Learn About 19135 Denture Problems

Metal Based Denture vs Plastic - Which is Best for You?

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

by Joseph J. Massad, D.D.S.

+Jim Du Molin is a leading Internet search expert helping individuals and families connect with the right dentist in their area. Visit his author page.

Learn About Conventional Over-Denture

A conventional over-denture rests over some healthy natural tooth roots. This approach was first reported in 1861. To understand this method, it is necessary to review some facts.

An Overview of Alveolar Ridge Dynamics

• Maintaining a denture on the jawbone ridge (called alveolar ridge) is essential to prevent it from becoming loose during eating, speaking, and other activities.
• Preserving the alveolar ridge facilitates denture stability.
• The body tends to conserve energy and nutrients by maintaining only structures with apparent immediate value. A typical example is the bulk reduction of a broken leg held immobile by a full-leg cast for a month or more.
• The body recognizes that the only one purpose for alveolar bone is to hold tooth roots.
• Alveolar bone no longer supporting a tooth root is removed, or literally dissolved away, by the body. This is called resorption, or simply shrinkage.
• Resorption progresses at varying rates in the same person at different times, and at different rates between different people. Resorption progresses rapidly within the first year of losing a tooth, after which time, the rate progresses at a slower pace.

From this overview, if the maximum amount of alveolar ridge is to be maintained, then preserving the maximum number of periodontally healthy tooth roots should achieve that end.

Preserving the Sensation of Having Teeth

Studies demonstrate that even though only roots are preserved, and a denture covers them, a patient still has sensory input sensations similar to that experienced with teeth, as opposed to individuals with conventional dentures and no preserved roots. Over-denture patients also appear to have a more natural perceived directional sense in their chewing activities. In other words, many patients relate that they still feel like they have teeth -- a positive comment.

Underlying Philosophy of the Conventional Over-Denture

If a patient's treatment plan to have a denture, and the roots of some remaining teeth are supported in healthy alveolar bone, then a conventional over-denture is a viable consideration.

However, only a licensed dentist can determine if a conventional over-denture is a suitable consideration for a certain person, after a comprehensive examination.

Some Characteristics of a Conventional Over-Denture

• Most of a tooth crown (that part of the tooth above the gums) is removed. This often necessitates root canal therapy if not already done.
• The remaining tooth, projecting above the gum, is rounded and usually covered with a similarly shaped artificial crown-like covering.
• Various configurations and extensions may be built onto some retained roots. In those cases, that portion of the denture overlying these configurations is modified to contain attachments that clip onto a framework or receive the individual extensions. In addition to preserving alveolar bone and sensory input, the denture is held securely in place, but may be comfortably and easily removed for cleaning.

Advantages of a Conventional Over-Denture

• Feels more like having teeth
• More retentive in many cases
• Helps reduce shrinkage of surrounding bone
• Reduces pressure to portions of the alveolar ridge
• Positive psychological advantage of still having teeth

Disadvantages of a Conventional Over-Denture

• Scrupulous oral hygiene is essential in order to prevent decay and gum disease
• The over-denture may feel bulkier than a conventional denture
• Frequent maintenance examinations are necessary
• Generally, this is a more expensive approach than a conventional denture

by Joseph J. Massad, D.D.S.

+Jim Du Molin is a leading Internet search expert helping individuals and families connect with the right dentist in their area. Visit his author page.