Apical position locator

10) A device comprising:

• a) a dental file electrode insertable into the root canal of a tooth of a patient;
• b) an external electrode adapted to contact a body surface of the patient;
• and
• c) a detection apparatus including a measurement signal generator adapted to produce a regulated current between said dental file and external electrodes, said detection apparatus adapted to sense an impedance related parameter to generate an output signal indicative of a distance between a fixed point on said dental file electrode and the apical position of the tooth.

13) A device comprising:

• a) a dental file electrode insertable into the root canal of a tooth of a patient;
• b) an external electrode adapted to contact a body surface of the patient;
• and
• c) a detection apparatus including a measurement signal generator adapted to produce between said dental file and external electrodes a voltage whose amplitude depends on a position of the dental file electrode within the root canal of the tooth, said detection apparatus adapted to sense an impedance related parameter to generate an output signal indicative of a distance between a fixed point on said first electrode and the apical position of the tooth.

16) A device comprising:

• a) a dental file electrode insertable into the root canal of a tooth of a patient;
• b) an external electrode adapted to contact a body surface of the patient;
• and
• c) a detection apparatus including a measurement signal generator adapted to produce between said dental file and external electrodes electrical signals having a frequency of at least about 50 KHZ and at most about 200 KHZ, said detection apparatus adapted to sense an impedance related parameter to generate an output signal indicative of a distance between a fixed point on said first electrode and the apical position of the tooth.

17) A device comprising:

• a) a root canal electrode insertable into the root canal of a tooth of a patient, at least a portion of an elongate surface of said dental file electrode being uninsulated;
• b) an external electrode adapted to contact a body surface of the patient;
• and
• c) a detection apparatus including a measurement signal generator adapted to produce between said root canal and external electrodes electrical signals having a frequency of at least about 50 KHZ, said detection apparatus adapted to sense an impedance related parameter to generate an output signal indicative of a distance between a fixed point on said first electrode and the apical position of the tooth.

18) A device comprising:

• a) a first electrode insertable into the root canal of a tooth of a patient;
• b) an second electrode adapted to contact a body surface of the patient;
• and
• c) a detection apparatus including a measurement signal generator adapted to produce between said first and second electrodes electrical signals having a frequency of at least about 50 KHZ, said detection apparatus adapted to sense an impedance related parameter to generate an output signal indicative of a distance between a fixed point on said first electrode and the apical position of the tooth, said measurement signal generator adapted to supply a maximum of about 40 microamperes between said first and second electrodes.

19) Apparatus for detecting an apical position depending on the change in the impedance between a first electrodes inserted into the root canal of a tooth of a patient and a second electrode contacting a body surface of the patient, the apparatus comprising:

• a) a detection apparatus including a measurement signal generator adapted to produce a measurement signal between the first and second electrodes, said detection apparatus adapted to sense an impedance-related parameter between the first and second current supply electrodes;
• and
• b) a processing unit for deriving from said sensed parameter a multiple of a distance between a fixed point on the first electrode and the apical position of the tooth,
• wherein said processing unit determines a capacitance-governed function when the first electrode is in the in the apical region, and said processing unit determines a function at least moderately governed by resistance when the electrode is in a dental neck region.

21) A method of measuring penetration in a root canal of a tooth of a patient comprising:

• a) inserting a first electrode into the root canal of a tooth;
• b) applying a second electrode to a body surface of the patient;
• c) supplying a regulated current between said first and second electrodes;
• and
• d) determining an impedance parameter between said first and second electrodes, said impedance parameter indicative of a distance between a fixed point on said first electrode and an apical position of said tooth.

34) A method of measuring penetration in a root canal of a tooth of a patient comprising:

• a) inserting a first electrode into a root canal of a tooth;
• b) applying a second electrode to a body surface of the patient;
• c) supplying a measurement signal between said first and second electrodes;
• and
• d) determining an impedance parameter between said first and second electrodes, said impedance parameter indicative of a distance between a fixed point on said first electrode and an apical position of said tooth,
• wherein said first electrode is inserted to a plurality of distinct depths within said root canal, and for each said depth, an amplitude voltage of said measurement signals depends on said distance between said fixed point and said apical position.

35) A method of measuring penetration in a root canal of a tooth of a patient comprising:

• a) inserting a first electrode into a root canal of a tooth of the patient;
• b) applying a second electrode to a body surface of the patient;
• c) supplying an electrical measurement signal having a frequency of at least 50 KHZ between said first and second electrodes;
• and
• d) determining an impedance parameter between said first and second electrodes, said impedance parameter indicative of a distance between a fixed point on said first electrode and an apical position of said tooth.

39) A method of measuring penetration in a root canal of a tooth of a patient comprising:

• a) inserting a first electrode into the root canal of a tooth;
• b) applying a second electrode to a body surface of the patient;
• c) supplying a regulated current between said first and second electrodes;
• and
• d) determining an impedance parameter between said first and second electrodes, said impedance parameter indicative of a distance between a fixed point on said first electrode and an apical position of said tooth,
• wherein said determining includes determining a capacitance-determined impedance parameter when said fixed point is in an apical region of said root canal, and determining an impedance parameter whose value is at least moderately governed by resistance when said fixed point is in a dental neck region of said root canal.

40) A method of measuring penetration in a root canal of a tooth of a patient comprising:

• a) inserting a first electrode into the root canal of the tooth;
• b) applying a second electrode to a body surface of the patient;
• c) supplying a regulated current between said first and second electrodes;
• and
• d) determining an impedance parameter between said first and second electrodes;
• e) deriving from said determined impedance parameter a multiple of a distance between a fixed point on said first electrode and the apical position of the tooth.