Why Consider a Metal-Based Denture?

By Brian J. Gray, DDS, MAGD, FICOI

A metal-based denture is one in which a portion of the denture body is made of a substantial metal casting rather than all plastic (acrylic resin). This procedure is usually done on the lower denture.

There are two types of metal-based dentures.

• Standard metal-based denture: The metal base portion of the denture is in direct contact with underlying supporting tissues.

  The base is fabricated from a special medical grade alloy that is hypoallergenic and very biocompatible with tissues. Generally, tissues in contact with this type of material are very healthy in appearance.

• Modified metal-based denture: The metal base portion of the denture is not in direct contact with underlying supporting tissues.

  A soft or hard plastic liner may be interposed between the metal and supporting tissues. A soft liner is generally preferred to hard plastic since it is more comfortable to wear; however, the soft liner usually should be replaced on an annual basis.

The Rationale for a Metal-Based Denture

• Facilitates the avoidance of disruptive forces: Sometimes it is necessary to construct a very narrow denture in order to avoid any structures that would loosen the prosthesis, such as muscles flexing, and so forth. In addition, necessary surgical procedures to reposition a muscle attachment (called a frenum) can sometimes be avoided with these narrow type dentures.

  However, such narrow dentures are weak and tend to break quite easily when fabricated just from plastic. A metal base provides the needed strength to design a very narrow denture in order to follow the confines of a patient's lower resorbed alveolar ridge (the remaining bony ridge). In addition, the metal base provides long-term dimensional stability and strength that is not enjoyed with an all-plastic denture base.

• Provides a more natural feeling: The added weight of the metal base provides a more natural perception for many patients. Many patients prefer the additional weight on the lower jaw.

  A private study measured the actual weight of cadaver jaw ridges and teeth that would normally be lost after the extraction of teeth and associated natural shrinkage of the jawbones. It was found that the weight of these tissues closely approximated the weight of a metal base. Therefore, it is likely that the more natural feeling perceived by persons wearing metal-based dentures is probably real rather than imagined.

  The additional weight of a metal base also contributes to lower denture stability by causing the denture to settle down onto a jaw ridge.

Advantages of Metal-Based Dentures

• Very biocompatible and hypoallergenic with healthy appearing supporting tissues
• May include a soft liner
• Can be relined easily
• Provides added strength for easily broken narrow dentures
• Facilitates fabrication of stable narrow-based dentures that are designed to avoid contact with disrupting muscle forces
• Sometimes facilitates the avoidance of surgical procedures to reposition frenum
• Patients perceive a more natural feeling from the added weight
• Weight may contribute to additional denture stability
• Dimensionally very stable when compared to all-plastic-based dentures during fabrication and over time

Disadvantages of Metal-Based Dentures

• Generally difficult to reline standard metal-based dentures; modified metal-based dentures (described earlier above) are easier to reline
• More costly to fabricate