Do lingual braces have any effect on your speech and the appearance of your jaw?

Possible: Lingual braces being places in the back of the teeth can effect speech. Since your tongue places itself in thus region when making certain sounds the braces being there can prevent the tongue from proper placement. The tongue can also become sore. However i haven't heard of this being a major issue for ppl who want these type of braces.

Maybe: It will probably take some time for the tongue to get used to the braces on the back of the teeth so you may talk funny or lisp for a bit. It shouldn't and won't change the appearance of your jaw, however.

Yes: they can impact your speech. There are also about 100 other reasons to choose a different treatment option. I have practiced for over 20 years and this is about the only treatment option I will not do because the pain/discomfort vs aesthetic benefits just don't add up for me. Consider clear brackets or invisalign.