Compressed air handpiece including a handle connected to a head housing a turbine. The turbine includes a moving wheel from a periphery of which extends a plurality of blades which define an outer diameter of the moving wheel. The handpiece also includes injection means, whose function is to direct onto the blades of the moving wheel a compressed air flow whose pneumatic energy is converted into kinetic energy when the compressed air flow strikes the blades of the moving wheel. The injection means take the form of an independent insert inside which is arranged a compressed air flow feed pipe and which is mounted inside the handle of the handpiece.
