Dental Treatments - Crowns

What is a crown?

A crown is a restoration that fits over a tooth, making it strong and giving it the shape of a natural tooth. A crown is sometimes known as a ‘cap’.

Why would I need a crown?

Crowns are an ideal restoration for teeth that have been broken, or have been weakened by decay or a very large filling. A crown could be used for a number of other reasons, for instance:

• You may have discoloured fillings/tilted teeth and would like to improve the appearance of the tooth.

• You may have had a root filling which will need a crown to protect what is left of the tooth.

• It may help hold a bridge or denture firmly in place.

What is a crown made of?

Crowns can be made of a variety of different materials and new materials are continually being introduced.
• Metal : Available in silver/gold with varying amounts of precious metal content. The higher the percentage of precious metal, the higher the quality. Hardwearing and robust.
• Porcelain and metal : this is what most crowns are made from. A metal base is made and then porcelain is applied in layers over it to make it appear like a tooth. The more precious the metal and more time taken by the technician increases the quality.
• All ceramic crowns : this modern technique offers a metal-free alternative, which can give strengths close to a metal crown with a very realistic appearance. These crowns can mimic the true translucency and colour of natural teeth. These types of crowns are commonly seen on smile makeover programmes. They will be offered on private basis.

How is a crown prepared?

First, the dentist will prepare the tooth to make it the ideal shape for the crown. Local anaesthetic (by injection) is used to numb the tooth to make the procedure comfortable. 1-2mm of the outer surface of the tooth is removed, leaving a strong inner core. Once the tooth is shaped, the dentist will take an impression (mould) of the prepared tooth and a temporary cover is made to cover the tooth. The impression is then sent to laboratory and a technician will use it to make a mould of the tooth. He will make a wax template of the tooth and metal is melted onto the surface and followed by layers of porcelain if a white crown is being made. The better materials the technician uses and the more time spent increases the quality of the crown (e.g metal free crowns).

What is a post crown?

In root-filled teeth it may be necessary to insert a metal ‘post’ before placing a crown. The post is needed if there is not a lot of tooth remaining to hold the crown. A short root can only receive a short post, which may increase the chance of it coming off.

What will happen between visits?

A temporary crown will be made so that you can use the tooth while you wait for the crown to be made. This will not look and feel like the final crown but is only a temporary measure. If the temporary comes loose and your appointment is several days away you may need it re-cementing. There may also be some temporary sensitivity following any treatment and crowns are no exception.

We would like you to understand that treatment of dental conditions requiring crowns and/or fixed bridgework includes certain risks and possible unsuccessful results, including the possibility of failure. Even when care and diligence is exercised in the treatment of conditions requiring crowns and bridgework and fabrication of same, there are no promises or guarantees of anticipated results or the length of time that the crown and/or fixed bridgework will last. There are some risks associated with crowns and/or fixed bridgework, which include but are not limited to the following:

1 Reduction of tooth structure: To replace decayed or otherwise traumatized teeth, it is necessary to modify the existing tooth or teeth so that crowns (caps) and/or bridges can be placed on them. Tooth preparation will be done as conservatively as practical.

2 Numbness following use of anesthesia: In preparation of teeth for crowns or bridges, anesthetics are usually needed. As a result of the injection or use of anesthesia, there may be swelling, jaw muscle tenderness or even a resultant numbness of the tongue, lips, teeth, jaws and/or facial tissues that is usually temporary; in rare instances, such numbness may be permanent.

3 Sensitivity of teeth: Often, after the preparation of teeth for the reception of either crowns or bridges, the teeth may exhibit sensitivity. It may be mild to severe. This sensitivity may last only for a short period of time or for much longer periods. If it is persistent, notify us so that we can determine the cause of the sensitivity and seek to treat the condition.

4 Crowned or bridge abutment teeth may require root canal treatment: After being crowned, teeth may develop a condition known as pulpitis or pulpal degeneration. The tooth or teeth may have been traumatized from an accident, deep decay, extensive preparation for the crown or bridge, or from other causes. It may be necessary to do root canal treatments on the affected teeth. If teeth remain sensitive for long periods of time following crowning, root canal treatment may be necessary. Infrequently, the tooth or teeth may abscess or otherwise not heal, which may require root canal treatment, root surgery or possibly extraction.

5 Breakage: Crowns and bridges may chip or break. Many factors could contribute to this situation such as chewing excessively hard materials, change in biting forces, traumatic blows to the mouth, etc. Undetectable cracks may develop in crowns from these causes, but the crowns and bridges themselves may not actually break until sometime later. Breakage or chipping because of defective materials or construction is somewhat uncommon, and if it occurs, it’s usually soon after placement.

6 Uncomfortable or strange feeling: Crowns and bridges are artificial and will therefore feel different from natural teeth. Most patients usually become accustomed to this feeling over time. In limited situations, muscle soreness or tenderness of the jaw joints — temporomandibular joint (TMJ) syndrome — may persist for indeterminable periods of time following placement of the prosthesis.

7 Aesthetics or appearance: Patients will be given the opportunity to observe the appearance of crowns or bridges in place prior to final cementation. When satisfactory, this fact is usually acknowledged by an entry into the patient’s chart initialed by patient.

8 Longevity of crowns and bridges: Many variables determine how long crowns and bridges can be expected to last. Among these are some of the factors mentioned in the preceding paragraphs, including the general health of the patient, oral hygiene, regular dental checkups and diet. As a result, no guarantees can be made or assumed to be made regarding the longevity of the crowns or bridges. It is a patient’s responsibility to seek attention from the dentist should any undue or unexpected problems occur. The patient must diligently follow any and all instructions, including the scheduling of and attendance at all appointments. Failure to keep the cementation appointment can result in ultimate failure of the crown/bridge to fit properly and an additional fee may be assessed.

Please feel free to take the opportunity to ask any questions regarding the nature and purpose of crowns and/or bridge treatment.