Almost 30 years ago, a dentist did a root canal on my right canine tooth. Although the tooth is not bothering me, my dentist suggested placing a crown to prevent it from breaking. She said that if the tooth breaks, I might lose it and need a dental implant. Should I be concerned about the tooth breaking? – Johandry

Johandry,

Thank you for your inquiry. Although Dr. Tostado would need to examine your tooth and x-ray to determine if it is susceptible to breaking, we will answer your question in general terms.

Does a Root Canal Tooth Require a Crown?

Some dentists prefer to place a crown over every root canal tooth. But whether a crown is a necessity depends on the tooth’s condition and location. Some teeth are more susceptible to breaking.

• Tooth condition – If a tooth is already is fractured or most of its healthy structure is missing, your dentist may recommend protecting it with a crown.
• Tooth location – Molar, premolar, and front teeth have different functions that naturally exert force and stress to teeth.
  • Molar teeth – Molar teeth chew and grind food, and the force causes stress that healthy teeth can handle. But the stress can push the four cusps, or peaks on the tooth, apart and lead to fracture. Premolars have similar risks.
  • Front teeth – Horizontal stresses affect front teeth, which we use for biting. Front teeth absorb some of the stress for molar teeth. Canine teeth have long roots to help them absorb horizontal stress. When your teeth are grinding from side to side, the canine teeth force the back teeth apart to relieve horizontal stress. Other front teeth absorb stress when you slide your lower jaw forward.

How to Protect a Root Canal Tooth from Fracture

Protecting a root canal tooth from fracture depends on whether a front or back tooth is affected.

• Back tooth – A crown or an only will cover the chewing surface to help the tooth absorb stress and prevent it from splitting.
• Front tooth – Although the traditional method is to place a crown over a front tooth, a crown can weaken the tooth. The neck of the tooth (near the gumline) is the weakest portion of the tooth. A porcelain crown requires your dentist to shave about one millimeter from every side of the tooth. Up to 30% of the tooth may be lost, and root canal treatment removes the tooth pulp. About 50% of the tooth original fracture resistance remains.

Unless a front tooth has a preexisting fracture, has little structure remaining, or is dark in color, many advanced cosmetic dentists avoid using a crown, which can further weaken the tooth.

Fiberglass post

After root canal treatment, some advanced cosmetic dentists use a method like this to strengthen a front tooth against fracture and prevent the need for extraction and a dental implant:

• Clean out the root canal filler material
• Insert a white, flexible fiberglass post deep inside the tooth to strengthen it
• Fill missing tooth structure with strong composite material

The post reduces the risk of horizontal fracture and prevents the need for a crown. If root canal treatment causes the tooth to darken over time, a dentist can use a porcelain veneer to conceal the discoloration.

Ask your dentist if your x-ray shows that your tooth is weakening and requires a crown. You can also schedule a second-opinion appointment with an advanced cosmetic dentist to determine if your tooth is at risk of fracture.

 

Gilberto Tostado, DDS, of San Antonio, TX sponsors this post. Dr. Tostado has post-graduate training in prosthodontics and dental aesthetics.