Jawline is mostly bone, but there is a muscle there, called the masseter, that is capable of growth.
It is the reason why guys who roid often get that wider jaw, and why guys like pic related have the impression of a jaw that is slightly wider than the skull line.
This muscle is mostly activated by chewing, which is why over-chewing the food you eat is good not only for better absorption and digestion, but also for face gains.
Bruxism is the condition of involuntary teeth grinding, clenching and tapping during sleep. It sucks and it fucks your sleep up, killing test and gains. But this clenching and grinding are activated by the masseter, and as a result, people with bruxism often display ..... you guessed it:
>In addition, bruxers exhibited tooth wear, with orofacial jaw muscle fatigue, tenderness or pain or masseter muscle hypertrophy.
ncbi.nlm.nih.gov
So what if we can do that without the bad part of hurting, fucking your teeth and sleep up?
Well, first, let's see what is leading to those involuntary gains. This study did it for us, this is the measured activation of masseter muscle with different types of bruxism:
ncbi.nlm.nih.gov
Grinding leads to biggest gains. Clenching second. Clenching can be made safe, grinding can't. So we'll clench strongly a few times a day.
So bite on a piece of cloth or something soft when you're alone in your room. I suspect that making your bit a bit wider is the best way, but don't overdo it. Add some chewing for further gains. Don't overtrain, people with Bruxism often have a tired jaw and we know that tiring the muscles is not the best way for gains and it's not healthy.
>are you sure this is safe?
I don't fucking know. Next time you see your dentist talk to them about it, they've heard all sorts of dumb shit already. If they tell you to stop doing it, ask if there's a safe way and share it with us.
See you nerds at the top.