Objectives of Artificial Tooth Replacement or Denture Prosthesis
Denture Prosthesis is that branch of prosthetic dentistry (concerned with the diagnosis, prevention, and treatment of diseases of the teeth, gums, and related structures of the mouth and including the repair or replacement of defective teeth) which deals with the procedures for the restoration of all the lost natural teeth in edentulous patients or patients who are soon going to lose them.
It is an artificial replacement for one or more natural teeth or part of a tooth, or associated structures, ranging from a portion of a tooth to a complete denture. The dental prosthesis is used for cosmetic or functional reasons, or both. Dentures and specific types of dentures are also available.
Your dentist will take an impression of your jaw, along with measurements of how your jaws relate to one another and how much space is between them (bite relationship). The color (shade) of your teeth will also be determined either from your natural teeth or a denture you may already be wearing. The impression, bite and shade are given to the dental laboratory so a denture can be made just for you.
It is an artificial appliance which restores all the lost natural teeth and their associated parts in an edentulous mouth, also trying to reproduce the lost natural functions (mastication, phonetics) and the loss of esthetics. Complete dentures are used to replace missing teeth for people with no remaining teeth. Dentures may also be used for people who have lost several teeth. In this case, the appliance is called a partial denture or an over denture.
The main objectives of complete denture prosthesis are as follows:
- Restoration of the function of mastication in compliance with biological requirements.
- Restoration and correction of the lost facial dimensions and contours in compliance with esthetic requirements.
- Restoration of speech due to complete or partial loss of natural teeth in compliance with phonetic requirements.
- Carrying out these procedures in such a manner that the dentures do not cause any harm or discomfort to the patients who will be using them.
The first objective of complete denture prosthesis is mastication, which is considered to be the most important one. We know it perfectly well that the natural teeth take part in cutting, slicing, grinding and crushing of food stuff before they enter into the stomach for proper digestion.
So, the natural teeth are simplifying the process of digestion and aiding the stomach and other digestive organs in the sense that enzymes can more readily activate the masticated food rather than the unmasticated or unbroken particles of food.
When the natural teeth are lost, the function of mastication is interfered with and necessarily the digestive organs are to perform extra amount of work to cope with the situation. Stomach or other parts of digestive system are devoid of teeth (they have movements only) and as such they are not at all fitted for the work of mastication. The result being impaired digestion, which will have effect on the general health as along with digestive disturbances, there will be impaired nutrition too.
Masticatory function has been extensively investigated in both animal and human.
Subjective masticatory function (defined as masticatory ability) has been studied by interviewing subjects as to their own assessment of that function. Masticatory ability appeared to be closely related to the number of teeth. Impairment of chewing ability occurs when less than 20 well-distributed teeth are present.
Objective masticatory function (defined as masticatory performance) has often been measured by determining an individual's capacity to grind or pulverize a test food. Several studies have shown that masticatory function is reduced in people who have lost postcanine teeth and in those who wear removable dentures.
When a posterior tooth that is intended to become an abutment tooth already possesses an intracoronal restoration, it might be in order to make that bridge abutment into an inlay or an onlay, instead of a crown. However, this may concentrate the torque of the masticatory forces onto a less enveloping restoration, thus making the bridge more prone to failure.
It has been observed that the partial or total loss of the function of mastication has definitely shortened the life span of an individual resulting from deteriorated general health.
Complete denture prosthesis restores this lost function of mastication and thereby helps in maintaining good health and normal bodily functions.
Restoration of the esthetics is the second objective of complete denture prosthesis. It is concerned with the artistic phase of the prosthesis. It relates to the ability of the prosthesis to construct or create the natural looking substitutes for the lost natural alveolar processes and teeth and to reproduce by artistic sense and skilful technique not only a successful masticatory apparatus but to restore the lost facial contour as well.
After the loss of natural teeth, resorption of alveolar processes starts on and continues. There is over closure of the jaws, loss of centric relation and occlusion by the individual and changes occur in the facial contour. The most affected part of the face being the lower one third. Here due to the loss of bony support (alveolar process) and support by the natural teeth, the lips lose their normal poise or characteristic features and assume an unnatural expression. Premature wrinkles set on the cheeks and mouth and the individual looks aged than the real age.
Now, it is the domain of the prosthedontist to correct, as far as possible, the ravages done by the disease and time and restore to the patient his normal appearance and facial contour.
To perform this, the prosthodontist should be a master of his art having the instinct and quality to imitate the nature as nearly as possible. In one hand he should be an artist, an anatomist, a sculpture, an artisan and engineer and on the other hand he should be thoroughly proficient in his own field of the science and art of prosthesis.
We know that the natural teeth are concerned with the esthetics of an individual. They not only impart beauty but personality too. Concerning the teeth, the noted Italian anthropologist, Paolo Mantegazza, in his book 'Physiognomy and Expression' says: "It is a flaw in beauty to have bad teeth; it is like a spot on the sun. Since the hygiene of the teeth is at the same time the hygiene of beauty, good dentists merit a golden statue, or at least a place of honor among the principal benefactors of humanity. The most beautiful teeth are not enough to make a man beautiful, but ugly teeth would spoil the beauty of the Venus of Milo herself."
