Even though dentures are fabricated from extremely durable materials - - they will break, wear out, a tooth will come out and their fit will change.
Accidents happen, dogs still like to chew on plates of the dental kind, and trash compacters have never taken kindly to dentures. In fact, it is frequently not a matter of "if" but rather a matter of "when" will a denture become broken, lost or damaged beyond repair.
One can be assured that a problem will likely happen when least expected, and immediate, usually important, plans will definitely be altered - - unless a person is prepared.
How to expect the unexpected and be prepared
A short-term use duplicate denture will bridge the gap of being without a regular denture while it is being repaired, renovated of replaced. Sometimes this type of denture is referred to an "embarrassment denture" because it helps a person avoid the embarrassment of being without teeth in an emergency or during planned denture maintenance.
While this type of denture may be made at any time from an existing functional denture, it is generally fabricated immediately after a new denture is made. The embarrassment denture is neither as accurate nor as esthetic and durable as the original, but it is adequate and only meant for short-term use. The cost is generally considerably less than the original denture.
Such an interim prosthesis may be relined annually and adjusted in advance to fit the current changing shape of an individual's jaws, and therefore be ready to use at a moments notice.
However, some individuals choose to have their embarrassment denture relined and adjusted only when they need the short-term denture. Following this latter course means that they will have to wait to wear their interim denture until an appointment can be scheduled with a dental professional to complete the reline and any adjustments. But a reline for an embarrassment denture can be done in the dental professional's office during a single appointment so a patient may leave with it refitted in the mouth.
In either case, a person would not be without a prosthesis while their regular denture is being worked on.
The embarrassment denture facilitates planned periodic maintenance
All dentures need to be periodically relined to accommodate the constant change in shape of a person's jaws. There are also times when the plastic body of a denture needs to be changed due to deterioration, or the entire denture replaced because of wear or poor fit from changing mouth conditions that can no longer be remedied by relining.
While relines can be completed in a one appointment office visit, more durable relines may require that a dental professional keep a denture for several days. Replacing the plastic body of a denture (called a rebase) takes several days and making a replacement denture takes several weeks.
It becomes easy to see how an embarrassment denture would solve being without one's regular denture for a period of time, even for planned maintenance, while getting on with one's life.
While dentures are marginally adequate substitutes for missing natural teeth, the lower denture can be troublesome for many individuals.
Inherent lower denture problems
- A lower denture interfaces with more movable mouth surfaces than an upper denture.
- The lower denture has less stabilizing surface to rest upon - - for example, there is no broad palatal surface (roof of the mouth) as in an upper denture.
- Loss of jaw bone over time brings a lower denture into closer contact with tissue extensions called frenum attachments which create dislodging forces.
While these problems are inherent to lower dentures, every person is different and not affected in the same way. There are ways to approach these problems.
Some considerations for improving lower denture stability
A thin band-like tissue extension (called a frenum) may attach between a jaw ridge (called alveolar ridge) and the inside of the cheek. This strip of tissue may become active while eating or speaking and can lift a denture from its alveolar ridge. This frenum attachment may be surgically moved (this is called a frenectomy).
Alveolar ridge bone profile lessens or literally comes closer to the floor of the mouth as jaw bone is lost over time. The bone loss is called resorption. This reduces the vestibule or space between the lip and alveolar ridge. Surgical extension of this vestibule (called vestibuloplasty) provides more alveolar ridge exposure for a denture to rest upon and reduces muscle pull due to a high frenum attachment.
As an alveolar ridge losses bone, it may often be built-up by surgically placing various substances beneath the gum tissue to increase both bulk and height of the ridge. This is called alveolar ridge augmentation.
As a person eats and speaks, the lips and cheeks exert forces towards the inside of the mouth while the tongue exerts an outward counter force. There is a space between the tongue and lips and cheeks, called the neutral zone, where there are balanced forces during function. These opposing forces can help maintain a denture in place, with surprising power, if the denture is fabricated so that it's bulk and teeth rest within this space.
Inserting metal implants into the jaw bone and fabricating a lower denture to receive and connect with these implants, in various ways, will help stabilize a lower denture - - while still allowing for comfortable and easy removal of the prosthesis for cleaning.
Ensuring that upper and lower teeth contact optimally during function (called balanced occlusion) is a basic means of stabilizing a lower denture. If one tooth strikes on one side only, the denture will rock. Even contact or biting is a necessity.
Fabrication of a denture that completely avoids contact with all potentially dislodging structures and having metal base for strength and some weight, will often facilitate stability.
What's the best approach?
Frequently several approaches are combined, and not all may be suitable for a particular patient. After a thorough examination, a licensed dental professional can best advise an individual as to the best means of helping stabilize a lower denture in their unique situation.
Denture adhesives enhance the retentive interface between the surface of a denture and underlying tissues upon which a denture rests.
Optimizing the interface space
There is a slight space at the interface between the inside of a denture and the jaw that is usually filled with saliva. As this gap increases a denture becomes less retentive and stable.
The interface space arises because of material and fabrication limitations used in making a denture. This gap is also contributed to by the constant changing contour and shrinkage of jaw bone.
