As we have seen before, we can deal with different groups of patients, namely:
- The completely toothless (edentate) patient;
- The patient who is toothless in one jaw and still has (all) elements in the other jaw, and who wants to retain his residual elements;
- The patient who misses elements in the lower jaw and / or upper jaw and therefore has chewing complaints or complaints regarding appearance and wants to retain the remaining elements;
- The patient who still has some or all of the elements and who wants to have all the elements pulled to switch to a full upper and lower prosthesis.
The patient who wants to retain his elements still present may be helped with refurbishing the elements, possibly in combination with the manufacture of a partial, removable dental prosthesis. Fixed facilities, such as etching bridge, crowns and bridges, are also possible, depending on the situation. The condition is, however, that the elements still present are or can be brought into good condition. The patient who is toothless in one or both jaws may be assisted with a complete upper and / or lower prosthesis.
Depending on the condition of these elements and his motivation, the patient who wants to have his remaining elements drawn may be convinced to have his teeth refurbished or to keep some teeth. If retention is not possible, a full dental prosthesis can be made.
First, the complete prosthesis is discussed and then the partial (partial) prosthesis.
If a patient is toothless in the upper and lower jaw, a full upper and lower prosthesis is made. If one jaw is toothless, a full prosthesis is made on that jaw. If a patient wants to have his remaining elements drawn, a so-called immediate prosthesis is made. This can be made for both jaws or for one jaw half. This depends on the wishes of the patient and the condition of the elements still present.
The complete prosthesis therefore has different types. Because the procedure for making these different prostheses is not very different, first a complete upper and lower prosthesis is discussed. The differences with the other types of prostheses are then indicated.
The complete upper and lower prosthesis restores the function and appearance of lost elements. An acceptable looking result can usually be achieved because the shape, size, color and position of teeth can be determined. The patient can (also) decide on this.
The prostheses have a base of synthetic resin or metal and the edges are made of synthetic resin. The elements are made of synthetic resin or porcelain. Restoring functions is more difficult. In terms of stuck and stability, the dental technician is bound to the shape, size and condition of the jaw, gums and surrounding tissues such as muscles and lip bands. A new prosthesis will usually affect speech. This usually recovers completely within a few weeks. The restoration of occlusion and articulation is an individual matter. Some patients can bite off apples and chew steak after a while; for others this is always a thing of the past. The willingness of a patient to get used to the prosthesis is also an important point. Habits, hobby or profession can make it difficult to make a prosthesis or get used to it; think of pipe smokers, horns or singers.
How a complete upper and lower prosthesis is made is described below.
The first, provisional, impressions of the lower and upper jaw are made. The prints are made with alginate. This material gives a good reproduction of the structures to be printed. It is advisable to mix the alginate a little more stiffly than normal to get a better representation of the sometimes bad jaws.
There are special impression trays for toothless patients. These are made of metal and have holes in them. Sometimes the old prosthesis can be used as a print spoon. The spoon is filled with the mixed alginate and, after curing, taken out and evaluated. All anatomical structures up to and including the transition from solid to non-attached gums must be visible.
Printing spoons are made on the models obtained from drawn synthetic resin or from chemically curing synthetic resin. These spoons are only suitable for the patient in question and are called individual spoons. To give these individual spoons the correct length, on the models the dentist first draws the boundary, taking into account the muscles and lip or tongue bands. The signed models go to the technician and the spoons are made.
If the dentist does not use individual spoons, but the first models serve as the definitive model, seat 2 will lapse (see images below).
An individual or precision print is now made using the individual spoon. The individual spoons are fitted in the mouth. The dentist checks whether the spoon edge is too short, too long, too thick or too thin. The spoon edges are milled if necessary.
