Traditionally the primary emphasis of preventive periodontics was daily patient performed plaque control. Recent studies indicate that frequent professional subgingival toothcleaning is a mandatory treatment for prevention of recurrent periodontitis. Pathogenic subgingival bacterial complexes are disrupted by frequent cleaning and require time to reestablish. Disease progression is prevented if the recall interval does not exceed the time required for reestablishment of a pathogenic plaque. Legally, patients have acquired the duty to comply with the prescribed recall interval. Both the patient and the practitioner will benefit from a preventive program that includes frequent professional subgingival toothcleaning.