Bacterial plaque at the dento-gingival margin is always associated with gingivitis. Measures which keep the area free from plaque will maintain health or encourage healing of existing gingivitis. Scaling and polishing at 6-month intervals may be sufficient for those patients who practice near-perfect oral hygiene but it is not an effective way of promoting the resolution of established gingivitis. A change to effective oral hygiene measures by the patient is the major factor in resolving gingivitis, but the association with scaling and polishing provides the ideal combination. Toothbrushing may only clean the oral and facial aspects of the teeth so interdental cleaning is necessary where gingivitis is established. There is no clear evidence that any particular oral hygiene routine is better than any other for all patients. It is generally agreed that thoroughness is extremely important. There is a variety of ways of motivating patients to practice effective oral hygiene but all reports indicate that it is most likely to be effective on a person-to-person basis. Motivation itself is not enough and must be associated with education and instruction. Long-term failure is likely unless the message is reinforced at regular intervals.