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Components of an RPD (Reciprocators (Each force exerted on a tooth by a…

- - - - Design of occlusal surface (teeth)
        
        How many teeth to replace?
        
        Number of missing teeth
        
        Length of edentulous span
        
        Facial symmetry
        
        Size of teeth
        
        Made of
        
        Porcelain
        
        Acrylic resin
        
        Hybrid resin
        
        Metal
        
        Colbalt chromium
        
        Gold
        
        Choice of teeth
        
        Number
        
        Shape/size
        
        Colour
        
        Must be in harmony with the existing dentition
        
        Steps
        
        Reduction in area of occlusal table using narrower posterior teeth or less teeth to
        
        Reduce force to underlying tissues
        
        Even occlusal contacts; try to achieve balance where possible and get rid of interferences
      - Base extension (flange)
        
        Considerations
        
        Amount of alveolar bone resorption
        
        Number of missing teeth (more teeth --> larger flange)
        
        Designing
        
        Thickness and extension corresponding to the amount of bone resorption to replace tissue that is lost and restore normal contour of the area
        
        Placement of the gum margin with respect to the neighbouring teeth
        
        Contour of flange sometimes follow the contour of the gingivae
        
        Placement of flange margin
        
        Colour of the flange (pigmentation)
        
        Buccal flanges contoured to accommodate the buccinator muscle
        
        End of flange follows gingival contour of abutment tooth
        
        Note: Flanges can be used to provide support. The more missing teeth there are, the larger the flange should be
        
        Advantages
        
        Better retention and stability
        
        Easier to reline
        
        Better protection of socket in the case of an immediate denture
        
        Replaced lost alveolar tissue
- - - - U-shaped/ Horse shoe shaped plate
      - Mid-palatal bar/ strap
      - Posterior palatal bar/ strap
      - Combined anterior and posterior bars
      - Ring connector
      - Full coverage
    - - Lingual plate
      - Lingual bar
      - Sublingual bar
      - Continuous clasp/ bar
      - Dental bar
      - Labial bar
- - - - 2 or more parallel surfaces on teeth either natural or created by the dentist which direct the path of insertion and withdrawl
      - Flat, rigid elements of the partial denture (bracing elements and proximal plate minor connectors) fit against these surfaces to ensure that a partial denture seats along one path of insertion
      - Mode of action: Frictional resistance
        
        can provide a path of insertion and withdrawal different from the common path of displacement --> allows path to function more effectively by engaging undercuts in relation to path of displacement
      - Location
        
        Opposite sides of the mouth
        
        Opposite sides of the same tooth
        
        Abutment teeth of bounded saddles
      - Length: 2-3mm is sufficient
        
        The longer the plane the greater the retention
      - Functions:
        
        To provide a path of insertion and removal of partial dentures
        
        To provide retention against dislodgement of the denture forces which are parallel to the common path of displacement
        
        To reduce detrimental strain to the abutment teeth and the components of the framework in placing and removing the prosthesis
        
        To reduce gross food traps between the abutment teeth and the denture base
        
        To improve the appearance of clasps required for retention of RPD
    - - Flanges which are processes into the undercuts (relative to path of displacement) are an aid to retention
      - Commonly, the areas are
        
        Anterior labial areas
        
        Buccal areas
        
        Tuberosity areas
      - note: flanges must not be over-extended/ enroach onto muscles; this will dislodge due to muscular imbalance
    - - Depends on
        
        Surface tension of the saliva
        
        Cohesive forces within the saliva
        
        Adhesive forces between saliva and denture and mucosa
        
        Viscocity of the saliva
        
        Closeness of adaptation to the oral mucosa
    - - The tongue and oral musculature can also help to hold the RPD in place
      - Shape of polished surfaces and position of teeth must be in balance with musculature
      - Some patients are better at this than others
    - - These are more sophisticated means of retaining and supporting RPDs
      - Not as commonly used as clasps because of cost
      - Also dependant on availability of lab support and skills of clinician