Dental crowns are made from all metal, porcelain-fused-to-metal, ceramic, resin etc. Details are given below.
Metallic dental crowns – the metals used are gold, palladium, nickel, chromium etc. The metal crown need less
removal of tooth structure and causes less tooth wear to the opposing teeth. Metal crowns last longer and can resist
wear-out due to chewing and biting. Chipping or breaking instances are very rare in metallic crowns. The main
disadvantage in using metal crowns is their color; hence they become better choice for out-of-sight molars.
Porcelain-fused-to-metal dental crowns – this has the advantage over metallic crowns in color matching to
your adjacent teeth. However, this wears out the opposite teeth more as compared to resin or metal crowns. It is also
possible that the porcelain portion of the crown might break or chip off. The porcelain-fused-to-metal crowns when
fixed adjacent to the all-ceramic crowns looks similar to normal teeth. The main disadvantage in this type of crown is
that at times the metal underlying the porcelain of the crown is seen as a dark line; this is all the more so if your gums recede.
These crowns look good on your front or back tooth.
All-resin dental crowns – cost less as compared to other crown types of dental crowns. But you will notice faster wear
out on these crowns; further they are susceptible for fractures than porcelain-fused-to-metal crowns.
All-ceramic or all-porcelain dental crowns – these crowns give you the best natural color match than other types of
crowns; further they are good for people having allergies to metals. The main disadvantage in this is that they are weak
compared to porcelain-fused-to-metal crowns; also the opposing teeth are worn out more by this. You could choose all-ceramic
crowns for your front teeth.
Temporary crowns are crowns that can be made in your dentist's office and normally they are made out of acrylic. Permanent
crowns are crowns that are made in a dental laboratory. Temporary crowns are used as a temporary restoration until the dental
laboratory makes a permanent crown using any of the above said materials.
This procedure normally requires two visits to your dentists. During the first visit your dentist takes x-rays to find out the root
conditions of the tooth that is to be provided with a crown. In case the root is decayed extensively he might perform root canal treatment.
Otherwise he will do the following.
He numbs your tooth and the gum tissue by anesthetizing.
File the chewing surface and sides of the tooth that receives the crown to facilitate fitting the crown. The extent of filing depends
on the material used for the crown. For example, metal crowns require less tooth structure removal because they are thin.
In case majority of the tooth area is missing the dentist fills up this area to support the crown.
Once the tooth is reshaped, your dentist makes an impression of the tooth receiving the crown by using an impression paste. He will
also take the impressions of the tooth above and below the tooth to ensure that the crown does not affect the bite.
The dentist sends the impressions to a dental laboratory for manufacture of the crown which normally takes 2 to 3 weeks.
For porcelain crowns the dentist will select the color that matches the color of adjacent teeth.
He will provide an acrylic crown to cover the prepared tooth temporarily until the permanent tooth is received from the lab.
During your second visit, your dentist your dentist will replace the temporary crown with a permanent crown if the fit and color match
of the permanent crown are satisfactory. He will administer a local anesthetic while cementing the new crown permanently in position.
You might face the following problems when you are fitted with dental crowns.
Allergic reaction – since the metallic crowns are manufactured using a mixture of various metals it might be possible that
some individuals become allergic to it; however such a phenomenon is not very common.
Chipped crown – this normally happens in porcelain crowns. Small chips can be repaired in situ using a composite resin.
However, if the chipping is large you might have to get your crown replaced.
Dark line on crowned tooth next to the gum line – if you have a porcelain-fused-to-metal crown there will be a dark line
next to the gum line and this line is only the metal of the crown showing through.
Discomfort or sensitivity – there will be immediate sensitivity on the tooth newly fitted with a crown once the effect of
anesthesia starts wearing out. You might experience cold and heat sensitivity if the crowned tooth has a nerve left in it. You may have
to brush your teeth with toothpaste meant for sensitive teeth. If you feel pain or sensitivity at the time of biting it indicates that
the crown is too high on the tooth and requires your dentist’s attention.
Falling off of Crown – If the fitting is improper or there is insufficient cement it is likely that the crowns fall off
at times. In such a situation you can temporarily glue the crown to your teeth after cleaning the crown and also the front of your
tooth. Contact your dentist for permanent fixing or replacement as the case may be.
Loose crown – occurs when the cement gets washed away under the crown. This causes the crown to become loose and also
allows the bacteria to get inside the crevices which in turn accelerate tooth decay.
In addition to the technique of dental crowns given above there are other techniques such as Onlays and 3/4 crowns. Basically
they differ in the extent of coverage of the underlying tooth. The conventional technique covers the whole tooth whereas Onlays and
3/4 crowns cover the underlying tooth to a lesser extent.
No special care is required for a crowned tooth. You must realize that the underlying tooth cannot be protected from gum disease or decay just by
crowning it. Hence you must follow good oral hygiene practices.