Dental crowns, once placed, can last for up to 15 years and in many cases much longer as long as they are cared for responsibly. With the additional support provided by the crown, which fits over the tooth, even a severely damaged tooth can survive with its nerve intact.
However, on occasion, even a recently placed crown cannot save the nerve. In fact, the simple act of placing a dental crown may actually lead to the nerve becoming infected.
Your Tooth is Alive
Your teeth are living things, despite their outward appearance. Under the outer surface of enamel lies a softer and more porous material called dentin. This material contains tubules which carry a fluid filled with nutrients from the pulp (nerve) in the centre of the tooth, to the outer tooth, which is also porous, keeping the tooth healthy and vital. Not only does this dentinal fluid keep your teeth healthy, it also helps neutralise the acid produced by bacteria and repels bacteria with its constant outward flow.
However, this flow can reverse, and this is what causes a nerve to become infected.
Decay and Damage Take Their Toll
Crowns are generally fitted over teeth that have experienced extensive damage due to decay, cracks or breakages. Crowns are also placed on teeth that may have had several fillings placed and removed over time. This constant trauma to your tooth, in such close proximity to the nerve, may cause the flow of dentinal fluid to reverse, and this is when the nerve of a tooth becomes inflamed and sensitive to cold or heat. The reversed flow creates a buildup of pressure within the tooth which will eventually kill the nerve, leaving an infection that may spread if not treated.
If this happens, you will need root canal therapy. Bear in mind that for your crown to be placed comfortably, your dentist will need to remove more of the already compromised tooth. Unfortunately, though crowns are designed to save structurally compromised teeth, the placement of the crown may finish off an already traumatised nerve.
The Crown May Save the Tooth but Not the Nerve
If your nerve becomes severely infected, you will likely need a root canal. The timeline for infection to occur varies between individuals. For some people, it might be one week after crown placement, and for others it might be several years. However, the good news is that root canal therapy has a 95 per cent success rate when it comes to saving teeth, and research shows that crowns give teeth a much greater chance of survival post root canal therapy
Even if your tooth does require a root canal after crown placement, it is very likely that your crown; once replaced, will allow you to keep your tooth intact for many years.