Recruited patients with necrotic pulp after application of conventional calcium hydroxide paste are assigned to group, Calcium hydroxide nanoparticle group and Combined Calcium hydroxide with silver nanoparticle group and record postoperative pain afterwards.

The investigator will recruit patients who are found eligible to the criteria, conventional calcium hydroxide paste , Calcium hydroxide nanoparticle and Combined Calcium hydroxide with silver nanoparticle . After 48 hours, patients will be randomly assigned to removal of intracanal medication

After the visit, patients will be asked to record post operative pain by Numerical Rating Scale)in a given sheet

Inclusion Criteria:

• • Medically free patients.

  • Patient's age between 25-50 years.
  • Sex includes both male and female.
  • Radiographic evidence of a periapical radiolucent lesion associated with tooth.
  • Necrotic pulp as indicated by thermal pulp testing.
  • No history of previous endodontic treatment of the tooth.

Exclusion Criteria:

• • Teeth with unfavorable conditions for rubber-dam application.

  • Teeth with acute periapical abscesses swelling.
  • Medically compromised patients.
  • Immature teeth with open apices.
  • Multi rooted teeth.
  • Pregnant women.

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