- Each retentive arm should be opposed by a reciprocal component capable of resisting any orthodontic pressure exerted by the retentive arm
- Functions of reciprocal arm 4m*
- It provides stabilization/reciprocation against the action of the retentive arm.
- It also stabilizes the denture against horizontal movements.
- The reciprocal arm may act as an indirect retainer to a certain extent, i.e. when it rests on a supra-bulge surface of an abutment tooth lying anterior to the fulcrum line.
- Design specifications for a reciprocal arm
- It is positioned on the side of the tooth opposite to the retentive arm.
- The reciprocal arm must be rigid and should not be tapered.
- It is positioned on a tooth surface that is reasonably parallel to the denture’s path of insertion and withdrawal.
- It is ideally located at the junction of the gingival and middle third of the abutment tooth.
Some special reciprocal elements
- At times, linguoplate can be used to provide reciprocation.
- Sometimes, an occlusal rest positioned on the opposite side of the tooth will provide reciprocation.