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Dentures

 

dentures

A maxillary denture.
dentures

Occlusal view of the same maxillary denture.
Dentures are prosthetic devices constructed to replace missing teeth, and which are supported by surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable, however there are many different denture designs, some which rely on bonding or clipping onto teeth or dental implants. There are two main categories of dentures, depending on whether they are used to replace missing teeth on the mandibular arch or the maxillary arch. There are many informal names for dentures such as dental plate, false teeth and falsies.

Causes of tooth loss

Patients can become entirely edentulous (without teeth) due to many reasons, the most prevalent being removal because of dental disease typically relating to oral flora control ie:periodontal disease and tooth decay. Other reasons include tooth developmental defects caused by severe malnutrition, genetic defects such as Dentinogenesis imperfecta, trauma, or drug use.

 Advantages of dentures

Dentures can help patients in terms of:
1. Masticatory - improving chewing ability by replacing the edentulous area with acrylic teeth. Thus enable better mastication and pleasure to enjoy food.
2. Aesthetic - providing the visual appearance of having natural teeth, providing support for their lips and cheeks, and correcting the collapsed appearance commonly seen between the nose and the chin.
3. Phonetic - Replacing the toothless area, especially the anteriors, to help patients to speak and pronounce certain words properly without air escapes.

 Types of dentures

1. Removable partial dentures

Removable partial dentures are for patients who are missing some of their teeth on a particular arch. Fixed partial dentures, better known as "crown and bridge", are made from crowns that are fitted on the remaining teeth to act as abutments and pontics made from materials to resemble the missing teeth. Fixed bridges are more expensive than removable appliances but are more stable.

2. Complete dentures

Conversely, complete dentures or full dentures are worn by patients who are missing all their teeth in an arch (i.e the maxillary(upper) or mandibular(lower) arch).

Problems with complete dentures

Problems with dentures include the fact that patients are not used to having something in their mouth that is not food. The brain senses this appliance as "food" and sends messages to the salivary glands to produce more saliva and to secrete it at a higher rate. New dentures will also be the inevitable cause of sore spots as they rub and press on the mucosa (denture bearing soft tissue). A few denture adjustments for the weeks following insertion of the dentures can take care of this issue. Gagging is another problem encountered by some patients. At times, this may be due to a denture that is too loose fitting, too thick or extended too far posteriorly onto the soft palate. At times, gagging may also be attributed to psychological denial of the denture. (Psychological gagging is the most difficult to treat since it is out of the dentist's control. In such cases, an implant supported palateless denture may have to be constructed or a hypnotist may need to be consulted). Sometimes there could be a gingivitis under the full dentures, which is caused by accumulation of dental plaque.
Another problem with dentures is keeping them in place. There are three rules governing the existence of removable oral appliances: support, stability and retention.

 Prosthodontic principles of dentures

1.  Support

Support is the principle that describes how well the underlying mucosa (oral tissues, including gums and the vestibules) keeps the denture from moving vertically towards the arch in question, and thus being excessively depressed and moving deeper into the arch. For the mandibular arch, this function is provided by the gingiva (gums) and the buccal shelf (region extending laterally (beside) from the posterior (back) ridges), whereas in the maxillary arch, the palate joins in to help support the denture. The larger the denture flanges (part of the denture that extends into the vestibule), the better the support.
More recently, there has been a move to increase denture stability with implants. When pressure is applied to alveolar bone bereft of teeth (alveolar bone is the bone in which teeth normally reside), the bone reacts to this pressure by resorbing. After many years of denture wearing, the ridges upon which the dentures rest deteriorate and can easily all but disappear. The insertion of implants into the bone below the dentures can help to seriously combat this unfortunate occurrence. The implants are strategically placed to bear the brunt of the pressure when the denture is used for chewing, keeping the bone from melting away. When implants are integrated into treatment, the denture is now referred to as being an implant supported overdenture and the implants are referred to as overdenture abutments.

2.  Stability

Stability is the principle that describes how well the denture base is prevented from moving in the horizontal plane, and thus from sliding side to side or front and back. The more the denture base (pink material) runs in smooth and continuous contact with the edentulous ridge (the hill upon which the teeth used to reside, but now consists of only residual alveolar bone with overlying mucosa), the better the stability. Of course, the higher and broader the ridge, the better the stability will be, but this is usually just a result of patient anatomy, barring surgical intervention (bone grafts, etc.).

3.  Retention

Retention is the principle that describes how well the denture is prevented from moving vertically in the opposite direction of insertion. The better the topographical mimicry of the intaglio (interior) surface of the denture base to the surface of the underlying mucosa, the better the retention will be (in removable partial dentures, the clasps are a major provider of retention), as surface tension, suction and just plain old friction will aid in keeping the denture base from breaking intimate contact with the mucosal surface. It is important to note that the most critical element in the retentive design of a full maxillary denture is a complete and total border seal (complete peripheral seal) in order to achieve 'suction'. The border seal is composed of the edges of the anterior and lateral aspects AND the posterior palatal seal. The posterior palatal seal design is accomplished by covering the entire hard palate and extending not beyond the soft palate and ending 1-2mm from the vibrating line.
As mentioned above, implant technology can vastly improve the patient's denture-wearing experience by increasing stability and saving his or her bone from wearing away. Implant can also help with the retention factor. Instead of merely placing the implants to serve as blocking mechanism against the denture pushing on the alveolar bone, small retentive appliances can be attached to the implants that can then snap into a modified denture base to allow for tremendously increased retention. Options available include a metal Hader bar or precision balls attachments, among other things.

