Denture of the lower jaw

Synonyms

Full denture, total denture, 28th, "The Third"

introduction

From a certain age, many people are faced with the question of which prosthetic tooth replacement is best in the event of a complete tooth loss. Either all of the teeth in the lower jaw can be replaced with dental implants, which is a larger and more expensive surgical procedure.

In most cases, patients have full dentures made from plastic. A dental prosthesis in the lower jaw guarantees the chewing and speaking function and also achieves an attractive result from an aesthetic point of view.

Advantages and disadvantages of a total lower jaw prosthesis

Dentures offer the patient several advantages. So it is not that expensive and is also supported by the health insurance. It can be made without bone grafting or other pre-treatments and subsequent extensions, improvements or additions are easy to handle.

However, it is disadvantageous that with a prosthesis one does not have the same chewing performance as with a fixed denture. In addition, there may be problems with the hold of the prosthesis, which are particularly common in the lower jaw. The lower jaw does not offer the same large contact surface as the upper jaw for a full denture, so that the hold in the lower jaw is mostly only due to the surrounding tissue, such as the muscles, and less due to the suction effect that occurs with the upper palate plate.

Manufacture of a full denture

As soon as it has been inserted in the patient's mouth, the full denture should not be distinguishable from natural teeth.
Regardless of whether the patient smiles, speaks or eats, the prosthesis should simulate normal gums and natural teeth as well as possible. Until then, however, it is a complex and lengthy manufacturing process in which a lot of time has to be spent in the dental laboratory to manufacture the prosthesis.

Usually the prosthesis is made entirely of plastic. Both the gums and the teeth are made of plastic.
This makes it possible to use any type of tooth color and shape and also to make the gums natural and pink. The right prosthesis can be made for each patient individually so that it matches the rest of the appearance. A tall, slender man receives different teeth than, for example, a smaller woman.

Several impressions are taken at the dentist, which are then forwarded to the dental laboratory.
The dental technician also receives all important information regarding the fullness of the lips, the smile line or the center line. There, the models are cast in plaster and are used for the further manufacture of the dental prosthesis. The lower jaw prosthesis is first set up in wax. The teeth are placed in the wax in such a way that they correspond to the natural dentition and chewing movements can be carried out so that the patient can later move the jaw to the right, left, front or back without any problems. If this is correct, more wax is applied and the gums are modeled.

Then the wax prosthesis is tried on in the patient's mouth. The dentist uses it to check whether the set-up, tooth shape and color match the patient and whether all movements are feasible and good chewing function can be guaranteed.

In the next step, the wax model is transferred to plastic, the finished end product. Different plastics and manufacturing processes are used. So it can be stuffed cold or injected warm. Thus the wax disappears and is replaced by liquid plastic, which hardens. The teeth remain in their position.

In the next step, the prosthesis is processed. It is polished to a high gloss and excess residues are removed. The different movements are also checked again so that they can be inserted into the patient's mouth at the end.

Modern plastics have already developed to such an extent that they are no longer harmful to the body. Nevertheless, there may be intolerances. Pressure points can be eliminated on the patient and the functions and aesthetics checked.

How does the full denture hold in the lower jaw?

At first glance it seems a bit puzzling how a full denture can hold at all, because after all there are no teeth left to attach them to. Nevertheless, it is possible to talk to her and eat her without her falling out. There are three important factors for this.

  1. The first factor is based on occlusal stabilization. This means that the row of teeth from the upper jaw, be it normal teeth or also a full denture, have contact with the teeth in the lower jaw in the closed mouth and sometimes also during movements. Static stabilization is thus ensured.
  2. The second factor is the embedding of the full denture in the surrounding soft tissue. The prosthesis is made so that it rests perfectly on the alveolar ridge and is covered on the sides by muscles and cheeks. This is also known as muscle grip. For example, the posterior tooth areas of the prosthesis are designed to be convex and the anterior tooth area to be concave in order to give the tissue and muscles the opportunity to snuggle up. This is the primary hold in the lower jaw.
  3. The third factor is due to a valve mechanism. There are air bubbles between the prosthesis to be placed (prosthesis base) and the tissue underneath (prosthesis bed). These are expressed when inserting the prosthesis. If the edges of the prosthesis are optimally designed, the air can no longer return, so that a negative pressure is created and the prosthesis adheres.

