An indirect retainer is a component of a removable partial denture (RPD) that functions away from the supporting tissues to prevent rotational displacement of the denture base. The indirect retainer resists movement of the denture base away from the tissues and prevents impingement of the major connector. Effective indirect retainers must be rigid and located as far as possible from the fulcrum line, which passes through the teeth and direct retainers. Common forms of indirect retainers include auxiliary occlusal rests, canine rests, palatal bars, and palatal coverage. They function to transmit forces through the long axis of supporting teeth to stabilize free-end saddles in RPD frameworks.

1. INDIRECT RETAINER
 RPD derives Support from two main sources :-
1. Natural teeth through rests on rest seats
2. Residual alveolar ridge for well adapted denture base
 RPD that is totally supported by healthy natural teeth (bounded saddle) such as (Class lll , short span Class IV)
possesses adequate stability and retention to resist functional displacement .
 RPD that is not totally bounded by natural teeth (free end saddle) such as (Class I, II, long span class IV) will
move (rotate) when a load is applied .
 When an occlusal load is applied to a distal extension RPD  the prosthesis rotates around a fulcrum line
that passes through the most posterior rests one on each side of the dental arch.
 When a dislodging force is applied (sticky food)  the associated fulcrum line passes through the tips of the
retentive clasps.
 Therefore , the axis of rotation (fulcrum) is an imaginary line passing through the teeth (rests) and direct
retainers (retentive tips) bilaterally.
 The framework component that resists rotational displacement of an extension base by functioning Away from
the supporting tissues is called an Indirect Retainer 
1. Prevent denture base movement away from the tissue.
2. Prevent major connector impingement upon underlying soft tissue.
 Factors Influencing Effectiveness of Indirect Retainers :-
1. Must be rigid (if flex, will not be effective)
2. The greater the distance between the fulcrum line and the indirect retainer, the more effective the
indirect retainer will be.
3. A line projecting at right angle from the fulcrum line and ending in a tooth that is capable of supporting
a suitable rest preparation will indicate the most effective location for the indirect retainer.
4. The direct retainer must prevent the denture base and rests from being lifted from the tissues and
abutment teeth … The indirect retainer does not resist displacement.
5. Effectiveness of the supporting tooth surface (Canines , premolars) It must positioned in definite
prepared rest seat (to transmit applied force through the long axis of the abutment tooth).
6. Tooth inclines and week teeth should never be used to support indirect retainer.
 Forms of indirect retainer :-
1. Auxiliary occlusal rest  The most frequently used indirect retainer Located on the occlusal surface as
far away from the distal extension base as
2. Canine rests  When the mesial marginal ridge of the first premolar is too close to the fulcrum line, a
rest on the adjacent canine may be used
3. Canine extension from occlusal rests  A finger extension from a premolar rest is placed on the
prepared lingual slope of adjacent canine tooth Located on the occlusal surface as far away from the
distal extension base as possible
4. Continuous bar and lingual plate  Technically, they are not indirect retainers because they rest on
unprepared lingual inclines of anterior teeth  The indirect retainers are actually the terminal rests at
either end that occur in the form of auxiliary occlusal rests or canine rests.
5. Support from the palate 
 In upper jaw  teeth and hard palate may be used to support as an indirect retainer Mainly from
rugea area (firm area)
 In lower jaw  teeth only can be used for this purpose .
 tissue support is less effective than positive tooth support
 Forms of indirect retainers supported by the palate :-
1. Palatal arm (Class I and II)
2. Anterior palatal bar (Class I and II)
3. Posterior palatal bar (Class IV)
4. Horseshoe palate (Class IV)
5. Full palatal coverage.
PROSTHEASY