Stresses from loading distal-extension removable partial dentures.

A concentrated load of 222 N in the region of the central fossa of the second molar resulted in stresses in the supporting bone which increased gradually from zero in the region of the retromolar pad to about 25 MN/m2 distal to the second molar. Stresses in the alveolar bone supporting the second premolar were about 30 MN/m2 at the cemento-enamel junction, decreased to about 20 MN/m2 distal to the apex of the root, increased to 100 MN/m2 at the apex, and decreased to 3 MN/m2 near the mesial upper third of the root surface. When a distributed load of 222 N was applied to the first and second molar region, the stress distribution was similar to that observed for the concentrated load, and stress magnitudes were about 20% lower. Dramatic decreases in stress, with the maximum stress at the apex being 40 MN/m2, occurred when a 222 N load was distributed in the area of the marginal ridge.