Professional Denture Help

"What about...?"

• Why have regular comprehensive denture check-ups?
• Dry mouth
• Porcelain versus Plastic denture teeth
• Soft Denture Liners

• Why Have Regular Comprehensive Denture Check-ups?

Regular and comprehensive examinations by a dental professional are critical to ensuring not only the proper function of a denture but also the maintenance of total oral health.

Two significant things that happen to a denture over time

	•	It loosens - - Jaw ridges (alveolar ridges) will shrink in size and become smaller due to gradual and continuing bone loss (bone resorption) that occurs in everyone, to varying degrees. This results in dentures becoming increasingly loose because they were fabricated originally to fit larger alveolar ridges.
	•	It wears - - Denture teeth will wear from use. In addition, uneven and irregular tooth wear develops as a denture becomes loose and starts shifting.

Denture loosening combined with uneven tooth wear results in a reciprocal and cyclical reinforcing synergism between the two destructive processes.

As a denture increasingly shifts on its soft tissue and jaw bone foundation, it rubs and chafes the alveolar ridge. This causes irritation, soreness and various types of pathology, including accelerated bone loss. In turn, this will cause more uneven tooth wear, which will cause more accelerated bone loss, and so on back and forth. This is a gradual and unrelenting process that worsens over time, frequently at the expense of excessive jaw bone loss, the thinning of overlying gum tissue and the need to prematurely replace a denture - - unless detected and corrected in a timely manner.

If these problems are detected early, as during a regular check-up, they often may be remediated by adding plastic (acrylic resin) to the inside of a denture in order to allow it to again fit closely against the alveolar ridge (called relining or rebasing). In addition, irregularly worn teeth may be adjusted, or sometimes replaced or built-up. Eventually a denture will need to be replaced, but generally there are few good reasons to do so prematurely.

Some other check-up considerations

	•	The need to adjust a denture, as determined by regular check-ups, helps keep a proper relationship between the jaws and thus maintains esthetics. Keeping jaws in a proper functional relationship, and, sometimes building-out certain denture surfaces, will support the face and help prevent a premature aging appearance.
	•	The temporomandibular joints or TMJs (the jaw joints located in front of each ear) undergo constant change in shape throughout life by a process called bone remodeling. This process is a functional response. If improper jaw function occurs, as a result of unadjusted dentures and improper bite, it is possible for the TMJs to remodel into a pathologic relationship. This could result in numerous pathological conditions, including impaired jaw function, headache and other head and neck pains.
	•	Sometimes, more importantly than finding denture problems is the opportunity to detect serious oral pathology, such as cancer, that may be discovered in early stages rather than later when radical and sometimes devastating therapy is necessary. The maintenance of healthy oral tissues is essential for optimum comfort in long-term denture wearers.

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• Dry Mouth And The Denture Patient

Persistent dry mouth, which is called xerostomia, can significantly complicate wearing dentures.

Xerostomia and wearing dentures
To a great extent, dentures stay in place comfortably and in a stabilized manner by development of an intimate interface between denture surfaces and soft tissues they rest upon. Presence of adequate amounts of saliva within this denture/tissue interface is essential. Without enough saliva, a denture will inadequately adhere to tissues, partly through loss of suction. In addition, tissues contacting a denture will become chafed and irritated without the lubricating effects of saliva.

Some common causes of xerostomia

Medications: There are approximately 500 commonly prescribed medications that have xerostomia as a possible side effect, and this is a frequent cause of dryness.

Aging: Productivity of salivary glands will diminish as some individuals age.

Illnesses: Xerostomia is usually or sometimes associated with certain illnesses or conditions such as: chronic diarrhea, liver dysfunction, Sjogren's syndrome, and so forth.

Radiation therapy: Radiotherapy is used to treat some cancers, and a side effect may be reduced salivary gland function.

Habits: Chronic mouth breathing and inadequate fluid consumption will often cause dry mouth.

Approaches to managing xerostomia

Before managing a persistent dry mouth, it is essential to first become aware of the problem - - then attempt to determine causation for the xerostomia. Sometimes the cause is easily eliminated, but in many instances that is not possible, and the condition is persistent and often progressive. There are several approaches to managing xerostomia.

