They are right. Profident a toothpaste brand as Colgate and MClean. "Sonrisa profident" means "Perfect smile". It was a popular expression, slang, because the Profident advert and slogan, was very popular.

Yes, this is from a toothpaste advertisement.It's like saying "a Colgate smile" And as Paco says, the language of well known brands is common currency these days. But I would add it's one thing to repeat a phrase that everybody has heard a million times like "sonrisa Profident" and another to make up a phrase. In the first case you are speaking a common language and in the second you are improvising and being creative.

Hola, Yann. La marca más conocida de dentífrico (casi la única) era, hace muchos años, Profident. Y el anuncio decía eso "Sonrisa profident", por eso se dice cuando alguien tiene una amplia sonrisa. Desde luego que puedes hacer frases de ese tipo utilizando marcas comerciales muy conocidas, te entenderá todo el mundo.