What are the pros and cons of waterpik or ultrasonic teeth cleaning?

It's all good: There really is no con to either of those. Regular waterpik use will help keep you teeth and gums clean and healthy; however, it's not a substitute for flossing. Dental floss is the only way to clean the point at which the teeth physically touch each other.

Benefit of waterpik : It’s an easier, more effective alternative to string floss; a study at the university of nebraska found that patients who added a water flosser to either manual or power toothbrushing reduced bleeding, gingivitis and plaque as well as manual brushing and string flossing. The water flosser was up to 93% more effective at reducing bleeding and up to 52% more effective at reducing gingivitis.

Use as directed: The only con to the waterpik is it needs to be used as directed. You don't want to point it straight down into a periodontal pocket.