Factors Affecting Retention Of Denture Health And Social Care Essay

Stability is the prevention for denture base to move in a horizontal direction and from sliding front or back and side to side.It is more important in lower complete denture.If the ridge is higher and broader than there will be better stability.

Support is the ability of denture to move vertically towards the arch.It is provided by gums and buccal vestibule in mandibular arch while in maxillary arch palate helps to support denture.In order to get good support denture flanges should be larger.

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IMPORTANCE OF COMPLETE DENTURE

Now a days.the dietary habits of the people increases need of using denture as the tooth decay or loss may occur as a result of careis,periodontal destruction and uncontrolled diabetes.In order to achieve success in treatment,some of the matters should be considered.In complete denture,the attitude and motivation of the patient should be evaluated.The dentist should know about the patient’s problem and demands and keeping in mind try to meet expectations.The whole procedure in the fabrication of complete denture including problems in retention,support and stability of denture must be explained to the patient.After this the dentist must work with the patient to get success in matters such as speech,mastication,esthetics and neuromascular control.By solving pateints complain positively,dentist can satisfy the patient and even train the patient to solve their problems in future.At last,it is the duty of dentist to inform patient that the success of complete denture depends on the maintainance of denture at home as well as giving regular visits to dentist.

FACTORS AFFECTING RETENTION OF DENTURE

ANATOMICAL FACTOR (DENTURE BEARING AREA)

Retention also depends on the size and quality of denture bearing area.The retention increases as the increase in size of denture bearing area.Maxillary denture bearing area is 24 sq.cm and mandibular denture bearing area is less 14 sq.cm. So mandibular denture has less retention than maxillary denture.

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Dr. Chetan ;Objectives of Impression making in complete denture; 2010

ROLE OFIMPRESSION MAKING FOR RETENTION

The impression of complete denture is a very important step.The impression of the upper and lower jaw the periphery of ridges,post dam area,recording of retromylohyoid fossa and recording of the depression of coronoid process in upper impression is important in to form good retentive denture.The displacement of tissue during impression making is also important in this regard. “Displacement of the tissues also affect the retention. Those tissues which were displaced during impression making can rebound while using dentures, leading to loss of retention.” Dr. Chetan 2010.

ATMOSPHERIC PRESSURE

The atmospheric pressure is considered to have some role in complete denture retention.It is only workable when there is lower pressure under the denture and presence of vaccum.The vaccum is created by applying pull which increase the volume between denture base and underlying tissue to maintain seal around some area for lower pressure to be constant.Thus the retention is produced because of pull and displacement.Some times the proper seal of acrylic to mucosa is not formed and some the other factors are required. “Thus, all parts of the system of denture and wearer are exposed to the atmospheric pressure, and the hydraulic nature of the soft tissue means that, under ‘resting’ conditions this will be transmitted into the region between denture and tissue hydrostatically”. Under normal conditions as there is no pressure difference and no static retaining force so the atmospheric pressure has no bearing on retention. “(B. W. Darvell,and R. K. F. Clark.)

ADHESION

Adhesion is the physical interaction between two unlike molecules with one another.In denture it is mainly applicable among the saliva and the denture base material(acrylic resin).The closer the surface of denture and saliva,the adhesion is increased.The adhesion is more if contact angle is less.The wetting of saliva is more on oral mucosa than on denture base.thus adhesion also depends upon the viscosity of saliva.The thin layer binds more effectively than thick but ropy saliva may have some advantage especially resisting flow into space between denture base and mucosa,this is negated if the film formed is thick in first place.

COHESION

This is a physical attraction of similar molecules with each other and occur in saliva layer.If the saliva is less,there is marked reduction in cohesive force.This means if the larger the surface area of denture base,there are more chances of cohesive force will act.These forces are less effective than cohesive forces.The formation of bubbles in saliva will also decrease retention.

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Dr. Chetan ;Objectives of Impression making in complete denture; 2010

SURFACE TENSION

It is the difficulty to seprate two well adapted surface having thin film of liquid between surfaces which is due cohesive forces occur at surface of liquid.It is same to the forces which causes the liquid to rise in capillary tube. These forces are increased when the denture base is close to the mucosal surface.The flatter the palate,difficult to displace the denture as compared to high palate.

WETTABILITY

When a solid surface is wetted by liquid ,its retention increases .Some of the strength is required to break the adhesion between them.It there is no or less wetting,the less force is needed for the sepration of denture from saliva and there is lack of retention.Although,the acrylic is wetted by water but as the saliva is rich in proteins and mucoplysaccharides form a strong bond and create a more wettable surface.If the surface is treated by any material may be adsorbed by saliva so may not help in providing good retention.

SURFACE ROUGHNESS

If the surface roughness is increased ,the adhesion between saliva and denture is also improved.