The requirements imposed on the precision impression are that the prosthesis must be given as much hold as possible, taking into account the muscle and tissue limitations in the area of the dental prosthesis, and that there is a precise representation of the tissue surface. To achieve this, the rim of the spoon is formed with stents or wax, both supplied as rods. The material is heated over a flame and applied to the edge of the individual spoon. Before the spoon goes into the mouth, the wax is cooled slightly in a bowl of warm water. After inserting the spoon, the heated stents or wax is pushed into shape to the correct length. Forming the edge can be done in two ways:
- The active method: the patient makes the muscle movements that are important for the relevant part of the peripheral structure. For the upper jaw edge, the patient must pucker lips and grin and move the lower jaw to the left and right. For the lower jaw limitation, especially the tongue movements are important, the patient also spouts his lips and he grins.
- The passive method: by massaging the patient's cheeks and lips the dentist can shape the stents edges to good thickness and length (see image below).
Any excess stents that have flown into the inside of the spoon can be removed with a scalpel blade. The edge of the individual spoons is built up step by step. When the edging has been completed, the spoon will seal and suck the jaw airtight especially in the upper jaw. This is harder to achieve in the lower jaw. This is because the contact area between the prosthesis and the gingiva is smaller here. Moreover, the movable tongue is located here.
You can check the spoons for pull and push retention. The retention of a prosthesis is the resistance to forces that want to release the prosthesis from the base. Pull retention can be checked by pulling the handle in a direction perpendicular to the base. Push retention is the retention against tilting forces that occur when biting. If the pull and / or Push retention is insufficient, there may be a leak at the edges or in the spoon or the edge is not the correct length.
If the built-up spoon is satisfactory, the shape of the jaw is printed with a thin-liquid precision printing material, usually an elastomer. The precision impression material is placed in the spoon and with slight pressure the spoon is placed in place, so that surplus impression material can flow out under the spoon. The patient or dentist then makes the same movements as in the edge building process. The resulting prints are checked again for the correct fit and retention. The individual spoons are packed and a hard plaster model is made in the laboratory, which serves as a definitive basis for the prosthesis to be made (see images below).
In the third seat, the vertical and horizontal relationship are determined, as well as the color and type of the upper front elements. This is done with the help of two base plates, which are produced on the working model. These base plates are usually made of shellac (just like stents, a thermoplastic material). Because these shellac plates have little retention, especially in the lower jaw, one can ask the technician if he wants to use the individual spoon as a base plate and, after stents and impression material have been removed, fill it on the inside with wax and then apply a wash wall to this spoon. The base plate with washing wall is fitted in the mouth.
Before the relationship can be determined, it is important to check the wash bags. The correct lip filling can be obtained with the aid of the upper wash wall and the direction of the occlusion surface can be determined.
- The lip filling is first applied by applying wax or removing it from the upper wash wall.
- If the correct lip filling is obtained, a mark is applied 1 mm below the upper lip at rest with a washing knife. That is where the incisal edge of the upper incisions comes. By having the patient pronounce the letter "F", they have a good indication of the correct height of the overhead washing wall. When pronouncing the "F", the upper washing wall may actually touch the lower lip. Younger people may see the front teeth slightly more than older people.
- Then the direction of the overhead washing wall is determined with the help of a so-called bite fork. With a rimformer that is heated in a flame, the washing wall is made completely flat. With a front view, the bite fork, which is placed against the wash wall, must run parallel with an imaginary line drawn between the two eye pupils; this is the pupil line. With a side view (profile view), the bite fork must be parallel to the Camper plane. This is the plane through the two ear exits to the bottom of the nose. The underside of the upper wash wall later becomes the plane of occlusion (see images below).
If the upper wash wall has a good direction and a good course, the vertical relation can be determined.
- Rest height. The patient must sit upright and, for example, swallow, hold lips loosely together, or pronounce the "m" or "i". This often results in a relaxed state of the muscles in the face. The distance between a point above the mouth, usually a tip on the nose, and a point under the mouth, usually a tip on the chin, is measured a number of times. If the patient always arrives at approximately the same rest height, this height is chosen.
