Stress analysis in distal extension partial dentures

Abstract Masticatory stresses exerted on the base of a distal extension partial denture are transmitted to the supporting anatomic structures through contacting parts of the appliance. If the parts are incorrectly designed or constructed, they will alter the direction and force of these masticatory stresses, and may create stresses which are not within the physiologic limits of tissue tolerance. Movement of the denture base as a result of vertical stresses and the displaceability of the mucosa must be recognized and dealt with in tissue-borne appliances. The partial denture should be constructed so this movement is vertical in relation to the supporting bone. Clasps and rests should be designed to allow for this vertical movement of the denture base. Stresses other than those vertical to the abutment teeth should be reciprocated. Reciprocation is best obtained by contact of rigid parts of the partial denture with modified axial surfaces of abutment teeth which are made parallel to each other and to the path of insertion.