How does a sonic toothbrush work?

The resonant motor

Inside a sonic handle is an electromagnetic drive. A coil and magnets push a spring-mounted shaft back and forth, and the system is tuned to resonate, so it moves a lot with little energy. The shaft passes the motion to the head, which sweeps side to side through a small arc many times a second.

Because the frequency is in the range people can hear, the brush is called sonic. It is the vibration of the bristles that does the work, not the sound.

Movements per minute

Philips quotes up to 62,000 movements per minute on many Sonicare handles, including the DiamondClean 9000 and 7900 in our sonic toothbrush guide. That figure counts each sweep in either direction, so it is roughly double the number of full back-and-forth cycles.

Comparing movements per minute between sonic and oscillating brushes is not like for like. An oscillating head turns through a larger arc at a lower rate, while a sonic head makes small, very fast sweeps. Neither number alone tells you how well a brush cleans.

Why sonic brushes feel and sound different

The high-frequency vibration passes into your teeth and lips, which gives the tingling feeling many people notice at first. Philips has offered an easy-start feature on many handles that gradually increases power over the first sessions to help you get used to it. Check your manual to see if your model has it.

The sound is a high buzz rather than a whirr. Sonic handles are often described as quieter than older oscillating brushes, though the iO's magnetic drive has narrowed that gap.

How to brush with a sonic toothbrush

Sonic brushes are used more like a manual brush than an oscillating one, but without scrubbing.

1. 1

   Put a pea-sized amount of fluoride toothpaste on the head.

2. 2

   Place the bristles against the teeth before switching on, to avoid splashing.

3. 3

   Angle the bristles slightly towards the gumline.

4. 4

   Glide the head slowly across the teeth with light pressure, letting the vibration do the work.

5. 5

   Follow the Quadpacer prompts, which signal you to move to the next quarter of your mouth.

6. 6

   Brush for the full two minutes, then spit out rather than rinse, as the NHS advises.

Note:Pressing hard does not help and can be uncomfortable. If you have gum problems, sensitivity or dental work, ask your dentist how to brush.

Modes, intensity and SenseIQ

Modes on a sonic brush change the pattern and amplitude of the vibration. Many Sonicare handles have three intensity levels. Premium models such as the 9900 Prestige add SenseIQ, which Philips says adjusts intensity if you press too hard. Our brushing modes explainer covers the common modes, and the Sonicare models compared guide lists which models have which features.

Compare sonic toothbrushes →

Sonic or oscillating?

Both types are widely used, and the NHS does not single out one technology. The choice is often about feel, head shape and the features of a particular handle. Our sonic vs oscillating comparison goes through the practical differences.

Frequently asked questions

Does a sonic toothbrush use sound to clean? No. Sonic refers to the vibration frequency, which is in the audible range. The bristles do the cleaning.

What does 62,000 movements per minute mean? It is Philips' figure for the number of sweeps the head makes each minute, counting each direction.

Why does my sonic toothbrush tickle? The fast vibration passes through the teeth and lips. Many people get used to it within a few sessions.

Do I need special heads for a sonic brush? Yes. Sonicare handles take Sonicare heads. See our Sonicare brush heads explainer.