- Bite height. The underwash wall is trimmed in such a way that after placing in the mouth left and right a full and simultaneous contact is created when close. The height of the washing wall must be such that the bite height is measured at close quarters. The bite height must be 2-3 mm less than the found resting height (see figure below).
Horizontal relation determination. With a toothless patient there is no longer any occlusion and therefore no relationship between the lower and upper jaw. This relationship must be established. It has already been noted that we would like to reach a position of the lower jaw relative to the upper jaw in which the lower jaw is in the central relation (see image above). There are a number of methods to find the central relationship:
- The dentist guides the lower jaw, starting from a wide open mouth, backwards by hand. The most backward position can then be felt. This is the guided closure method;
- Let the patient swallow and then close;
- Have the patient close to the palatum with the tongue tip behind;
- The arrowhead registration, in which use is made of a writing table and a writing pin. The latter method is effective because it is verifiable. Lateral errors are almost impossible with this method. The writing table is colored with a black marker. If the writing table is placed in the wash basin and the writing pin in the wash basin, we will get the seagull (seagull flight) registration. If both are placed the other way round, then the gothic arc registration is obtained. Of both methods, it is the intention that the patient, while the pin sits against the writing table, has the lower jaw make the various sliding movements. A somewhat V-shaped registration then occurs on the writing table. The point of this v is the central relationship. Once the central relationship has been found, it will be recorded (see image below).
There are various methods for this:
- Stripes are placed on the upper and lower washing walls so that the washing bags can be put back in the correct position relative to each other after removal from the mouth.
- A gypsum lock is made with fast-hardening plaster. Both ramparts are provided with wedges, which are filled with plaster.
- Thin-liquid wax is used to make a wash bite on the walls.
- Balls are placed in the underwash wall that are lightly heated and the patient is allowed to get close, which results in an impression of the balls in the top wash wall.
- The most reliable form is the plaster lock, because technicians and dentists can always replace it after the models and bite plates have been inserted into the articulator (see image below).
After establishing the central relationship it is time to determine the color and shape of the teeth. Sometimes the patient can indicate what the upper front teeth of his prosthesis should look like. This can be the same as the front of the old prosthesis. In this case we make an alginate print of the old upper prosthesis and send it as an example to the laboratory. It may also be that the patient wants to make the teeth of his new prosthesis look like his own teeth from the past. In that case, a good description of the patient or a photo can be useful.
The width of the entire front is measured by the dentist on the upper wash wall. An aid to determine this width is that the distal surface of a cuspidate in the upper jaw lies on average behind the corner of the mouth with the lips at rest. The length of the teeth is determined by the height of the smile line. The smile line indicates to what extent elements are visible during laughter. This is different per person. The cervical part of the element coincides with the smile line. The shape of the teeth is adjusted to the shape of the face.
If the dentist knows the width, length and shape of the upper front teeth, he can pick out a front on a so-called tooth chart. The color of the elements is determined by means of a color ring and the wishes of the patient are taken into account. Too light a color can enhance the artificial appearance of a prosthesis (see image below).
The material that the elements can consist of is porcelain or synthetic resin. Both materials have their advantages and disadvantages (see table below). At the back of the porcelain front elements are the so-called crampons, small pins that ensure that the element is extra firmly attached in the synthetic resin (see image below). The adhesion of the resin elements is chemical. It is useful for the dentist or technician to set the upper front in the presence of the patient. If this does not happen and the technician sets up the front in the laboratory, the form, color and position of the elements and any color variations must be indicated on the technical receipt.
