effectively being greater than said chamber wall exit port rim effective diameter D 1 , said end wall portion of said elongated body having a hemispherical exterior surface and an arcing interior surface, said end wall portion having substantially greater thickness than said inner chamber wall of said elongated body, and said piston being inserted into said elongated body, wherein said piston has a side wall and semi-circular front-facing portion, said side wall being complementary to said inner chamber wall of said elongated body and said front-facing portion having a complementary shape to said interior surface of said end wall portion of said elongated body, and applying force to said piston to extrude said dental material through said nozzle of said cartridge.