After i took a root canal procedures on some of my dental filled teeth, i changed all my other teeth dental fillings. how long a dental fillings last?

Varies: Amalgam or composite? In addition, longevity depends on your diet, how well you brush and floss your teeth, and the size of the restorations. Don't look for a guarantee... they don't last forever. But if you need a number, use 10 years as average. Some last 5 years, others 15 years and longer. All the best...

Dental fillings: Dental filling have no specific shelf time . It depends on the material were used and also on the way the dentist placed the fillings . I have seen silver or amalgam fillings done 40 years ago believe it or not ..

Depends on material: Not all fillings materials are created equal and the lifespan of a restoration also depends in a patient's oral hygiene, where in the mouth the restored tooth is located and professional care. So not a straight forward answer! That being said, on average, I'd expect a filling to last 10 to 25 years. The more specific details you can provide, the more precise an answer I can provide!