The aim of the study: is to evaluate efficiency of using either intracanal corticosteroids or intracanal cryotherapy as a final flush irrigation on post endodontic pain in lower molar teeth with symptomatic irreversible pulpitis. The materials and methods: In this study forty patients with symptomatic irreversible pulpitis in lower molar teeth with pain level of 4 or higher on the visual analogue scale (VAS) will be selected.

This study will involve 40 adult patients (18-60 years) for both genders equally .all of patients must provide written informed consent and commit to the full trial period. Eligible participants must present with a lower molar diagnosed with symptomatic irreversible pulpitis, characterized by moderate-to-severe preoperative pain (VAS score ≥ 4) that lingers after stimulus removal. Conversely, the study excludes vulnerable groups (e.g., pregnant or mentally ill), medically compromised individuals, and those who have taken analgesics or antibiotics. Specific dental exclusions include teeth with open apices, calcified canals, prior endodontic treatment, or periodontally affected tooth

Inclusion Criteria:

• both gender -
• age range of (18-60 years ) -medical free patients with lower molars with symptomatic irreversible pulpitis and indicated for single visit root canal treatment with pain score 4 or more on VAS- Patients that commit for the entire period of the trial and agreed to sign the informed consent .

Exclusion Criteria:

• vulnerable group -teeth with open apex or calcified canals-curved canals-
• patients on analgesics or antibiotics
• periodontaly affected tooth