Advantages and disadvantages of synthetic resin and porcelain prosthetic elements.
|Color fastness (short term)||–||+|
|Color fastness (long term)||–||+|
|Wear resistance||+ / –||+|
|Bonding in the synthetic resin base||+||+ / –|
|Friendly to antagonists (eg full prosthesis above, natural dentition below)||+||–|
|Applicability if there is little space between the jaw walls||+||–|
The two base plates with washing bags and other data are sent to the laboratory. The models are cast in an articulator and the teeth and molars of the upper and lower jaw are set in wax (see image below). The dentist has informed the technician in advance what type of occlusion and articulation pattern he wants to have made in the prosthesis. We have already seen that balanced occlusion and articulation have advantages with regard to the stability of the prosthesis and the shrinking of the jaw. There are different types of molars on the market, which have certain lump gradients and where the lump inclination determines how the molars should be placed on the jaws. We speak of an occlusion concept. Each of the so-called occlusion concepts has its advantages and disadvantages. There is a mechanical concept, a physiological concept and a lingualized occlusion concept. The latter can provide a solution for strongly shrunk jaws and also has benefits for appearance.
The dental laboratory has made an arrangement in wax in the articulator. This setup is appropriate (see image below). The selected elements are placed on the base plates in wax in the correct central relationship and bite height. Moreover, a balanced articulation has been ensured. The prosthesis is placed in the mouth and viewed on:
- The appearance of the prosthesis, the color, shape and position of the teeth, lip filling and wax finish;
- The central relation;
- The occlusion and articulation;
- The bite height.
When the arrangement has been found to be good in wax, it is sent to the laboratory. The wax is finally finished in the laboratory. The models with the arrangement of the prostheses in wax are embedded in special brass bowls and the prostheses are pressed or cast. The wax and the bite plates are replaced by synthetic resin.
This synthetic resin must be as little as possible deformable in the mouth and look good. The synthetic resin must not have an irritating effect on the mouth. The most commonly used synthetic resin consists of a powder component and a liquid component. Hardening occurs by mixing both of these. After curing, the not yet finished prostheses are removed from the mold and placed back into the articulator together with the models. It is checked whether there have been any changes in the occlusion and articulation pattern. If this is the case, the technician improves the occlusion and articulation by means of grinding. If everything is fine, the prosthesis is polished.
The technician delivers the pressed prosthesis with the models and articulator to the dentist. The dentist checks everything in the articulator and places the prosthesis in the patient's mouth. He pays attention to the fit of the prosthesis, the occlusion and articulation, what the prosthesis looks like and the central relationship. If there are already undercuts or very painful spots in the mouth, he can already slightly adjust the edges with a small cutter in a handpiece (see image below).
The new situation in his mouth requires the patient to make the necessary adjustments. Initial problems, such as changes in speech, chewing capacity, space for the tongue, amount of saliva, taste and appearance, decrease and disappear completely after a while. The patient must be made aware of these problems because the expectations are often (too) high. Painful pressure spots can also occur. As many agreements are made with the patient as necessary to resolve all complaints. For a check-up, the prosthesis must be worn for several hours, because otherwise the painful places in the mouth cannot be seen.
The patient must never grind or use adhesives on the prosthesis if the prosthesis does not stay in place properly.
Pressure spots (pressure ulcers) are sores that are caused by (see image below):
- Irritation of a too long or sharp prosthesis edge: the prosthesis presses in these places in the gums;
- Incorrect occlusion or articulation: the prosthesis presses more in certain places through tilting.
The cause of the pressure site is sought and removed. If the pressure site is not clearly visible in the mouth, we can try to locate the pressure site by inserting a material into the prosthesis and placing it back. Where the prosthesis prints, the impression material is pressed away.
If all complaints have been resolved to the satisfaction of the patient and dentist, the treatment is ready. In connection with constant change in the shape of the jaws, a mouth examination is regularly desired.
Wearing the prosthesis and daily maintenance at night is discussed in the discussion of the full immediate prosthesis.
Full immediate prosthesis
The full immediate prosthesis is placed immediately after the last elements have been drawn. This has the following advantages:
- The patient does not have to walk without teeth during the first period after the extractions.
- The patient keeps his elements up to the last minute and with that, albeit limited, the chewing and stripping capacity.
There are also disadvantages: the prosthesis becomes looser over time, because the jaw shrinks at the extraction wounds and must therefore be filled regularly and adjusted to the jaw shape after three to six months.