GRAVITY

It is only appied when the denture is resting on mucosa under its own weight.In order to hold the denture gravity should be raised but in case of upper denture it may result in lack of retention and dropping of denture as person wearing denture face in downward position.The lower denture is only few grams in mass and increasing it can be resulted in fatigue of the jaw carrying load and may contribute to temporomandibular joint problems.

VISCOSITY

The viscosity of saliva plays an important role in a sepration of two surfaces after the force is applied.The viscosity of saliva is not under control and is time dependent.The viscous material is useful in denture retention to some extent as washing of it with time can reduce efficacy.

SEATING FORCE

After the inserting denture in oral cavity ,a pressure or force is applied to get retention. “The instantaneous effect will be to confirm the thinnest possible saliva film and so the best result is caused by the viscous retardation of displacement. This must also be achieved at the expense of some displacement of the supporting soft tissue, and if this created a better fit, it would not last long as that tissue rebounded elastically”. (B. W. Darvell, and R. K. F. Clark)

PERPHERAL SEAL

In order to get good retention denture base is closely attach to the oral mucosa with a thin film of saliva between them .The disruption of this may result in loss of retention. This can occur on the borders of denture because the movement of tissue here is under the control of musculature.so a layer of saliva should be maintained at the external surface of denture.If the flange of denture is thin and the tissues is at rest, the saliva flows rapidly between the tissue surfaces ,flange and then to the fitting surfaces will result in the easy displacement of denture.If the space between denture flange and tissue is narrow,there is slow and even flow of saliva and the good retention of denture.The dimension of the flange of denture should promote the proper movement of muscle and overlying tissues without displacing denture base. If extension of denture is too far in the sulcus than the muscular movement can result in displacement of denture along with sulcus ulceration.If it is less extended into sulcus there is less retained saliva and the loss of retention.The upper denture is extended as far as possible but not on the soft palate.This shows that the posterior seal is not present.It is obtained if the displaced tissue also move with the denture during function.This can be done by making post dam area by creating raised grooves on posterior surface.

Buccal

Compliance

Low pressure

Narrow space

for viscous flow

Surface tension

(B.W Darvell and R.K.F CLARK; The Physical Mehanism Of Complete Denture Retention;2000)

ORAL AND FACIAL MASCULATURE

The normal movement of oral and facial musculature can also provide retention,if the denture work in harmony with the muscles.The flanges of upper denture slope outwards and upwards in way that the action of buccinator muscle helps to seat the denture.During incision,forces acting anteriorly on the denture is may tend to tip the denture and posterior border of denture move downwards because posteriorly the base of tongue may respond forces which occur anteriorly on denture.

In case of lower denture,the buccal flange move outward and downward from the teeth so that the buccinators propely seat the denture.The lingual flange slopes towards floor of mouth helping the tongue to rest against it.The distal end of flange rests in retro mylohoid fossa to maintain peripheral seal and to prevent displacement of denture against lateral forces.

OCCLUSION

The placement of artifical teeth and arch form should me maintain in the same postion as that of natural teeth so that they will work in a harmony with musculature.The teeth is then better to place in a neutral zone.In order to get balance occlusion the maximum number of teeth should be in contact with eachother.After the insertion of denture,high occlusal spots should be removed to enhance the efficacy and retention of denture.

MECHANICAL AND OTHER FACTORS AFFECTING RETENTION

The under cut which is present on one side of the ridge helps in retention but bilateral under should be surgically corrected as they cause difficulty in retention of denture.The use of denure adhesives and pastes also improve the retention of denture.The magnets and suction disc also play an important role in this regard.Now a days,the use of suction disc is prohibited as continuous use of denture with suction disc affect the palate and may result in oroantral communication.

The continuous use of denture in diabetic patient may loss retention due to bone resorbtion.Thus relining or rebasing of denture is required to increase retention.In pshycomotor patient retention of denture is a problem which is solved by proper counselling of patient.” A training device is made in combination with an exercise program to teach muscle control for retention of a mandibular denture. It consists of a shellac record base which is connected with string to an extraoral spring balance scale. The patient is guided to use the tongue, cheek and lip muscles for denture retention. The patient is then instructed to displace the seated record base by pulling on the scale. The increase in measurements on the scale show good resistance to displacement of the denture base”.( Escoe R 1989)

REFRENCES

1.Escoe R. Psychomotor patient training to enhance retention of complete dentures. (1989) May-Jun;2(3):243-4.

2. Dr. Chetan. Objectives of Impression making in complete denture( 2010).

3. Terry Weber.Comfortable Dentures Need Support, Stability and Retention.

4. David M. Roessler. Complete denture success for patients and dentists(2003).

5. B. W. Darvell, and R. K. F. Clark, The physical mechanisms of complete denture retention(2000).