Hill's Prescription Diet t/d Dry Dog Food is clinically proven nutrition to reduce plaque, stain and tartar buildup. The kibble contains a special matrix of fibers which act like a toothbrush to scrub the tooth to remove bacteria. Prescription Diet t/d is the only therapeutic dry dog food that is accepted nutrition for the reduction in buildup of plaque & tartar by Veterinary Oral Health Council (VOHC).