Years ago I used a waterpik. My gums started to have problems. When I visited the dentist, the dentist told me that a waterpik does ok in massaging your gums but didn't do the job between the gums nearly as well as flossing.
Once I gave up the waterpik and just flossed, my gum problems went away.
I would write the problem that I had with my gums but it is the type of thing that my cause a custom title.