Acrylic removable partial denture
It is a dental prosthesis which artificially supplies teeth and associated structures in a partially edentulous arch, made of acrylic resin and can be removed from the mouth at will. An acrylic removable partial denture consists of an acrylic resin denture base, artificial teeth, and wrought wire clasps.Types of acrylic partial dentures:
1- Temporary removable partial denture: It is a removable prosthesis used temporarily for a period of time until a more definite prosthesis can be provided.2- Interim removable partial denture: A dental prosthesis to be used for a short intend of time as an artificial substitute for missing natural teeth.
3- Transitional removable partial denture: A partial denture which is to serve as a temporary prosthesis and to which more artificial teeth will be added as more teeth are lost and which will be replaced after post-extraction and tissue changes have occurred.
4- Treatment partial denture: A dental prosthesis used for the purpose of treating or conditioning the tissue.
5- Immediate partial denture: It is prosthesis used to replace one or more teeth and is inserted on the day of extraction of teeth. It is a partial denture constructed before the extraction of unwanted teeth and is inserted immediately after this extraction.
Indication of acrylic removable partial denture:
In young patients when the pulp chamber is so large that a fixed prosthesis is not feasible.As space maintainer: recent extraction or premature loss of teeth resulting in a space, to maintain this space we have to make an acrylic temporary treatment.
Elderly patients, whose general health contraindicate lengthy procedure.
Cost: acrylic removable partial denture is considerably less than that for metallic partial denture or fixed partial denture.
Use as a stand for periodontically weakened teeth.
Interim (temporary) prosthesis: may be used:
A- When denture is needed while healing is progressing after extraction or surgery.
B- Denture is needed while prolonged treatment is being accomplished.
C- The patient has no enough time at the moment for lengthy definite treatment.
Clinical Procedure for Placement:
It is important to consider proper fitting of the prosthesis to ensure comfortable use during the temporary phase of treatment. Careful attention to planned use of the teeth for support, stability, and retention without undue stress from gingival tissue contact or improper occlusal loading will ensure more comfortable use.
To ensure proper use of the remaining natural teeth, the prosthesis must be completely seated in the arch. Common areas requiring adjustment to ensure complete seating include interproximal extensions, regions where clasps exit from the acrylic-resin base, tissue undercuts (labial undercuts from recent extractions or the lingual/retromylohyoid region), and any portion of the prosthesis that lies inferior to the height of contour, especially if bilaterally opposed
Once seated, it is important to check that no excessive pressure to the marginal gingival region is present. To facilitate this step, and to help with the complete seating requirement, it is possible to have the laboratory block out the marginal gingival region and infrabulge regions to reduce seating problems. Infrabulge regions may include lingual and palatal tooth surfaces, as well as modification space regions. Because temporary prostheses are generally fabricated on unprepared teeth, these regions often require correction. However, if the blockout is not accomplished carefully, the prosthesis may seat easily, but it may not be as stable as possible because of insufficient tooth contact. Stability and retention are improved when it is possible to have the prosthesis contact portions of the teeth superior to the height of contour because of tooth-dictated control of movement.
It is possible to create occlusal imbalance if the lingual/ palatal portion of the prosthesis is too bulky. Consequently, an opposing cast should be provided to allow placement of clasps and acrylic-resin contours that do not cause occlusal interference. Once fully seated and relieved appropriately, the occlusion should contribute to the remaining natural dentition (as in a definitive prosthesis) and harmonize with natural tooth–dictated function. Typically, the prosthesis should not be the sole source of occlusal contact. In such situations, the functional forces are concentrated at the acrylic-resin-to-tooth junction, and predictably a change in orientation occurs, allowing tissue-ward movement and a change in occlusion with an increase in soft tissue contact.
Designing the acrylic partial denture:
The acrylic denture base: The base acts as a saddle and as connectors and has a reciprocal function for the retentive wrought wire clasp arm.
Wrought wire clasps: Wrought stainless steel wire clasps are used with acrylic partial dentures; they are attached to the acrylic denture base by embedding their non-retentive portion into the denture base. The wrought wire clasps consist of a retentive portion and non-retentive portion, which should be looped to help anchorage it in the acrylic resin of the base.
The most commonly clasp design used for acrylic partial denture:
Simple circular clasp: It is used for the teeth adjacent to the edentulous ridges. It starts lingually and passes over the relieved ridge along the proximal surface of the clasped tooth to engage buccal undercuts. It should pass 3-4 mm away from the proximal surface of the clasped tooth, to allow grinding.
Half Jackson clasp: It finds its application on molars and premolars when no edentulous space exists on either side of the tooth. It starts lingually and passes up to cross the occlusal plane on the embrasure between two neighboring teeth, then down to the buccal surface to engage the undercut.
Acrylic teeth: They are attached by chemical bond to acrylic denture base.