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CROWNS

A dental crown is a tooth-shaped "cap" that is placed over a tooth – covering the tooth to restore its shape and size, strength, and/or to improve its appearance.

The crowns, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line.

Why is a Dental Crown Needed?

A dental crown may be needed when at least one of the following occurs:

1. To protect a weak tooth (for instance, from decay) from breaking or to hold together parts of a cracked tooth
2. To restore an already broken tooth or a tooth that has been severely worn down
3. To cover and support a tooth with a large filling when there isn't a lot of tooth left
4. To hold a dental bridge in place
5. To cover misshaped or severely discoloured teeth
6. To cover a dental implant

What Types of Crown Materials are Available?

Permanent crowns can be all metal, porcelain-fused-to-metal, all resin, or all ceramic.

Metals used in crowns include gold alloy, other alloys (for example, palladium) or a base-metal alloy (for example, nickel or chromium). Compared with other crown types, less tooth structure needs to be removed with metal crowns, and tooth wear to opposing teeth is kept to a minimum. Metal crowns withstand biting and chewing forces well and probably last the longest in terms of wear down. Also, they rarely chip or break. The metallic colour is the main drawback. Metal crowns are a good choice for out-of-sight molars. Porcelain-fused-to-metal dental crowns can be colour matched to your adjacent teeth (unlike the metallic crowns). However, more wearing to the opposing teeth occurs with this crown type compared with metal or resin crowns. The crown's porcelain portion can also chip or break off. Next to all-ceramic crowns, porcelain-fused-to-metal crowns look most like normal teeth. However, sometimes the metal underlying the crown's porcelain can show through as a dark line, especially at the gum line and even more so if your gums recede. These crowns can be a good choice for front or back teeth. All-porcelain dental crowns provide the best natural colour match than any other crown type and may be more suitable for people with metal allergies. However, they are not as strong as porcelain-fused-to-metal crowns and they wear down opposing teeth a little more than metal or resin crowns. All-ceramic crowns are a good choice for front teeth.

What Steps are involved in Preparing a Tooth for a Crown?

Preparing a tooth for a crown usually requires two visits - the first step involves examining and preparing the tooth, the second visit involves placement of the permanent crown.

1. Examining and preparing the tooth. At the first visit, our dentist may take a few x-rays to check the roots of the tooth receiving the crown and surrounding bone. If the tooth has extensive decay or if there is a risk of infection or injury to the tooth's pulp, a root canal treatment may first be performed.
   Before the process of making your crown is begun, our dentist will anesthetize your tooth and the gum tissue around the tooth. Next, the tooth receiving the crown is filed down along the chewing surface and sides to make room for the crown. The amount removed depends on the type of crown used. (If, on the other hand, a large area of the tooth is missing our dentist will use filling material to "build up" the tooth enough to support the crown.
   After reshaping the tooth, our dentist will use impression paste or putty to make an impression of the tooth to receive the crown. Impressions of the teeth above and below the tooth to receive the dental crown will also be made to make sure that the crown will not affect your bite.
   The impressions are sent to our dental laboratory where the crown will be manufactured. The crown is usually returned to our dentist's office in less then a week. If your crown is made of porcelain, our dentist and you will choose the shade that most closely matches the colour of your neighbouring teeth.
2. Receiving the permanent dental crown. At your second visit, our dentist will check the fit and colour of the permanent crown. If everything is acceptable, a local aesthetic will be used to numb the tooth and the new crown is permanently cemented in place.

BRIDGES

Dental bridges literally bridge the gap created by one or more missing teeth.

A bridge is made up of two crowns for the teeth on either side of the gap – these two anchoring teeth are called abutment teeth – and a false tooth/teeth in between. These false teeth are called pontics and can be made from gold, alloys, porcelain or a combination of these materials. Dental bridges are supported by natural teeth or implants.

What Are the Benefits of Dental Bridges?

Bridges:

• Restore your smile
• Restore your ability to properly chew and speak
• Maintain the shape of your face
• Distribute the forces in your bite properly by replacing missing teeth
• Prevent remaining teeth from drifting out of position

What Types of Dental Bridges Are Available?

There are three main types of bridges:

Traditional bridges involve creating a crown for the tooth or implant on either side of the missing tooth, with a pontic in between. Traditional bridges are the most common type of bridge and are made of either porcelain fused to metal or ceramics.    Cantilever bridges are used when there are adjacent teeth on only one side of the missing tooth or teeth.   Maryland bonded bridges (also called a resin-bonded bridge or a Maryland bridge) are made of plastic teeth and gums supported by a metal framework. Metal wings on each side of the bridge are bonded to your existing teeth.

What Is the Process for Obtaining a Dental Bridge?

During the first visit, the abutment teeth are prepared. Preparation involves recontouring these teeth by removing a portion of enamel to allow room for a crown to be placed over them. Next, impressions of your teeth are made, which serve as a model from which the bridge, pontic, and crowns will be made by a dental laboratory. Your dentist will make a temporary bridge for you to wear to protect the exposed teeth and gums while your bridge is being made.

During the second visit, your temporary bridge will be removed and the new permanent bridge will be checked and adjusted, as necessary, to achieve a proper fit. Multiple visits may be required to check the fit of the metal framework and bite. This is dependent on each individual's case. If the dental bridge is a fixed (permanent) bridge, your dentist may temporarily cement it in place for a couple of weeks to make sure it is fitting properly. After a couple weeks, the bridge is permanently cemented into place.