Poorly Cemented
Inadequate adherence of the cement to the tooth can be due to moisture contamination. This causes the crown to become loose much quicker and eventually fall out. It can be aggravated with biting and chewing.
Tooth Decay
Keep in mind that there is a natural tooth present beneath the crown; therefore it can still become decayed. It is very important to practice adequate brushing and flossing methods to prevent decay of the tooth.