Hi, I'm sorry but I do not speak German.
After two years of fixed braces I have retainers now. I have "invisible retainer" for my upper teeth and "traditional" Hawley retainer for my lower teeth.
With "invisible retainer" is not problem to speak. But when I have my Hawley retainer here is a really big lisp
When I'm going to my dentist for a periodical control, I'm always wearing my retainers. In many cases it is not problem, because when I'm sitting in waiting room I do not talk with other peoples.
One time here was young girl and she was wearing her bionator apliance. When we was waiting for a doctor, her mobile phone began ring and she removed her binator from mouth and after the call she put it back to mouth. During the call she hold her bionator in her hand I had a nice view on her appliance