IANAD, but if you're good at brushing, it probably won't cause you to have fewer cavities. But speaking from personal experience, it's better at actually cleaning your teeth surfaces (you can see this yourself when you visit the dentist: notice how much smoother they feel after polishing), and it's just plain easier to use since you don't have to move your arm/wrist around and don't have to worry about making sure you're using circular motions like your dentist recommends. The brush head on an electric brush moves much faster than you possibly could, so all you have to do is put it on your teeth and apply proper pressure. No, it's not as cheap as a $2 toothbrush, but for some at least, the convenience is worth the extra cost. Plus, most dentists I've had in the last decade have recommended using one.

Just be aware electric toothbrushes can cause more abrasion, damaging the dentin. This leads to tooth sensitivity and increased risk of cavities!

https://journals.plos.org/plosone/article?id=10.1371/journal... Conclusion

Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5—year simulation.

This seems to be obvious, since you're specifying the same toothpaste and the same brushing force (and I assume the same amount of time brushing). Electric toothbrushes move much, much faster than your arm possibly could, so of course it's going to abrade more. It's like comparing hand-sanding with a piece of sandpaper and a wooden block, to sanding with a powered orbital sander (or any power sander). Of course the power tool is going to wear away a lot more wood (given the same sandpaper grit) than you can with your arm.

So when you're using an electric toothbrush, you don't need to brush as long, or as firmly. It doesn't help that many people tend to brush with way too much force anyway.

I would agree it's marginally better, particularly around the back teeth where it's hard to move a regular brush back and forth very much.

But in general if you spend 2-3 minutes brushing with a conventional toothbrush, that's going to be good enough if you're also seeing a dentist regularly to remove tartar and check for cavities.

The problem most people have with a regular toothbrush is they brush like a madman for 20-30 seconds and that's just not enough. That's another advantage of the electric brushes, they run on a timed cycle which is a lot longer than most people would brush on their own.

>that's going to be good enough

It's like many tools we use: sure, doing it the old-fashioned way will work well enough if you do it properly, but the new tool makes it easier and more foolproof (and maybe faster), in exchange for higher cost. This doesn't make the new tool bad.