Dental Crowns

Dental Crowns, Core Build-Up, Inlays/Onlays (Partial Crowns)

Dental crowns are a protective covering that shield and protect your teeth. It looks exactly like a tooth and restores it to its normal shape, size, function and is generally the same color.

What are dental crowns made of?

Crowns are either made of metals, resins, or ceramics.

Below are the most common types of dental crowns

  • Gold crowns are still held to the highest standard due to proven longevity, least amount of wear on opposing teeth, tooth conservation, and compatibility to the natural tooth. However, due to high cost and poor aesthetics it has become less in demand.
  • Porcelain fused to metal (PFM) crowns have also been around for a very long time but have poor aesthetics. They have a metal layer underneath and is covered by a porcelain exterior which may be a more aesthetic option than a gold crown. However, due to the metal base layer it is hard to achieve the translucency of a natural tooth. Sometimes a metal lining or darkness around the gum line can be seen.
  • All ceramic (porcelain) dental crowns are the most widely used . These materials are known to be very aesthetic, mimicking the natural translucency of our teeth and thus used in many cosmetic cases.
  • Zirconia crowns are also one of the most widely used crowns today. These materials are pressed porcelain and can also be very aesthetic, but are also known for their strength and durability. These are the strongest crowns made available today.

How long do dental crowns last?

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.

Crown Diagnosis

Do I really need dental crowns?

A crown may be recommended or indicated when you:

  • Have a tooth with a large cavity
  • Have a tooth with a broken filling
  • Have a fracture or crack
  • Have had a root canal
  • Have compromised unhealthy tooth structure which cannot be replaced with a filling
  • Have had a crown with an open space where a new cavity has occurred

What can happen if I don’t get a crown when one was recommended?

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.

Dental Crown Treatment

What is the process of a crown? Does it hurt?

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)

Preparation Stage

  • 1. The dentist prepares the tooth by removing any large cavity, existing filling material or fracture.
  • 2. A core build-up is placed when a large cavitation or fracture is present so that you are not left with a large hollow hole. A core build-up is material placed for strength and support of the tooth and crown. In some cases, it may not be necessary.
  • 3. An impression is taken to provide the lab the exact model in order to fabricate the crown. Impressions can be made by a mold or a digital scanner.
  • 4. A temporary crown is placed in the meantime during the lab’s fabrication of the crown. This will shield and protect the tooth for a couple of weeks. While the temporary crown is in, it is important to avoid direct contact, chewing crunchy, hard, or taffy-like things to prevent the temporary crown from breaking or coming off. Since the tooth has been worked on, patients will usually feel some soreness around the gums in that area and may have some hot/cold sensitivity. These symptoms usually resolve after a couple of days.

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.

Core Build-Up

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:

  • Significant cavity or damage
  • Root canal treated teeth

Inlays/Onlays (Partial Crowns)

What is an inlay?

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.

What is an onlay?

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.

What types of inlays and onlays are there?

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.

Porcelain Inlays/Onlays

Pros

  • Longevity – Porcelain inlays/onlays can last around 10-15 years.
  • Strength – Porcelain inlays/onlays are stronger than resin materials, thus lasting longer.
  • Aesthetic – Porcelain inlays/onlays are more resistant to staining and unlike resin fillings do not change much in color. They can be matched to your natural tooth color, thus being the most aesthetic.

Cons

  • Tooth Removal – Porcelain inlays/onlays may need more removal of natural tooth structure.
  • Cost – Porcelain inlays/onlays can be very expensive and cost almost as much as a gold filling.
  • Office Visits – Porcelain inlays/onlays require at least two office visits.

Gold Inlays/Onlays

Pros

  • Longevity – Gold inlays/onlays can last around 10-15 years, and usually do not corrode.
  • Strength – Gold inlays/onlays are strong and most compatible to your natural teeth, it can bear load from chewing forces.

Cons

  • Colors – Gold inlays/onlays are not as popular today due to aesthetics of the material.
  • Cost – Gold inlays/onlays can be very expensive and are higher in cost than all other fillings.
  • Office Visits – Gold inlays/onlays require at least two office visits.

Composite Inlays/Onlays

Pros

  • Aesthetic – Resin inlays/onlays blend with your natural teeth and rarely can be distinguished.
  • Adhesion – Resin inlays/onlays creates a bond with your natural teeth, which helps insulate the tooth from temperature changes.

Cons

  • Longevity – Resin inlays/onlays may need future replacement and do not last as long. Overtime color can change from foods/drinks.
  • Office Visits – Composite inlays/onlays require at least two office visits.

What is the process of an inlay or onlay? Does it hurt?

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)

Preparation Stage

  • 1. The dentist prepares the tooth by removing any large cavity, existing filling material or fracture.
  • 2. An impression is taken to provide the lab the exact model in order to fabricate the crown. Impressions can be made by a mold or a digital scanner.
  • 3. A temporary inlay or onlay is placed in the meantime during the lab’s fabrication of the restoration. This will shield and protect the tooth for a couple of weeks. While the temporary restoration is in, it is important to avoid direct contact, chewing crunchy, hard, or taffy-like things to prevent the temporary restoration from breaking or coming off. Since the tooth has been worked on, patients will usually feel some soreness around the gums in that area and may have some hot/cold sensitivity. These symptoms usually resolve after a couple of days.

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.