Patients with Dental issues often end up confused about what kind of restorative material to go with - given there is a sea of options to choose from. The world of dental research and research on the various dental materials has evolved so much in the recent past. Today, there are so many materials to choose from unlike a few decades ago when metal crowns or porcelain crowns were the only options. There is a variety of dental material that has come up in recent years such as Composite Resin crowns, PFM or Porcelain fused to metal crowns, Ceramic crowns, All Ceramic crowns and the newer variant - Zirconia Crowns. All of these crowns have their own advantages and a small list of disadvantages as well.&
Although the two major types of crowns remain Metal and Porcelain or Ceramic today, there are many varieties of the same that have come up in the recent past. One of the notable types of dental restoration material in this regard is the Porcelain Fused to Metal. Remaining relevant throughout the various changes that have happened in the dental industry, Porcelain Fused to Metal is still a commonly used crown in many specific case scenarios. Closest to the metal crown in strength and durability and providing the esthetics of Porcelain and Ceramic Crowns, Porcelain Fused to Metal crowns is one of the few crowns that has stood the test of time.
Dental Crowns and Dental Materials
Dental crowns and the various dental materials are closely correlated. This is because the choice of the dental material for the dental crown plays a vital role in how the crown behaves and functions in the patient's mouth. It is important for the patient and the dentist to take a mutual decision when it comes to the selection of the dental material for the crown. The selection of dental crown depends on various things such as:
1. Position of Crown
There are two different kinds of crown material that are suggested based on where the crown is placed - for anterior crowns a more aesthetically pleasing crown which does not give away the use of crown is preferred. For posterior crowns, a highly durable and strong crown is to be recommended. Therefore the position of the crown is important for the selection of the dental material. Anterior crowns are preferred in esthetically pleasing shades whereas posterior crowns need to have a high flexural strength along with a higher threshold for bite force.
2. Patient Characteristics
The patient may have some unique habits and characteristics such as Bruxism where the patient grinds their teeth in the night. Some patients may have metal allergies which eliminates the usage of metal based crowns. Some patients may have low accessibility or low co-operation when it comes to dental care and for such patients, a durable low maintenance crown needs to be prescribed.
3. Dental Hygiene
Dental hygiene is especially important for the health and durability of the crown. Patients who have low dental hygiene such as young children or older adults or those who have low access to dental healthcare need a strong and durable dental crown that needs low maintenance. Choosing a crown that is esthetically pleasing often comes with high maintenance leaving only metal based crowns as an option.
4. Cost of the Crown
Economic affordability is one of the most important things for dental procedures as not all medical insurances cover dental procedures. Patients who cannot afford to have premium dental material based crowns need more economic options that they can choose from. Esthetically pleasing crowns come with a cost and therefore a variety of hybrid options have come up that combine esthetics with functionality and with a reduction in cost.
5. Dental Procedure Followed
Sometimes the type of dental procedure that has been followed is important in the selection of the dental material that is chosen. If a major portion of the tooth has been removed, then a dental material that has the need for more space and contouring cannot be considered. Ceramic based crowns have a thicker structure and when there is not enough original tooth structure to support, the restoration may not have the required strength.
Porcelain Fused to Metal Crowns
Porcelain Fused to Metal Crowns is a perfect hybrid of Metal crowns and porcelain crowns. The dental material combines the strength of the metal crown with a metal substructure in the core along with a porcelain exterior that fulfils the need for aesthetics in patients. Because of the need for a teeth like exterior structure in both posterior as well as in anterior restorations, PFM or Porcelain Fused Metal Crowns were invented by dental researchers. It has been in use for a long time, ever since the 1950’s perhaps and is still a relevant restoration material in the dentistry world.
When it comes to the alloy of choice, patients can choose from 3 categories:
Non-precious metals are base metals that include metals such as Nickel, Chromium, Beryllium or Cobalt. These metals are often found in combination with Noble metals as well but the strength of the metal composition is less than 25% in Non-precious crowns. These crowns are more affordable and offer a good alternative to metal crowns or pure porcelain crowns.
