Dentures are prosthetic devices constructed to replace missing teeth, and which are supported by surrounding soft and hard tissues of the oral cavity. In Medicine, a prosthesis (plural prostheses) is an Artificial extension that replaces a missing Body part. The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up Conventional dentures are removable, however there are many different denture designs, some which rely on bonding or clipping onto teeth or dental implants. A dental implant is an Artificial tooth root replacement and is used in prosthetic Dentistry to support restorations that resemble a tooth or group of teeth 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. The mandible (from Latin mandibula, "jawbone" or inferior maxillary bone forms the lower Jaw and holds the lower teeth in place This article is about the Mammal maxilla For Arthropod maxillae see Mouthparts; for Insect maxillae in particular see Insect mouthparts There are many informal names for dentures such as dental plate, false teeth and falsies.
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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. Oral hygiene is the practice of keeping the Mouth and Teeth clean in order to prevent dental problems and bad breath. Dental caries is a disease that damages Tooth structures resulting in what is commonly called tooth decay or cavities which are holes in the teeth Other reasons include tooth developmental defects caused by severe malnutrition, genetic defects such as Dentinogenesis imperfecta, trauma, or drug use. Malnutrition is a general term for a medical condition caused by an improper or insufficient diet. Dentinogenesis imperfecta (hereditary Opalescent Dentin is a Genetic disorder of Tooth development. A drug, broadly speaking is any chemical substance that when absorbed into the body
Advantages
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. Aesthetics or esthetics ( also spelled æsthetics) is commonly known as the study of sensory or sensori-emotional values sometimes called Variations in the physical appearance of humans, known as human looks, are believed by Anthropologists to be an important factor in the development of personality and
3. Phonetic - Replacing the toothless area, especially the anteriors, to help patients to speak and pronounce certain words properly without air escapes. Speech refers to the processes associated with the production and perception of Sounds used in Spoken language.
Types of dentures
Removable partial dentures
Removable partial dentures are for patients who are missing some of their teeth on a particular arch. A removable partial denture (RPD is for a partially edentulous dental patient who desires to have replacement teeth for functional or esthetic reasons and who cannot have 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. A dental bridge, otherwise known as a fixed partial denture is a Prosthesis used to replace missing Teeth and is not removable by the patient Fixed bridges are more expensive than removable appliances but are more stable.
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).
History
Around 700BC, Etruscans, in northern Italy, made dentures out of human or other animal teeth. Etruscan civilization is the modern English name given to the culture and way of life of a people of ancient Italy These deteriorated quickly but, being easy to produce, were popular until mid 19th century[1]
The first European sets of dentures date from the 15th century and most probably existed before that time. They were carved from bone or ivory, or made up of teeth sourced from graveyards, the recent dead or living donors who exchanged their teeth for profit. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Ivory is formed from Dentine and constitutes the bulk of the Teeth and Tusks of animals such as the Elephant, Hippopotamus, These dentures were uncomfortable, attached visibly to a base supported by any remaining teeth with a thread of metal or silk. The false teeth were often made with ivory from the hippopotamus or walrus, and usually rotted after extended use. The hippopotamus ( Hippopotamus amphibius) from the Greek ἱπποπόταμος ( hippopotamos, ιππος hippos meaning "horse" The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and
London's Peter de la Roche is believed to be one of the first 'Operators for the Teeth', men who fashioned themselves as specialists in dental work. London ( ˈlʌndən is the capital and largest urban area in the United Kingdom. Often these men were professional goldsmiths, ivory turners or students of barber-surgeons. A goldsmith is a Metalworker who specializes in working with Gold and other Precious metals usually in modern times to make Jewelry. The Barber surgeon was one of the most common Medical practitioners of medieval Europe - generally charged with looking after Soldiers during [2]
The first porcelain dentures were made around 1770 by Alexis Duchâteau. Porcelain is a Ceramic material made by heating raw materials generally including Clay in the form of Kaolin, in a Kiln to temperatures In 1791 the first British patent was granted to Nicholas Dubois De Chemant, previously assistant to Duchateau, for De Chemant's Specification, "a composition for the purpose of making of artificial teeth either single double or in rows or in complete sets and also springs for fastening or affixing the same in a more easy and effectual manner than any hitherto discovered which said teeth may be made of any shade or colour, which they will retain for any length of time and will consequently more perfectly resemble the natural teeth. The Kingdom of Great Britain, also known as the United Kingdom of Great Britain, was a State in northwest Europe, in existence from 1707 to 1800 " He began selling his wares in 1792 with most of his porcelain paste supplied by Wedgwood. Wedgwood, strictly Josiah Wedgwood and Sons, is a British Pottery firm originally founded in 1759 by Josiah Wedgwood, which in 1987 Single teeth in porcelain were made since 1808. In London in 1820, Claudius Ash, a goldsmith by trade, began manufacturing high-quality porcelain dentures mounted on 18-carat gold plates. Claudius Ash (1792–1854 was an English goldsmith and dental manufacturer Later dentures were made of vulcanite (Claudius Ash’s company was the leading European manufacturer of the dental vulcanite, into which porcelain teeth were set), and then, in the 20th century, acrylic resin and other plastics. Vulcanite is a rare Mineral composed of the two elements Copper and Tellurium. Acrylic resins are a group of related Thermoplastic or Thermosetting plastic substances derived from Acrylic acid, Methacrylic acid or other Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products In Britain in 1968 79% of those aged 65-74 had no natural teeth, by 1998 this proportion had fallen to 36%.
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. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The salivary glands in mammals are exocrine glands that produce saliva For the band see Saliva (band; for the village in Azerbaijan see Səliva. New dentures will also be the inevitable cause of sore spots as they rub and press on the mucosa (denture bearing soft tissue). The mucous membranes (or mucosae; singular mucosa) are linings of mostly endodermal origin covered in Epithelium, which are involved in 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. The soft palate (or velum, or muscular palate) is the soft tissue constituting the back of the roof of the Mouth. 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). The palate (ˈpælɨt is the roof of the Mouth in humans and Vertebrate animals 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
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. Prosthodontics is one of the 9 specialties recognized by the American Dental Association, Royal College of Dentists of Canada, and Royal Australasian College 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 gingiva (sing and plur: gingiva) or gums, consists of the Mucosal tissue that lies over the Alveolar bone. Human anatomical terms make up a distinct nomenclature to describe areas of the body to provide orientation when describing parts of Human anatomy, and to The larger the denture flanges (part of the denture that extends into the vestibule), the better the support. The vestibule of mouth (or oral vestibule) is the anteriormost portion of the Oral cavity.
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.
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. ).
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. A removable partial denture (RPD is for a partially edentulous dental patient who desires to have replacement teeth for functional or esthetic reasons and who cannot have 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.
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 denturist, clinical dental technician or (in Australia) a dental prosthetist, is a member of the oral health care team who provides an oral health examination Prosthodontics is one of the 9 specialties recognized by the American Dental Association, Royal College of Dentists of Canada, and Royal Australasian College 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.
See also
- Dental implant in Dental Implantology
- Dental crown
- Dental bridge
- Gingivitis
External links
- Dentures - Information, Resources and Forums
- Dentures Frequantly Asked Questions & Answers
- Dentures Quest - Personal Experience, Questions and Answers
References
- ^ The inventions that changed the world, Reader's Digest (1982) [Portuguese edition of 1983]
- ^ John Woodforde, The Strange Story of False Teeth, London: Routledge & Kegan Paul, 1968
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