US 4,308,012 A · Dental pulp vitality tester

Abstract

A dental pulp vitality tester for selectively applying heat, cold, or electrical stimulation to a patient's tooth in a controlled reproducible manner. Broadly, the device includes a handle having a thermally and electrically conductive probe tip, a heat sink within the handle, and a thermoelectric element having a first junction thermally coupled to the probe tip and a second junction thermally coupled to the heat sink. Heating or cooling of the probe tip is accomplished by passage of electric current through the thermoelectric element. A temperature sensing device such as a thermistor is thermally coupled to the probe tip, and temperature regulation circuitry responsive to the state of the temperature sensing element regulates the current to the thermoelectric element to maintain the temperature of the probe tip constant at a predetermined desired value. The present invention includes circuitry for quantifying the stimulus applied. In particular, circuitry is provided for sensing electrical contact with the tooth, which electrical contact is strongly correlated with thermal contact. Additionally, timing circuitry measures and displays the length of time that the probe tip has been in contact with the tooth so that the precise time at which a patient response occurs may be used to render the diagnosis quantitative. Electrical stimulation is provided by regulating the current that is passed through the probe tip into the tooth rather than the voltage that is applied to the probe tip. This current is applied in pulses, and the amplitude of the current pulses is gradually increased from a minimum value in an automatic fashion so that the patient's sensitivity may be determined. Electrical contact with the tooth is monitored as with the thermal testing.

Claims19

Dependent claims

A device for providing local stimulation of a selected portion of a subject's body by subjecting said body portion to heat transfer, comprising:

a heat conductive probe tip;
a heat sink;
a thermoelectric element having a first junction thermally coupled to said tip, a second junction thermally coupled to said heat sink, and electric current path means, said thermoelectric element having the property that the passage of electric current through said electric current path means causes heat transfer between said first and second junctions to occur, the direction of said heat transfer depending on the direction of said electric current;
current providing means for making available an electric current to said thermoelectric element, said current providing means being operatively coupled to said electric current path means;
temperature selection means defining a desired one of at least two predetermined temperatures;
temperature sensing means thermally coupled to said probe tip;
and
current regulation means operatively coupled to said current providing means and responsive to said temperature sensing means and to said temperature selection means for automatically varying the electric current provided by said current providing means to maintain said probe tip at said desired temperature.

5 more elements

A device for providing localized electrical stimulation of a selected portion of a subject's body comprising:

an electrically conductive probe tip;
means for supplying a driving voltage at periodic intervals for driving a current pulse of predetermined amplitude through said probe tip and body portion;
current regulation means for gradually increasing the predetermined current amplitude on successive pulses;
means responsive to the electrical resistance between said probe tip and said body portion;
means for suspending said gradual increase in predetermined amplitude under a condition wherein the electrical resistance between said probe tip and said body portion is too high to allow said driving voltage to drive a current pulse of said predetermined amplitude;
and
means for withholding said driving voltage under said condition of high resistance.

4 more elements

A device for testing physiological response of a selected portion of a subject's body by providing local electrical or thermal stimulation, comprising:

a thermally and electrically conductive probe tip;
a heat sink;
a thermoelectric unit having a first junction in thermal contact with said probe tip, a second junction in thermal contact with said heat sink, and current path means, the passage of current through which causes heat transfer between said first and second junctions, the direction and magnitude of said heat transfer being correlated with the direction and magnitude of said current through said current path means;
current supply means for passing current through said current path means;
current regulation means for maintaining said probe tip at a predetermined desired temperature;
current pulse supply means for supplying repeated electric current pulses to said probe tip by making available a driving voltage sufficiently high to cause current pulses of a predetermined desired amplitude to flow;
means for varying said predetermined desired current over a range;
and
selection means for selectively enabling either of said current supply means and said current pulse supply means.

6 more elements

Dependencies are inferred from the claim text.

Dental pulp vitality tester

Life of this patent

Dental pulp vitality tester

Life of this patent

Abstract

Claims19