Dental Crown Materials
A dental crown is used to replicate the part of a natural tooth which is above the gum line and encases a damaged, decayed or heavily filled tooth to give strength, function and better appearance. Crowns are also used to restore a missing tooth when a dental implant is placed. So, its a kind of cap which sits on top of what is left of the natural tooth or on top of an implant which looks and feels like your natural tooth.
There are a lot of different materials and manufacturing techniques when it comes to dental crowns. Frankly, it can be quite confusing. The combinations of different types of dental porcelain (or ceramic, these terms are basically interchangeable), the different manufacturing techniques, firing temperatures, and crystalline structure need an expert knowledge to full understand. Our advice is to listen to the advice of a knowledgeable dentist who can select the right materials for your particular situation and budget.
Crowns are made by highly skilled dental technicians – the skill of the dental technician is often far more important than the material itself. Great quality material in the hands of a poor technician will still be a poor result. Very often the best looking crowns are not perfect but blend in naturally with the remaining teeth. You do not want your dental restoration work to be obvious!
Porcelain or Ceramic Fused to Metal Crowns (PFM)
PFM crowns are made up of a visible and functional part made up of a tooth coloured ceramic which is fused at high temperature to an underlying metal alloy structure which provides additional strength and durability to the ceramic. The metal base is bonded to the remains of the natural tooth using a cement. The metal is not visible but may sometimes give the finished crown a slight grey effect. PFM crowns are still the most commonly used worldwide and are the most cost-effective solution. Your dentist will use high quality porcelain/ceramic and your dentist and technician should be able to get the size, shade and shape just right for you. However, people with sensitivities or allergies to the metal alloy should avoid these type of crowns.
Porcelain or Ceramic Fused to Gold or Titanium
The porcelain, functional, part of the crown can also be fused to gold, gold alloy or titanium instead of a base metal alloy. These materials are as strong or stronger, mould more easily to fit the underlying tooth more snugly, and in the case of gold can be easier to mask with the layers of porcelain over-topping the metal base. Titanium is used as the material for dental implants because of its excellent bio-compatibility and resistance to infection. It is said that gold crowns have the potential to wear least and last longest and are often recommended for back teeth where the pressures are greatest.
Porcelain only Crowns
Porcelain only or full ceramic crowns also come in many flavours and may be made up of one material (monolithic) or more commonly are also made up of layers of one ceramic or porcelain fused to a base made of another ceramic. Porcelain only crowns are considered by many to be more natural looking and in many situations can be extremely hard-wearing and long-lasting. Your dentist will advise you whether they are suitable for the whole or part of your treatment based on your individual requirements and bite characteristics. It is very important to consider not only the look and functionality of the crown itself, but also the effect that a very hard material might have on the tooth above or below it – you do not want a super hard-wearing crown to cause damage to your own teeth through excessive force during chewing or teeth-grinding at night!
Zirconium Crowns or Porcelain Fused to Zirconium
Zirconium is normally used just for the front teeth with standard crowns being placed in the back of the mouth if needed. High quality porcelain is fused to a structure made from Zirconium. This is one of the strongest man made materials on the market and is white in colour. Unlike metals the white of the zirconium material shines through the porcelain making the tooth look even more natural. The clear advantage over any of the metals is excellent aesthetics without losing strength. This is ideal for both cosmetic dentistry and patients who have sensitivity to metals.
There are also crowns which are made purely of Zirconia (again its not very helpful when dentists use the two terms interchangeably, Zirconium is in fact a metal element and Zirconia is an oxide of the metal, but you will see them both used).
Normally a two layer system where the bright white Procera is the base and porcelain is layered over. The result is often said to be highly suited to crowns on the front teeth because of the pleasing appearance which can be achieved with this technique. Because they are made using CAD/CAM technology they are custom fit to the remaining tooth underneath and can therefore afford even more confidence than some other fitting methods.
Emax Crowns (IPS e.max)
Lithium disilicate (e.max) crowns may also be made in the monolithic manner, using only the e.max material, or may be made up from a pressed lithium disilicate base with layers of porcelain added for the desired aesthetic effect. This material is strong, looks very natural, and can be used reliably for very thin veneers or crowns without the need to remove so much of the underlying tooth. But care needs to be taken if there is a natural tooth on the opposite jaw due to the additional strength of this material.
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