A Guide to Modern Prosthodontic Materials

Prosthodontics has significantly advanced due to new materials, offering dentists and patients a variety of high-performance options for dental restorations. These modern materials provide a mix of strength, durability, and a natural look, moving beyond the limited and less aesthetic choices of the past. Understanding these options is key to making informed dental care decisions.

Zirconia in Prosthodontics

Zirconia (zirconium dioxide) has become a cornerstone of restorative dentistry due to its exceptional strength and biocompatibility. It’s a ceramic material known for its toughness, making it highly resistant to fracture and wear. Initially used primarily for posterior crowns and frameworks for bridges, advancements have improved its translucency, expanding its use to aesthetic anterior restorations.

Properties and Advantages

• Superior Strength: Zirconia has a flexural strength that can exceed 1200 MPa, making it one of the most durable materials in dentistry. This makes it ideal for full-arch restorations, long-span bridges, and for patients who grind their teeth (bruxism).
• Biocompatibility: It is highly biocompatible, meaning it rarely causes allergic reactions or tissue irritation. This makes it a safe option for long-term placement in the oral cavity.
• Aesthetics: Modern monolithic and multilayered zirconia options offer improved translucency and shading capabilities, allowing for restorations that mimic the appearance of natural teeth more closely than ever before.
• Versatility: Zirconia can be used for a wide range of applications, including single crowns, bridges, dental implant abutments, and full-arch implant-supported prostheses.

Limitations

Despite its many benefits, zirconia does have some drawbacks. Its extreme hardness can sometimes cause wear on opposing natural teeth, although modern polished zirconia has minimized this issue. It can also be more challenging to adjust and polish in the dental office compared to other materials. Finally, while its aesthetics have improved, it may not achieve the same level of translucency as materials like lithium disilicate in highly demanding anterior cases.

Lithium Disilicate in Prosthodontics

Lithium disilicate is a glass-ceramic material praised for its outstanding aesthetic qualities. Marketed under brand names like E.max, it has become the gold standard for single-unit anterior restorations where appearance is the primary concern.

Properties and Advantages

• Exceptional Aesthetics: Lithium disilicate’s high translucency and light-diffusing properties allow it to blend seamlessly with natural teeth, creating lifelike restorations that are virtually indistinguishable from the surrounding dentition.
• Good Strength: While not as strong as zirconia, lithium disilicate offers a flexural strength of around 360-500 MPa, which is more than sufficient for single crowns, inlays, onlays, and veneers.
• Bondability: Unlike zirconia, lithium disilicate can be etched and bonded to the tooth structure. This strong adhesive bond enhances the overall strength of the restoration and the tooth, provides a better marginal seal, and allows for more conservative tooth preparation.

Limitations

The primary limitation of lithium disilicate is its lower strength compared to zirconia. This makes it unsuitable for long-span bridges or for patients with severe bruxism. Its use is generally restricted to single-tooth restorations or short-span anterior bridges where biting forces are lower.

PEEK in Prosthodontics

PEEK (Polyetheretherketone) is a high-performance thermoplastic polymer that has recently gained traction in dentistry. Originally used in medical implants like spinal cages and hip joints, its unique properties make it an interesting alternative to traditional metal and ceramic materials in prosthodontics.

Properties and Advantages

• Shock Absorption: PEEK has a modulus of elasticity similar to human bone. This means it can flex slightly under load, absorbing biting forces rather than transmitting them directly to the underlying bone or implants. This property is particularly beneficial for implant-supported prostheses.
• Lightweight: PEEK is significantly lighter than metal alloys, which enhances patient comfort, especially for large, full-arch restorations.
• Biocompatibility and Radiopacity: It is biocompatible and does not show up on X-rays, making it easier to evaluate the underlying structures.
• Digital Workflow: PEEK is well-suited for CAD/CAM manufacturing, allowing for precise and efficient fabrication of frameworks for dentures and bridges.

Limitations

PEEK’s main drawback is its aesthetic quality. It has an opaque, off-white color that is not suitable for monolithic (full-contour) restorations where appearance is critical. As a result, it is almost always used as a framework that is then overlaid with composite or other aesthetic materials. It also has lower wear resistance compared to ceramics.

Comparing the Materials

Feature	Zirconia	Lithium Disilicate	PEEK
Strength	Very High	Moderate	Moderate
Aesthetics	Good to Excellent	Excellent	Poor (as a monolith)
Biocompatibility	Excellent	Excellent	Excellent
Primary Use	Crowns, bridges, implants	Crowns, veneers, inlays	Implant frameworks, dentures
Bondability	Poor (requires special protocol)	Excellent	Requires mechanical retention
Shock Absorption	Low	Low	High

Factors to Consider When Choosing a Material

Selecting the right material is a collaborative decision between the dentist and the patient. Several factors must be taken into account:

• Location in the Mouth: Anterior teeth require the highest aesthetics, making lithium disilicate a top choice. Posterior teeth endure greater biting forces, often making zirconia the more durable option.
• Functional Demands: Does the patient grind their teeth? Are they receiving a single crown or a long-span bridge? These questions will guide the choice toward a material with the necessary strength.
• Opposing Teeth: The material of the teeth that will bite against the restoration is a consideration. A super-hard material might wear down a softer, natural opposing tooth.
• Aesthetic Expectations: The patient’s desire for a natural-looking smile is paramount. In some cases, a layered approach combining a strong core (like zirconia) with a more aesthetic porcelain overlay may be the best solution. For those seeking the very best dental implants in Las Vegas or any other city, discussing material options is a key part of the consultation process.

Conclusion

When choosing between zirconia, lithium disilicate, and PEEK, the best material depends on the specific clinical situation. Zirconia is ideal for strong, long-lasting restorations. Lithium disilicate is best for aesthetic results in the front of the mouth. PEEK is a lightweight, shock-absorbing option, especially for implant-supported restorations.