This could also be of interest to you if the prosthesis no longer holds up well: Reline the denture

What to do if the lower jaw prosthesis does not hold

Due to the very narrow lower jaw bones and the constant movement of the soft tissue there (mucous membrane and muscles), problems arise with the seating of the prosthesis, especially in the lower jaw. First of all, the dentist should clarify why the prosthesis no longer holds up sufficiently.

Changes in the lower jawbone or a change in the bite relationships can be considered. These lead to a reduction in the suction effect between the base of the prosthesis and the oral mucosa, which is generated by the saliva in between. If this effect decreases, the hold of the prosthesis is reduced.

In addition to relining the prosthesis, the use of adhesives such as Denture adhesive creams, adhesive powder, etc. ensure an improvement in the wearing situation. The installation of additional anchoring elements such as an implant or a push button can improve the fit of the prosthesis in the lower jaw.

Read more on this topic: Loosening of the dentures

Relining the prosthesis

Relining is one way of improving the hold and fit of a prosthesis. With the help of specific plastics, the ill-fitting prosthesis is adapted to the current jaw conditions. The relining can be done in the form of a direct method by the dentist or in the form of an indirect method in the dental laboratory or in the dental technician laboratory.

Read on under: How is a denture relined?

Push button

The push-button prosthesis is a dental prosthesis in which a push-button, in the form of a ball anchor, acts as a stabilizing connection element between the jaw and the prosthesis, an implant being required as the anchor.

A cap is anchored in the dental prosthesis, which can be placed precisely onto the spherical head anchor and snaps into place there in the form of a snap mechanism.

This procedure can improve the hold of the prosthesis. At the same time, this can be removed daily from the push button and cleaned thoroughly, which prevents the development of gingivitis. The aesthetics of a pushbutton prosthesis is also to be assessed positively, since the retaining elements are not visible.

Adhesive

The use of an adhesive cream is another way of improving the hold of a prosthesis. Nevertheless, it should only be used as an emergency solution, as it reduces the sense of taste on the one hand and the production of saliva on the other.

Regardless of whether the adhesive is in the form of a cream or powder, the method of application remains the same: a thin layer is applied to the clean and dry denture base, then the denture is inserted and held in place for a few seconds with light pressure.

Adhesive is not a permanent solution and some patients have to repeat the application of the adhesive several times a day in order to have adequate prosthesis hold in the lower jaw.
When the prosthesis only fits like this, a visit to the dentist is recommended. This can possibly improve the fit and hold in the long term by relining or reassembling.

Learn more at: Denture adhesive

Getting used to the new prosthesis

After inserting a new denture in the lower jaw, it initially feels like a large, uncomfortable foreign body. One wonders how one can talk and eat with them without everything being bothersome. This is completely natural because the body has to get used to it. It is not possible to simulate an identical feeling to natural teeth, but once you have spent a certain amount of time with the denture, you hardly notice it.

It can also be difficult to speak correctly at the beginning, especially when it comes to "s", "sch", "f" or "w" sounds.With a little practice, this is not a permanent problem either. The cheek muscles and the tongue have to learn to hold the prosthesis correctly and to make sounds with it.

In addition, the stress can lead to increased degradation of the bone substance. This goes hand in hand with frequent relining of the prosthesis in order to adapt it to the new conditions in the mouth and thus avoid pressure points and improve the hold. In addition, there are also sharp edges from the jawbone in the lower jaw, which also affect the hold.

Regular visits to the dentist are therefore mandatory. Food residues can also get caught under the prosthesis and cause an uncomfortable feeling. The sense of taste can be impaired as large parts of the palate are covered with a plastic sheet. In unsuitable situations, the prosthesis can fall out or rattling noises occur when speaking.

If the lower jaw prosthesis is not held properly, push buttons can be anchored in the jaw, onto which the prosthesis is pressed. There are holes in the denture into which the button heads in the lower jaw fit. This significantly improves the hold of the prosthesis and it is difficult to fall out. However, there must be enough bone to insert the implants on which the button is placed. Furthermore, there are higher costs for the patient.

Bruises

After inserting a new denture in the lower jaw, minor pressure points or inflammation can occur on the oral mucosa. These are due to the new situation and disappear on their own after the familiarization phase.

