What is Prosthetic Dentistry?
Prosthetic dentistry is the replacement of missing teeth, which may have been lost for a variety of reasons, with either fixed or removable dentures. However, in Great Britain, prosthetic dentistry is usually understood to relate to removable dentures. Until relatively recently, most of the population of the British Isles assumed they would need dentures at some stage in their lives but, with improved oral hygiene, better diet and, particularly, the advent of fluoride supplements, the vast majority will retain sufficient teeth to serve them all their days. Nevertheless, many people still require dentures.
Why might I need dentures?
Natural teeth may have been lost due to caries (dental decay), periodontal (gum) disease, or trauma. If you have lost posterior (back) teeth and still have all your premolar teeth and those in front, you will have what is called the "shortened dental arch" and should manage well. If you have lost more teeth you may well require replacements. Depending upon a host of factors these replacements might be fixed or removable but, for our purposes here, please assume we are talking about removable dentures.
What are Partial Dentures?
As the heading suggests, partial dentures are made to replace a proportion of lost teeth and they have the advantage that support and retention can be derived from adjacent retained natural teeth using design features such as occlusal rests and clasps. Some natural teeth may require modification (mouth preparation) to ensure they are compatible with the denture design and this will be discussed with you. In general, partial dentures are ideally constructed with a metal (cobalt-chromium) base and the superstructure and teeth will be in a high quality acrylic resin. However, on occasions dentures will be made entirely in acrylic resin for clinical or economic reasons.
What are Complete Dentures?
A complete denture replaces all the teeth in one dental arch. For people who are already edentulous (i.e. have no natural teeth), the objectives of prosthetic treatment are similar to those for patients who are having other kinds of dentistry. Specifically, they would wish to have (in orders of importance which vary between individuals), good speech, good appearance, effective chewing and biting, comfort, and the ability to engage in various social and interpersonal activities such as laughing, shouting, kissing, applying lipstick etc., without the dentures becoming dislodged.
Of these, only good appearance can be guaranteed (and then only if sufficient care is taken). The remaining objectives depend upon each patient's anatomy and denture-wearing skill, as well as the skill of the prosthetist and dental technician.
Why do Problems arise with Dentures?
Any type of prosthesis, from a wooden leg to a pair of spectacles, is an alien item and none is more so than a denture which is inserted into one of the most sensitive parts of our body. Moreover, the mouth is a very mobile and functional area which is changing shape all the time eating, speaking, coughing and swallowing so it's hardly surprising difficulties occur. Furthermore, our mouths change shape with time: the human body is terribly economical and once natural teeth have been removed it removes the bone that held them and remodels the area. Thus the ridge on which a denture sits reduces in size rapidly at first but then more gradually throughout life. About 80% of this resorbtion, as it is called, takes place during the first year and 90% has occurred by the end of 2 years. This is why we try to provide simple dentures, which can be easily updated, at first.
How can denture problems be overcome?
Good prosthetic dentistry is a team effort involving patient, nurse, dental technician and dentist. It is also time consuming because attention to detail is paramount in order to produce appliances which can be most easily adapted to by the patient. Having said all this, patients cope well with dentures if they are determined to succeed. This is especially true with partial dentures and complete upper dentures, the former because natural teeth can help to secure them, and the latter because the large surface area of the palate spreads the load and aids retention. Complete lower dentures can present problems because the lower ridge often has a small surface area and an unretentive shape. Good prosthetic technique can usually overcome these difficulties but, for really intractable cases, we recommend the use of implants.
How do implants help with lower complete denture problems?
Lower complete dentures are largely retained by the skill of patients using the tongue, lips and cheek muscles to exert pressure on the denture to resist destabilising forces, for example during speech and chewing. Sometimes this is not enough, especially if the ridge is markedly reduced. We can now place 2 titanium implants in the bone on either side of the lower jaw around the region where the eye teeth have been. These have either a sort of press-stud attachment, or a bar between them, so the denture can click on. Implants take some of the chewing load and are particularly successful at keeping the denture in place during most functional movements of the lower jaw.