Note the use of different prepositions in these sentences:
Tomorrow I’m going to the dentist = Domani vado dal dentista and Tomorrow I’m going to the dental surgery = Domani vado allo studio dentistico.
Ero dal parrucchiere quando mi hai chiamata = I was at the hairdresser’s when you called me and Ero nel salone del parrucchiere quando mi hai chiamata = I was in the hairdressing salon when you called me.
So, when you’re talking about a person do not say ‘domani vado al dentista, al parrucchiere, but dal/dalla’.
On a totally different topic, Italian has a handy little word – ne. One of its meanings is of something/someone that you have talked about. Check out these examples:
Sai qualcosa di Carlo? No, non ne so più niente = Do you know anything about Carlo? No, I no longer know anything about him [note the double negatives that are allowed in Italian].
La tua torta? Non ce n’è rimasta nemmeno una fetta = Your cake? There isn’t even a slice left.
Ne vuoi ancora? No, non ne voglio più; ne ho già mangiata abbastanza [per es., pizza] = Do you want some more? No, I don’t want any more [of it]; I’ve had enough [for instance, pizza].