It's common knowledge that hear loss causes tinnitus yet I've had my hearing tested by an otologist with no signs of hearing loss with the only thing out of the ordinary being slightly more sensitive to loud sounds. The only logical conclusion that I have for the cause of my tinnitus if my orthodontic treatment and/or cranialfacial dystrophy.
My tinnitus started occurring after my TMJ and my TMJ started happening during my HERBST appliance treatment. I can't really say if the metal spring things in the appliance that were supposed to fix my bite caused TMJ; maybe I would have gotten TMJ without them, but I did start getting jaw crackling and popping about 6-12 months into the treatment. The other thing I noticed was my jaw/chin getting more lopsided and asymmetrical; I'm not sure if this is because I was more aware of my flaws going through puberty in all, or if these asymmetries were to be blamed on my orthodontic treatment.
Another interesting thing is that my left eyebrow arches higher than the other and the left side of my face is lower. I know that ptosis can cause arching eyebrows from the fact that the muscles around the eyelid are pulling the eyelid up to compensate for its droopiness, which makes me wonder if it's really just a lack of support from the maxilla.
Soon as my braces came off I got tinnitus. Fast forward to palate expansion and modest forward growth and it is all but gone. It may linger like every 2 months or so for 1 episode.
There's a guy called Gray who often comments on the orthotropics youtube videos. He suffers from tinnitus and has made some videos on his own channel discussing the link with CFD like this one:
https://www.youtube.com/watch?v=KoMaNI-d0dU