The outward appearance of the dental arch and the normal facial contour of an individual are convex. This convexity, to a large extent, is dependant upon the presence of natural teeth and alveolar bones which support the cheeks and lips. The loss of teeth and the resultant resorption of alveolar bones allow the lips and cheeks to sink in resulting in an alteration in the facial profile and contour.
A deep and sharp artistic sense is essential for the development of the correct lines of facial contour just to restore the harmony in each individual case. The size and shape of the artificial teeth must bear harmony with the face form and face profile of the individual, the color of the artificial teeth must match and harmonize with the color of the patient's hair, eyes and skin. The alignment and treatment of artificial teeth also depend on the age, sex, face form and face profile of the patient.
So, in the field of esthetics, the highest achievement of a prosthodontist lies in imitating the nature so keenly and closely that his work cannot be differentiated from the standing natural teeth even by close observation. On the other hand, the patient, who will be using the artificial appliance, should be so satisfied with the work of the prosthetist that he does not seriously feel the loss of the natural teeth.
Patient demands for improved esthetics have prompted the development of all-ceramic restorative systems for dental implants, but material strength and restorative costs have presented clinical challenges. A tooth needs to be paid extra attention for their esthetics appearance along with medical treatment. Esthetics Dentistry which has been improving from day to day serves for this purpose. Addition to this material that we use for esthetics dentistry is much more qualified when we compare it with past. Also we can add that new techniques are improved and new ways are discovered.
Restoration of the phonetics is the third objective of complete denture prosthesis. Defective speech is the result of complete or partial loss of natural teeth or improper alignment of artificial teeth in a denture. Phonetics made by tongue and teeth: describes a consonant that is formed by placing the tongue against the back of the top front teeth.
Phonetics is the study of the sounds of language. These sounds are called phonemes. There are literally hundreds of them used in different languages. Even a single language like English requires us to distinguish about 40! The key word here is distinguished. We actually make much finer discriminations among sounds, but English only requires 40. The other discriminations are what let us detect the differences in accents and dialects, identify individuals, and differentiate tiny nuances of speech that indicate things beyond the obvious meanings of the words.
"From a phonetic point of view, [consonants] are articulated in one of two ways: either there is a closing movement of one of the vocal organs, forming such a narrow constriction that it is possible to hear the sound of the air passing through; or the closing movement is complete, giving a total blockage. The closing movement may involve lips, tongue, or throat." Phonetics deals with the following:
- The study of speech sounds (phones)
- Articulatory phonetics
- Acoustic phonetics
- Auditory phonetics
A prosthetist can restore proper speech while dealing with the esthetic phase of the denture by aligning the artificial teeth, as nearly as possible to the positions previously occupied by the natural teeth. Apart from this, the correction of speech defects can be materially aided by the following factors which are concerned in the restoration of phonetics in artificial dentures:
a) Form of the teeth selected.
b) Bulk of the material used in the denture base.
c) Reproduction of the rugae of the palatal vault.
d) Contours of the alveolar ridges.
The skills to develop complete dentures for patients with extensive structural, physiological or emotional deficiencies are an important mission. This will be taught through the treatment of patients with increasing levels of complexity and by utilizing techniques that are formulated to address those problems. Restoring ones appearance to a desirable standard when a person is missing one or more of their natural teeth there may be one or more problems that occur –
- Over eruption of teeth
- Tooth drift
- Facial muscle collapse
- Reduction in face height (occlusal vertical dimension)
- Loss of certain sounds during communication (phonetics)
Comfort of the patient with the artificial appliance constructed for him, is the most important fourth objective.
Well-constructed dentures that fulfill the requirements of both esthetics and utility will prove to be a failure at the end if they are not comfortable to the wearer i.e., cannot be worn by the patient with ease or comfort.
Some of the causes of discomfort that impair or at times, may seriously jeopardize the success or usefulness of a denture are as follows:
a) Imperfect adaptation of the denture to the tissues, causing undue pressure at certain points.
b) Extension of the denture base on the soft palate beyond the vibrating line as far as to cause irritation, retching or excite vomiting reflex.
c) Extension of the denture base on resistant tissues or muscles when during their contractions the denture will be dislodged from the seat.
d) Encroachment of the denture flanges on the labial and buccal frenae and muscles.
e) Malocclusion of artificial teeth due to defective registration of jaw relationships.
f) Alignment of artificial teeth (especially the posteriors) away from the midpoint of ridge crest that will give rise to instability of the denture.
g) Rough and unpolished surfaces of the denture, especially its palatal portion.
The prosthetist should have the insight and ability to recognize and anticipate such troublesome conditions and should develop the cleverness to overcome them most efficiently and effectively.