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

- Similarities, differences, capabilities, applications.

Animation of a rotary electric toothbrush's motion.

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

While as a group sonic toothbrushes represent a very effective and technologically advanced form of powered toothbrush design, 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 now even feature "sonic" capabilities.

What are "rotary" toothbrushes?

Although this category encompasses a wide range of individual designs, "rotary" electric toothbrushes are all similar in the fact that they have a set of rotating bristles.

Their configuration 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 continuously in a single direction (as represented by the Rota-dent brand).
  • A brush head that looks like a normal manual toothbrush. But featuring individual tufts of bristles that rotate back-and-forth independently (the Interplak toothbrush).

 

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, as compared to the usual manual or typical sonic toothbrush.

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 usually intended to be used to clean one tooth at a time, as opposed to brushing multiple teeth simultaneously (like you do with a regular toothbrush).
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 seem to claim that they've documented that using (most all 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 either. (We discuss the topic "Why choose an electric toothbrush?" here.) But 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.

Rotary electrics that create both an "oscillating and pulsing" brush head motion, like the Oral-b models that feature their "3D" brushing action, 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 range of 40,000 pulses per minute can generate a "non-contact" brushing effect, just like sonic toothbrushes do (e.g. Sonicare).

(As a comparison of similarity: Sonicare toothbrushes oscillate at a frequency of 260hz. Oral-b 3D brushes oscillate at a frequency of 340hz.)

Section references - Busscher

What is non-contact brushing?

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), having it is considered a plus. And thus makes a reason to seriously consider getting a high-frequency oscillating-pulsating model, rather than just a conventional one.

Pictures of Oral b rechargeable toothbrushes.

Our affiliate links can be used to shop for  rotary-style toothbrushes,  like Oral-b on  Amazon.com  or  Walmart.com

Tip:  In terms of brushing effectiveness, it's Oral-b's non-contact brushing capabilities (3D motion/40,000 pulses-per-minute brushing action) that sets them apart from other rotary-movement brushes.


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 tend to gravitate toward one more so 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. That will be the brush you'll be more likely to continue to use over the long-term.)

 

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."

Section references - Veeregowda, Verkaik

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-dent.

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 paintbrush 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.

Counter-rotational toothbrushes.

Interplak.

Interplak electrics fall under the category of "counter-rotational" 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 (counter-rotation).
  • 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 1980s and on into the early 1990s.

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.]

Pictures of Oral b rechargeable toothbrushes.

Our affiliate links can be used to shop for  rotary-style toothbrushes,  like Oral-b on  Amazon.com  or  Walmart.com

Tip:  Oral-b is unquestionably the dominant player in the field of rotary brushes. And for most people's application, probably the best choice (due to their 3D motion/40,000 pulses-per-minute brushing action).


 
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 Page references sources: 

Busscher HJ, et al. Energy transfer, volumetric expansion, and removal of oral biofilms by non-contact brushing.

Veeregowda DH, et al. Boundary lubrication by brushed salivary conditioning films and their degree of glycosylation.

Verkaik MJ, et al. Oral biofilm models for mechanical plaque removal.

All reference sources for topic Electric Toothbrushes.

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