Great-tasting multi-grain biscuits help clean teeth and freshen breath. Crunchy texture helps promote clean teeth and healthy gums. The most common cause of bad breath in dogs is plaque buildup on teeth. Plaque is a combination of bacteria, minerals and decomposed food that can cause irritation of sensitive gums and loosening or loss of teeth. Veterinarians agree that proper dental health hygiene is very important for maintaining your dog's good health.