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 clasping 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.
Dentures can help patients in a number of ways:
- Mastication – chewing ability is improved by replacing edentulous areas with denture teeth.
- Aesthetics – the presence of teeth provide a natural facial appearance, and wearing a denture to replace missing teeth provides support for the lips and cheeks and corrects the collapsed appearance that occurs after losing teeth.
- Phonetics – by replacing missing teeth, especially the anteriors, patients are better able to speak by improving pronunciation of those words containing sibilants or fricatives.
- Self-Esteem – Patients feel better about themselves.
TYPES OF DENTURES
Removable Partial Dentures
Removable partial dentures are for patients who are missing some of their teeth on a particular arch. Partial dentures are fitted to the remaining teeth and are held in place by clasp located in certain areas on the partial. Regular hygiene is recommended to maintain the remaining teeth so that loss of those teeth will not occur.
Complete Dentures
Conversely, complete dentures or full dentures are worn by patients who are missing all of the teeth in a single arch (i.e. the maxillary (upper) or mandibular (lower) arch). 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. This will only happen in the first 12 to 24 hours, after which, the salivary glands return to their normal output. Dentures can also be the cause of sore spots as they compress the soft tissues (denture bearing soft tissue). A few denture adjustments for the days 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, too thick or extended too far posteriorly onto the soft palate. Another problem with dentures is keeping them in place. There are three rules governing the existence of removable oral appliances: support, stability and retention.
Support
Support is the principle that describes how well the underlying soft tissues, and including gums 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 gums and 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.
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 soft tissue), 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 such as 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. Suction on the denture 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’.