Rotary (oscillating) electric toothbrushes - Braun Oral-B, Rotat-dent, Interplak.

- Similarities, differences, capabilities, applications.

As a group, sonic toothbrushes represent a very effective and technologically advanced form of powered toothbrush design.

But in addition to them there's another group, the "rotary" brushes (e.g. Braun Oral-B, Interplak, Rotat-dent), that also offer some unique benefits and, in some cases, advanced technology too. In fact, some of these models even have "sonic" capabilities.

What are rotary powered toothbrushes?

Although this category encompasses a wide range of designs, "rotary" electric brushes are all similar in the fact that they have a set of rotating bristles. This can either be:

  • Bristles arranged in a circular pattern on a circular brush head. The entire head then oscillates back and forth. (Braun Oral-B utilizes this design.)
  • A brush head composed of a single tuft of bristles that rotates (as represented by the Rota-dent brand).
  • A "normal" looking brush head whose individual tufts of bristles rotate independently (the Interplak toothbrush).
Animation of a rotary electric toothbrush's motion.

The back-and-forth motion of a rotary brushing action.

Overall, you'll find that rotary brushes make up a large percentage of all powered toothbrushes available, both high and low-end models.

With some rotaries, you'll brush just one tooth at a time.

Rotary toothbrushes often have a comparatively small-sized brush head (when compared to the typical manual or sonic toothbrush), or else a head that is really unlike a normal toothbrush at all (Rota-dent).

Rotary brush heads tend to be smaller than a conventional toothbrush.

Picture showing how rotary brush heads are smaller than conventional toothbrushes.

They tend to lend themselves to cleaning just one tooth at a time.

These smaller heads are generally designed for tooth-by-tooth cleaning, as opposed to brushing two or more teeth together as a group (like you do with larger brushes). Some people may find that this method of brushing does not appeal to them.

How fast do rotary brushes spin?

The units we describe on this page generate brushing actions ranging from just 1,300 up to 8,800 oscillations (or rotations, depending on brush type) per minute.

One manufacturer, Braun Oral-B, has added a high frequency pulsating motion to some of its models to enhance their cleaning action (see below).

How do these brushes remove plaque?

  • Just like with all previous generations of toothbrushes before them, conventional rotary electrics rely on the scrubbing action of their bristles against tooth surfaces to remove dental plaque.
  • As a secondary cleansing action, rotaries that generate a high frequency pulsing motion are able to remove plaque at a distance beyond where their bristles actually touch (see below).

Are they effective?

Modern rotational brushes are frequently shown to have greater effectiveness than earlier models. This is likely due to advancements in both brushing action and brush head design.

There's no shortage of research studies that feel they have shown that using most types of powered rotary brushes is more effective/efficient than using a manual one. But that's not to say you can't do a good job with both (we discuss this topic here).

Generally, if the idea of using a powered rotary brush appeals to you, there's no reason not to buy one. They can be good, effective tools.

Oscillating / pulsating rotary electric toothbrushes.

Advanced Oral-B electrics feature both a pulsating + oscillating-rotating brushing action.

Animation showing the pulsating/oscillating motion of an Oral-B electric toothbrush.

That means they offer both contact and non-contact cleaning.

Braun Oral-B.

Powered toothbrushes that have both an oscillating and pulsing motion, such as most of the higher-end Braun Oral-B models, can be considered to be the pinnacle of rotary toothbrush design.

These brushes have a round brush head that oscillates back and forth at a rate of 8,800 brush strokes per minute. In addition to this action, there's an added pulsating motion that creates movements as high as 40,000 pulses per minute.

Non-contact cleaning.

A brush head vibrating in the area of 40,000 pulses per minute can create a "non-contact" brushing effect, just like regular sonic toothbrushes (e.g. Sonicare) do.

Non-contact brushing is a phenomenon where a powered brush is able to dislodge dental plaque beyond where its bristles actually touch, due to the way it agitates the fluids that surround the teeth. (Use the link above for more information.)

And although this cleaning action is only of secondary importance (as compared to the direct scrubbing action of the brush's bristles directly against teeth), it's reason enough to seriously consider a high-frequency oscillating-pulsating brush, rather than just a conventional rotary one.

Sonic vs. pulsating-rotary brushes.

Since both sonic and high-frequency oscillating-pulsating powered toothbrushes create a non-contact brushing effect, you might wonder which one makes the better choice.

We'd be of the opinion that either can make an excellent selection. But we also think that due to their different designs, most people will gravitate toward one over the other, in the sense that one just looks more like the type of brush they want to use. If that's the case for you, go with your hunch.

What does research say?

We did find two research studies that compared both types of brushes.

  • The first study (Verkaik 2010) evaluated the issue of non-contact brushing effectiveness. It found that "Non-contact removal was slightly more effective for the sonic than for the electric rotating brush."
  • The second study (Veeregowda 2011) evaluated an issue we had never encountered before.

    It studied the effect of both types of brushes on the films that lubricate our mouths (make it easy for us to eat and speak, reduce friction between hard and/or soft tissues). In regard to this factor, they used the term "mouthfeel" (literally how the subject's mouth felt after using their toothbrush).

    The paper stated: "Volunteers reported a slightly preferred mouthfeel after sonic brushing as compared to powered rotating–oscillating brushing."

