A composition, comprising: (a) a hydrogel comprised of: (i) a water-swellable, water-insoluble polymer; (ii) a blend of a hydrophilic polymer with a complementary oligomer capable of hydrogen or electrostatic bonding to the hydrophilic polymer; and (iii) an active agent which is selected from the group consisting of a whitening agent, a non-steroidal anti-inflammatory or analgesic agent, a steroidal anti-inflammatory agent, a local anesthetic, a bactericide or disinfectant, an antibiotic, an antifungal, a tooth desensitizing agent, a fluoride anticavity or antidecay agent, an anti-tartar or anti-calculus agent, an enzyme which inhibits the formation of plaque, a calculus or dental caries agent, an abrasive agent, a metal chelator, an anti-oxidant, a nutritional supplement for local delivery to the teeth and surrounding tissue and a cosmetically active agent which is breath freshener or an agent which effects whitening or bleaching of the teeth; and (b) a backing member, where the backing member is comprised of a polymer composition that erodes in a moist environment at a slower rate than the hydrogel; wherein the hydrogel erodes in 1 second to 24 hours after placement in a moist environment; and wherein the water-swellable, water-insoluble polymer and the backing member are comprised of acrylate polymers, and the backing member acrylate polymer has a lower solubility than the water-swellable, water-insoluble acrylate polymer. (a) a hydrogel comprised of: (i) a water-swellable, water-insoluble polymer; (ii) a blend of a hydrophilic polymer with a complementary oligomer capable of hydrogen or electrostatic bonding to the hydrophilic polymer; and (iii) an active agent which is selected from the group consisting of a whitening agent, a non-steroidal anti-inflammatory or analgesic agent, a steroidal anti-inflammatory agent, a local anesthetic, a bactericide or disinfectant, an antibiotic, an antifungal, a tooth desensitizing agent, a fluoride anticavity or antidecay agent, an anti-tartar or anti-calculus agent, an enzyme which inhibits the formation of plaque, a calculus or dental caries agent, an abrasive agent, a metal chelator, an anti-oxidant, a nutritional supplement for local delivery to the teeth and surrounding tissue and a cosmetically active agent which is breath freshener or an agent which effects whitening or bleaching of the teeth; and (i) a water-swellable, water-insoluble polymer; (ii) a blend of a hydrophilic polymer with a complementary oligomer capable of hydrogen or electrostatic bonding to the hydrophilic polymer; and (iii) an active agent which is selected from the group consisting of a whitening agent, a non-steroidal anti-inflammatory or analgesic agent, a steroidal anti-inflammatory agent, a local anesthetic, a bactericide or disinfectant, an antibiotic, an antifungal, a tooth desensitizing agent, a fluoride anticavity or antidecay agent, an anti-tartar or anti-calculus agent, an enzyme which inhibits the formation of plaque, a calculus or dental caries agent, an abrasive agent, a metal chelator, an anti-oxidant, a nutritional supplement for local delivery to the teeth and surrounding tissue and a cosmetically active agent which is breath freshener or an agent which effects whitening or bleaching of the teeth; and (b) a backing member, where the backing member is comprised of a polymer composition that erodes in a moist environment at a slower rate than the hydrogel;