Method and apparatus for apical detection with complex impedance measurement

An apical detection apparatus, comprising:

• a first electrode, the first electrode including a conductive probe shaped for penetrating a root canal of a tooth;
• a second electrode configured to electrically contact a patient's body;
• a phase detector coupled to the first and second electrodes, the phase detector being operative to detect a phase of a complex impedance having a real component and a reactive component;
• a user interface coupled to the phase detector to provide an indication to a user of a parameter that is a function of the detected phase;
• and
• a signal source coupled to the first and second electrodes, the signal source providing a testing signal to the first and second electrodes, the testing signal including a plurality of test frequencies, wherein the phase detector is operative to detect the phase of the complex impedance at each of the test frequencies.

An apparatus for detecting contact with a body tissue of a first type in a patient, comprising:

• a first electrode coupleable to the patient's body;
• a second electrode movable to contact the tissue of the first type, the second electrode including a probing member for contacting the patient's body;
• and
• a complex impedance sensor coupled to the first and second electrodes and configured to detect a plurality of amplitude relationships among at least three different frequencies and a plurality of relationships between real and reactive components of impedances at at least three different frequencies between the first and second electrodes.

A method of detecting an apical location in a root canal of a patient comprising the steps of:

• electrically coupling to the patient at a first location;
• probing the root canal at a second location;
• detecting a complex impedance between the first location and the second location, the complex impedance having a first phase component and a first magnitude component;
• and
• producing an indicator of the second location as a function of the first phase component;
• the step of detecting a complex impedance between the first and second locations comprising the steps of:
• detecting a first impedance at a first frequency;
• and
• detecting a second impedance at a second frequency different from the first frequency,
• wherein the first phase component corresponds to the first impedance and a second phase component corresponds to the second impedance.

A method of indicating apical position, comprising the steps of:

• probing a root canal with a probe;
• detecting a complex component of a complex impedance between the probe and a location on a patient's body;
• producing a first test score as a function of the complex component;
• and displaying the first test score to a user;
• and
• producing a second test score indicating testing conditions based upon a selected component of the complex impedance;
• and producing a visible indication of the testing conditions in response to the second test score.

A method of indicating apical position, comprising the steps of:

• probing a root canal with a probe;
• detecting a complex component of a complex impedance between the probe and a location on a patient's body;
• producing a first test score as a function of the complex component;
• displaying the first test score to a user;
• identifying undesirable measuring conditions in response to a selected component of the complex impedance;
• and
• providing an audible indication of the undesirable measuring conditions.

A method of determining a probe location, comprising the steps of:

• applying the probe to a patient's body;
• applying a multifrequency signal to the probe, the multifrequency signal having spectral components at a plurality of more than two frequencies;
• detecting a response signal produced in response to the applied multifrequency signal;
• extracting more than two selected spectral components of the response signal;
• and
• in response to the extracted spectral components, producing an output indicating the probe location based on a sum of amplitude ratios and of phase angles of the extracted spectral components.