An interim prosthesis (synonyms: transitional prosthesis, provisional prosthesis, temporary prosthesis) is a simple, removable partial denture (partial denture) used to replace missing teeth. Its service life is limited to the wound healing phase after surgery until a definitive (final) restoration is made. During the wound healing phase after a tooth extraction (tooth removal), not only the soft tissues covering the jawbone regenerate. Rather, the alveolus (the bony tooth compartment) of the extracted tooth is also restructured, so that the alveolar ridge undergoes a change in shape. Therefore, it is usually not very useful to make a definitive (final) denture immediately after a surgical procedure. An interim prosthesis (from Latin: meanwhile, temporarily) bridges the necessary period of about two months. The same applies to the healing phase of implants. Due to their short service life, interim dentures are generally inexpensively manufactured PMMA-based (polymethyl methacrylate) plastic dentures that are attached to the remaining dentition with hand-bent wire clasps and thus largely restore chewing function and esthetics. The interim denture is a purely mucosal or gingival (on the mucosa or gums) restoration, which transfers the chewing pressure to the alveolar ridge without resting on the remaining teeth. In the long term, the ridge reacts to this with atrophy (bone regression). In addition, the curved clasps are not very gentle on the cervical area of the clasp tooth in the long term. For these reasons, the service life of the interim prosthesis should not be extended unduly. Definitions: Interim denture – Immediate denture
According to health insurance guidelines, a distinction must be made between an interim prosthesis and an immediate prosthesis. Whereas the latter is a definitive restoration inserted immediately after surgery, the interim prosthesis, as explained, serves only to bridge the time gap. It only makes sense in exceptional cases to fit a definitive denture that is to remain in function for several years without waiting for the restructuring processes of wound healing. On the other hand, masticatory function and esthetics must be ensured and more extensive wound areas must be protected from mechanical irritation if necessary. Therefore, the procedure of an interim restoration inserted immediately after the surgical intervention is practical.
Indications (areas of application)
- Temporary restoration of masticatory function, phonetics and esthetics after tooth extraction or implant placement (placement of an implant).
- Preservation of vertical jaw relation (distance from the base of the upper jaw to the base of the lower jaw).
- Preventing elongation (outgrowth of a tooth from the jawbone in the absence of opposing teeth).
- Prevent tooth migration and tilting.
- Protection of the surgical wound
Contraindications
- Proven allergy to PMMA plastic.
The procedure
I. Dental office – preoperative impressions.
On a date that is far enough in advance of the surgical procedure so that the interim prosthesis can be fabricated in the dental laboratory in the meantime, impressions of the jaw to be restored and the opposing jaw are taken from alginate (impression material). With the help of a bite registration (made of wax or silicone), the positional relationship of the upper and lower jaws is brought into relation to each other. II. laboratory – fabrication of the interim prosthesis
- In the dental laboratory, plaster models are made based on the impressions.
- The models are articulated based on the bite record (articulator: device used to imitate the movements of the temporomandibular joint).
- The crowns of the teeth planned for extraction are erased (removed) on the plaster model.
- Clasps bent by hand are adapted to the brace teeth and fixed on the model. The brace will later fit the neck of the tooth below the tooth equator (greatest curvature of the tooth crown) with slight tension.
- The denture base, in which the clasps are anchored and the denture teeth are set up, is first modeled from wax. Regarding the finished plastic base must be accepted for stability reasons restrictions on wearing comfort in favor of the material thickness.
- The wax modeling is implemented in plastic.
- The hardened denture acrylic is finished and final polished.
III. dental surgery – insertion of the interim prosthesis.
Immediately after the surgical procedure, the patient is provided with the interim prosthesis. Minor corrections to clasps and occlusion (final bite and chewing movements) can be made. The denture base is checked for pressure points, but with the restriction that the patient cannot yet perceive pressure points themselves at this time due to the local anesthesia (local anesthetic) still being administered.
After the procedure
- After the surgical procedure, an appointment for wound and pressure point control is scheduled promptly in the following days.
- Regular checks should also be made in the course of further wound healing to make corrections to the prosthesis fit, if necessary.
