
Aim: Comparative evaluation of effect of two demineralising agents on the apical microleakage in root end cavities filled with MTA Plus. Materials and Method: Forty five single rooted teeth were selected and biomechanical preparation was done upto F2 Protaper. Root canals were obturated with AH Plus sealer and Guttapercha. Access cavities were sealed with GIC. Apical root-resection was then performed by removing 3mm of the apex at 90° to the long axis of the root with a straight fissure bur. Root-end cavities were prepared using diamond fissure bur upto 3mm. The teeth were randomly allotted into three groups of 15 each. Group A: root-end cavities demineralized with citric acid 10% (1 min). Group B: root-end cavities demineralized with 17% EDTA (1 min). Group C: root-end cavities with no demineralizing agent (Control Group). All the groups were retro filled with MTA Plus. The samples were then stored in 100% humidity for 24-hours and coated with nail varnish except the resected root end. After drying, they were immersed in methylene blue dye for 24-hours. The teeth were sectioned and examined under stereomicroscope. Results: Control group with no demineralizing agent showed least mean microleakage (0.166±0.040mm) and group demineralised with 17% EDTA showed highest mean microleakage (0.210±0.16mm) Conclusion : Removal of smear layer increases dentin permeability, facilitating bacterial penetration, hence it can be concluded that application of demineralising agents during apical surgery cannot be recommended.