Dental crowns restore strength, shape and size to a tooth that is damaged or broken. They also cover up discolored teeth to improve appearance. Resin crowns are less expensive than other types of dental crown, but they lack the supportive noble metals of porcelain fused to metal and don’t last as long as other options. They can also be more prone to cracking.
Before a crown can be placed, the tooth will need to be filed down. How much filing depends on the crown material. Surveyed dentists prefer feldspathic porcelain, layered zirconia, lithium disilicate or leucite reinforced ceramic for front teeth and PFM or VMK crowns for back molars.
Porcelain Crowns
Porcelain crowns have become a popular choice because of their beauty, strength, and durability. They closely match the color and translucence of your natural tooth enamel, blending in seamlessly to create a beautiful smile. They are also stain-resistant and can withstand the force of chewing and biting.
They are the ideal choice for front teeth or any teeth that show when you smile or speak, but they can be used to restore almost any damaged tooth. They are also the best option for people who have metal allergies.
Before you get a porcelain crown, your dentist will take a series of periapical and bite-wing radiographs to assess the state of your jaw and teeth. This will give the dentist a clear idea of how much structure you have remaining and if a porcelain crown is the right restoration for your needs.
Zirconia Crowns
Many dental practices are moving away from conventional PFM crowns and towards zirconia, a stronger and more aesthetic restorative material. They offer similar advantages to porcelain and are incredibly durable, but they’re also a popular choice because of their high translucency, which lets light pass through them like natural tooth enamel.
Zirconia crowns are biocompatible, meaning your body is unlikely to reject them or trigger an allergic reaction. This makes them a great option for people with metal allergies.
Zirconia is a relatively new technology and, as such, it hasn’t been in use for quite as long as other tried-and-true materials. That being said, the longevity of these restorations is on par with other types of crowns and can be expected to last from 10 – 15 years with proper oral hygiene and care. However, the inherent strength of zirconia can make it difficult for a dentist to fabricate an aesthetically-pleasing preparation with adequate gingival margins and thin walls.
All Resin Crowns
A resin tooth crown is created through a process that begins with a digital scan of the patient’s tooth. The scanned model is then adjusted to create the crown using specialized software. The crown is then printed using a 3D printer that utilizes a permanent crown resin selected for its strength, biocompatibility, and aesthetic properties.
Two popular examples of resin crowns include Procera and Empress crowns. Procera crowns have an aluminium oxide core that is custom milled on a CAD/CAM machine, while Empress crowns have a feldspathic porcelain outer layer that is more translucent and lifelike than standard dental ceramics. Both types of crowns can be customized to match the appearance of a patient’s natural teeth, but they don’t have the strength of a porcelain-fused-to-metal or metal crown.
Metal Crowns
Metal crowns are made of base metal alloys such as gold and nickel-chromium. They are incredibly durable and last for decades, can withstand heavy chewing forces, and require less tooth reduction during preparation, preserving more of your natural tooth structure. Metal crowns also have excellent biocompatibility and resist corrosion.
They are more visible in the smile due to their metallic color, and thus may not be suitable for front teeth. However, they are a popular choice for out-of-sight molars or back teeth that undergo the most chewing stress.
Like all other crown types, a metal crown starts with an investment mould that contains a wax pattern of the final restoration. The investment is heated, the wax melts away, and the molten metal enters the mould cavity. The crown is then cooled, and the investment mould is removed, leaving the finished metal crown. If you need a permanent crown, your dentist will cement it in place, ensuring a tight fit and excellent aesthetics.