Hi dear, nice to know that you are brushing twice daily and using mouthwash too.. those black spots may be something which are not going even though you are following good oral hygiene techniques, that means it needs something more. May be oral prophylaxis if those are just stains or may be you need some tooth colored cosmetic fillings if those are cavities.. just don't worry, consult a dentist. After through examination, he will suggest you the right treatment for the same.. take care

Those black spots can be food stains developed over period of time or it can be a decayed tooth. In both cases brushing and rinsing won't help you have to visit dentist