Complete replacement for upper or lower teeth
Dentures or prosthetic teeth are commonly referred to as false teeth. They are specially designed to replace an individual’s missing or diseased teeth. Made to order exclusively for each patient, the dentures fit snugly in the mouth cavity, well supported by the soft and hard tissues that surround them.
Need for Dentures
People who have lost their teeth or have been suffering for some years from the ill effects of decayed teeth caused by periodontal disease, Dentinogenesis imperfecta, etc., are often advised by their dentist to have their teeth replaced either partially or fully by a set of dentures, after having ruled out all other treatment options like cleaning, medication, gum flap surgery or a combination of these.
The teeth, whether natural or artificial, provide a support to the lips and cheeks, and lend to their owner a more ‘youthful’ look than if the person were to be completely devoid of teeth. Thus, having a set of dentures will not only allow the patient to chew or masticate his food well, but will also serve to improve the facial appearance to a significant extent.
Types of Dentures
Dentures can be either partial or complete. The type of dentures used will depend essentially on the specific needs of the individual.
Partial dentures
Partial dentures are used in cases where the patient has only a few missing teeth. They may be of either the removable or the fixed variety, and the patient is generally asked to choose between the two. If a patient has lost only one or two teeth either from an accident or by way of extraction of decayed teeth, the dentist would in all likelihood suggest a fixed partial denture in the form of a ‘crown & bridge’ arrangement. Here, the bridging tooth fits into the gap left by the missing tooth, while the attached crowns sit firmly on the tops of the adjoining teeth on either side. The appliance is cemented in place.
Removable partial dentures are similar to this, but do not have the crowns. They are held in place by means of clips. It is easy to see that these are less stable than the fixed partial dentures, and are correspondingly less expensive than the latter.
Complete dentures
When the entire set of teeth on either the lower jaw (mandibular arch) or on the upper jaw (maxillary arch) have to be replaced, complete dentures are used.
There are 4 kinds of complete dentures. They are standard dentures, immediate dentures, implant retained dentures, and Cu-Sil dentures.
Standard dentures are made for people who have already lost their entire set of teeth. The back of a standard denture ends just behind the hard bone in the roof of the mouth, in order to maximise the surface area for achieving the best possible retention and stability. Retention of the top denture is achieved by suction, while stability is dependant upon the hardness of the underlying tissues. It takes about 4 appointments to have a set of standard dentures fitted comfortably.
Immediate dentures
These are often referred to as temporary dentures, and are actually constructed before the extraction of the natural teeth. The prefabricated denture is inserted immediately after extraction, right over the bleeding sockets. The denture serves to numb the pain, and most patients do quite well with these. It takes one or two appointments with the dentist to have the immediate dentures ready for fitting.
Cu-Sil dentures
Having even a single healthy, natural tooth aids the stability of the denture to a significant degree. The Cu-Sil denture has holes in it which are surrounded by a gasket of stable silicone rubber which adheres to the natural teeth thereby allowing the rest of the denture to rest on the gums. This provides good stability by improving suction in addition to the mechanical stability offered by the immobility of the natural teeth. CuSil dentures thus help stabilise loose teeth and extend the life of the teeth.
Implant retained dentures
Dental implants involve having a titanium ‘screw’ fitted into a hole drilled into the underlying bone, to secure the position of the tooth. The procedure can be quite expensive (about 1000 Pounds or more), but retention is much enhanced. The insertion of implants into the bone below the dentures can help to mitigate the problem of wearing of the bone. The implants are placed in a way that they take the pressure applied when the denture is used for chewing, and thus keep the bone from eroding. Over a period of time, the titanium gets integrated into the bone, and the implant is then exposed, at which point a post which thrusts through the gums into the mouth is attached to the implant.
Plastic or porcelain dentures
Denture teeth can be made of plastic as well as of porcelain, and the latter are a better match with natural teeth. Also, porcelain teeth last much longer than do the plastic counterparts. However, dentists tend to advise patients to go for plastic teeth, and have some very valid reasons for doing so:
Although porcelain teeth are relatively much hardier, they are set on a plastic base which suffers wear and tear. Also, given the mechanical means that are used in fixing the tooth to the base, called the ‘diatoric’ method, the porcelain teeth will begin to fall off the base over a period of time. Another argument against using porcelain dentures, especially if some of the natural teeth are being retained, is that the porcelain dentures will begin to wear down the natural teeth to a considerable extent, leaving them misshapen and weak over the years.
Common problems associated with complete dentures
The human body is well accustomed to consider anything that is placed in the mouth, as foodstuff. Accordingly, when a new set of braces or dentures are inserted in the mouth, the brain recognises this as food, and signals for increased salivary secretions. It takes some time for the body to get adjusted to this. New dentures are also apt to rub or scrape against the delicate epithelium lining the mouth cavity, giving rise to mouth sores in the process. This can be corrected by the dentist in a few weeks, by making the necessary adjustments. Some patients may also experience gagging on dentures, which may be either to an ill-fitting appliance or stem from psychological reasons.
Important factors to consider
Three important factors have a bearing on the denture wearing experience: support, stability and retention.
Support: It is the underlying tissues and gums, collectively termed the oral mucosa, that support the dentures by preventing them from moving vertically and deeper into the respective arches. In the case of the upper teeth, the gums and the buccal shelf play a major role here, while the palate helps support the denture of the lower jaw. Typically, dentures having larger flanges offer better support, so the denture supplier must use the border molding process to make sure that the denture flanges are extended to the right degree.
Stability: This has to do with keeping the denture base from moving in the horizontal plane, either sideways or forwards and backwards. The more the denture base stays in continuous contact with the edentulous ridge; the better will be the stability. A higher and broader ridge, will also afford better stability.
Retention: This relates to prevention of the denture movements in a direction opposite to that of insertion. The inner surface of the denture base must match exactly well with the surface of the underlying mucosa, in order to achieve the best possible retention.
Replacing a set of dentures
Dentures are not expected to last a lifetime, and they have to be replaced when the time is ripe. The bone that supports the dentures is gradually eroded over a period of time, causing the denture of the upper jaw to rise higher and higher under the upper lip, with corresponding downward movements of the lower set. While this is happening, the distance between the nose and the tip of the chin gets reduced, and changes in the shape of the face set in, which may become irreversible. With such changes in muscle length and bulk, it would become virtually impossible for the dentist to make a new set of dentures that are satisfactory to the patient if the old dentures are used beyond a reasonable length of time. It is therefore recommended to have a new set of dentures made once every 5 to 7 years.
