Dental crowns (also known as caps) are fixed on the top of damaged teeth. These crowns cover the teeth and protect them from further harm. They also restore the shape of teeth.
Dental crowns are made up of different materials such as metals, ceramics, composite resins, or a combination of metal and ceramic.
Usually, a dentist would suggest which crown might be best for you.
However, understanding the benefits and shortcomings of each type, along with the cost involved, will help you make the right choice.
In this article, we help you understand the pros and cons of different materials for dental crowns.
Why do you need a crown?
The placement of the crown helps strengthen the tooth and improve its appearance. Here are some of the common conditions that may need dental crown fixation:
- To restore the weakened tooth due to large decay or filling.
- To protect the weakened tooth structure after root canal treatment.
- To restore the tooth that is broken.
- To mask off the discolored or badly shaped teeth.
- To cover a dental implant.
- To restore the missing tooth with the help of a bridge (crown placed on missing tooth site using the support from the adjacent teeth).
What are the different types of crowns?
Based on the materials used for fabrication, dental crowns can be divided into the following types:
a. Metal crowns: Metals such as gold, platinum, or base metal alloys (e.g., nickel-chromium and cobalt-chromium) are used to fabricate dental crowns.
Advantages:
- Rarely break, chip, or wear off.
- Highly durable and long-lasting.
- Only a small amount of tooth structure is trimmed (prepared) to accommodate the crown on top of the tooth.
- Can withstand heavy biting and chewing forces
Disadvantages:
- The metallic color of crowns gives them an unappealing appearance. It is preferred to restore teeth (behind ones) that are not so visible while talking or smiling.
- Gold crowns are quite costly compared to other types. However base metal crowns are cost-effective.
b. All ceramic crowns: Ceramic crowns are considered the material of choice for the fabrication of dental crowns. These crowns have no metal inside them. They are entirely prepared from ceramic.
Emax crowns and zirconia are variants of all ceramic crowns commonly available in clinics.
Both are long-lasting and have high aesthetic qualities. However, E-max crowns are more translucent compared to zirconia. This enables light to pass through E-max crowns, creating a more natural tooth appearance.
Advantages:
- Offer high aesthetics.
- More resistant to corrosion.
- Thermal conductivity is low, so ceramic crowns are not sensitive to changes in temperature (heat or cold).
- Biocompatible with the oral tissues.
Disadvantages:
- Ceramic crowns are quite expensive (The cost of each crown may range between 150-250 USD in Turkey).
- A considerable amount of tooth structure is trimmed (prepared) to accommodate the ceramic crowns on the top of the tooth.
- Excessive tooth preparation may cause sensitivity or tooth pain in some patients.
- Wearing off the tooth opposing the ceramic crown can occur if the crown is not adequately polished.
- Ceramic crowns can fracture if excessive chewing or biting forces are applied.
c. Porcelain fused metal crowns (PFM): Porcelain fused metal materials are commonly used in the day-to-day clinical practice for crown and bridge fabrication. They are fabricated with an inner layer of metal alloys and an outer ceramic layer. PFM offers outstanding mechanical properties. However, due to the superior esthetics offered by all ceramic crowns, their usage is slowly declining especially for front teeth.
Advantages:
- PFM crowns are durable and offer good aesthetics.
- The presence of metal offers high strength and greater biting ability.
- PFM crowns are more resistant to cracking and chipping compared to all ceramic crowns.
- Cost-effective compared to all ceramic crowns. For instance, in Turkey, the cost of each PFM crown is ~ 110 USD compared to 150-250 USD for a single all ceramic crown.
Disadvantages:
- The aesthetics offered are inferior to all ceramic crowns.
- The presence of metal on the inner surface may form a gray line around the gums over time.
- The ceramic portion of the crown can wear off easily if the thickness of the material used is not adequate.
d. Composite resin crowns: In this type, a fractured or hypoplastic portion (less mineralized areas) of the front tooth is rebuilt using composite resins. Due to limited durability, these are also known as semi-permanent restorations.
Advantages:
- Less time-consuming
- Less expensive compared to other crowns
Disadvantages:
- Durable for a limited period (3-5 years)
- More prone to wear off or fractures compared to other crowns.
Are there any allergic reactions to dental crowns?
The short answer is yes. The use of metals such as nickel, cobalt, or chromium for the fabrication of metal crowns or bridges can cause allergic reactions in some individuals.
Sensitivity to nickel is reported in 0.1-0.2% of individuals. It is about 4-10 times more common in females than in males.
Meanwhile, an allergic reaction to cobalt and chromium is rare.
- Redness of gums
- Irritation of the gums
- Swelling in the gums
- Numbness on the sides of the tongue
- Burning sensation in the mouth
- In sensitized individuals, exposure to nickel can cause systemic contact dermatitis which includes symptoms such as dryness, redness, itching, flaking, and cracking of the skin.
What is the safest material for dental crowns?
All ceramic crowns are considered biocompatible, aesthetic, and safest material for dental crowns. However, placement of such crowns should be avoided in people with the tendency of grinding or clenching their teeth for a long. This can cause ceramic crowns to fracture or chip off. Besides, these crowns are quite expensive. People looking for pocket-friendly treatment can opt for PFM crowns which offer decent aesthetics and better strength to the tooth restored.
Conclusion:
Crowns or caps are placed over damaged teeth to protect them from further damage and restore their shape. These crowns are made up of different materials. Knowing the benefits and shortcomings of each material can help an individual make an informed choice.
References:
http://www.mouthhealthy.org/~/media/ADA/Publications/Files/ADA_PatientSmart_Crowns.ashx
Knosp H, Holliday RJ, Corti CW. Gold in dentistry: alloys, uses and performance. Gold bulletin. 2003 Sep;36(3):93-102.
Dolidze T, Bitarova I. Advantages and dısadvantages of E-max and Zırconıa crowns. Eur Sci J. 2017;12:465-8.
AlJehani, Y.A., Baskaradoss, J.K., Geevarghese, A. and AlShehry, M.A. (2014) Current Trends in Aesthetic Dentistry. Health, 6, 1941-1949
Dalal Mohammed AlRumayyan and Naif Ahmed AlRumayyan. All-Ceramic Versus Metal-Ceramic Tooth Supported Single Crowns; A Systematic Review. Donnish Journal of Dentistry and Oral Hygiene 5(1) 2019 pp. 013-019.
ULVESTAD H. A 5‐year evaluation of semipermanent composite resin crowns. European Journal of Oral Sciences. 1978 May;86(3):163-8.
Syed, M., Chopra, R., & Sachdev, V. (2015). Allergic Reactions to Dental Materials-A Systematic Review. Journal of clinical and diagnostic research : JCDR, 9(10), ZE04–ZE9.
Allergies to dental materials. Vital 4, 39 (2007).
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