The dental crown is a cap placed over a tooth. The purpose of the crown is to restore the shape, size and strength of the tooth besides improving its appearance. The visible portion of a tooth above the gum line will be fully encased by the crown once they are cemented properly.
The dental crowns are provided under the following circumstances:
- To protect a tooth that has become weak either due to tooth decay or tooth wear.
- To hold the cracked tooth in position.
- To hold a dental bridge in its place.
- To cover a dental implant.
- To cover a stained tooth or crooked tooth.
- To cover a tooth with a large filling.
- After a root canal treatment.
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 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. The main disadvantage is the strength.
- All-ceramic or all-porcelain dental or metal-free ceramic 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 they are more expensive. They should be the first choice in replacing front tooth.
This procedure normally requires two-three visits to your dentists.
- Firstly, the chewing surface and sides of the tooth that receives the crown is reduced in size 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.
- 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 apposing jaw to ensure that the crown does not affect the bite.
- The dentist then sends the impressions to a dental laboratory for manufacture of the crown which normally takes 2 to 4 days
- For porcelain crowns the dentist will select the color that matches the color of adjacent teeth.
- During the iterim period the dentist will provide an acrylic crown to cover the prepared tooth temporarily until the permanent tooth is received from the lab.
You might face the following problems when you are fitted with a 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 causes tooth decay.
Dental bridges are basically false teeth; these are anchored onto neighboring teeth so as to replace one or more missing teeth. The false tooth is called a pontic and this is fused in between two crowns serving as anchors by attaching to the teeth on each side of the false tooth, thereby bridging them together.
You must replace the missing Teeth for the following reasons:
- To improve your smile as well as appearance.
- To improve your speech if affected.
- To improve the shape of your face when affected.
- The gap left by the missing tooth causes strain on the teeth that are at either side of the missing tooth.
- This gap also affects your “bite” because the neighboring teeth can lean into the gap and alter the way the upper and lower teeth bite together.
- There will be accumulation of food I the gap that might cause gum disease and tooth decay.
Partial denture is a plate wherein false teeth are attached. This could either be made out of plastic or a mixture of metal and plastic. In both these types clips are provided to fasten the denture in the mouth. Depending on the location these clips might or might not be visible at the time of your smiling or opening your mouth.
The main alternative to a partial denture is a fixed bridge. In this crowns are provided for the teeth remaining on either side of the missing teeth space and these crowns are joined together by providing a false tooth in the space. Once fitted the bridge cannot be removed.
Alternately you can opt for adhesive bridge (Maryland bridge). In this wings are bonded to the back of the supporting teeth and this procedure involves very little drilling.
The following items constitute a dental bridge:
- A pontic or false tooth – this is used to replace the missing tooth; this can be made from gold, alloys, porcelain or a combination of these materials.
- Two crowns – this helps in anchoring the false tooth in place.
There are three main types of dental bridges and these are as follows:
- Traditional fixed bridge – this type of bridge is the most common bridge and it consists of a pontic fused between abutment crowns that are anchored on neighboring teeth or implants. Normally the pontic is of either metal, porcelain fused to metal or ceramics. These are fixed bridges and cannot be removed.
- Resin-bonded bridges or Maryland-bonded bridges – these are normally used when the gap to be filled is in between the front teeth, or when the teeth on either side of the missing tooth are strong and healthy without large fillings. The false tooth is made of porcelain and is fused to metal wings that are bonded to the adjacent teeth using resin that is hidden from view.
- Cantilever bridges – these are chosen in areas like the front teeth that are subject to lower stress. Cantilever bridges are used when there are teeth present on only one side of the space, where the false tooth is anchored to one or more adjacent teeth on one side.
- They appear natural.
- They can last for a long period depending on your dental hygiene.
- They improve your appearance, bite issues and speech problems occurring as a result of missing teeth.
- The teeth may become mildly sensitive to extreme temperatures.
- They require healthy tooth tissue from neighboring teeth to be prepared.
- Your teeth and gums are vulnerable to infection as a result of accumulation of bacteria due to the food acids (if proper hygiene is not maintained).
The best alternative to a dental bridge are dental implants.