After i took root canal on my amalgam dental filled teeth,i changed the rest to composite & most of them are in molars.how long i need to replace it?

Composite fillings: How long fillings last is different for each person. Just make sure you see your dentist regularly so he can monitor your fillings and your oral health.

Varies: 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...

Replace w/crowns: Teeth that have had root canal therapy are best restored with a crown. Composite fillings will allow for replacement of the old filling material and decayed tooth structure, but a crown really provides the strength needed to maintain that tooth's ability to function!