Yes, it is still possible to get a cavity after having a crown placed. The most common area to get a cavity after getting a crown is at the interface where the crown meets the tooth. The crown is made of a material (metal, porcelain, zirconia, etc.) which does not get decay. However, the area of the tooth right next to the crown is still susceptible to decay and cavities. This is usually where a cavity starts. Hope this helps.
My best to you!
William F. Scott IV, DMD
Every day! This will keep your mouth and body healthy.