4.  Complications and recommendations

The fabrication of a set of complete dentures is a challenge for any denturist, including those who are experienced. There are many axioms in the production of dentures that must be understood, of which ignorance of one axiom can lead to failure of the denture case. In the vast majority of cases, complete dentures should be comfortable soon after insertion, although almost always at least two adjustment visits will be necessary to remove sore spots. One of the most critical aspects of dentures is that the impression of the denture must be perfectly made and used with perfect technique to make a model of the patient's edentulous (toothless) gums. The denturist must use a process called border molding to ensure that the denture flanges are properly extended. An endless array of never-ending problems with denture may occur if the final impression of the denture is not made properly. It takes considerable patience and experience for a denturist to know how to make a denture, and for this reason it may be in the patient's best interest to seek a specialist, either a Denturist or a Prosthodontist, to make the denture. A general dentist may do a good job, but only if he or she is meticulous and usually he or she must be experienced.
The maxillary denture (the top denture) is usually relatively straightforward to manufacture so that it is stable without slippage. The lower full denture tends to be the most difficult because there is no "suction" holding it in place. For this reason, dentists in the late 1990s have come to a general conclusion that a lower full denture should or must be supported by 2-4 implants placed in the lower jaw for support. A lower denture supported by 2-4 implants is a far superior product than a lower denture without implants, held in place with weak lower mouth muscles. It is routine to be able to bite into an apple or corn-on-the-cob with a lower denture anchored by implants. Without implants, it is quite difficult or even impossible to do so.
Some patients who believe they have "bad teeth" may think it is in their best interests to have all their teeth extracted and full dentures placed. However, statistics show that the majority of patients who actually receive this treatment wind up regretting they did so. This is because full dentures have only 10% of the chewing power of natural teeth, and it is difficult to get them fitted satisfactorily, particularly in the mandibular arch. Even if a patient retains one tooth, that will contribute to the denture's stability. However, retention of just one or two teeth in the upper jaw does not contribute much to the overall stability of a denture, since a full upper denture tends to be very stable, in contrast to a full lower denture. It is thus advised that patients keep their natural teeth as long as possible, especially their lower teeth.

Conclusion

As can be expected with any removable appliance placed in the mouth, there will be some problems (in respect to the three principles mentioned above) with dentures no matter how well they are made. This is because the best the denturist can do is fabricate the upper denture to work in harmony with the lower denture when the patient is at rest. If the only variables in the equation are the patient's edentulous ridges and the two dentures, the denturist can set the teeth in certain ways to help prevent dislodgement during opening, closing and swallowing. Once food enters into the picture, though, the stability of the denture bases is not impervious to disruption. During chewing, the denture bases will sometimes act as class 1 levers, and when the patient bites down on the anterior, or front, teeth, the posterior, or rear, teeth are bound to move away from the ridge. Although the ideals of denture design will have it that the intaglio surface is in perfect, intimate contact with the ridge and the margins of the denture base will create a perfect suction seal (the seal is actually only on the maxillary denture), ideals are rarely if ever met in this imperfect world, and thus some movement is to be expected. Denture adhesive can then be utilized to compete against the forces trying to pull the denture base away from the mucosa. In a perfect world, a patient with a perfect edentulous ridge with a perfectly fitting denture would require no adhesive, as the actual form of the denture base should work in tandem with the three principles mentioned above, thus precluding movement in any way, shape or form.

What's the difference between conventional dentures and immediate dentures?
Complete dentures are called "conventional" or "immediate" according to when they are made and when they are inserted into the mouth.
Immediate dentures are inserted immediately after the removal of the remaining teeth. To make this possible, the dentist takes measurements and makes the models of the patient's jaws during a preliminary visit.
An advantage of immediate dentures is that the wearer does not have to be without teeth during the healing period. However, bones and gums can shrink over time, especially during the period of healing in the first six months after the removal of teeth. When gums shrink, immediate dentures may require rebasing or relining to fit properly. A conventional denture can then be made once the tissues have healed. Healing may take at least 6-8 weeks.

What is an overdenture?
A removable denture that fits over a small number of remaining natural teeth or implants. The natural teeth must be prepared to provide stability and support for the denture. Your dentist can determine if an overdenture would be suitable for you.

What will dentures feel like?
New dentures may feel awkward for a few weeks until you become accustomed to them. The dentures may feel loose while the muscles of your cheek and tongue learn to keep them in place.
It is not unusual to experience minor irritation or soreness. You may find that saliva flow temporarily increases. As your mouth becomes accustomed to the dentures, these problems should diminish. One or more follow-up appointments with the dentist are generally needed after a denture is inserted. If any problem persists, particularly irritation or soreness, be sure to consult your dentist.

