does this make a sense?

la mamma si lava i denti.

See a translation

私は毎食後歯をきれいに磨く。
(io) mi lavo i denti dopo ogni pasto.
Io lavo i denti dopo ogni pasto.

お母は毎食後歯をきれいに磨く。
La mamma si lava i denti dopo ogni pasto.
La mamma lava i denti dopo ogni pasto.

"mi/si" Reinforce the action of the verb on the subject (as myself/herself). It is not mandatory, because it is obvious that a person brushes their teeth but it is often used, anyway is very common use "mi/si". So, in italian "I brush" and "I brush myself" has the same meaning.

もちろん Of course you don't need "mi/si" when a person brush the teeth of someone else but you will specify the owner of the teeth :)

お母は息子の歯を磨く
La mamma lava i denti del bambino.