T The preparation phase of root canal on endodontic treatment compriseof mechanically cleansing using endodontic instrument to clean up andcompose root canal, until it can accept root canal material filling perfectly,together with chemically cleansing using chemical irrigation solution. Thepurpose of using irrigation solution is to flush out dentin left overs from thepreparation phase and pulpa residue that experience necrotic, and also todispose of the microorganism in root canal wall. The irrigation solution thatoften use is natrium hipoclorit 5.25%, because it has anti microbecharacteristic and it can dissolves organic substance like a necrotic pulpatexture and also non toxic to the texture. Natrium hipoclorit has adisadvantage of not able to dissolves smear layer (organic substance) as theresult of root teeth canal instrumentation, therefore NaOCI usage must becombine with irrigation solution that can dissolves smear layer in dentintubula. Chelating agent such as EDTA and citric acid could be used todissolve smear layer. However, organic substance like pulpa necrotic texturecould not be dissolve using chelating agents such as EDTA and citric acid.Therefore, irrigation solution should be combined for the treatment of rootteeth canal, namely the combination of EDTA and NaoCI or citric acid andNaOCI. The best combination is 15% of EDTA and 5.25% of NaOCI, becausethe result of this irrigation solution combination could attract more Ca+2 fromthe smear layer to compose chelate, and the chelate could be easily dissolvein water, so it would be simple to remove it from the root teeth canal.