Bad smell is due to so many factors... Main cause is due to presence of calculus/tartar or food remnants and lastly but very few situations any hyper gastritis. Caps r highly polished and if properly done don't cause any sort of I'll effects. So please meet your dentist for proper diagnosis of your problem and it's treatment.

Other then bad smell is there any pus oozing out or have you felt bad taste around the crown or in mouth lately? Smell can be due to improper cleaning of tooth in case of absence of any other condition. Get yourself checked again by your dentist so that we can rule out other possiblities.

Bad breath could be cos of some food lodgement between the crown margin & gums  & also could be cos of some gum infection. Pl use floss, mouthwash & get a thorough check up done to get to the root cause of the problem.

Hello, Keeping the embrassure areas around the crown clean is very important to avoid food lodgement and gum problems which over a period of time could lead to foul smell in the mouth. You shoukld use a good interproximal brush and a mouth wash to keep the area clean. Regards Dr Suman Makam Dental Arts Bangalore

It is not common to get any smell from crown . Main reason will be gum infection. Please visit your dentist for check up..

Hi is there any gap between the Crown and adjacent tooth?? Bad smell from the Crown occurs if there is food lodgement between crown and gums/adjacent tooth. Try to use floss and remove if any food is getting struck over there