Tooth Preparation
Amount of Reduction in Tooth Preparation for Fixed Partial Denture
Porcelain Fused to Metal Fixed Partial Dentures like this, requires 1.2 - 1.5mm facial reduction, 0.75 - 1mm lingual reduction and 1.5 - 2mm incisal reduction.
Attachments for Removable Partial Dentures can be categorized into: intracoronal attachment or extracoronal attachment, rigid attachment or resilient attachment, and precision attachment or semi-precision attachment.
Let’s limit the discussion on the first 2 categories of attachments mentioned, the intracoronal attachment and extracoronal attachments. Intracoronal attachment for removable partial denture is either cast or attached totally within the natural contours of an abutment tooth or teeth. Typically, it is composed of prefabricated key and keyway with opposing parallel walls, which serve to limit movement and resist removal of removable partial denture through friction. The principle of internal attachment was formulated by Dr. Herman E.S. Chayes in 1906.
O-SO distal extension attachment male component on the proximal of the Fixed Partial Denture
Linguoplate is a type of major connector for Removable Partial Denture. Major connector is the component of partial denture that connects the parts of the denture located on one side of the arch with those on the opposite side. It is the unit of the denture to which all other parts are directly or indirectly attached. Linguoplate, also know as lingual plate, results if the rectangular space bounded by the lingual bar, the anterior tooth contacts ang cingula, and the bordering minor connectors is filled in.
Lingual plate upper border should follow the natural curvature of the teeth.
Fixed partial dentures with cantilevers (CFPD) are among the treatment options for partial edentulism.
A cantilever beam by definition (Tylman, 1970), is a beam that is supported by only one fixed support at one of its ends. A direct cantilever bridge, is when the pontic is attached to an adjacent retainer.
The main indications for cantilever bridgework are situations in which:
1 . the teeth on either side of the proposed pontic that might ordinarily be used as abutments for fixed bridgework are unsuitable by reason of morphology, periodontal pathology or unfavorable angulation
2. cosmetic needs cannot be met by conventional fixed bridgework
3. the need to avoid unnecessary involvement of sound teeth is an overriding factor on grounds of pulpal risk, cosmetic implications or the temperament of the patient. (H. S. M. CRABB 1974)
Double Abutting Fixed Partial Denture with Cantilever
Overdentures have significant advantages compared with complete dentures. Some of these are:
1. Greater functional stability due to preservation of residual ridge contours
2. Better retention
3. Chewing efficiency
4. Less pressure on the mucosa
5. Reduced extension of denture base in the maxilla
Overdentures are complete dentures that are partially supported by natural teeth or implants. Overdentures are superior to conventional complete dentures in biting force, chewing efficiency and force discrimination.
Bar Connector
Equipoise is balance of force design. The design creates forces along the long axis of the abutment tooth with passive retention. All clasping in this Removable Partial Denture System is designed intra-arch. E-clasps are designed on the mesial or distal aspect of the teeth facing the edentulous area. This is to reduce the lateral torque. There are no clasps on the buccal or lingual of teeth.
Principles of Equipoise Removable Partial Denture
1. Minimum strain to the abutment.
2. Greater retention.
3. Improved esthetics.
Equipoise Removable Partial Denture
A lower Unilateral Extension Fixed Partial Denture was fabricated with the purpose of restoring the center of occlusion, and create a premolar occlusion. The Cantilever Fixed Partial Denture design will also provide functional stability for the complete denture on the upper. It will also protect the anterior part of the maxillary ridge from excessive load or resorption.
Minimal occlusal preparation was done on both premolars. Selective grinding on maxillary denture was done to obtain balanced occlusion in the muscular contact position.
Unilateral Extension Fixed Partial Denture (abutments are 44 and 45, missing teeth are 46, 47 and 48 with only the first molar restored)
Cantilever Fixed Partial Denture
A lot of times, we do long Fixed Partial Dentures for cases which are indicated for RPD. This is due to patient’s demand and his/her willingness to pay for fixed prostho treatment.
Long Fixed Partial Denture
Common problems with long fixed bridgework are inaccuracy of the final restoration due to cast errors, problems with non parallel abutments and difficulty to repair.
You may decide not to do it, but the dentist next to your office will do it anyway. So why not do it?
But instead of a long bridge, a Fixed Partial Denture can be done for such cases by segmenting it. By using attachments, segmented FPD can be done for the patient.
Segmented Fixed Partial Denture (Photo by Dr. Carlos Melo)
Screw Retained Denture
To overcome problems in Prosthodontics, dental screws can be used. Screws may permit combination of advantages of fixed partial dentures and removable partial dentures.
A Fixed Partial Denture is the restoration of choice where the edentulous area is small. But the problem of malaligned abutment results to too much tooth tissue to be removed to the extent that inadequate retention is achieved. Dental screws can be used where the restoration is made in two parts and secure these parts with Dental Screws.
Screw retained Dental Prosthesis allows damaged pontics be removed and modified. Screws facilitate routine maintenance as the area under the pontics can be examined by unscrewing them.
Acrylic Resin Upper Removable Partial Denture - Occlusal
Acrylic resin removable partial denture with wire retainers is sometimes recommended for frail elderly patients. It is justified by the notion that acrylic resin is faster and easier to work with, affordable and amenable to repair. Acrylic resin prosthesis treatment is used because the remaining teeth are periodontally compromised, patients tend to exhibit poor oral hygiene and poor cooperation. Acrylic RPD can also be transformed if extractions become necessary.
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