Metal Crown Guide: Dentists’ frequently asked questions

Metal Crown Guide: Dentists’ frequently asked questions image

Metal crowns offer a range of advantages that make them a popular choice for dental restorations. Various metals such as gold, platinum, palladium, cobalt-chromium, and titanium used in metal crowns achieve exceptional durability, longevity, biocompatibility, and corrosion resistance. 

Avant Dental’s expert technicians craft a range of metal alloy, semi-precious, and precious metal crowns for durable, cost-effective restorations. Here’s what you need to know about our metal crowns.  

What metals are commonly used in metal crowns?

Some of the main metals used in metal crowns include:

Gold (Au): Gold crowns are highly biocompatible and well-tolerated by oral tissues, which reduces the risk of allergic reactions or tissue irritation. 

Platinum (Pt): Platinum crowns exhibit exceptional corrosion resistance, which contributes to the overall durability and reliability of platinum crowns in dental restorations.

Palladium (Pd): Palladium crowns provide good durability and resistance to wear while also delivering a natural-looking appearance that blends well with adjacent teeth.

Cobalt-Chromium (Co-Cr): Cobalt-chromium crowns are renowned for their exceptional strength and hardness. They can withstand significant chewing forces without fracturing or deforming.

Titanium (Ti): Titanium crowns offer excellent biocompatibility and corrosion resistance. They are also lightweight and strong, providing durability and longevity in dental restorations.

What are the key advantages of a metal crown?

Metal crowns hold several key advantages over other crown types, including:

Strength and durability: Metal crowns exhibit exceptional strength and resilience against mechanical stresses. This makes them particularly suitable for restoring posterior teeth that are subjected to substantial chewing forces. A metal crown is typically stronger than ceramic alternatives, and also generally exhibits higher flexural strength. This makes them more resistant to bending or deformation under stress.

Longevity: Metal crowns experience minimal wear over time due to their hardness and resistance to abrasion. The robust nature of metal crowns also reduces the risk of structural damage or fracture over time. They also exhibit pronounced resistance to corrosion.

Conservative tooth preparation: Metal crowns typically require minimal removal of tooth structure during the preparatory phase in comparison to alternative crown types such as porcelain crowns. This facilitates the preservation of a greater extent of natural tooth structure.

Biocompatibility: The metals commonly used in metal crowns are generally biocompatible, ensure favourable interactions with oral tissues, and minimise the likelihood of eliciting allergic reactions or adverse responses.

Cost-effectiveness: Metal crowns are often a cost-effective alternative to other crown materials, which can make them a good choice for patients in need of durable and dependable dental restorations on a limited budget. 

What are the best applications for metal crowns?

Metal crowns are particularly well-suited for certain dental applications due to their durability, strength, and other beneficial properties. Some of the best applications for metal crowns include:

Restoring molars and premolars: Metal crowns are highly effective for restoring posterior teeth that endure significant chewing forces. Their strength and durability make them ideal for withstanding the pressure and wear associated with these teeth.

Patients with bruxism: Patients with bruxism may benefit from metal crowns due to their ability to withstand excessive forces without chipping or fracturing.

Restorations with limited visibility: Since metal crowns are not as aesthetically pleasing as other types of crowns, they are often recommended for restoring teeth in areas with limited visibility, such as the back of the mouth. This helps to maintain a natural appearance for visible teeth while ensuring durability and longevity of posterior teeth.

Patients with limited budget: Metal crowns are typically more cost-effective than other types of crowns, such as all-ceramic crowns, and may be a fully functional restoration choice for patients with budget constraints.

What are the preparation considerations for a metal crown?

Reduction of tooth structure and margin placement are crucial aspects of preparing a tooth for a metal crown. Tooth preparation considerations include:

Reduction of tooth structure: The amount of tooth structure removed during a metal crown preparation depends on various factors, including the type of metal crown being used, the extent of damage or decay, and the desired final restoration.

Typically, the dentist will aim to remove approximately 0.5 millimetres of tooth structure from the outer surface and top of the tooth. This ensures adequate space for the crown to fit securely without encroaching on the surrounding tissues or impinging on the opposing teeth.

