Compressed air handpiece comprising a handle (32) that is connected to a head (34) inside which a turbine (36) is housed, the turbine (36) comprising a mobile wheel (38) from a periphery (40 ) of which extends a plurality of blades (42) defining an outer diameter (44) of the movable wheel (38), the handpiece (30) also comprising injection means having the function of directing on the paddles (42) of the mobile wheel (38) a flow of compressed air whose pneumatic energy is transformed into kinetic energy when the flow of compressed air hits the blades (42) of the mobile wheel (38), further comprising the handpiece (30) an exhaust duct (58) enabled in the handle (32) of the handpiece (30) and through which the air escapes after having hit the blades (42) of the movable wheel (38), the exhaust duct (58) communicating with the head (34) through an opening that is at least opposite the zone in which the compressed air hits the blades (42) of the movable wheel (38), the compressed air injection means extending into the exhaust duct (58), this opening completely surrounding the compressed air injection means, characterized in that the compressed air injection means are presented in the form of an insert (46) inside which a conduit (48) for supplying the flow of compressed air is enabled and which is coupled inside the handle (32) of the part of working hand (30), the insert (46) being arranged inside the exhaust duct (58), the insert (46) being mounted coaxially inside the exhaust duct (58), the section of the exhaust duct extending ( 58) at least the height of the blades (42) of the movable wheel (38).Pieza de mano de aire comprimido que comprende un mango (32) que se conecta a un cabezal (34) en cuyo interior se aloja una turbina (36), comprendiendo la turbina (36) una rueda móvil (38) desde una periferia (40) de la que se extiende una pluralidad de palas (42) que definen un diámetro exterior (44) de la rueda móvil (38), comprendiendo también la pieza de mano (30) unos me
