One word
"Toothbrush" is countable because you can refer to one toothbrush or multiple toothbrushes.
Cobra
Yes, that is the correct possessive form of the singular noun toothbrush. example: Don't buy that one, the toothbrush's cover is cracked.
2
Some benefits of an ultrasonic toothbrush over a regular toothbrush include that you get a better clean because an automatic toothbrush such as the ultrasonic can average thousands of strokes per minute more than a regular toothbrush. Another advantage is that it is easier for people with arthritis to use an electric toothbrush over a regular one.
An electric toothbrush typically uses around 1-2 watts of power while in use. This is a low power consumption compared to other household devices.
No in nam
throw it out or get a new one.
buy a new one
Compound words whose elements have not been combined, like toothbrush, into one word are generally hyphenated.
An Interplak toothbrush is an electric powered toothbrush. The head rotates so that one can brush their teeth the same as they do when using a standard toothbrush. The head will polish the teeth and get in those hard to brush places.
Its easy. As many words there are in the universe. Just like toothbrush, rocket ship and account!