Before a complete immediate prosthesis can be made, as many elements as possible must be drawn, usually all molars and premolars. After these extractions in the lateral parts one can wait three months because of the aforementioned shrinking.
The patient still has his front teeth. Treatment usually starts after three months. The seats are the same as with the definitive full prosthesis, but with the following differences.
Seat 1. Special metal ready-made spoons with holes are used to make the preliminary dental impressions.
Seat 2. The individual impression. The procedure is the same as with a definitive complete prosthesis.
Seat 3. The bite plates with wash bags leave the front free. Determining the bite is easier because there is still contact in the front. If the patient wants the same shape and arrangement of the front teeth as that of his own teeth, one can ask the technician to copy them using the model of the preliminary print. The color can be determined on the basis of your own teeth. Once everything has been determined, the bite plates with wax bags are returned to the laboratory. The technician must now determine the shape of the jaw in the front, as it becomes approximately after extraction of the front teeth. According to certain rules, he removes the front teeth on the plaster model. This is called cogs (see image below).
Seat 4. Fitting in wax is limited to fitting the lateral parts. The front cannot be fitted in the mouth.
Seat 5. Inserting the entire immediate prosthesis. The remaining elements are drawn, sutures may be applied and the prosthesis is placed. Any minor corrections to the prosthesis can be made. The patient returns after 24 hours, with the express instruction to keep the prosthesis in the mouth during this time. aftercare and audit sessions. The next day the patient returns and the prosthesis is removed from the mouth. The wounds are cleaned with gauze pads and physiological salt. An explanation is given about inserting and removing and about the maintenance of the prosthesis. The dentist checks for any pressure spots and the occlusion and articulation are examined.
aftercare and audit sessions. The next day the patient returns and the prosthesis is removed from the mouth. The wounds are cleaned with gauze pads and physiological salt. An explanation is given about inserting and removing and about the maintenance of the prosthesis. The dentist checks for any pressure spots and the occlusion and articulation are examined.
The further checks are the same as with the definitive complete prosthesis and the patient is informed that the prosthesis will loosen over time. An attempt is made to postpone filling of the prosthesis until about six months after the last extractions. If the prosthesis becomes too loose in the meantime, it can be adjusted with a tissue conditioner. It may be necessary to apply a layer of tissue conditioner several times during the first six months after placement.
Instruction to the patient
The patient is asked to hold the prosthesis for the first 24 hours. After the prosthesis has been removed and discharged, the swelling will increase and the prosthesis can no longer be replaced or will be difficult to replace. The patient should take it easy on the first day and not do any heavy work. If bleeding does not stop after the extractions, contact the dentist, who can then attach the wounds.
The patient is advised that pressure spots can be felt and that problems with chewing and talking can certainly occur in the beginning. These adjustment difficulties usually disappear over time. Pressure sites do not disappear automatically. The dentist can remedy this by sharpening the prosthesis. Grinding yourself on the prosthesis should be strongly discouraged.
The patient is told how to maintain his prosthesis. If the patient does not clean the prosthesis regularly, food residues may remain on or under the prosthesis, which can eventually cause inflamed gums. Tartar and deposits may also appear on the prosthesis. The teeth are cleaned with a nail brush with green soap or a toothbrush with paste. There are also special cleaning products for prostheses for sale. It is important to use an agent that does not affect the gloss layer of the prosthesis. This is because the surface becomes rough and dirt adheres to it earlier.
The gums must also be cleaned by the patient after the wounds have healed. It is best to use a soft brush for this.
Patients often ask whether they should keep the prosthesis at night or not. The first time it is wise to keep the prosthesis. If the wounds are healed, it is better to take out the prosthesis when sleeping. This is better for the blood circulation in the mucous membranes. The jaw walls will shrink less quickly. If a patient finds this psychologically very difficult, then it is recommended to only let out the lower prosthesis. The prosthesis must be stored in cold water. If the prosthesis is stored without water, the synthetic resin shrinks and the prosthesis will no longer fit properly.
