Abstract: A dental handpiece having a turbine rotatable in reverse contains a main handpiece body, a turbine head mounted at a distal end of the main handpiece body, a plurality of turbine vanes for rotatably driving a dental tool romovably mounted within the turbine head, a first air supply passage for ejecting compressed air to one surface of each of the turbine vanes for rotating the turbine vanes in one direction, a second air supply passage for ejecting compressed air to the other surface of each of the turbine vanes for rotating the turbine vanes in the other direction, and an air discharge passage for discharging the compressed air.

Abstract: An air-powered dental handpiece and a connecting means comprises a handle portion and a powerhead assembly. A sleeve bearing having a forwardly reducing cylindrical internal surface is integrally held into another end opening of the handle portion. The surface has three stepped annular space walls, and a central air supply passage and two axial passages for exhaust and water are provided to extend to the stepped annular space walls. An air supply pipe is fixedly inserted into the central passage and two pipes are fixedly inserted into two passages. A front portion of a connecting means is so formed into a forwardly reducing cylindrical plug as to fit into a socket of the sleeve bearing.

Abstract: A cylindrical member of the present dental handpiece is provided with a cup bearing held into an opening adjacent its upper end and also with an annular bearing disposed into said opening adjacent its lower end. A metallic member having a substantially inclined bottom face is secured to the cup bearing. A top end face of a bushing having a worm wheel is coincidentally inclined to fit to said inclined bottom face of the metallic member so as to form a cam mechanism. The bushing is formed with an annularly widened opening therein adjacent its lower end to receive a collet chuck and also a screw thread around said bushing, which is rotatably inserted into the cylindrical member through the cup and annular bearings. A reamer is firmly held into the bushing through a collet chuck, and a worm gear is associated with the worm wheel. According to the dental handpiece, the reamer is driven to rotate slowly once at its each vertical mot motion, enabling to carry out a finger touch operation.