Digital Versus Conventional Altered Cast Techniques For Constructing Mandibular Distal Extension Removable Partial Dentures Using Digitally Fabricated Frameworks: Alveolar Bone Height Changes

Inclusion Criteria: 1. All patients having completely edentulous maxilla and class I Kennedy mandible. 2. Sufficient (not less than 15 mm) restorative space must be available (from the mucosa covering the crest of the residual ridge to proposed occlusal plane). This will be detected by a tentative jaw relation. 3. All patients are of angel's class I maxillo-mandibular relationships 4. Abutment teeth must meet certain requirements : A. Abutment teeth should be healthy with good periodontal and bone support. B. should not show advanced destructions. C. should not show a pronounced degree of mobility or advanced gingival recession. D. Crown Root Ratio for an abutment is 1:2 Exclusion Criteria: 1. Sever undercuts or concavities on the buccal or lingual sides of the ridge. 2. Systemic diseases that may affect bone changes such as diabetes and osteoporosis. 3. History of radiotherapy in the head and neck region. 4. Crown Root Ratio for an abutment is 1:1.