nope but it dont sound nice

its the body attacking itself and those type conditions never seem to be that easy - from quick google, it can be managed but expect more slobber and mushed up food plus vet bills and possibly anaesthetic if the jaw needs manually opening. it seems it can clear up but can also re-occur.
GSD / large breeds seem to be the affected ones
also - if it reaches end stage you can lose the dog to it "In more advanced cases of Masticatory myositis the patient’s jaws will not open even under general anesthesia." (and IMO its probably kinder to leave them under than a life from a feeding tube)
Claire x