Semi-precious metals have a noble metal content of 25% on average or slightly more - and includes the likes of Gold, Platinum or Palladium. These crowns offer better strength and durability than Non-precious crowns. They are slightly more expensive than Non-precious crowns.
3. High Noble
High Noble metals include 40% and more of the noble metal of choice. Mostly, Gold is used for these types of restorations with about 40% strength in the overall composition. The rest of the structure is layered with Feldspathic porcelain.
There are many advantages and a few disadvantages of PFM crowns just like any other dental crowns that have existed. Like the name suggests, the metal substructure within offers strength and durability of metal but also comes with the greyish metal shadow and the margin around the crown which can become unpleasant to look at. Even though Porcelain offers a good cover and provides a teeth like appearance from the outside, from closer observation, it does look artificial. Porcelain is also not famously popular for its chipping tendency and the ability to cause wear in the opposing teeth.
Below are some of these points in comparison with each other:
|Metal Substructure core||Greyish appearance upon close proximity|
|Porcelain Exterior gives natural esthetic||Porcelain is prone to chipping and fracture|
|Good lifespan of upto 10 years||Not as durable as other options available in market today|
|Cost economy is provided||Needs maintenance|
|Restoration can be done even when major original tooth portion is removed||Gum recession can cause grey lining on the exterior|
Zirconia Dental Crowns have recently become extremely popular. The surge in the use of Zirconia Tooth crowns happened around 2008 when many private brands started making their own versions of Zirconia crowns. These crowns are made from Zirconium Dioxide blocks and are known for some of the best characteristics such as:
Zirconia Ceramic crowns are known to be the strongest version of ceramic crown to exist and is both an advantage and slightly a disadvantage. The strength of Zirconia makes it an apt restorative material for posterior teeth as well, which most ceramic crowns are not suitable for. Anterior restorations are one of the most sought after techniques with Zirconia Tooth crowns
Zirconia crowns are extremely durable thanks to its strength and higher load bearing threshold. The crowns rarely ever need any maintenance and can easily last upto 15 years or more with proper hygiene and maintenance.
For patients who cannot tolerate metals or with nickel allergy, Zirconia is the best alternative as it is a 10% biocompatible material which is known to cause no allergies or irritations while in place in the patients’ mouth.
When it comes to aesthetics, Zirconia crowns are the best option because of its highly suitable appearance that looks just like teeth. Although they were initially believed to be too opaque to look teeth like, with the latest glazing technique, teeth like enamel shades can be custom created in labs.
The cost of zirconia crowns may be a little higher than PFM crowns but it needs to be noted that these crowns have lesser maintenance and last longer than PFM. Zirconia crown price may vary from one maker to another but on average, the Zirconia crowns cost a few hundred dollars based on the type, brand and the technique followed.
Zirconia v/s PFM Crowns
Zirconia crowns are better than PFM crowns in most cases. There are only a few scenarios where PFM crowns are preferred over Zirconia crowns such as when a dental bridge needs to be made such as the 3 unit PFM bridges that are wildly popular in modern day dentistry. Precision attachments are also done with PFM in a much more established manner than Zirconia crowns. PFM is a more established and researched crown material that has survived in the market for a long time giving a better time and research based advantage over Zirconia crowns.
But the latest innovations in Zirconia crowns are making it more usable in most scenarios and is becoming a more popular alternative to PFM crowns.
1. Restorations with Zirconia crowns are now done with precision fitment and therefore the margin accuracy is extremely perfect with Zirconia crowns today.
2. They are a great option for full tooth restorations as it is stronger and more durable and provides a cosmetic advantage to patients than PFM crowns.
3. Zirconia crowns also address issues with Bruxism as they can be custom made to reduce chipping and prevent wearing of the crown
4. Long term results and studies on the lifespan of the Zirconia crowns are increasing and becoming more favourable by the day.
5. Zirconia crowns are also more favourable for hypersensitivity in the teeth when compared to PFM crowns. They are also great for patients who have soft tissue irritation.
To conclude, Zirconia crowns and their recent forms are gaining far more advantage than the other crowns such as PFM and new and latest improvements are being done every single day to make these crowns better and safer.