Abstract: Perfect apical sealing is desirable to prevent the remaining bacteria and their endotoxins from reaching the root apex, and to advance the healing of disease of apical. Apical leakage is considered to be a common cause for endodontic therapy failure. Researchers have evaluated the quality of the apical sealing using dye penetration method, fluid filtration or transportation method, bacteria and toxin infiltration method. The various methodologies used for assessing root canal sealing capacity are critically analyzed, as there are not standardized.