A loose crown on a tooth can be a very bad sign. Here are the reasons why this is happening. This article won't be able to help you much if you are the queen and your royal crown is loose. Please contact your blacksmith if that is you.
A crown on a tooth is like a metal hat stuck with cement on your head. If it is stuck on well, the hat will be very hard to take off your head.
Crown has lost adhesion
The cement that is used to secure the crown to the tooth can break down over time, excessive force, poor crown design or poor crown fit.
Some cements will degrade over time, especially older ones. If your crown is 20 years old and the cement has degraded, that is still a pretty good result. In such a case, your dentist will be able to remove the old cement and recement your crown on again. This should last a long time again.
Excessive force on a crown can happen from teeth grinding, biting excessively hard foods like ice or bones, loss of other teeth in your mouth, abnormal bite, a crown that is too high in the bite or even weird habits. This can cause the crown to fracture or crack the cement.
Poor crown design could be a short tooth which will not be able to hold onto the tooth as strongly, which places more stress on the cement. A tooth that has been prepared imprecisely or of an unfavourable shape will not be able to hold onto the crown as strongly. There are different material choices of the crowns to help alleviate such issues but will also have their pros and cons.
A poorly fitting crown will be like a hat that is either too big or too small. There is an optimum thickness of cement for maximum strength. Friction is also a bit factor in how secure a crown is onto a tooth.
Keeping with the hat on your head analogy, the hat will feel loose if your head is loose. A tooth is a rigid structure so if the crown is still strongly cemented but still loose, it could be a tooth fracture. This will more likely happen if there isn't much natural tooth remaining, a root canal has been performed or a post was placed inside the tooth. Of course, excessive forces will also be a high risk factor.
A tooth fracture is likely to cause the tooth to be unsalvagable and need to be extracted.
Tooth loose in the jaw
A crown will feel loose if the entire tooth is loose in the jaw. This could be from periodontal disease or a tooth infection. A clinical examination by your dentist and x-rays will be able to confirm which is the cause.
If you have had gum issues in the past, it is more likely it is a periodontal cause.
The best thing to do is to see your dentist and they will be able to identify what is the cause for your loose crown. There is little that you can do at home to fix these problems by yourself. Every case is unique and your dentist will advise you on the options to solve the problem.