Types of dental crowns (2)

Dental crowns are a common restorative treatment used to repair damaged, decayed, or aesthetically compromised teeth. They are designed to encase the entire visible portion of a tooth, providing strength, protection, and improved appearance. Depending on the patient’s specific needs, dental history, aesthetic goals, and budget, several types of dental crowns are available, each with distinct materials, characteristics, and advantages.

Porcelain-Fused-to-Metal (PFM) Crowns

Porcelain-fused-to-metal crowns have been a traditional choice for decades. These crowns combine a metal base for strength and durability with a porcelain overlay for a natural appearance. The metal substructure provides resilience against chewing forces, making PFM crowns ideal for both front and back teeth.

One of the advantages of PFM crowns is their balance between strength and aesthetics. They mimic the natural translucency of teeth better than full metal crowns. However, they are not as esthetically pleasing as all-ceramic crowns because of the underlying metal, which can sometimes appear as a dark line near the gum line over time. Additionally, the porcelain layer can chip or fracture under pressure, which may require repair or replacement.

All-Ceramic or All-Porcelain Crowns

All-ceramic or all-porcelain crowns are the most aesthetic option available and are often recommended for front teeth. These crowns are made entirely from porcelain or other ceramic materials, offering a color and translucency that closely resembles natural teeth.

They are metal-free, making them a great choice for patients with metal allergies or sensitivities. Their biocompatibility also reduces the risk of gum irritation or allergic reactions. However, while they offer excellent esthetics, they are not as strong as crowns that incorporate metal. Therefore, they may not be ideal for molars or patients with bruxism (teeth grinding).

Technological advancements, particularly in zirconia-based ceramics, have improved the strength and durability of all-ceramic crowns. Zirconia crowns are increasingly used in both anterior and posterior restorations due to their superior strength, aesthetic properties, and compatibility with the body.

Zirconia Crowns

Zirconia crowns are a subtype of ceramic crowns made from zirconium dioxide, a very strong type of ceramic. These crowns are known for their strength, longevity, and biocompatibility. They are often used for posterior teeth due to their resistance to wear and fracture.

Zirconia crowns can be milled from a single block of zirconia using CAD/CAM technology, ensuring a precise fit. Some zirconia crowns are layered with porcelain to improve their appearance, combining strength with aesthetics. Solid zirconia crowns are more opaque and best suited for molars, while high-translucency zirconia can be used in the front for a more natural look.

Because of their durability, zirconia crowns are often chosen for patients with a history of grinding or clenching. They also cause minimal wear to opposing teeth compared to metal crowns.

Gold Crowns

Gold crowns are composed of a gold alloy, often mixed with other metals like platinum, palladium, or copper. These crowns are extremely durable, resistant to wear and fracture, and offer an excellent fit.

Gold crowns are particularly suitable for back molars, where their metallic color is less noticeable and where strength is crucial. They have the least likelihood of causing damage to opposing teeth and are gentle on surrounding tooth structures. In addition, gold crowns are less likely to fracture compared to ceramic or porcelain crowns.

The primary disadvantage is their aesthetic appearance, which makes them less popular for front teeth. However, for patients who prioritize function and longevity, gold crowns remain a reliable choice.

E-max Crowns (Lithium Disilicate Crowns)

E-max crowns are a type of all-ceramic crown made from lithium disilicate, a high-strength glass-ceramic. These crowns are prized for their natural appearance and durability. E-max crowns are often used for both anterior and some posterior teeth because they combine strength with superior aesthetics.

They are ideal for patients seeking highly cosmetic dental restorations and are especially effective for veneers, inlays, onlays, and full crowns. E-max crowns can be milled using CAD/CAM systems, ensuring a high degree of precision and a strong bond with the tooth when using adhesive techniques.

Although E-max crowns are stronger than traditional ceramic crowns, they may not be the best choice for patients with heavy bite forces or bruxism. They also tend to be more expensive than other options.

Stainless Steel Crowns

Stainless steel crowns are typically used as temporary solutions or in pediatric dentistry. In children, they are often used to cover primary teeth that have been treated for extensive decay or after a pulpotomy. These crowns are pre-fabricated, making them quick and easy to place.

In adults, stainless steel crowns may serve as temporary restorations while a permanent crown is being fabricated. They are cost-effective and durable but lack aesthetic appeal, making them unsuitable as a long-term solution for visible teeth.

Resin Crowns

Resin crowns are made from composite resin materials and are generally used as temporary crowns. They are more affordable and quicker to produce than other types, making them suitable for short-term use.

However, resin crowns are less durable and more prone to fractures and wear than other crown types. Their longevity is limited, and they may stain over time. Due to these limitations, resin crowns are rarely used as permanent restorations.

Hybrid Crowns (Porcelain-Zirconia or Porcelain-Lithium Disilicate)

Hybrid crowns are designed to offer a balance between aesthetics and strength. A common example is a porcelain crown layered over a zirconia or lithium disilicate core. This combination leverages the translucency of porcelain with the strength of a more robust core material.

These crowns can be tailored to match the shade and contour of natural teeth, making them ideal for patients who demand both functionality and cosmetic appeal. However, the porcelain layer can still be vulnerable to chipping, similar to PFM crowns.

Temporary Crowns

Temporary crowns are usually made from acrylic or composite materials and serve as a short-term solution while the permanent crown is being prepared. They protect the prepared tooth, maintain space, and help patients adjust to the feel of a crown.

Though not meant for long-term use, temporary crowns play a crucial role in the overall success of a crown procedure by ensuring comfort and protection during the waiting period.

Choosing the Right Type of Crown

The ideal dental crown depends on multiple factors, including:

• Location of the tooth (front or back)

• Aesthetic requirements

• Functional demands

• Material allergies or sensitivities

• Budget constraints

• Bite force and oral habits (e.g., grinding)

Dentists consider these elements when recommending a crown type. For instance, an all-ceramic E-max crown may be chosen for a front tooth that demands a lifelike appearance, while a zirconia or PFM crown may be better for molars due to their strength.

Conclusion

The diverse types of dental crowns available today offer a range of options tailored to individual patient needs. From the high aesthetics of E-max and all-ceramic crowns to the unmatched durability of zirconia and gold crowns, dental professionals can restore both function and beauty to compromised teeth. Understanding the properties and applications of each type helps patients make informed decisions and ensures long-term satisfaction with their dental restorations.