Toothbrush including a device for indicating brushing force

1. A toothbrush comprising:

a handle;

a head;

bristles positioned on the head;

a neck joining the handle to the head; and

a piezochromic polymer effective to emit an optical signal indicative of brushing force, wherein the piezochromic polymer comprises an electrocyclic ring-opening mechanophore; and

wherein at least a bristle-contacting surface of the head comprises the piezochromic polymer, and the bristles are sufficiently transparent or translucent such that a color of the bristle-contacting surface of the head is visible.

2. The toothbrush of claim 1 , wherein the piezochromic polymer is contained in a cavity within the toothbrush, and at least a portion of the toothbrush overlying the cavity is transparent or translucent such that the piezochromic polymer is visible.

3. The toothbrush of claim 2 , wherein the portion of the toothbrush overlying the cavity is a window located on a back side of the toothbrush, such that the piezochromic polymer is visible when teeth of a user are being brushed in front of a mirror.

4. The toothbrush of claim 1 , wherein the piezochromic polymer comprises spiropyran.

5. The toothbrush of claim 4 , wherein the piezochromic polymer comprises poly(methyl acrylate) or poly(methyl methacrylate).

6. The toothbrush of claim 1 , wherein the optical signal is at least one color change indicative of at least one of excessive brushing force, acceptable brushing force and inadequate brushing force.

7. The toothbrush of claim 1 , wherein the toothbrush is free of a power supply and electrical circuitry.

8. The toothbrush of claim 1 , further comprising a lever inside the head and neck, wherein the lever is adapted to transmit force from the head to the piezochromic polymer, wherein the piezochromic polymer is located in or on the neck.

9. The toothbrush of claim 1 , wherein at least some of the bristles comprise the piezochromic polymer.

10. A toothbrush comprising:

a handle;

a head;

bristles positioned on the head;

a neck joining the handle to the head; and

a proximity dye based polymer effective to emit an optical signal indicative of brushing force; and

wherein at least a bristle-contacting surface of the head comprises the proximity dye based polymer, and the bristles are sufficiently transparent or translucent such that a color of the bristle-contacting surface of the head is visible.

11. The toothbrush of claim 10 , wherein at least some of the bristles comprise the proximity dye based polymer.

12. The toothbrush of claim 10 , wherein the proximity dye based polymer is contained in a cavity within the toothbrush, and at least a portion of the toothbrush overlying the cavity is transparent or translucent such that the proximity dye based polymer is visible.

13. The toothbrush of claim 12 , wherein the portion of the toothbrush overlying the cavity is a window located on a back side of the toothbrush, such that the proximity dye based polymer is visible when teeth of a user are being brushed in front of a mirror.

14. The toothbrush of claim 10 , wherein the optical signal is at least one color change indicative of at least one of excessive brushing force, acceptable brushing force and inadequate brushing force.

15. The toothbrush of claim 10 , wherein the toothbrush is free of a power supply and electrical circuitry.