Patent ID: 8118594

Claim:
A dental handpiece including mechanical components and comprising a tool-holder assembly for attaching and for rotationally driving a dental instrument about a drive axis, and an assembly for transmitting rotational movement to the tool-holder assembly; wherein the mechanical components are mounted in interior portions of a body having a head and a handle, wherein the body is formed as a unitary, electrically insulating envelope including one part which serves as the handle and another part which constitutes the head; wherein the head includes a first housing having at least one opening dimensioned to permit component parts of the head to be introduced into and assembled within interior portions of the first housing; wherein the handle includes a second, longitudinal housing having a longitudinal axis, and an opening at an end of the handle opposite to the head which is dimensioned to permit internal component parts of the handle to be introduced into and assembled within interior portions of the second housing, and a lateral opening communicating with the first housing; wherein electrical current is conducted from a casing associated with the end of the handle opposite to the head, for connection to a drive motor, to the lateral opening communicating with the first housing by internal component parts of the handle; and wherein the head includes a barrel pinion assembled for rotation about the drive axis, wherein the barrel pinion includes teeth operatively coupled with teeth of an output pinion associated with the internal component parts of the handle, and wherein the barrel pinion is electrically conductive and ensures an electrical connection between the internal component parts of the handle and the dental instrument coupled with the tool-holder assembly.