During a dental cleaning, your hygienist will likely do a few things. They may use scraping tools to remove tartar and plaque that is almost impossible to remove with toothbrushes, mouthwash, or flossing. When plaque first forms it can usually be cleaned off with a toothbrush, but over time it hardens and bonds to the tooth. Without a scraper tool it can be almost impossible to clean.
Additionally, a dentist can provide special treatments like fluoride treatment or dental sealants to help protect your teeth. Fluoride strengthens teeth and sealants provide a synthetic barrier that protects our most vulnerable teeth (molars) from cavities.