Dental Crowns

A Dental crown is like a tooth covering that completely or partially covers and encases the visible part of the tooth. It is an artificial restoration that fits on the remaining tooth, thus making it stronger and sturdier and giving it the required shape and aesthetic. A dental crown is sometimes also referred as a cap.

When does one needs a dental crown?

Whenever a tooth is too damaged and could not support a tooth filling, dental crowning is done. Crown protects the tooth from further damage, giving it the required strength to sustain the pressure while performing talking and chewing. Capping a damaged tooth unnecessarily with a dental crown removes more tooth structure than needed, which ends up in damaging the tooth. Also, a large dental filling weakens the remaining structure of the tooth, causing the tooth to break and crack.

Depending upon the requirement and the types of materials used, there are various types of dental crowns. These are basically categorized into five distinct types.

1) Metals Crowns: These types of crowns are made of soft metals like gold, silver. The advantage of metal crown is that it can withstand high biting and chewing force. Metal crowns haves very less wear and tear and thus lasts longer. These crowns rarely break or chips apart. The main disadvantage of these crowns is there distinct colour.

2) Stainless Steel Crowns: These are prefabricated crowns that are used for temporary purposes and mostly are used when the permanent crown is being manufactured and the tooth is being taken care by the stainless steel for the time being. This type of crown covers the entire tooth and protects it from further damage. Stainless steel crowns are also used for children with tooth decay and is commonly used to fit over a primary tooth that’s has been prepared to fit it.

3) Porcelain fused to metal: Porcelain fused to metal or sometimes called just PFM, is a mix of metal and porcelain crown. The substructure is made of hard metal and this is further layered with porcelain and fused in a high heat oven, resulting in a crown which is very hard and has an appearance of the natural tooth. PFM crowns are relatively stronger and can be used for front and back teeth. But, sometimes the metal underlying the crown's porcelain can show through as a dark line, mostly at the gum line.

4) All Resins Dental Crown: As the name suggests these crowns are made of resins/plastic like material and hence lack the natural glow and shine of a tooth. It is also not as strong as the other crowns but it is the cheapest among all. Thus, dentists hardly prefer these crowns over others.

5) All Ceramic or All Porcelain Dental Crown: These crowns are completely made of porcelain or ceramics, giving it a complete resemblance of natural tooth. These are more shiny and suitable form of dental crown and if put properly there is no difference between the natural tooth and the crown. People who have allergy and issues with more sensitiveness, generally prefer these types of crowns. Aesthetic wise all ceramic or all porcelain crowns are best but they are not very sturdy and strong and are often prone to wear and tear.

The average life span of dental crowns is in the range of 5- 10 years in some cases even up to 15 years, depending upon the care and precautions taken to upkeep the crown and also on the material used to make the crown.

Steps involved in preparing a dental crown

This can be categorized into two steps, as there are mostly two visits required to place dental crown on the damaged tooth.

On the day 1 of the visit the orthodontist for the crowning purposes, the damaged/decayed tooth is properly examined by taking X-rays, to check the roots of the tooth to be crowned and surrounding bone. If, there is extensive decay and if there is further risk of tooth infection, the doctor would suggest to go through RCT, what is called as a root canal treatment. After, analysis of the tooth, anesthesia is administered to the tooth to be crowned to make it numb. After that chipping is done depending upon the type of crown to be used followed by proper filling of the decayed tooth and the area around it. This helps in reshaping the tooth to build up the crown. After that an impression of the tooth is made by using paste (now a days digital 3-D scanner are also used).

Now these impressions and scans are send to lab for preparing the dental crown depending upon the shape and the size of the tooth. Meanwhile, the doctor will place a temporary crown on the tooth, to avoid any further damage.

In the second Visit, the dentist fits the permanent crown after removing the temporary crown and thoroughly checks for the fits and the aesthetic part of it. After checking if everything is as desirable, the anesthesia is administered and the crown is permanently cemented to the tooth.

Following are the problems faced because of dental crowns

Irritation & sensitivity: Since, the tooth is newly crowned, it initially causes irritation and sensitivity while chewing or drinking. Hence, it is required initially to maintain certain precautions as suggested by the doctor. If the sensitivity pertains for longer period of time, there might be some issue with the fit of the crown and it is hence advisable to visit the doctor.

Chipped crown: Crowns which are made of porcelain or ceramics, are prone to chipping. If the chipping is major, then the crown has to be removed.

Loose crown: Sometimes, the cement used to fix the crown is washed out, and hence the crown becomes loose. The dentist then again fixes the crown after cementing it, as ignoring it may cause several other issues.

Crown falls off: Rarely, the crown falls owing to improper fit. The simple way to fix it, is by using adhesive.

Onlays and ¾ Crowns

Both Onlays and ¾ Crowns are used to cover broken/damaged tooth. These are dental prostheses or support used to restore damaged teeth, particularly the cusps. These are made of porcelain, composite resin or sometimes soft metal material and are molded to fit the exact shape of the damaged part of the tooth. Initially these techniques required orthodontists to take a mould and then make these caps and again make fit in the tooth. But, now with advancement and 3-D technique on the spot fix is made within very short period of time.

The distinction between these restorations is the relative portion of the underlying tooth that is covered. Although, dentists use both restorations to cover the surface of the tooth, they have different purposes and scopes.

Whereas Onlays cover only a small surface because dentists place them on the cusps and ridges on top of the tooth, ¾ crowns extend from the surface to cover three of the four sides of the tooth.

The obvious question strikes the mind is that, how to take care of the Dental crown?

The answer as simply the way one takes care of his/her natural tooth. There is no special care needed barring the initial day.

Cost of Onlays and Crowns

Onlays are comparatively cheaper than crowns because they require a smaller amount of material. The price of both dental restorations is dependent upon various factors like- clinic, extent of repair and materials used. All-Ceramic crown costs anywhere between 12000-15000, Metal crown covered with ceramics cost somewhere between 3000-5000/- and simple metal crowns being the cheapest can cost around 2000-4000 INR.