Objectives: the aim of this study was to evaluate the effect of Platform Switching when using different abutment materials namely; Titanium abutments and Ceramic (zirconium) abutments On the; Stresses transmitted to implant supporting structure and Fracture resistance of the abutments (zirconium).Materials and methods: The first part of this study was conducted to explore the biological behavior of Activ GP obturation System in comparison to the conventional gutta percha, and AH Plus root canal sealer. Thirty male albino Sprague-Dawly rats were used for the evaluation of biocompatibility. Rats were sacrificed at 1, 2 and 4 weeks post implantation. The second part of the study was concerned with a series of laboratory studies. A total of 180 single rooted permanent human freshly extracted teeth were used. Teeth were decoronated, root canals were instrumented with K3 0.06 taper nickel-titanium rotary system. Each canal was enlarged to size #40.Samples were classified into six groups according to the obturation system and obturation technique. Group 1 (Activ GP + Activ GP glass ionomer sealer / single cone), group 2 (Activ GP +Activ GP glass ionomer sealer/ multiple), group 3 (Activ GP + AH Plus sealer l single cone technique, group 4 (Activ GP + AH Plus sealer / multiple), group 5 (gutta percha + AH Plus sealer / single cone), and group 6( gutta percha +AH Plus sealer / multiple cone ). Access cavities were sealed with Coltosol, all samples were stored in humid environment at 37oC for one week to allow sufficient time for the sealers to set. A total of thirty-six single rooted teeth were used to measure the bond strength. Ninety-six single rooted teeth were used for the apical sealing ability assessment(n=16/group). Two teeth from each group were prepared in order to study the interface between the obturating materials and dentine, at the coronal, middle, and apical sections using SEM.Thirty six teeth were used for the main six groups (n=6 teeth / group) to be used for assessment of the residual material after removal.Results: the first week acute inflammatory response was noticed with no statistically significant difference between the four groups, at two weeks one month and duration period, showed moderate to severe inflammation, as for the bond strength test, the statistically significantly highest mean push-out bond strength value was recorded for group 6. leakage study showed that at one week period group;1 showed the statistically highest leakage value followed by groups 3, 4, 5 and 6 with no statistically significant difference among them. While, after one month period; groups 1, 3, 4 and 6 recorded the statistically significant highest mean score leakage values with no significant difference among them. SEM showed the Activ GP sealer well adapted to the dentinal wall and core material in some areas, while other areas showed gaps between Activ GP sealer and Activ GP cones especially at the coronal sections. On the other hand, good adaptation was noticed between the AH Plus sealer and dentinal walls only. Evaluation of the residual material after removal showed that all groups showed filling remnants at all levels after removal of obturating materials.Conclusion: Activ GP sealer showed almost similar biocompatibility to that of AH Plus sealer but it failed to make monoblock .