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Abstract
The present study was designed to assess the effect of surface geometry and different surface treatments on retention of cement retained implantsupported crowns. Thirty titanium abutments (7mm height shortened to 5 mm, 3.7 mm diameter) were divided into two main groups according to the abutment geometry as follows: group (I): (n=15) Straight abutments were attached to the implant analogs. group II: (n=15) 15 degree Angled abutments were attached to the implant analogs. Each group was further subdivided into three subgroups according to abutment surface treatment: (Subgroup1): (n=5) untreated abutments (control). (Subgroup 2): (n=5) sandblasting surface treatment of abutments with 50 om aluminum oxide. (Subgroup 3): (n=5) Silicoating surface treatment of abutments (cojet ) with 30 um cojet sand followed by salinization. Thirty implant analogues were inserted in epoxy resin blocks using a specially constructed centralizing device. After surface treatment of all samples, the treated and untreated samples were subjected to roughness testing and scanning electron microscope analysis. Samples received Ni-Cr crowns that were luted with temporary resin cement to the abutments. Then the samples were subjected to retention testing using a universal testing machine. Within the limitation of this study, the following conclusions could be drawn: Retention of cement retained implant supported crowns is affected by interaction between the abutment geometry and its surface treatments.Abutment geometry significantly affected the retention of cement retained implant supported crowns with the superiority of the angled abutments regardless of its surface treatment