Tooth whitening compositions

1. A liquid, substantially anhydrous tooth whitener composition for delivery of a tooth-whitening amount of active whitening ingredient onto teeth, with effective bioadhesion and retention thereof, and, thereupon, sufficient penetration of said ingredient through the tooth enamel, providing efficacious bleaching of stained teeth, comprising, by weight,

(a) 10% to 75% of a complex which is (i) a mixture of 78 to 90% of water soluble polyvinylpyrrolidone (PVP) having K-values of K-12 to K-120 and (ii) 10 to 22% of H 2 O 2 ; releasing 1 to 20% of active H 2 O 2 from said complex onto a tooth surface;

(b) 0 to 20% of PVP K-60 to K-90, said PVP being present in said composition at a K-value of the PVP in said complex of less than 30, and/or the amount of PVP therein is less than 20%, and

(c) 30 to 90% of anhydrous ethanol, said composition having a Brookfield viscosity measured at 25° C. of 50 to 10,000 cps, an in vitro bioadhesion/retention on hydroxyapatite (HAP) of at least 10% after 5 minutes while immersed in water, and a bleaching efficacy defined by ΔE values in the CIE (L*a*b*) color scale of at least 5.

2. A tooth whitener composition according to claim 1 wherein the PVP in (a) is PVP K-30.

3. A tooth whitener composition according to claim 1 wherein the PVP in (b) is PVP K-90.

4. A tooth whitener composition according to claim 1 wherein the PVP in (a) is K-90.

5. A tooth whitener composition according to claim 1 wherein said amount of in (c) is 65 to 80%.

6. A tooth whitener composition according to claim 1 having a viscosity measured at 25° C. of 75-1500 cps.

7. A tooth whitener composition according to claim 6 having a viscosity measured at 25° C. of 100 to 800 cps.

8. A tooth whitener composition according to claim 1 wherein the amount of said complex comprises: (a) 20 to 60%, and (b) 0.1-10%.