What Is a Removable Partial Denture?

Removable partial dentures have a wide range of indications. Removable partial dentures can be used from the absence of one tooth to the remaining one. It is especially suitable for those who have a large number of missing teeth, free loss, tissue defects, and remaining periodontal teeth with poor periodontal health. For patients with cleft palate, they can repair missing teeth and use denture bases to close the cleft palate; for excessive wear, etc. If the height of the lower 1/3 of the face is reduced, the vertical distance can be increased by using the removable partial denture cushion; children with missing teeth during growth and development are also suitable to use removable partial dentures to repair the missing teeth without affecting the jaw bone. Growth and development; removable partial dentures are also often used as a short-term transitional repair during treatment (immediate dentures, temporary dentures); meet certain special aesthetic requirements (beauty dentures, cosmetic dentures); intolerable due to physical health reasons Fixed denture repair, those who do not accept a large amount of tooth tissue removal, or those who are unwilling to use fixed dentures to repair dentition defects.

Yang Yadong

(Chief physician)

Department of Prosthodontics, Peking University Stomatological Hospital

A removable partial denture is a prosthesis that can be removed and worn by a patient for partial tooth loss (dental defect). The denture mainly maintains the position of the denture in the dentition by retaining devices such as snap rings fixed on the remaining natural teeth and the base. The natural tooth and the remaining alveolar ridge in the missing tooth area are used as support to restore the missing tooth and its surrounding defects. Tissue anatomy and physiological functions.

Western Medicine Name: Removable partial denture
Affiliated Department: Department of Physiology-Stomatology

Disease site: tooth
Contagious: Non-contagious

Indications and contraindications for removable partial dentures

Indication of removable partial denture

Contraindications for removable partial dentures

Without normal behavior, life cannot take care of itself. Patients whose dentures are inconvenient to remove, store, and clean, and who are at risk of swallowing dentures, such as those with hemiplegia, dementia, limb and hand disability, epilepsy, and severe mental disorders; those with severe caries who are not cured; too small repair gaps, which affects Denture strength; those with oral mucosal ulcers, tumors and other diseases that are not cured; those who are allergic to the materials of dentures and have no other materials to replace, or individual patients who have obvious feelings about the foreign body of the dentures and cannot overcome them.

Advantages and disadvantages of removable partial dentures

Compared with fixed dentures, the advantages of removable partial dentures are that they have a wide range of indications. In many cases that are not suitable for fixed dentures, removable partial dentures can be used, such as a large number of missing teeth, unsatisfactory abutment periodontal health, and tissue defects. Etc .; the abutment of removable partial denture does not need to be abraded as much as the fixed denture abutment; the cost of removable partial denture is lower than that of fixed denture, which can be repaired after the denture is damaged, and can be added to the original denture after some parts are missing Artificial teeth.

Disadvantages of removable partial dentures are that the dentures are large and cover a large amount of normal tissues. Nauseous discomfort and articulation are often caused when they are first worn. Food residues and soft dirt are easy to accumulate between dentures and natural teeth and tissues. Removable dentures and Clean, otherwise it will affect the health of the remaining teeth. Functional restoration of removable partial dentures is not as good as fixed dentures.

Classification of removable partial dentures

Removable partial dentures are classified by structure and material

1. Cast stent denture

The main structure of the denture is an integrally cast metal bracket, and artificial teeth and bases are attached to the cast bracket. Common metal materials are cobalt chromium alloys and titanium metals.

2. Rubber-linked dentures (plastic base dentures)

The artificial teeth of the denture and the retaining snap ring are connected together by a plastic base. The material is methyl methacrylate.

Comparison of advantages and disadvantages of two types of dentures

Cast stent-type dentures have high strength, small volume, small covering tissue area, good comfort and easy self-cleaning. The cemented denture has poor strength, large volume, large coverage tissue area, poor comfort, and poor self-cleaning. However, the manufacture of cast-scaffolding dentures is relatively complicated, expensive, and difficult to repair after being damaged; glue-linked dentures are simple to make, low in cost, and easy to repair after being damaged. Formal dentures for long-term use are mostly cast-supported dentures, while glue-connected dentures are mostly used as temporary transitional dentures.

Removable partial dentures are categorized by support

1. Dental support denture

When the number of missing teeth is small and the remaining teeth are relatively stable before and after the missing tooth space, the occlusal force of the artificial tooth is supported by the natural teeth before and after the missing tooth space. Tooth-supporting dentures have good retention, stability, and support, and good repair results.

2. Hybrid support denture

When there is no remaining tooth behind the missing tooth area (distant and free loss), or the number of missing teeth is long and the gap is long, the occlusal force of the artificial tooth will be partially borne by the natural tooth adjacent to the gap, and the other part by the base Covered alveolar crest bears. That is, the occlusal force is shared by the natural tooth and the alveolar ridge. Such dentures are prone to instability such as warpage and rotation, adjacent abutments with free gaps are vulnerable to torsional damage, and alveolar ridges are prone to bone resorption and mucosal tenderness. The restoration effect is not as good as dental support dentures.

