Routine brushing can only clean up to 3 mm. If food remnants(a thin film) remain under the gum line, the space between the gums and the tooth can deteriorate and become even deeper(sometimes reaching 9 to 10 mm). Deep cleanings, one form of periodontal therapy, involves cleaning the root surface of this film.

Topical antibiotics can also be placed in this area to help the gums regain their health.