This study compare the effect of applying ice after single visit endodontic treatment with lasers to reduce post operative pain .

one of the most popular complications after single visit endodontic treatment is pain either spontaneous or on biting so in this study we choose one of the most difficult and challenging cases " Hot tooth " to compare lasers and cryotherapy different applications to reduce post operative pain after single visit endodontic treatment

Inclusion Criteria:

• • Vital teeth display symptomatic apical periodontitis (Symptomatic apical periodontitis was determined based on the clinical symptoms of severe preoperative pain (visual analogue scale [VAS] > 60) and severe percussion pain (VAS > 60).

  • Teeth, with a periapical index score (PAI) of 2 or 3 indicating small changes in bone structure and slight mineral loss respectively.
  • Mobility less than 1 mm in either direction.
  • Absence of periodontal pocket around the tooth.
  • Symptomatic pulpitis with spontaneous pain or lingered by cold or heat.
  • Teeth without pus or inflammatory exudates draining through the canal.
  • Teeth without anatomic variations

Exclusion Criteria:

• • Patient with any systemic disease.

  • Immunocompromised patients.
  • Pregnant or lactating patients.
  • Apparently narrow roots in which apical preparation with the #40 file would be overzealous.
  • Retreatment cases.
  • Necrotic painful teeth with absence of sinus tract for drainage.
  • Patients on analgesics or sedative medication up to 6 hours before treatment

all participants have an equal chance to be enrolled in any of the study groups. This pattern was the most suitable way to ensure the balance of the anonymous prognostic factors in the participants between the three groups thus, eliminating the selection or allocation bias