	•	Modify medications: If a certain medication is suspected of causing xerostomia, consultation with a person's physician may make it possible to use a different, but equally effective, drug that no longer causes dry mouth or causes it to a lesser degree. However, there are often not suitable alternatives for a particular person's individual problem. Under no circumstances should someone discontinue or attempt to change a medication without the explicit knowledge and approval of their physician - - to do otherwise may result in serious illness or death.
	•	Sialagogues are substances that stimulate the production of saliva. There are two important types of sialagogues. 1) Gustatory sialagogues such as sugar free hard candies will frequently cause some increase in salivation, and citrus flavors such as lemon are sometimes more effective than others. While sugar free low-sticking gum has been suggested, the process of chewing gum could more easily irritate already poorly lubricated tissues by increasing denture movement. 2) Pharmaceutical sialagogues (called parasympathomimetic agents) sometimes improve salivation and must be prescribed by a person's physician - - if their health status allows such a consideration.
		Salivary substitutes are commercially available solutions that help keep the mouth moist and more lubricated. These compounds must usually be applied frequently and they generally necessitate having a container of the substance nearby.
	•	Water: Water is a salivary substitute and often is used in place of commercial salivary substitutes. Regularly moistening the mouth, and drinking increased amounts of water may both hydrate tissues and facilitate some increase in production of saliva in certain individuals. While increased intake of water is generally healthful, persons with certain medical conditions such as but not limited to congestive heart failure should first check with their physicians before significantly increasing their routine consumption of fluids.

Alternative denture therapy for patients suffering from xerostomia

Those patients who are not able to comfortably wear conventional dentures, due to severe xerostomia, might consider implant-supported dentures. If this course of treatment is pursued, intense oral hygiene practices are necessary to maintain healthy implants in the presence of reduced salivary production. A person should always consult with their dental professional to determine which treatment is best for them.

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• Porcelain Versus Plastic Denture Teeth

In the past, artificial porcelain teeth were generally preferred over plastic teeth due to their greater durability and esthetics. However, in recent years, new generation biomaterials have resulted in development of very wear resistant plastic teeth. Clinically, the esthetics of plastic and porcelain denture teeth is nearly comparable, with good quality porcelain teeth still being the standard for esthetics. The majority of dentures today are probably fabricated with plastic teeth. For all practical purposes, the cost of porcelain and plastic teeth are about the same.

While porcelain and plastic teeth are competitive with regards to durability and to a lesser extent esthetics and wear there are other factors that may favor the selection of one type of tooth over another.

Some selection factors

	•	Balanced bite and force transmission: Denture bite (called occlusion) changes due to constantly changing jaw bone (called alveolar bone) upon which a denture rests, and, to varying degrees, uneven tooth wear resulting from use. Unless a denture is evaluated and its occlusion adjusted to a uniform and even contact (called balanced bite or balanced occlusion) at regular intervals, denture occlusion will become unbalanced. Since porcelain teeth are more wear resistant, their occlusion will not become significantly self-altered by wear, as will plastic teeth. However, when alveolar bone changes cause an unbalanced occlusion, the resulting biting forces from porcelain teeth will be unevenly transmitted to underlying supporting alveolar bone. Frequent tissue refitting of the denture usually eliminates or lessens this problem. Porcelain denture teeth tend to transmit the impact of biting forces to the alveolar ridge with greater intensity than that transmitted by plastic teeth in an unbalanced tooth contact situation. Some practitioners are of the opinion that this greater force, especially when uneven as in an unbalanced occlusion, may be damaging to the alveolar ridges and could result in accelerated bone loss. Therefore, unless denture occlusion is checked and balanced on a regular basis, plastic teeth would probably be a preferred choice than porcelain teeth.
	•	Bone loss: If a person has lost a great deal of supporting alveolar bone and their gum tissue is not of a sturdy type, then plastic denture teeth might be a better choice. These teeth are more forgiving of excessive forces developing from habits such as clenching, grinding and tapping or "clacking" of teeth - - which seems to be more prevalent among older individuals. Plastic teeth do not transmit forces to underlying bone as intensely as porcelain teeth.
	•	Noise: If porcelain teeth are vigorously used or sometimes habitually tapped together, a "clacking" sound can be heard. Plastic teeth will muffle this sound and be quite during normal function or habit jaw motions (called parafunction).

