Sonic vs oscillating: which electric toothbrush motion is yours?

Buy oscillating-rotating if you want a round head that cups one tooth. Buy sonic if you want a sweep that feels closer to a manual brush and throws fluid between teeth. Both beat a tired manual brush when you actually brush for two minutes. The motion is a preference with a few clinical leanings, not a religion.

Oral-B's current magnetic line, the iO series, is oscillating-rotating plus micro-vibrations. The older Pro, Smart, and Genius handles are the classic 3D version of that idea, louder, with cheaper heads. Philips Sonicare is sonic: 31,000 strokes a minute on the 4100, up to 62,000 movements a minute on the premium handles. The Dyson CameraJet is also a sonic oscillator, 245 times a second, with a jet added. It is not a third everyday motion so much as a sonic brush that does another job.

Does the round head clean better?

It cleans differently, and some dentist-facing trials give oscillating-rotating a plaque edge. Oral-B funds a lot of those trials. Independent writeups, including the long Wirecutter testing notes, still find both families effective. A round head forces a tooth-by-tooth pace. A sonic head covers a few teeth at once and relies on you not scrubbing. If you rush, the sonic is easier to misuse. If you press, the round head is harsher unless a sensor slows it.

Which is quieter?

Sonicare is quieter. Owners describe Oral-B's older handles as a mechanical buzz and iO as a softer version of that buzz. Sonicare is a hum. The CameraJet adds a pump. If a partner sleeps through a thin wall, this is not a small spec.

What should you buy?

iO Series 3 if you want the round head done properly. Sonicare 4100 if you want the sweep at a sane price. Then open the pair page and read the head math, because that is where the motion decision keeps charging you. iO Series 3 vs Sonicare 4100.