However, if there are larger pressure points, even after a long period of wear, an appointment with the dentist is advisable, as the prosthesis will not fit correctly and the pressure will be distributed unevenly, which can damage the tissue and the bones. As a result, the alveolar ridge degrades faster. The shrinkage of the jawbones occurs due to the pressure load, because the jaw is not suitable for compressive forces, but for tensile forces.

If the jawbone breaks down, this not only has dental effects, but also affects the external appearance, as the proportions of the face change, the lower jaw moves "forward" and more wrinkles appear.

Also read the article on the topic: Inflammation under a denture

What can you do about pressure points?

Pressure points occur when the dental prosthesis is no longer precisely adapted to the current jaw conditions. This results in increased pressure on the oral mucosa, which causes painful pressure points to develop. These can become inflamed and cause further damage to the mouth area. Therefore, they should be removed early by the dentist. As a preventive measure, the fit of the prosthesis should be checked regularly.

To relieve pressure points, the dentist can grind away the imperfection on the prosthesis. If there are major pressure points, relining or, if the prosthesis has been worn for several years, reassembly of the full denture is advisable. In this way, the base of the prosthesis is adapted to the situation in the mouth and the fit of the prosthesis improves considerably.

You may also be interested in this topic: Interim prosthesis

Prosthetic care

Even if relining cannot be avoided after at least 1 1/2 years in most cases and the dentures are not "real" teeth, it is still very important to clean them thoroughly every day. Bacteria can still settle in the oral cavity and cause inflammation and an unpleasant odor.

A clean and well-maintained prosthesis not only looks better, it also increases its comfort and durability. This gives the mouth its "fresh feeling" back. After every meal, it is advisable to rinse the denture under running water, as food scraps may have gotten under the denture. The prosthesis should be thoroughly cleaned once a day. Care must be taken that it does not fall down and break. However, should this happen, it can be reassembled by the dental technician.

With a special denture toothbrush, the denture can be cleaned thoroughly from all sides to remove food residues and plaque. It is advisable to use special denture toothpaste for this, or everyday toothpaste that has a low proportion of abrasive particles, as otherwise the surface of the denture could become roughened. Special cleaners in powder or tablet form can be used as a supplement, but do not replace manual cleaning.

In addition, a regular check-up by the dentist is recommended. If tartar remains, it is best to have it removed by the dentist using ultrasound.

Read more about this under:

  • Denture cleaning
  • Cleaning the prosthesis with tablets

costs

The cost of a dental prosthesis can vary from dentist to dentist to a certain extent, but is subsidized by the health insurance company. The subsidy from the health insurance company can be increased by keeping a bonus booklet.

The total is made up of three pillars. These are the dentist's fee costs, the costs for the laboratory and material costs. For the lower jaw, you can expect an average of € 460-520, of which the cash register will cover around € 320 (without bonus). The health insurance share is increased with the bonus.

You can also find out more at: Denture cost

The anatomical structure of the lower jaw

The bony basis in the lower jaw is formed by the alveolar process of the mandible. Similar to the upper jaw, the tooth sockets in the lower jaw ossify over time. Here, too, the structures are covered by an immovable mucous membrane. This is also called the fibrous edge zone. Located further towards the pharynx, in the area of ​​the wisdom teeth, there is a pear-shaped bone bulge, the retromolar trigonum. There is a bone edge in the area of ​​the molars. This serves the insertion of the mylohyoid muscle.

In addition, the sublingual carunculae (ducts of two large salivary glands) can be found in the lower jaw, as well as the mental foramen, via which the inferior alveolar nerve leaves the bone.

Read more on this topic at: Lower jaw

Figure lower jaw

Figure skull from the front and from the left (lower jaw blue)
  1. Lower jaw - Mandible
  2. Crown process -
    Coronoid process
  3. Lower jaw rest -
    Ramus mandibulae
  4. Mandible angle -
    Angulus mandibulae
  5. Upper jaw - Maxilla
  6. Zygomatic bone - Os zygomaticum
  7. Zygomatic arch -
    Arcus zygomaticus
  8. Temporomandibular joint -
    Articulatio temporomandibularis
  9. External ear canal -
    Meatus acousticus externus
  10. Temporal bone - Temporal bone
  11. Frontal bone - Frontal bone
  12. Chin hole - Mental foramen
  13. Eye socket - Orbit
  14. Upper jaw, alveolar process -
    Alveolar process

You can find an overview of all Dr-Gumpert images at: medical illustrations

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