Which type of tooth is best?

	•	If a person has been successfully wearing dentures with porcelain teeth then they should probably continue with porcelain teeth. These teeth will not wear as fast as plastic teeth, and the relationship between upper and lower jaws will tend to stay normal for a longer time than with plastic teeth.
	•	Regardless of which type of tooth is selected, the success of the selection is strongly based upon regularly checking dentures for proper balanced occlusion and fit on regular intervals.
	•	If a denture is going to be worn against opposing natural teeth than plastic teeth should be selected because porcelain teeth, being harder, could excessively wear natural teeth away.
	•	After a thorough examination and frank discussion of what a person wants from wearing a denture, a licensed dental professional can effectively discuss which type of tooth would best meet a particular individuals unique needs and desires.

Tooth strength

Because porcelain teeth are extremely hard in comparison to plastic teeth, they tend to chip and crack easier. For this reason, when dentures having porcelain teeth are brushed and cleaned, they are generally handled over a sink filled with water or over a towel. Should the denture accidentally fall, the water or towel would help break the fall and hopefully reduce tooth breakage.

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• Soft Denture Liners

A soft liner is placed in that part of a denture base that contacts tissues. This provides comfort for those persons experiencing considerable pain while wearing a denture that has a hard plastic interface (the inside of the denture).

These individuals may have a low threshold for pain, and/or the gum tissue that overlays jaw bone is usually thinner than normal and does not resist pressure well. When such tissue is compressed between hard jaw bone and hard denture plastic, pain is easily elicited. Replacing one of these hard interfaces with a soft denture liner helps eliminate or reduce this painful tissue compression.

Some characteristics of soft denture liners

	•	Denture liners are usually fabricated from special medical grade rubber or silicone type compounds. The silicone materials are generally more compressible and consequently softer.
	•	In order for these materials to function adequately they must be reasonably thick. Therefore, the amount of plastic that needs to be removed from the inside of a denture, to allow room for these liners, may weaken some dentures. In those cases it becomes necessary to incorporate a reinforcing metal framework within the body of certain dentures. There are several steps involved in installing a soft liner, such as impressions and various laboratory procedures.
	•	Soft denture liners tend to continually harden, though a patient may not be aware of this happening because the process is gradual. However, they will eventually begin to have increasing problems until a new soft liner is placed.
	•	Denture liners are porous in nature with accounts for why they are soft. However, this porosity contributes to their deterioration and collection of microorganisms.
	•	If a soft denture liner become contaminated with disease causing microorganisms (a fungus for example), it may not be possible to decontaminate the denture without having to replace the liner.
	•	Persons with dry mouth usually have difficulty wearing dentures due to pain and irritation caused by the hard denture surface rubbing against underlying tissues that are not lubricated with adequate saliva. While soft denture liners would appear to be ideal for such individuals, they are generally much more difficult to maintain. Because impaired saliva production allows a very significant collection of microorganisms to build-up in the mouth, this usually results in unacceptable contamination of porous soft denture liners unless meticulous hygiene is maintained.
	•	While denture liners will generally last longer than a year, they should be considered to be replaced on an annual basis or sooner. The frequency of replacement depends on each situation and the patient's oral hygiene.
Advantages of soft denture liners
	•	A gentle and kinder denture interface for those individuals with sensitive underlying tissues.
	•	The soft denture liner tends to compress and conform to a constantly changing jaw bone surface. While this helps prevent pain from a moderately unbalanced bite resulting from jaw bone shrinkage, it is not a long-term substitute for regular adjustments to balance a denture bite.
Disadvantages of soft tissue liners
	•	Soft denture liners continually deteriorate and collect microorganisms easily; therefore, they are generally replaced on an annual basis.
	•	Because soft denture liners help reduce pain from an uneven bite, patients may get a false sense of security - - thinking their denture is adequately functioning while the bite continues to deteriorate. Routine dental check-ups are a necessity.
	•	Generally more expensive than a conventional hard denture liner.

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