Titanium Versus Soft Metal CAD/CAM Frameworks for All-on-4 Implant Supported Prosthesis

This study will compare between titanium framework and soft metal framework used for mandibular All-on-4 implant supported prosthesis regarding bone level changes around implant using periapical x-ray after 6 months and 12 months and 18 months from insertion of fixed prosthesis. Patient selection Twenty patients will be selected from the out-patient clinic of Prosthodontic Department, Faculty of Dentistry, Mansoura University seeking for prosthetic rehabilitation. All patients will be informed about all surgical and prosthetic procedures that will be done. Also; they will sign the consent form of ethical committee of faculty of dentistry. All implants will be installed in the edentulous mandible in each target positions according to their arrangements guided by stereolithographic stent. * A cone beam computerized tomographic scan will be taken prior to surgery to determine the bone quality and bone volume and construct the surgical stent. * Infiltration local anesthetic solution will be given for each patient. * Each patient will receive 2 distally tilted implants in the posterior region anterior to mental foramen followed by 2 anterior implants. * The stent will allow for optimal positioning, alignment, parallelism, and inclination of the implants for subsequent anchorage and prosthetic support. * Once implant is placed, multiunit abutment will be placed. Hand tightens will take x-ray to verify seated properly. Torque to 15Ncm for tilted, 35Ncm for straight. * Antibiotics (Augmentin 1g) will be given 1 hour before surgery and then daily for 5 days. Anti-inflammatory medication will be given after surgery if needed. Analgesics (brufen 600mg) will be given after surgery if needed. * Immediate loading of the implants will be done by modifying the mandibular denture. * The mandibular denture will be modified by shortening the flanges and cutting the posterior part till the 1st molar then 3D scanned for recording the correct dimension of each tooth to be concerned during construction of the titanium and soft metal superstructures and the final prosthesis. * Digital impression technique will be made using intraoral scanner and scan bodies and the resultant scan will be used in construction of titanium and soft metal superstructures with the abutments. Patient grouping: * Patients will be classified into 2 equal groups, first group will have titanium framework manufactured by dry milling technique, second group will have metal framework manufactured by dry milling/post sintering of Co-Cr soft metal blocks. * The fit of the frameworks will be verified intraorally and the final fixed prosthesis will be constructed from PMMA for both groups. The evaluation will be for: • Bone level changes around implant using periapical x-ray after 6 months and 12 months and 18 months from insertion of fixed prosthesis.