A molar or premolar that has had a root canal usually needs a crown. A front tooth often does not, provided most of it is still intact. The root canal treats the infection inside the tooth, but it does nothing to make the tooth stronger, and the crown is what protects it from splitting under the force of chewing.
The root canal fixes the inside, not the shell
By the time a tooth needs a root canal, it has usually already lost a fair amount of structure to decay, an old large filling or a crack. To reach the canals, the dentist then has to make an opening through the biting surface. What is left can be a hollowed tooth with thin walls, which is why root-treated back teeth are prone to fracture.
It was once commonly said that these teeth crack because they "dry out" once the nerve is removed. The more widely accepted explanation now is the loss of tooth structure itself, particularly the ridges of enamel and dentine that brace the tooth from side to side. The fewer of those walls that remain, the stronger the case for covering the tooth with a crown. If you are still weighing up whether to keep the tooth at all, our article on root canal treatment versus extraction looks at that choice.
Crowned back teeth tend to last longer
The link between crowns and tooth survival comes from long-term clinical data rather than theory. A University of Iowa study (Aquilino and Caplan, Journal of Prosthetic Dentistry, 2002) followed root-treated teeth for around a decade and found that teeth left without a crown were lost at about six times the rate of crowned teeth, after allowing for tooth type and decay. A systematic review (Stavropoulou and Koidis, Journal of Dentistry, 2007) pooled ten studies and reported 10-year survival of about 81% for crowned root-treated teeth, against about 63% for those restored with fillings.
These are older studies, and filling materials have improved since, so the gap may not be as wide today. They still support the usual advice for molars and premolars.
Which teeth can manage with a filling
Front teeth take much lighter forces than molars, and the access hole is often small. Where a front tooth has lost little structure, a bonded tooth-coloured filling may protect it well, and avoids removing more tooth to make room for a crown. A front tooth that is badly broken down or heavily filled is a different matter and may need a crown, sometimes with a post and core to give the crown something to hold on to.
| Situation | What is commonly advised |
|---|---|
| Molar after root canal | Crown or similar full coverage |
| Premolar after root canal | Crown in most cases |
| Front tooth, little structure lost | Bonded filling may be enough |
| Front tooth, heavily broken down | Crown, possibly with a post and core |
A numb tooth gives little warning before it cracks
Because the nerve has been removed, a root-treated tooth cannot warn you with sensitivity when a crack starts. Many people only notice when a piece breaks off or the tooth splits. A crack that runs down into the root usually cannot be repaired, and the tooth then has to come out and be replaced with a dental implant, a bridge or a denture, all of which are larger undertakings than the crown would have been.
How soon the crown should follow
The tooth is sealed with a temporary or interim filling at the end of the root canal. That seal is not designed to last, so the crown is generally done within a few weeks. Until then, chewing hard food on that side is best avoided.
As a general guide, crowns in the Australian market typically cost about $1,500 to $2,500 per tooth, depending on the material and the laboratory. This is a market range, not a Lumi fee. Our dental crown guide explains the options in more detail, and current offers are on our deals page.
Questions we are often asked
Is having the crown fitted painful?
The nerve inside the tooth has been removed, although the gum and surrounding tissues can still feel, so local anaesthetic is used if they need to be numbed. Most people find the appointments comfortable.
What if I decide not to have the crown?
On a front tooth with plenty of structure left, that may be reasonable. On a molar or premolar, the risk of a fracture that ends in losing the tooth is higher. Your dentist can explain the risk for your particular tooth.
How long does a crowned root-treated tooth last?
Many last for years, but nothing is permanent. Regular check-ups, careful cleaning around the crown edge and a night guard if you grind all help.
If you have recently had a root canal, or are about to, ask your dentist which restoration that tooth needs and when it should be done. You can book an appointment with us at Melrose Park to have the tooth assessed.
