Every patient matters
All it takes is one canceled appointment and a good patient can become "lost" to the practice for months or longer. Most practices are carrying a high percentage of inactive patients who could and should be brought back onto the schedule.
Contact inactive patients. Call every patient who hasn't been seen in at least nine months. Most patients will gladly schedule, once they have talked with someone at the practice. A full hygiene schedule keeps the practice growing and leads to other productive treatment.
Don't wait for patients to call you. Everyone is extremely busy. If the practice makes the effort to contact inactive patients, most will schedule and show up for their next appointment.