Abdullah Salem Ibrahim, Maged Negm And Alaa El-Baz,

ABSTRACT
Seventy Six Human Single Canaled Teeth Were Decapitated, Instrumented Using K3 Ni-Ti Rotary System, And Then Divided Into 4 Main Groups Of 19 Teeth Each, According To The Type Of Irrigation Protocol Used; Group I, 1:1 Mixture Of 5.25% NaOCl + 18% Etidronic Acid (HEBP). Group II, 1:1 Mixture Of 5.25% NaOCl + 18% Etidronic Acid (HEBP), Followed By 17% EDTA As A Final Rinse. Group III, 17% EDTA. Group IV, 5.25% NaOCl (control Group). The Quantity Of Irrigation Was 5 Ml For 2 Minutes. Then, A Final Rinse Of 5 Ml For 2 Minutes Of Distilled Water. Sixteen Roots Of Each Group Were Subdivided Into 2 Subgroups (each Of 8 Roots), According To The Type Of Sealer Used: A Single Gutta-percha Cone Size 40 Taper 0.06 With AH Plus Root Canal Sealer. A Single Activ GP Cone Size 40 Taper 0.06 With Activ GP Root Canal Sealer. The Obturated Roots Were Horizontally Divided Into Three Equal Sections. The Middle Third Specimens Were Subject To Push-out Test By Means Of An Instron Testing Machine. Then, The Specimens Were Examined Under Digital Microscope To Determine The Type Of Bond Failure. The Remaining Three Roots Of Each Group Were Longitudinally Split Into 2 Equal Halves. The Walls Of Their Middle Thirds Were Examined For The Presence Of Debris And Smear Layer Under Environmental Scanning Electron Microscope (ESEM). The ESEM Showed Superior Results Of EDTA And NaOCl/HEBP/EDTA Groups Respectively In Smear Layer Removal Over NaOCl/HEBP And NaOCl Groups. It Was Found That EDTA Group Recorded The Highest Mean Value Of Push-out Test With AH Plus Sealer, While NaOCl/HEBP/EDTA Group Recorded The Highest Mean Value Of Push-out Test With Activ GP Obturation System.