Guiding planes Major connectors Reciprocation
McCracken’s [6] Stewart’s [7] The direction of placement or removal of the denture (path of insertion, path of placement) is regulated by the guiding plane. It becomes difficult to float and detach in any direction other than the regulated direction, and it is possible to regulate the movable direction. This is an important requirement for exerting bracing action. ([6]: pp. 142; [7]: pp. 216, 217) By covering the lingual surface with the major connector, the functional pressure applied to the denture is effectively and appropriately distributed. In addition, the lingual and palatal plates, which are in wide contact with the axial surfaces of the remaining teeth, resist the lateral forces applied to the dentures and exert bracing action. ([6]: pp. 35, 42; [7]: pp. 29, 33, 34, 116) When the denture is placed or removed, the retentive clasp passing over a height of contour are counterbalanced by a reciprocal clasp (bracing clasp), passing along a reciprocal guiding plane. Therefore, the buccolingual clasp should contact the tooth surface at the crown at approximately the same time. ([6]: pp. 210, 21; [7]: pp. 59, 60, 288)