to separate a catalyst for polymerizing a monomer contained in a liquid or paste dental composition containing at least a monomer , such as a dental resin cement , an autopolymerizing dental resin or a resin - reinforced dental glass ionomer cement , from the liquid or paste dental composition to thereby improve storage stability of the dental composition and reduce number of division of the dental composition , an extrusion nozzle for a dental composition mounted on one end of an extruder for extruding a liquid or paste dental composition containing at least a monomer , the extrusion nozzle contains a catalyst for polymerizing the monomer contained in the dental composition during extrusion , and the catalyst is attached to an inner wall of an extruding channel of the extrusion nozzle .