Tempero-Mandibular Joint syndrome based on the formal name of the jaw hinge on either side of the face, about an inch or two lower than and to the front of your ears. You might refer to that condition as "arthritis of the jawbone" - though in my case it might have been induced by accident rather than age. I can't know the cause with any certainty.
More than 35 years ago I was a passenger in a car-pool accident on our Interstate system (which I believe is equivalent to what you call "Queen's Highways", or at least that is what they called it when we were in Canada.) A piece of broken leaf spring from a big truck, steel about the size of an axe head but not sharpened, flipped up into the air after it was rolled over by another truck. It came through the windshield, bounced around in the car, and hit me three times - but tried to hit me FOUR times. It hit my metal-framed briefcase and left a dent in it, then ricocheted around to hit my hand, chest, and jaw. Since the briefcase was in my lap at the time, I'm glad it was steel-framed. That would have hurt a LOT, I'm sure.
My jaw wasn't broken from the impact but I had a concussion, a nasty bruise for a few days, and one side of my face was swollen. After the fact, I remembered that the other members of the car pool were telling me to stay with them, but things were a bit hazy. They went to an emergency room because the car was still drivable, and the driver's insurance covered it all. I had X-rays and other tests, but they found nothing that required further treatment. I went to my dentist later and he confirmed no broken teeth.
It is possible that the impact to the side of my jaw damaged that joint by misaligning it, which would lead to that condition. The effect is that sometimes my teeth don't align properly, leading to soreness and the inability to chew well. The treatment is called a night-guard or jaw splint, worn at night to help keep the jaw in proper alignment. It mostly works though there are a few moments when I wish it worked better.
