Write the symptoms and causes of submucus fibrosis disease.

It is a chronic debilitating disease of oral cavity characterized by inflammation and progressive fibrosis of submucosal tissues. Its symptoms are the inability to open mouth, scarring, pain and burning sensation of consuming spicy foods, increased salivation, change in gustatory sensation etc. Jaw lock problems occur due to hardening of muscles of jaws. It is caused due to consumption of gutkha, tobacco, and other intoxicant substances.