3 Mucosal supported denture

When there are too many missing teeth and the remaining periodontal health is poor to provide support, the occlusal force of the denture artificial teeth is completely borne by the alveolar ridge under the denture base. Mucosa-supported dentures have poor repair results and are prone to tenderness and bone resorption. The scope of the base should be expanded as much as possible to disperse the bite force.

Removable partial denture

Removable partial denture examination and treatment plan

First, the number and location of teeth loss in patients with dentition defects, the health status of the remaining teeth, the alveolar ridges, and the mucosa of the missing tooth area, and a comprehensive and detailed examination and evaluation of the existing fixed and movable restorations in the mouth. Including oral examination, X-ray examination and research model analysis. And understand the patient's overall health and requirements for denture restoration. Determine whether the patient is suitable for removable partial denture restoration (in line with the indication for removable partial denture); determine the content and time sequence of other diseases and problems that need to be treated before the denture restoration (ie, preparation before restoration); determine the preliminary partial denture Design (including the type of denture, material selection, etc.), the cost, start time, process of the prosthetic restoration, the prosthetic effect that may be achieved, the problems that may occur, and the treatment method. Doctors and patients should communicate fully during the development of the treatment plan. The design of the denture and the selection of materials should meet the requirements of the patient as far as possible in accordance with the principle of restoration. For the possible restoration effects and possible problems and treatment methods, Get informed consent from the patient.

Preparation for removable partial dentures

1. Remove fixed restoration

Existing fixed restorations in the mouth should be removed if there are the following problems. Poor restoration design and production affects functional recovery and tissue health; periodontal, endodontic, and root apical lesions are present in the abutment; those who need to restore the overall restoration design.

2. Oral surgery

Including extraction and alveolar process, soft tissue surgery.

Tooth extraction should be considered, including teeth that are severely damaged, cannot be retained for long periods of time, cannot be repaired or impede the restoration of dentures. For example, third-degree looseness, alveolar bone resorption of 2/3 of the teeth, unusable residual roots and residual crowns, imperfect dental pulp treatment, poor prognosis teeth, misplaced teeth that affect repair and cannot be corrected, and excessive tilt Teeth, excessively extended teeth, etc.

If the alveolar ridge has a sharp bone tip or a large tissue depression after tooth extraction, the proliferated soft tissue and soft mucosal tissue on the alveolar ridge affect the denture prosthesis and should be removed surgically.

3 Dental pulp treatment

Dental caries and tooth defects (such as wedge-shaped defects) in the remaining teeth should be treated with dental filling; those with pulp and apical lesions should be treated with root canals; those with incomplete root canals should be re-rooted Treatment; more grinding is required, which may cause extended or tilted teeth that are sensitive to perforating the pulp or dentin, and pulp inactivation and root canal filling should be performed first.

4 Periodontal treatment

Periodontal health of the remaining teeth is essential to maintain long-term stability of the repair effect. Therefore, periodontal treatment should be performed on the remaining teeth before restoration, and long-term periodontal maintenance treatment should be performed afterwards. Periodontal treatment is not just a simple treatment. Patients with periodontal disease need to receive systematic periodontal treatment, including periodontal surgery. For teeth with tooth defects deeper than the gingival margin, crown extension surgery is required to obtain a good restoration edge position and normal periodontal biological width.

5. Orthodontic treatment

Some dentition defects can take orthodontic methods to correct the inclination and displacement of the remaining teeth before repair, reduce the extension of the teeth, close or concentrate the interdental space; orthodontics can be used for deep overlap, deep coverage, and adjustment of the curve Wait.

6. Oral Mucosal Disease Treatment

People with denture stomatitis need antifungal treatment. Soak old removable dentures with baking soda and stop wearing if necessary. The ulcers and inflammation of the oral mucosa must be cured before the denture repair. Other oral mucosal lesions should also be actively treated, and repair procedures and restorations should be avoided to stimulate and aggravate mucosal lesions.

7. Temporary denture restoration

Patients with dentition defects want to repair as soon as possible. However, in general, the extraction socket is basically healed after three months of tooth extraction before formal restoration can be performed. For patients with more complex dentition defects, the process from preparation before restoration to completion of formal restoration takes a long time, and chewing and aesthetic functions cannot be restored for a long time, which causes great inconvenience to patients' lives. Therefore, temporary denture repair can be performed in the preparation phase before restoration, that is, take an impression before extraction, remove the tooth to be removed from the model and make removable denture, and then you can wear denture (immediate denture) after extraction, to a certain extent Restore chewing function and beauty.

