This is a randomized , prospective , control trial to assess the effectiveness of intracanal cryotherapy on post operative pain after root canal treatment in patients with symptomatic apical periodontitis

Diagnostic procedures to include patients history taking , clinical and radiographic with all findings being recorded in patients .

patients diagnosed with symptomatic irreversible pulpitis with symptomatic apical periodontitis.

patients will be asked to rate their pre treatment pain on visual analogue scale from 0-10

patients with pain score <8 will be considered

Anesthesia and isolation : after administration of local anesthesia , rubber dam application will be done

Acess cavity : acess will be gained with round bur using air turbune handpiece with copious water cooling

Working length : a size 10k file will be inserted into the canal to determine the working length with the help of radiograph

Cleaning and shaping : Extirpation of pulp will be done followed by canal preparation with manual and endodontic motor using naocl and EDTA .

final irrigation will be performed using 17% EDTA and 5.25% NaOCl

Patients will be divided into 2 group in control group : final irrigation will be done using 5ml of saline at room temperature in cold group : final irrigation will be done using 5ml of cold saline at 2.5°C

the solution will be stored in the refrigerator until use irrigation will be performed for 5 min in both groups using 27 G beveled needle tip inserted 2mm short of WL.

Obturation ; In both groups , canals will be dried with paper points and obturated using gutta percha cones with zinc oxide eugenol sealer

Restoration : acces cavity will be restroed with direct composite restoration or high viscosity glass ionomer cement

each patient will be given instruction to acess the post operative pain .

Inclusion Criteria:

• patients with symptomatic irreversible pulpitis and symptomatic apical periodontitis
• maxillary or mandibular single rooted teeth
• systemically healthy patients
• patients having pain score < 8

Exclusion Criteria:

• patients on preoperative analgesics or antibiotics within past 12 hours
• teeth with calcified canals and previously treated teeth
• tooth with immature apices or resorption
• patients allergic to local anesthesia
• pregnant or lactating mothers
• patients who are immunocompromised .