There are cheap brands of toothbrush. Your standards or label preference could be why they are so expensive.
Sonicare toothbrushes are rather expensive. They can be over a $100. Sometime though, they will have coupons in the Sunday Newspaper for them though?
Radius makes great toothbrushes that last a good while.
Many, many countries make toothbrushes.
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toothbrushes weren't invented then!
Yes, peanut butter people can eat toothbrushes.
Toothbrushes for dogs come in a variety of colors. My dog's toothbrush is blue.
Any toothbrush is only as effective as the person using it. If used properly, most manual toothbrushes can adequately clean your mouth. I typically recommend electric toothbrushes to people who have some kind of physical limitation, such as arthritis.
Dog toothbrushes are angled so you can get to the back teeth of the dog's mouth. Dog's teeth are pointed, not flat like human teeth. The angle helps you reach all surfaces of each tooth.
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It's not common but probably somewhere in the world it is possible, especially in countries where toothbrushes are in short supply.