Hi dear , As per your query you are on regular tobacco chewing and smoking habit , you also have black spots on your cheeks . Well the spots or lines you mention in query are pointing towards a condition known as leukoplakia . Mild leukoplakia is usually harmless and generally goes away on its own. Usually the spots or lines are white to grey in color, but sometimes they turned into red which also appear black sometimes . When this reddening occur means they need proper medical attention . Because these are not good signs , this could also point towards oral cancer . So i would suggest you to consult oral pathologist for proper evaluation of the condition and rule out cause like cancer . For now quite smoking also , maintain proper oral hygiene and do warm saline rinses regularly . Hope your concern has been resolved. Best Wishes, Dr. Harry Maheshwari