We think it's important to notice that the statements quoted from both studies each contain the word "slightly."

Additional types of rotary toothbrushes.

Beyond the typical Oral-B design discussed above, there are other types of rotary electric toothbrushes.

Single-tuft toothbrushes.


Rota-dents have a unique design among rotary brushes.

  • Their brush head has just a single tuft of bristles, which rotates at 1,350 revolutions per minute.
  • The bristles themselves are referred to as "microfilaments," implying that they are extremely fine and as a result can clean in nooks and crannies that other brushes can't. (Rota-dent states that they're 1/3 the diameter of conventional brush bristles.)
  • The tuft contains roughly 4,500 individual bristles, making it more akin to a soft, stubby artist paint brush than a standard toothbrush.
How you use the brush.

Brush heads come in either pointed or cup-shaped (hollow) form. The cup-shaped ones splay out over tooth surfaces, while the pointed ones are designed for use in between teeth or along the gum line.

A Rota-dent is generally used on, or around, one tooth at a time, not unlike the way during professional cleanings each tooth is polished individually. (Any single user might or might not find this method of brushing especially appealing.)

Due to the shape of its brush head and the length of its bristles, it's easy to imagine how a Rota-dent could excel in cleaning in between teeth and other difficult to reach areas (such as underneath bridgework). And in this regard, there is no other type of powered brush like it.

Counterrotational toothbrushes.


Interplak electrics fall under the category of "counterrotational" toothbrushes. This is the only brand of brush that we're aware of that uses this design.

  • The brush head generally looks like a normal toothbrush.
  • But each of the 8 (possibly 10) individual tufts of bristles on it rotate back and forth, in an opposite direction as its neighbor (counterrotation).
  • The speed of this action is 4,200 rotations per minute.

This brush is relatively older powered toothbrush technology, whose heyday was in the late 1980's and on into the early 1990's.

During that time frame, this brush was frequently included in research studies and its effectiveness was generally found to be superior to previous generations of electric toothbrushes.

Since then, this brush seems to have been eclipsed by newer (although more expensive) toothbrush designs. The last published research we could find that included it in its study was dated 2001. Purchasing an Interplak isn't necessarily a bad choice, just a dated one.

[Braun Oral-B is a registered trademark of The Gillette Company. | Interplak is a registered trademark of The Conair Corporation. | Rotat-dent is a registered trademark of Professional Dental Technologies, Inc.]


Topic Menu ▶  Powered Toothbrushes

  • Sonicare Toothbrushes Pages -
    • Sonicare models reviewed. - A comprehensive review of the features/prices of all of the current models of the Sonicare lineup. Differences and comparisons between each of the individual product lines are pointed out.
    • The best Sonicare models - A narrative that outlines how to determine which Sonicare model makes the best choice for you. It discusses Sonicare features, which of these features we think are important to have, and which models seem to offer a reasonable manifestation of them.
    • How sonic toothbrushes work. / Effectiveness. - If you're wondering how sonic toothbrushes work and what's special about the brushing action they create, this page explains.
  • Sonicare Features Pages -
    • Brush Heads - Information about Sonicare brush heads, including: What styles of heads are available, in which sizes? Which heads can be used with which models? Comparative cleaning efficiency. How long does a brush head last? Screw-on vs. Click-on design. Standard vs. Compact sizes.
    • Sonicare brushing features - An outline of the various brushing modes different Sonicare models have, and what we think of each of them. It explains the importance of having the 31,000 strokes-per-minute brushing action.
      We also explain details about the Easy-start, Smartimer, KidTimer, QuadPacer, BrushPacer and Smartphone App functions (how they work, what we think of them).
    • Additional Sonicare features - We discuss Sonicare's UV brush head sanitizer in this section. We also explain features and issues associated with Sonicare battery types, charging units, working voltages, battery replacement and travel features.
  • Oral-b Toothbrushes Pages -
    • All Oral-B rechargeable models - A comprehensive review of the features/prices of all of the current Oral-b rechargeable models. Some comparisons between each of the individual toothbrush lines are made.
    • The best Oral-B models - Our narrative outlining how to figure out which model makes the best choice for you. It covers Oral-b features, which of them we think are important to have, and which models seem to offer a reasonable manifestation of them.
  • Oral-b Features Pages -
    • Brush heads - Details about Oral-B replacement brush heads: styles, options, differences. Which are the best ones?
    • Brushing modes - An explanation of the different Oral-B brushing modes found on various models. The importance of 3D vs. 2D brushing action.
    • Additional Oral-b features - Information about the Oral-b Bluetooth/Smartphone app and the wireless Smartguide, as well as what we think of them. Also details about Oral-b brushing timers, quadrant timers and brushing pressure indicators, as well as charging units, operating voltages and battery types.
  • More about electric toothbrushes Pages -
    • Powered vs. Manual toothbrushes - Do you really need an electric toothbrush? This page can help you to decide. Advantages and potential benefits of electrics. What does research say?
    • Rotary electric toothbrushes - Types and brands of rotary-brush head powered toothbrushes (Rota-dent, Interplak, Braun Oral B). Pros and cons of their design differences.
    • The best electric toothbrushes for Senior Citizens. - Elder persons in different age groups, with differing situations, need different features. This page discusses the pros and cons of various models in meeting those needs.