When teeth erupt into the mouth, they have 100% life. They are charged to feel hot and cold. Over time, they degrade, the nerve shrinks and there may be a lot less sensitivity. Do they die sometimes? Yes. Why? Insults and injuries. Who would insult a tooth? Developing cavities and cracks irritate the nerve.
When the tooth is treated for this problem with a filling or crown it has to rebound. When it does, it doesn’t spring back with quite as much life. It may become hypersensitive for a while to chewing and temperatures. It finally settles down with maybe 60-80% of its life.
Treating a tooth over and over again is zapping the life out of it. It springs back a little less each time and eventually may require nerve treatment known as a root canal. Sometimes the tooth dies a slow, painless death and sometimes it goes out kicking and screaming- begging to go. As dentists, we can tell if a tooth is alive or dead by cold and heat tests. We can also test pain while chewing and tapping on the tooth. Teeth that are sensitive to hot usually mean the nerve is dying. We cannot tell how sick a tooth is, only if it is lifeless. X-rays may show a halo around the edge or abscess from a nerve being lifeless for a long time. Many situations, root canal treatment can be performed by removing the lifeless material inside of the tooth and sealing it. This eliminates the infection cyst that is inside of the bone. It will become more brittle so make sure you check with your dentist for the best way to save the tooth in your particular situation. Many times in the back chewing teeth will require a crown to prevent breakage.
If a tooth does need treatment, ask your dentist how best to fix the tooth so it lasts the longest time in your mouth. Conservative patching may work for a period of time but the battery life of the tooth may not be able to withstand how many times the tooth may need to be treated over the course of your life.