Dentures are removable devices designed to replace missing teeth and the surrounding gum tissue. Modern prosthetics represent a substantial advancement over historical options, offering significant improvements in fit, comfort, and natural appearance. Contemporary denture construction relies on a combination of highly engineered polymers and specialized metal alloys. These materials are selected for their biocompatibility, durability, and ability to mimic the look and feel of natural oral structures.
Materials Used for the Denture Base
The pink-colored foundation, known as the denture base, is predominantly constructed from a rigid plastic called Polymethyl Methacrylate (PMMA) acrylic resin. PMMA is the standard material because it is cost-effective, easily manipulated, and can be pigmented to match natural gum tissue. Its low density contributes to patient comfort, and its processing is straightforward, allowing for easy adjustments and repairs. However, PMMA is susceptible to fracture under high impact and can absorb water, which slightly affects its mechanical stability.
Another choice for the base involves flexible thermoplastic resins, such as those made from nylon. These materials are highly valued for their strength, elasticity, and comfort, as they flex slightly in the mouth. Nylon-based resins are metal-free and semi-transparent, allowing the patient’s underlying tissue tone to show through, which enhances the natural look of the appliance. This flexibility makes them suitable for certain partial dentures where the appliance must navigate existing undercuts.
For applications requiring exceptional rigidity and minimal bulk, particularly in partial dentures, a metal framework is often incorporated into the base. The gold standard for this component is a cobalt-chromium alloy, which offers an exceptional strength-to-weight ratio and high resistance to corrosion. Modern manufacturing techniques like Selective Laser Melting (SLM) are used to create these frameworks, resulting in a more precise fit and thinner, lighter prosthetics. The metal framework provides the necessary stability and support, while the gum-colored acrylic resin is processed over it.
Materials Used for the Artificial Teeth
The artificial teeth are generally made from acrylic resin or porcelain. Acrylic resin teeth are the most common selection today, composed of a blend of polymers that allow for multilayered construction. This layering helps mimic the subtle variations in color and translucency found in natural teeth, resulting in a highly realistic appearance. A major practical advantage of acrylic teeth is that they form a strong chemical bond with the PMMA denture base, preventing the teeth from detaching easily.
Historically, porcelain teeth were prized for their superior aesthetics, offering remarkable translucency and resistance to wear. However, porcelain is rarely used in modern denture construction due to several significant drawbacks. Because porcelain does not chemically bond to the acrylic base, it requires a mechanical attachment, which is inherently weaker and can lead to fractures. Moreover, the extreme hardness of porcelain can cause excessive abrasion on any opposing natural teeth and may transmit greater chewing forces to the jawbone.
How Material Choices Differ by Denture Type
Material selection is tailored to the specific type of prosthetic being fabricated. For a conventional full denture, which replaces all teeth in an arch, the appliance relies heavily on PMMA acrylic resin for both the base and the teeth. This combination is chosen for its ease of repair, lightweight nature, and the strong chemical fusion between the base and the teeth. The entire structure rests on the gum tissue, so the light weight of the acrylic is advantageous for retention and comfort.
Partial dentures replace only some missing teeth and must integrate with remaining natural teeth. This often necessitates a cobalt-chromium metal framework to provide the rigidity and strength needed to withstand chewing forces and securely clasp the remaining teeth. Alternatively, a flexible partial denture uses nylon-based thermoplastic material for the entire appliance, relying on the material’s elasticity to clasp natural teeth without visible metal components.
Implant-supported dentures, whether fixed or removable, utilize materials offering enhanced stability and durability to match the support from underlying implants. The implants themselves are titanium or zirconia, chosen for their ability to fuse with the jawbone. The restorative portion often incorporates a metal bar within the acrylic base for maximum strength and rigidity. The teeth on these appliances may be made from higher-grade composite resins or ceramics like zirconia, which offer superior resistance to wear compared to conventional acrylic.