Most whitening treats every tooth equally, but stains rarely work that way — canines and lower incisors usually yellow first. The Gel Pen Pro exists for exactly that: twist the base, paint the gel onto the teeth that need it, keep your lips clear for a few minutes, done.
In testing it earned its place as the maintenance tool after a strip course: a weekly touch-up on the fast-staining teeth kept results even. It is also the only product in the range you can realistically use in an office bathroom before a meeting.
Transparency note: ONOSONIC WHITE TEETH Expert® is our sister brand — Oral Care Guide UAE and ONOSONIC share the same publisher. We apply the same testing criteria to our own products as to every other brand, and we flag this relationship on every ONOSONIC review so you can weigh it for yourself.