Toothbrush tracking system

1. A method of monitoring tooth brushing comprising:

receiving a position signal from a position sensor disposed on a toothbrush comprising a handle and a head;

receiving a force signal from a force sensor disposed on the toothbrush;

calculating a position of the head of the toothbrush using the position signal in combination with the force signal, wherein the position of the toothbrush head is determined by augmenting a position of the head indicated by the position signal with a calculation of a deflection of the head relative to the handle determined from the force signal.

2. The method of claim 1 , wherein the deflection is determined as a function of the force signal and predetermined mechanical properties of the toothbrush.

3. The method of claim 2 wherein the mechanical properties of the toothbrush comprise a measure of flexural stiffness in one or more directions.

4. The method of claim 3 wherein the mechanical properties of the toothbrush comprise measures of flexural stiffness in two directions orthogonal to a longitudinal axis of the toothbrush.

5. The method of claim 4 wherein force signals from two force sensors in the toothbrush are used to determine the toothbrush head flexure in directions lateral and normal to the teeth of an individual.

6. The method of claim 5 wherein the lateral and normal forces applied to the teeth are measured using a force or pressure sensor attached to the toothbrush.

7. The method of claim 1 wherein the positional and force data are transmitted to a data processing unit, the position of the head of the toothbrush calculated by the data processing unit.

8. The method of claim 7 wherein a computer model of the teeth of the user is combined with the position of the head of the toothbrush to determine an indication of brushing effectiveness.

9. A tooth brushing monitoring system comprising:

a toothbrush comprising a handle and a head, the toothbrush comprising a position sensor and a force sensor; and

a data processing unit configured to receive a force signal from the force sensor and a position signal from the position sensor,

wherein the data processing unit is configured to calculate a position of the head of the toothbrush from a combination of the position signal with the force signal by augmenting a position of the head indicated by the position signal with a calculation of a deflection of the head relative to the handle determined from the force signal.

10. The tooth brushing monitoring system of claim 9 wherein the data processing unit is remote from the toothbrush.

11. The tooth brushing monitoring system of claim 10 wherein the data processing unit is configured to wirelessly receive the position and force signals from the toothbrush.

12. The tooth brushing monitoring system of claim 9 wherein the toothbrush head comprises an optical probe.

13. The tooth brushing monitoring system of claim 9 wherein the toothbrush head comprises a chemical sensor.