Removable partial denture repair process

1. Conditioning, restoration and preparation of abutment teeth

Dentition defect patients often have abnormalities in the shape, resistance, position and occlusal relationship of the remaining teeth, and the remaining teeth need to be adjusted and repaired before the missing teeth are repaired. If necessary, a research model is needed to observe to determine the position of the removable partial denture, the guide plane and the position of the retained undercut, and to determine the position and the amount of adjustment on the research model. Then guided by the research model, the remaining teeth were modified. Adjust the sharp tooth tip, edge ridges, wear surface and filling tooth tip caused by uneven wear, adjust the occlusal contact point, remove occlusal interference, occlusal trauma, shorten the elongated teeth, and adjust the occlusion curve.

For teeth with tooth defects, especially removable partial denture abutments with poor morphology and resistance, full crowns, pile crowns, inlays, etc. can be used to restore the shape, resistance, occlusal contact and occlusion curve to obtain the ideal The abutment retains the undercut and guide plane.

The axial surface of the abutment should be removed from excessive undercuts to form a guide plane. Supporting sockets are prepared for the posterior occlusal surface and the anterior lingual surface to support the dentures. Gap grooves should be prepared when retaining rings are placed on the non-missing side. The support socket and gap card groove must have sufficient depth and width to ensure the strength of the denture bracket and gap card.

2. Take impressions, cast models

Tooth-supported dentures are made using a single impression. Select the finished dentition tray of appropriate size, and use the alginate impression material to take the mold. For mixed-supported and mucosal-supported dentures, the secondary impression method should be used. First use the finished tray and alginate impression material to obtain the initial impression, inject the model, and make individual resin trays on the model. After the edge is plasticized, add the final impression material to obtain the final impression. For hybrid support dentures, a functional impression should be obtained at the free end. The final impression was filled with anhydrite as a working model for making dentures.

3 Determine the relationship

Those with missing teeth can directly and accurately align the upper and lower jaw models. There are many missing teeth, such as free loss, stable occlusion in the mouth, but the model occlusion is unstable, you need to lay resin temporary base or base wax base temporarily on the model, and add a soft wax bank to form the holder Stabilize the occlusal relationship at the gap. When there are more missing teeth and the relationship between posterior teeth occlusion and stable jaw position cannot be maintained, it is also necessary to make a rest bracket to redefine the patient's vertical distance and horizontal jaw position relationship.

4 Working model observation and denture design

5. Manufacture of denture casting metal bracket

6. Try on the denture bracket

After the denture metal stent is completed, you can try it on in the patient's mouth to check whether the stent is in place smoothly, whether the parts of the stent are tight, the retention and stability effects, and whether there is interference in the occlusion. Appropriate adjustments are necessary when necessary.

7. Arrange teeth to complete the denture.

8. First denture

9. Proper use and maintenance of dentures

(1) Removal method

When wearing dentures, use the square position, gently press the he surface of the artificial teeth with your fingers, and gently put them into place. When removing the denture, push and pull the snap ring towards he with your nails, in the opposite direction of the seat. Patients who are not skilled in removing and wearing dentures can go home to practice, but the doctor must teach the patient how to remove or wear them, otherwise the patient may not be able to remove or wear dentures after returning home.

(2) Oral hygiene and denture cleaning

It is important to maintain oral hygiene after wearing dentures. You should brush your teeth after meals and before going to bed. Do not wear dentures and brush your teeth. Remove your dentures and clean your real and dentures. Dentures can be gently brushed with a soft-bristled toothbrush dipped in toothpaste. Brushing too hard and brushing too hard will wear the denture. If the surface of the denture is not easy to brush off, soak it with a denture cleaning sheet before brushing. Do not soak the dentures with hot water, alcohol, or other aggressive cleaning agents. When not wearing dentures, they should be immersed in cold water.

(3) Practice and adaptation after first wearing dentures

After wearing dentures for the first time, there will be foreign body sensation, nausea, articulation, and inconvenience in chewing. It requires patient practice and habits, and can be improved in 1 to 2 weeks.

It is recommended to eat softer foods first, and cut the large pieces of food with the anterior teeth as little as possible, and gradually increase the hardness of the food according to the situation. After wearing dentures, the burden on the abutments and alveolar ridges supporting the dentures increases, and they should be gradually adapted, otherwise the pain of the abutments and alveolar ridges is prone to occur.

(4) Problems and treatment

Possible problems when wearing removable partial dentures (especially after initial dentures) include pain in the remaining teeth or mucous membranes, loose dentures, difficulty in removing, biting the cheeks and tongues, impaction of food, poor chewing function (not biting bad food) Pronunciation is unclear, nausea, increased saliva, discomfort in the masticatory muscles and temporomandibular joint, and unsatisfactory appearance. If you have any problems such as discomfort, or the denture is damaged, you should go to the hospital for inspection, adjustment or repair in time. Patients should not modify the dentures themselves. If the denture is not worn for a long period of time, it may cause difficulty in removing the denture or even prevent it from being inserted due to changes in the position of the remaining teeth.

(5) Long-term maintenance

Periodic review every six months to one year, timely detection and treatment of possible problems with remaining teeth and dentures, maintaining the health of remaining teeth and normal use of dentures ^[1-3] .