Irrigation activation in endodontics is considered now a very important step for the success of root canal treatment. In this study, the investigator will examine the effect of two recent activation systems ( XP-endo Finisher file and the new sonic EDDY system) in comparison with the conventional needle irrigation on irrigant penetration depth into root canals using radiopaque contrast media and digital radiography and on the postoperative pain after single-visit endodontic treatment using a visual analog scale.

Inclusion Criteria:

• Asymptomatic vital/non vital teeth requiring root canal treatment.
• Teeth with sound periodontal apparatus.
• Teeth without pus or inflammatory exudates draining through the canal.
• Teeth without anatomic variations.
• Teeth with sinus tract.
• Teeth without history of trauma.
• Patients not on analgesics or sedative medication prior to root canal therapy

Exclusion Criteria:

• • Patients with any systemic diseases.

  • Pregnant or lactating patients.
  • Immunocompromised patients.
  • Apparently thin roots in which apical preparation with #40 file would be overzealous.
  • Patient allergic to anything used in this procedure especially rubber dam material and Iohexol (radiographic contrast media).
  • Teeth with calcified canals.
  • Patients with acute apical periodontitis, acute apical abscess, and weeping canals.
  • Necrotic painful teeth with the absence of sinus tract for drainage.