A dental cleaning is a professional cleaning you receive from a dentist or dental hygienist. Most dental cleanings take only between 25 and 30 minutes. According to preventive dentistry standards, cleanings should be performed every six months to prevent excessive plaque buildup. Plaque left untreated can lead to unhealthy gums and tooth decay. A routine dental cleaning should include scaling, root planning and polishing. Practicing preventive dentistry techniques, such as bi-annual dental cleanings, make all the difference in the world in maintain a healthy smile.