Written information in the form of a brochure or instruction booklet can be useful.
If dentist and patient choose to retain the residual elements or to retain some strategic elements, then either a partial prosthesis or a roof prosthesis, also known as overdenture, can be made. The canopy prosthesis can completely or partially cover the jaw. A partial prosthesis only covers the toothless parts of the jaw.
A roof prosthesis retains a number of strategically important elements. The canopy prosthesis can be used in both the lower and upper jaw. The lower jaw shrinks more than the upper jaw, which can lead to loosening. That is why the roof prosthesis is mainly used in the lower jaw. By maintaining the residual elements, the jaw retains its height.
A canopy prosthesis is a prosthesis in which one or more elements and / or roots are covered by the prosthesis. The covered elements are used as pillars, whereby the chewing force is distributed over both the elements still present and the toothless parts of the jaw. This means that the roof prosthesis is much more stable than a normal full prosthesis.
The procedure is as follows. First the residual elements are treated. In most cases, the residual elements are lowered to about 1 mm above the gums. We call this the decapitation of an element. Such a shortening almost always results in the relevant elements being treated endodontically. The remaining stumps can be restored in two ways after endodontic treatment (see images below).
- The elements are filled with a plastic filler material, such as glass ionomer cement or composite, or are provided with a smooth root cap. Both are polished to a high gloss. This root cap shape has a supporting function.
- The elements are provided with a root cap in which retention provisions are fitted. This can be push buttons, magnets or a bar between two pillar elements. The prosthesis then contains the negative of the push button or bar. By placing the prosthesis, the push button or bar clicks into the negative. This makes the prosthesis more secure.
The manufacture of the prosthesis is done in the same way as with the normal full prosthesis, but it is not started until the residual elements have been treated.
The benefits of a roof prosthesis are:
- The prosthesis is better attached and is more stable.
- The sagging of the jaw is reduced and the better distribution of the chewing force reduces the risk of gum trauma.
- By preserving the residual elements there is preservation of the chewing feeling. A patient with a roof prosthesis has better control of his chewing movements.
- It is less psychologically invasive for the patient. In the long run, it can be an easy transition to a normal full prosthesis, especially with regard to getting used to it.
The disadvantages of a roof prosthesis are:
- The costs are higher than with a normal prosthesis.
- The caries sensitivity of the residual elements and periodontal problems remain. The patient must have perfect oral hygiene, otherwise the roof prosthesis will be lost prematurely.
- Because the prosthesis passes over the elements, the roof prosthesis is often larger than a normal prosthesis. This may mean for a patient on the one hand that the appearance appears slightly fuller and on the other hand that a longer adjustment period may be needed.
Complete prosthesis with maxillofacial prosthetics
Maxillofacial prosthetics is a separate component within prosthetics. The patient is treated in a team, in special centers or in hospitals. The treatment is provided by specialized teams consisting of plastic surgeon, ENT specialist, SCA surgeon, orthodontist, dentist and dental hygienist, speech therapist and dental assistant. Qualify:
- Patients with developmental disorders in the face, such as patients with gnatho, palato or cheiloschisis or a combination thereof;
- Patients who are eligible for a prosthetic device as a result of tumor surgery in the face area;
- Patients who need a prosthetic device due to an accident or other cause.
Often the prosthetic device will not be limited to a dental prosthesis, but parts of the face must also be replaced, such as a part of the palatum in a schisis patient whose gap in the palatum cannot be surgically closed, or in a patient in whom due to an accident or tumor, a part of the jaw, nose, ear or eye must be replaced by a prosthesis. Often a facial prosthesis (epithesis) is then made with a dental prosthesis attached (see image below).
The partial (partial) prosthesis is a removable dental device that replaces one or more (but not all) elements with associated support tissue. Its purpose is to restore the chewing function, appearance and other functions of the teeth in a manner acceptable to the patient. Roughly, a distinction can be made between two groups of partial dentures, the resin plate ("plate") and the frame prosthesis.
