The type of cleaning you get depends on your dentist’s clinical findings after a full exam is conducted. Most insurance plans provide for a healthy mouth or preventive cleaning every 6 months, which removes plaque and calculus above the gum line. When gums aren’t healthy or an active infection is present, periodontal therapy is needed to treat the areas below the gum line. Treating infected and unhealthy gums with a healthy mouth or preventive cleaning would be ineffective, unethical and unwise. It would be like waxing a dirty car, but much more dangerous.