While an interface space exists in all dentures and increases with time, optimum denture function and retention depends upon reducing it. Denture adhesives fill this increasing space and improve suction, and also create a sticky contact between a denture and underlying surfaces. This also helps resist foods from collecting under the denture base.
How to use denture adhesives
Thin paste adhesives are preferred to powders since they are already fluid and easier to manage and apply. However, some prefer powder types. Whatever works best for an individual should be used.
Pea sized amounts of the paste may be placed in a few places within a denture where jaw ridges fit and middle where the roof of the mouth contacts. A thin film of adhesive spreads out as a denture seats in the mouth. Use the least amount to do the "job."
If excess amounts are necessary, then the opinion of a dental professional should be sought since denture maintenance may be necessary. A licensed dental professional should be routinely seen at six-month intervals for routine oral examinations and bite adjustments.
A person needs to experiment with how often to apply adhesives. Some apply it before meals while others function satisfactorily all day with one application.
A denture and mouth should be cleaned of all adhesives at least once a day, and the denture should be left out of a cleaned and rinsed mouth for at least an hour a day.
How to clean up
It can be difficult removing adhesives. The denture may be cleaned with a brush, soap and running water or with a little white distilled vinegar in water.
All adhesives should be removed from the mouth for hygienic purposes. Rinsing with extremely warm water or salt water helps removal. It may be necessary to use a soft toothbrush or wash cloth-like material to assist removal from the mouth tissues.
Advantages of adhesives
- Effectively fills the interface gap between a denture and underlying jaw.
- Provides a sense of security with wearing dentures, even with well fitting dentures when additional confidence is desired.
- Facilitates acceptability and builds confidence with wearing new dentures.
- Reduces food impaction beneath dentures by closing prosthesis borders.
- Helps an individual open their mouth wider for more confident chewing (increases the chewing stroke) rather than eating with small strokes to compensate for concerns about the potential for a denture coming loose.
- Decreases the irritation and chafing of mouth tissues from habits such as grinding teeth together (parafunctional activities).
- Facilitates wearing dentures for individuals with persistent dry mouth (xerostomia).
Disadvantages of adhesives
- Difficult to remove adhesive from the mouth and denture.
- A false sense of security that a denture is still satisfactory may develop using adhesives with a poorly fitting denture that should be relined, replaced or maintained in different ways.
There is no specifically agreed-upon chronological answer to, ”when should a denture be replaced?" There are instances where dentures have been replaced after one year or less, and on the opposite side of the spectrum, we have all heard of people who have worn the same denture for twenty-five or more years. These ranges are obviously extremes.
However, on average, dental professionals seem to be replacing dentures somewhere between four to eight years. This would seem to imply that the average denture fabricated from contemporary biomaterials will wear out and deteriorate within that time and/or the average denture patient's jaws have changed so much that a new denture must be redone.
Each individual's denture needs are different. There are some factors that a licensed dental professional takes into consideration when evaluating the need to replace dentures.
Denture longevity considerations
Lost vertical dimension: The proper linear distance relationship between the upper and lower jaws is called vertical dimension. This is unique for each individual.
As jaw bone changes and the ridges upon which dentures rest shrink, a denture becomes loose and vertical dimension begins to change (the vertical dimension is said to be lost by a certain linear measurement unit such as millimeters). Additional plastic (acrylic resin) is added to the inside of a loosening denture (called relining a denture) to stabilize it by reducing looseness caused from jaw shrinkage. However, relining does not restore vertical dimension in an accurate way.
The current position, held by most dental professionals is that when vertical dimension has been lost by three millimeters or more a new denture should be fabricated in order to restore vertical dimension and maintain functional health.
There are individuals who have worn the same denture for extended periods with considerable loss of vertical dimension over time. Since vertical dimension loss is a slow, but nevertheless progressive, process they have gradually adapted to a continually increasing closed bite position. These individuals often have a sunken facial appearance and usually appear much older than their chronological age.
Functioning in such a progressive and excessively closing vertical dimension position may eventually result in alterations of the temporomandibular joints (TMJ, the jaw joint located in front of the ears). This can lead to significant pain and difficulty with effective eating and even the jaw motions involved with speech. It frequently becomes quite difficult, if not impossible, to restore such individual's proper vertical dimension and chewing efficiency by relining and repairing this older denture.
Tooth wear: Aside from impaired ability to chew effectively, excess tooth wear will adversely affect esthetics and cause other problems associated with lost vertical dimension, as described above. While porcelain denture teeth will wear at a slower rate than plastic teeth, they nevertheless will wear and are more susceptible to chipping and cracking. Multiple cracked teeth will ned to be replaced.
Deterioration: While the biomaterials used to fabricate dentures today are quite durable, they still deteriorate and exhibit dimensional change over time - - no longer properly fitting, even after relining.
Aging plastic looses its natural appearance and texture, and coloration fades, making dentures look quite artificial.
Deteriorating plastic also makes it easier for dentures to become excessively contaminated with microorganisms. This contributes to mouth irritation and bad taste, and socially unacceptable odors will develop that no amount of denture cleaning will seem to eliminate.
Keeping regular dental check ups so that one's dentures, soft tissues and jaw bone may be checked is essential to extending the life of a denture and maintaining oral health.
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.
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.
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.
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.
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.