الفهرس 
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Abstract
Sometimes unfavorable situations for implantation can arise, such as a dearth of bone or anatomical structures (such as mental foramen and maxillary sinus). In these circumstances, if an implant-supported cantilever FPD could be used to restore a problematic edentate area, it would provide a simpler rehabilitation procedure and would circumvent additional cost and reduce therapeutic time associated with surgical procedures.
There have been technological improvements in dental implant designs, an increased understanding of biomechanics related to cantilever bridges and emerging data indicating a high survival rate for short-span implant supported cantilever fixed partial dentures.
One-piece design implant was introduced to offer several advantages over the conventional two-piece implant design. Studies are under way to depict the potential of CBCT to accurately assess bone quality and indicate that CBCT may yield structural analysis of bone.
Finite-element analyses is a valuable instrument used to study the stress/strains in bone and dental implants, when associated with clinical findings and accumulation of reliable data on implant loading.
The objectives of this study were to:
Clinical and radiographic evaluation of the effect of stresses on bone and peri-implant soft tissue using Cone beam computerized tomography (CBCT).
Evaluate and compare the influence of implant design (one-piece, two-piece) on stress distribution around dental implant supporting cantilever restorations under loading conditions using 3-D finite element analyses.
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In the clinical part of the study a total of 24 implants were divided on 12 systemically healthy patients (N=6) with unilateral mandibular free-end saddles, every patient received two implants at the location of the second premolar (3.5mm(Ø) and 10mm length) and first molar (4mm(Ø) and 10mm length), they referred as primary and secondary implant respectively. group I received porcelain fused to metal three unit implant-supported cantilever FPDs over conventional two-piece implants. group II received porcelain fused to metal three unit implant-supported cantilever FPDs over one-piece implants. All groups were subjected to clinical parameters as specific plaque index(PI), gingival index(GI), and periodontal probing depth(PPD) and then Cone beam computerized tomography for densitometric analysis and marginal bone height detection around each implant at time of FPD loading (baseline), 6, and 12 months. Also both biological and technical success and failure were verified during the follow up period.
The 3D finite element analysis (FEA) methodology: Two models for both implant design was composed of a bone block of the mandibular area around implants at the second premolar and first molar region and the trabecular bone in the center was surrounded by 2 mm of cortical bone. Information for the bone block was obtained by cone beam computerized tomography used to facilitate the reproduction of details and design of simulated bone tissue. Modeling was performed with Materialize software. Both osseointegrated implant designs were obtained from a simplified version of the original implant connection, with different geometries, a diameter of Ø 3.5 and Ø 4 mm and a length of 10 mm that included their specific abutments. The implant and abutment geometries were simplified by 3-D computer-aided design software. The bridge design was configured and digitized using CBCT image and the occlusal surface details were added by CAD software.