Management of Loading Forces Distribution in Mandibular Distal-extension Prostheses

The two structures that support a mandibular distal extension removable partial denture differ markedly in their visco-elastic response to loading. The difference between the resilience of the residual ridge tissues and the teeth permitted by the periodontal ligament presents a disparity of support that is in contrast to the uniform support accorded a tooth-supported removable partial denture. Hence the denture tends to rotate about its most distal abutments, inducing heavy torsional stresses on alveolar ridges. Many methods have been used to control this movement, some of them: 1. Implant support on distal extension removable. 2. Stress breakers provide a mean of interposing a flexible connection between the tooth-borne retainer portion of removable partial denture and its distally extended tissue-borne segment. 3. Altered-cast technique. 4. Design development by using mesial indirect retainers rather than distal ones. The purpose of this study is: (1) to compare bone absorption around abutment teeth nearby the free saddle; (2) denture displacement and pressure on the soft tissue under the denture base of distal extension RPD (Removable Partial Denture) (3) cellular changes in the soft tissue under the denture base of distal extension RPD.