Oral health is as important to cats as it is to humans and brushing your cat’s teeth is the safest & cheapest way to make sure their teeth are clean and their gums are healthy. Having your cat’s teeth cleaned by a veterinarian requires anesthetic and is much more expensive.
Even so, I don’t think most people brush their cat’s teeth. We certainly aren’t good about it with our cats. Cornell University College of Veterinary Medicine has an excellent set of instructional videos that could change that. You can watch the complete video. Or watch Part One, Two, Three, and Four.
The videos instruct you on what to use–only use toothpaste especially made for cats, on how to brush, and on how to introduce brushing over four weeks by associating it with a high value reward like baby food, treats, etc.