Crowns are either made of metals, resins, or ceramics.
This is a complicated question. Dental crowns are not invincible, they are like your natural teeth and when neglected or without proper care, can form another cavity underneath. If you bite into something very hard, open a bottle or a jar for example, they can break. Some older crowns may show open margins, which is spacing between the tooth and the crown. Within these openings, bacteria and saliva may enter and cause a new cavity. This can be detected by radiographic x-rays and tactile. Early detection of these instances can help avoid further extensive treatment, such as a root canal.
With proper care (brushing/flossing) and proper maintenance (bi-yearly cleanings) crowns can last years and maybe even a lifetime. Insurance will usually cover a crown every 5 years. Longevity can be maintained with routine care and careful monitoring by your dentist. This is why seeing a preventative dentist is crucial.
A crown may be recommended or indicated when you:
When more than a fourth of your tooth is significantly damaged or compromised and/or is supported with more dental material than tooth, it can cause a lot of stress. This type of stress can lead to tooth fractures, resulting in situations where further treatment (such as a root canal) may be needed. It can also result in a tooth that was once savable no longer being savable.
By placing a crown over a fragile unsupported tooth, it helps distribute the biting forces more evenly and provides strength and support.
A root canal treated molar is great example of a fragile tooth. The tooth is very brittle and weak since there is not enough remaining healthy tooth structure for support. Your molars are the back teeth that bear most of the forces and need the strongest protection. If you are constantly putting pressure or force on a weakened tooth it will be bound to break. This is why it is important to consult with your dentist for the best preventative outcome.
The process of a crown is similar to a tooth colored filling. Local anesthetic is administered so you will not feel any pain during the procedure. Your dentist should make sure you are completely comfortable in the chair. In general, the procedure takes about an hour, but can take longer depending on how extensive the cavity or fracture is.
Usually the dental crown is a two-appointment process. (Preparation and Final Cementation)
Once the dental crown is back from the lab, the dentist will make sure your crown properly fits, and is adjusted to your original bite. The fit can be double checked by taking a radiographic x-ray before the crown is permanently cemented. Once it is permanently cemented you will be able to go back to chewing properly and flossing regularly in that area.
A core build-up is a resin-based restoration used to hold together remaining tooth structure that has decayed or been damaged.
When there is an extensive cavity or damage, the damaged part of your tooth will be removed. In order for the tooth to hold its strength, it will need something (core build-up) to fill that space. If nothing is placed, the tooth would have a hollow hole and be susceptible to fracture.
A core-build procedure is similar to a filling. Many times a core build-up is placed during crown preparation. This is so there is enough tooth structure to hold up the crown to be cemented for stability and strength.
Indications of a core build-up:
An inlay is an indirect custom-made filling/restoration to fill a part of a tooth that has been damaged or decayed. The design of an inlay is structured that the filling is confined within the cusps (tips/bumps) of the tooth. It is similar to a filling in that it can be bonded.
An onlay is the same as an inlay with the exception that the design is structured that the filling extends over the cusps of the tooth.
Both inlays and onlays are made of porcelain, gold or composite resin material. Below is a table describing some pros and cons to each of the materials.
The process of an inlay or onlay is similar to a crown preparation. Local anesthetic is administered so you will not feel any pain during the procedure. Your dentist should make sure you are completely comfortable in the chair. In general, the procedure takes about an hour but can take longer depending on how extensive the cavity or fracture is.
Usually the inlay or onlay is a two-appointment process. (Preparation and Final Cementation/Bonding)
Once the inlay or onlay is back the dentist will make sure your restoration properly fits, and is adjusted to your original bite. The fit can be double checked by taking a radiographic x-ray before the restoration is permanently cemented or bonded. Once it is permanently cemented/ bonded you will be able to go back to chewing properly and flossing regularly in that area.