Will dentures make me look different?
Dentures can be made to closely resemble your natural teeth so that little change in appearance will be noticeable. Dentures may even improve the look of your smile and help fill out the appearance of your face and profile.

Will I be able to eat with my dentures?
Eating will take a little practice. Start with soft foods cut into small pieces. Chew slowly using both sides of your mouth at the same time to prevent the dentures from tipping. As you become accustomed to chewing, add other foods until you return to your normal diet.
Continue to chew food using both sides of the mouth at the same time. Be cautious with hot or hard foods and sharp-edged bones or shells.

Will dentures change how I speak?
Pronouncing certain words may require practice. Reading out loud and repeating troublesome words will help. If your dentures "click" while you're talking, speak more slowly.
You may find that your dentures occasionally slip when you laugh, cough or smile. Reposition the dentures by gently biting down and swallowing. If a speaking problem persists, consult your dentist.

How long should I wear my dentures?
Your dentist will provide instructions about how long dentures should be kept in place. During the first few days, you may be advised to wear them most of the time, including while you sleep. After the initial adjustment period, you may be instructed to remove the dentures before going to bed. This allows gum tissues to rest and promotes oral health. Generally, it is not desirable that the tissues be constantly covered by denture material.

Should I use a denture adhesive?
Denture adhesive can provide additional retention for well-fitting dentures. Denture adhesives are not the solution for old, ill-fitting dentures. A poorly fitting denture, which causes constant irritation over a long period, may contribute to the development of sores. These dentures may need a reline or need to be replaced. If your dentures begin to feel loose, or cause pronounced discomfort, consult with your dentist immediately.

How do I take care of my dentures?
Dentures are very delicate and may break if dropped even a few inches. Stand over a folded towel or a basin of water when handling dentures. When you are not wearing them, store your dentures away from children and pets.
Like natural teeth, dentures must be brushed daily to remove food deposits and plaque. Brushing helps prevent dentures from becoming permanently stained and helps your mouth stay healthy. It's best to use a brush designed for cleaning dentures. A toothbrush with soft bristles can also be used. Avoid using hard-bristled brushes that can damage dentures.
Some denture wearers use hand soap or mild dishwashing liquid, which are both acceptable for cleaning dentures. Avoid using other powdered household cleansers, which may be too abrasive. Also, avoid using bleach, as this may whiten the pink portion of the denture.
Your dentist can recommend a denture cleanser. Look for denture cleansers with the ADA Seal of Acceptance. Products with the ADA Seal have been evaluated for safety and effectiveness.
The first step in cleaning dentures is to rinse away loose food particles thoroughly. Moisten the brush and apply denture cleanser. Brush every surface, scrubbing gently to avoid damage.
Dentures may lose their shape if they are allowed to dry out. When they are not worn, dentures should be placed in a denture cleanser soaking solution or in water. Your dentist can recommend the best method. Never place dentures in hot water, which could cause them to warp.
Ultrasonic cleaners are also used to care for dentures. However, using an ultrasonic cleaner does not replace a thorough daily brushing.

Can I make minor adjustments or repairs to my dentures?
You can seriously damage your dentures and harm your health by trying to adjust or repair your dentures. A denture that is not made to fit properly can cause irritation and sores.
See your dentist if your dentures break, crack, chip, or if one of the teeth becomes loose. A dentist can often make the necessary adjustments or repairs on the same day. A person who lacks the proper training will not be able to reconstruct the denture. This can cause greater damage to the denture and may cause problems in your mouth. Glue sold over-the-counter often contains harmful chemicals and should not be used on dentures.

Will my dentures need to be replaced?
Over time, dentures will need to be relined, rebased, or remade due to normal wear. To reline or rebase a denture, the dentist uses the existing denture teeth and refits the denture base or makes a new denture base. Dentures may need to be replaced if they become loose and the teeth show signs of significant wear. Dentures become loose because a mouth naturally changes with age. Bone and gum ridges can recede or shrink, causing jaws to align differently. Shrinking ridges can cause dentures to fit less securely. Loose dentures can cause health problems, including sores and infections. A loose denture also makes chewing more difficult and may change your facial features. It's important to replace worn or poorly-fitting dentures before they cause problems.

Must I do anything special to care for my mouth?
Even with full dentures, you still need to take good care of your mouth. Every morning, brush your gums, tongue and palate with a soft-bristled brush before you put in your dentures. This removes plaque and stimulates circulation in the mouth. Selecting a balanced diet for proper nutrition is also important for maintaining a healthy mouth.

How often should I schedule dental appointments?
Your dentist will advise you about how often to visit. Regular dental check-ups are important. The dentist will examine your mouth to see if your dentures continue to fit properly. The dentist also examines your mouth for signs of oral diseases including cancer
With regular professional care, a positive attitude and persistence, you can become one of the millions of people who wear their dentures with a smile

 

 

 

 

 

 

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