Dental crowns and bridges are two forms of dentistry used to repair damaged teeth or replace teeth that have been lost secondary to caries, trauma, periodontal disease, etc. For patients, regaining function and improving aesthetics are often prerequisites for dental implant treatment. Throughout the last fifty years, materials used for dental implants have been extensively researched, and an understanding of how the physical and chemical properties affect the clinical outcome of the treatment has considerably improved.
These properties include the surface composition and the microstructure of dental implants. Ideally, implant materials should be biocompatible and resistant to corrosion and fracture. Implants can be made from titanium or zirconia (ceramic).
At DDS Lab, the material we recommend for crown restorations will depend on several factors, including which tooth the crown will restore, the presence or absence of parafunctional habits, and metal allergies. Before choosing the material for crowns or fixed prostheses, it is essential to discuss the benefits and limitations of each option.
Titanium Dental Implants
Titanium has been used to make dental implants for decades. It is widely regarded as the “gold standard of implants.”
Commercially pure titanium is represented by four distinct grades, specifically grade 1, grade 2, grade 3, and 4. Pure titanium ranges from grade 1, which has the highest corrosion resistance, formability, and lowest strength, to grade 4, which offers the highest strength and moderate formability.
Titanium alloys are metals that contain a mixture of titanium and other chemical elements. For most applications, it is alloyed with small amounts of aluminum and vanadium, typically 6% and 4%, respectively, and for some, it's also alloyed with palladium. Such alloys have very high tensile strength and toughness, are light in weight, have corrosion resistance, and can withstand high temperatures.
The heat resistance enables a heat treatment process after the alloy has been worked into its final shape before it is put to use, allowing much easier fabrication of a high-strength product. The most common titanium alloy has 6% aluminum and 4% vanadium and is heat treated to improve its strength, resulting in a low-density material that is resistant to corrosion and fatigue.
Implants made from titanium are biocompatible; thus, when the metal comes in contact with the bone, the bone grows next to the metal without disruption.
There have been some concerns over titanium sensitivity, possibly associated with surface corrosion of implants, but most of the research relates to orthopedic implants. There is little evidence to show allergies to titanium, although some people may have a sensitivity or an allergy to other metals used in titanium alloys. Also, some patients prefer not to have any form of metal in their bodies.
Benefits of Titanium
High proven success rate of 95%.
Titanium implants have proven longevity.
Limitations of Titanium
Potential allergic reactions in some patients
Some patients complain of a metallic taste in the mouth.
Porcelain Fused to Metal (PFM) Dental Implant-Supported Restorations
As the name suggests, porcelain fused to metal (PFM) crowns combines porcelain and metal. The porcelain overlay is color-matched to the patient’s natural teeth. Sometimes, the dark metal margin could show at the gingival margin, especially with gingival recession or high smile lines. Dentists may recommend PFM restorations for patients who desire strength and a natural appearance.
Benefits of PFM restorations
The material is durable.
Matching a patient’s tooth coloring to PFM restorations may be relatively easy.
Limitations of PFM restorations
PFM restorations contain various types of metals, which can cause allergic reactions in some patients.
The metal around the margins of PFM crowns can become visible at the gingival margin, which is considered unappealing for some patients.
Zirconia Dental Implants
Zirconia dental implants are ceramic dental implants; they are not metal. They may break more easily than titanium implants. Zirconia, a metal in the periodic table of elements, is found worldwide. Everyday household items such as dinnerware, pipes, and electrical fixtures are made from zirconia.
Because of its natural strength and durability, zirconia is ideal for dental crowns. Zirconia crowns are best for patients who need posterior crowns, which require much strength for masticating food and parafunctional habits.
Benefits of Zirconia
Is compatible with human tissues
Implants have a low bacterial attraction
Have high strength and decent fracture resistance
They hold up well regarding wear and corrosion
Have excellent esthetics (no metal margins)
Limitations of Zirconia
Over time, the material may deteriorate and lead to microfractures. Implants are typically only available in one-piece implants; titanium implants are a better option if angle correction is needed.
Grinding zirconia can decrease its fracture resistance.
Although evidence is limited, zirconia implants may have higher failure rates when compared to titanium implants.
Less clinical research has been conducted on zirconia implants than titanium and PFM restorations.
Implant-supported zirconia crowns can be more costly.
The skilled technicians at DDS Lab have in-depth knowledge about zirconia, titanium, and PFM materials used for restorations and are always willing to discuss specific cases with you.