Ahmed Mohamed Amr Abdelmoez 1, Mohammed M Fouad2, Elsayed Abdallah Abdel-Khalek3 1B.D.S, Colleague of Master Degree.Faculty of Dentistry, Mansoura University, Mansoura, Egypt. 2Professor of Removable Prosthodontics, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.. 3Lecturer of Removable Prosthodontics Mansoura University, Mansoura, Egypt. Abstract: Objectives:This clinical comparison study compared between different designs of solitary attachments used to retain implant assisted mandibular distal extension RPD regarding alveolar bone height changes around abutment teeth. Methods:Twelve patients with mandibular Kennedy Class I were selected for this study.  The remaining natural teeth were extended from the first premolar on one side to first premolar on the other side. one implant was placed in each first molar region bilaterally. The  removable partial dentures were retained anteriorly by RPA clasp design and posteriorly either by ball attachment (group I) or by OT-equator attachment (group II) . Alveolar bone height changes around the primary tooth abutments were radiographically evaluated using cone beam volumetric CT. Results:Regarding bone loss around the primary abutment teeth, Ball attachment group (0.72 ± 0.15) significantly (p value = 0.008) showed less crestal bone resorption when compared to OT-equator attachment group (1.01 ± 0.25). Conclusion: Within the limitation of this study and regarding the preservation of abutment teeth, the use of  ball attachment may be the suitable choice for anchoring distally extended removable partial denture to dental implants with improved longevity of the natural tooth abutments.