Indirect retainer lecture

Mahmoud Ramadan, BDS, HDD

Factors influencing effectiveness of indirect retainer :
1- Proper seat of the principal occlusal rests on the primary abutment teeth by the retentive arm of direct retainer .so activation of the indirect retainer during rotation about an axis.
2- The distance between the fulcrum line and the indirect retainer , us the greater the distance , the more effective will be the indirect retainer.
3- The location for proper indirect retainer. A line projected alright angle from the fulcrum line to the tooth that is capable of supporting a suitable rest preparation .
4- Rigidity of the minor connectors of the indirect retainer, if it is flex, forces would be multiplied instead of dissipated.
5- The indirect retainer must be placed on a definite rest to avoid slippage, so tooth inclines and weak teeth should never be used to support indirect retainer.

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