الفهرس 
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Abstract
Purpose: To evaluate the Poly-ether-ether-ketone (PEEK) framework of mandibular two implant supported overdenture on zirconium oxide bar with and without cantilever retained with heat cured soft liner. Material and methods: Ten male edentulous patients were chosen for this study (average age from 55-65 with main age 60). A complete denture was constructed and adjusted for insertion and delivery for all patients. Bone density evaluation was performed for the patients using cone beam computerized tomography (CBCT). On the planned sites in the canine region, CAD-CAM limiting surgical stereolithographic Stent (STL) was fabricating. Implant fixtures have been surgically placed. CAD-CAM constructed zirconium oxide bar after the osseointegration period. The patients were divided into two groups according to the shape of a zirconium oxide bar into group (I) zirconium oxide bar without cantilever extension and group (II) zirconium oxide bar with cantilever attachment extension which was 7mm in length. The master cast was scanned with zirconium bar. PEEK overdenture with 1 mm space for heat cured soft liner was constructed. CAM manufacturing of PEEK overdenture was done. Soft liner was incorporated in the surface of the overdenture. The peri-implant soft tissue changes were evaluated by using the following variables (1) modified gingival index (MGI) (2) modified bleeding index (MBI) (3) probing depth (PD). The measurements were evaluated immediately following mandibular overdenture insertion (T0), six months (T1) and one year (T2) after mandibular overdenture insertion. The peri-implant alveolar bone height was evaluated immediately (T0), six months (T1) and one year (T2) after mandibular overdenture insertion. This was done using standardized periapical radiographs using long-cone parallel technique. Results : • Modified gingival index significantly increased with advance of time for group I (p<.001) and group II (p=.015). group II showed significant higher modified gingival index than group I at T1 (p=.045). • Modified bleeding index significantly increased with advance of time for group II only (p=.005). There was no significant difference in modified bleeding index between groups at different observation times. • Probing depth significantly increased with advance of time for group I (p<.001) and group II (p<.001). group II showed significant higher probing depth than group I at T2 (p=.021). • There was no significant difference in vertical bone height loss between groups at T1 and T2. Conclusion : 1- Using PEEK framework over mandibular two implant supported zirconium oxide bar without cantilever and without retaining mechanism of the bar in form of clip or sleeve is considered a promising treatment solution. 2- Using heat cured soft liner in the desired areas beneath the bar maintain good peri-implant results either with or without cantilever extension.