Dental handpiece with a root canal length measurement function

A handpiece for measuring root canal length, comprising:

• an outer sleeve that is substantially non-insulating and has no insulating coating,
• a connecting device for coupling the handpiece to a control and evaluation unit, to a measuring circuit with a current source for measurement of root canal length and to a drive unit,
• an instrument carrier configured to receive a dental instrument,
• at least one transmission element within the outer sleeve that transmits force to move the instrument carrier so that the dental instrument received in the instrument carrier executes a rotating, reciprocating and/or vibrating working movement,
• a length measuring circuit portion disposed inside the handpiece and operable to transmit measuring signals for measuring length,
• a contact portion operable to establish a conductive path between the dental instrument serving as an electrode and the length measuring circuit portion, and
• an insulating portion that insulates the length measurement circuit portion and a contact device, through which a voltage is applied during measurement, from the outer sleeve,
• wherein the contact portion comprises the contact device for use with a dental instrument having a non-conductive shaft, the contact device establishing a connection between a conductive section of the dental instrument and the length measuring circuit portion,
• wherein the length measuring circuit portion comprises a conducting wire and the insulating portion comprises a wire sheath of non-conductive material,
• wherein the contact device comprises a sleeve extending from the handpiece and a U-shaped elastic wire connected to the sleeve and positionable to contact the conductive section of the dental instrument,
• wherein the conducting wire extends into the sleeve and is connected to the U-shaped elastic wire, and
• wherein the sleeve comprises a stem projecting outwardly through a bore in the outer sleeve, the stem having a flanged inner end that retains the stem within the handpiece.

A handpiece for measuring root canal length, comprising:

• an outer sleeve that is substantially non-insulating and has no insulating coating,
• a connecting device for coupling the handpiece to a control and evaluation unit, to a measuring circuit with a current source for measurement of root canal length and to a drive unit,
• an instrument carrier configured to receive a dental instrument,
• at least one transmission element within the outer sleeve that transmits force to move the instrument carrier so that the dental instrument received in the instrument carrier executes a rotating, reciprocating and/or vibrating working movement,
• a length measuring circuit portion disposed inside the handpiece and operable to transmit measuring signals for measuring length,
• a contact portion operable to establish a conductive path between the dental instrument serving as an electrode and the length measuring circuit portion, and
• an insulating portion that insulates the length measurement circuit portion and a contact device, through which a voltage is applied during measurement, from the outer sleeve,
• wherein the contact portion comprises the contact device for use with a dental instrument having a non-conductive shaft, the contact device establishing a connection between a conductive section of the dental instrument and the length measuring circuit portion,
• wherein the contact portion is operable to connect a conductive section of the dental instrument received in the instrument carrier to the 1ength measuring circuit portion via a conductive head spindle of the instrument carrier and at least one associated conductive gearwheel, and
• wherein a U-shaped elastic wire is detachably connected to the sleeve with a terminal connection, and wherein the insulating portion includes the sleeve and a stem of the sleeve that receives an end of a conducting wire, an opposite end of the conducting wire being connected by a sliding contact to the head spindle.

A handpiece for measuring root canal length, comprising:

• an outer sleeve that is substantially non-insulating and has no insulating coating,
• a connecting device for coupling the handpiece to a control and evaluation unit, to a measuring circuit with a current source for measurement of root canal length and to a drive unit,
• an instrument carrier configured to receive a dental instrument and having a movable head spindle,
• at least one transmission element within the outer sleeve that transmits force to move the instrument carrier so that the dental instrument received in the instrument carrier executes at least one of a rotating movement, a reciprocating movement, and a vibrating working movement,
• a length measuring circuit portion disposed inside the handpiece and operable to transmit measuring signals for measuring length,
• a dual mode contact portion operable to establish a conductive path between the dental instrument serving as an electrode and the length measuring circuit portion,
• the dual mode contact portion having a first contact device for use in a first mode with a dental instrument having a conductive shaft comprising a sliding contact operable to establish a connection between the head spindle and the length measuring circuit portion,
• the dual mode contact portion having a second contact device for use in a second mode with a dental instrument having a non-conductive shaft, the second contact device comprising an external mounted wire positioned to contact a conductive portion of the dental instrument and connected to the length measuring circuit portion, and
• insulating portions that insulate the length measurement circuit portion and the first and second contact devices, through which voltage is applied during measurement, from the outer sleeve.