Synthetic resin plate prosthesis
A plate consists of a synthetic resin carrier part with a number of synthetic resin or porcelain prosthetic teeth attached to it. Sometimes metal reinforcements are applied to the resin to reduce the risk of breakage. The plate can also be provided with extra cleats, which increase the hold. The plate lies linguistically or palatally against the elements of the residual teeth. The part where the prosthetic teeth are arranged is called the saddle. Buccal can run through the resin. We call this the buccal edge. The plate is completely supported by the underlying gums and not by the teeth. As a result, there may be a poor distribution of the occlusal forces, resulting in rupture of the plate. Also the hold of a record is often less.
Manufacture of a resin plate:
- Seat 1. Alginate impressions are made of the lower and upper jaw. These go to the laboratory to be poured. On the models, a base plate with washing wall is made or, if one chooses the method of the individually constructed prosthetic edges, individual spoons. A wash bite is sufficient for pictures of limited size.
- Seat 2. The individual impression. This seat is canceled if base plates with wash bags are made immediately. If individual spoons are used, they are stented and printed.
- Seat 3. In this seat the bite is determined and the color and shape of the teeth are chosen.
- Seat 4. The partial prosthesis is fitted in wax if necessary.
- Seat 5. The plate is placed.
This is followed by one or more checks until the patient and dentist are satisfied (see image below).
A frame prosthesis consists of a support part that is cast in steel. The base of the saddle is also cast in metal. The synthetic resin prosthetic teeth with pink synthetic resin are attached to the metal on the saddle section. The metal of the frame rests on a number of elements of the residual teeth, the so-called pillar elements (see image below). Usually so-called support fossa are applied. These are pre-prepared cavities in the pillar elements, into which the metal occlusal supports of the frame exactly fall. The metal hooks, which are called anchors, provide the frame with the elements. They fall over the vestibular and lingual / palatal bulging of the pillar elements (see image below).
A frame can be designed so that the chewing forces on the frame are entirely supported by the pillar elements. The partial prosthesis is then fully supported by the periodontium of the pillar elements and not by the gums on the toothless parts. We then speak of a frame that is worn completely periodically, also called a star frame. We also have a frame design in which the chewing forces are distributed over the pillar elements and over the gums at the height of the saddle sections of the frame. The frame is then partly worn periodontally and partly mucosal. We call this a power-breaking frame.
With extensive remediation of the mouth it is sometimes necessary to provide pillar elements with crowns before a frame is made. In these crowns, support fossa can be applied to support the frame or the crowns can be provided with a "lock" in which the frame can be attached. We call this precision anchoring (see image below).
A frame has a number of advantages over a synthetic resin plate:
- The frame has more grip in the mouth and is often easier to accept for the patient.
- It is more robust and can be made smaller than a synthetic resin plate.
- There is generally less irritation of the gums.
- There is support on both elements and on the gums. The chewing forces are better distributed.
Disadvantages of a frame are:
- It is more expensive than a synthetic resin plate.
- The anchors of the frame can lie in view and cause problems with the view.
- Due to the anchors, the frame prosthesis requires perfect oral hygiene, otherwise the residual elements will be accelerated.
Manufacture of a frame prosthesis:
Seat 1. Alginate impressions are made of the lower and upper jaw and the dentist makes a frame design. The prints go to the laboratory, where they are poured and where an individual spoon is made for the frame to be printed.
Seat 2. The dentist grinds support fossa in the elements he requires. This grinding is done with special drills. An individual print is then made. First the individual spoon is built with stents and then a sprayed print is made in connection with the correct representation of the fossae. The individual spoon goes to the laboratory, and the frame metal is poured onto the model.
Seat 3. The frame metal, with a wash wall on the saddle sections, comes back and is fitted to the patient. The bite is determined and the shape and color of the elements are chosen.
Seat 4. The frame metal with the elements arranged in wax is fitted and occlusion and articulation are viewed.
Seat 5. The frame is placed. This is followed by one or more checks.