The reduction may be adjusted based on the specific requirements of the case. For example, if the tooth has extensive decay or damage, more tooth structure may need to be removed to create a stable foundation for the crown.

Margin placement: The ideal margin for a metal crown is typically 0.4 millimetres below the gum line. This ensures that the margin of the crown remains accessible for proper cleaning and maintenance while minimising the risk of irritation to the surrounding tissues.

Special care should be taken to ensure that the margin is continuous and well-defined around the entire circumference of the prepared tooth to provide a stable foundation for the crown and facilitate optimal aesthetics and function.

What’s the difference between a semi-precious metal crown and a precious metal crown?

Precious metal crowns are made from high-quality metal alloys containing noble metals such as gold, platinum, or palladium. These metals are considered precious due to their rarity, corrosion resistance, and biocompatibility.

Precious metal crowns are known for their exceptional longevity, superior biocompatibility, and high level aesthetics. The addition of precious metals, such as gold or palladium, enhances the properties of the alloy, making it more biocompatible, corrosion-resistant, and easier to work with during fabrication. However, precious metal crowns tend to be more expensive than other types of crowns due to the cost of the precious metals used in their composition.

Semi-precious metal crowns, on the other hand, are made from metal alloys that contain a combination of base metals along with a smaller percentage of precious metals. Common base metals used in these alloys include nickel, chromium, cobalt, and copper. 

What are the pros and cons of a titanium crown vs a gold crown

Titanium crowns and gold crowns are both popular choices for dental restorations. Each has its own set of advantages and disadvantages: 

Titanium crown: Titanium is known for its exceptional strength and durability, which makes titanium crowns highly resistant to wear and tear.

Titanium is also biocompatible and well-tolerated by the body, and highly resistant to corrosion and oxidation.

Titanium crowns are also relatively lightweight compared to other metal crowns, which may contribute to patient comfort. They can also be fabricated using CAD/CAM technology for precise customisation and a perfect fit.

However, titanium crowns may not have the same aesthetic appeal as gold or tooth-coloured crowns and may be less desirable for visible teeth.

Gold crown: Some patients favour the aesthetic appeal of gold crowns, particularly for posterior restorations. Gold is also biocompatible and well-tolerated by the body. It’s also highly malleable and can be easily shaped and manipulated during fabrication to achieve a precise fit with minimal tooth preparation.

However, gold crowns are typically more expensive than other types of crowns. It is also relatively soft compared to other metals, which may result in increased wear or abrasion over time.

How are metal crowns made?

Casting and milling are two common techniques used to manufacture a metal crown:  

Casting: The first step is to create a wax pattern of the crown based on the impression or scan taken of the prepared tooth. Then the wax pattern is attached to a wax sprue, which serves as a channel for the molten metal to flow into the mould. 

The wax pattern and sprue are then attached to a base or casting ring and placed in a flask. A heat-resistant material called investment is mixed and poured around the wax pattern and allowed to set.

The investment mould with the attached wax pattern is placed in an oven or furnace, where the wax pattern melts and flows out of the mould. This process is known as ‘burnout’, and leaves the mould ready to receive the molten metal.

The chosen metal alloy, such as gold, platinum, palladium, or a combination of base metals, is melted in a crucible at high temperature and poured into the mould cavity. Once the metal has completely solidified, the investment material surrounding the crown is carefully removed.

The metal crown then undergoes a finishing process to remove any excess metal, rough edges, or surface imperfections. 

Milling: Metal crowns can also be milled using computer-aided design and computer-aided manufacturing (CAD/CAM) technology. This process involves the use of specialised milling machines and software to fabricate the crown from a solid block of metal alloy. 

The process begins with a digital scan or impression of the prepared tooth and surrounding teeth. CAD software is used to create a virtual model of the metal crown that is precisely designed to ensure optimal fit and function.

A solid block of the chosen metal alloy is loaded into the milling machine, which then uses precision milling tools to carve out the crown shape according to the digital design. 

After milling, the metal crown may undergo additional surface finishing processes to remove any rough edges or imperfections and achieve the desired surface texture.  

 

Avant Dental designs and manufactures a range of metal crowns to suit all restoration needs. To find out more about working with us, please email contact@avantdental.com.au or phone 1800 287 336.

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