IRCT201306121760N24.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study Single dose Study medication provided in capsules, placed in envelope
Participants	Root canal treatment (acute apical periodontitis of pulpal origin) N = 45 Age 18 to 65 years M and F Pain intensity ≥ moderate (≥ 4/10)
Interventions	Paracetamol 325 mg + ibuprofen 200 mg + caffeine 40 mg, n = 15 Paracetamol 325 mg + ibuprofen 200 mg, n = 15 Placebo
Outcomes	Pain intensity (VAS) at 4, 6, 12, 24, 48, 72 h
Notes	Recruitment due to end April 2008 Email sent to contact person (Dr Ali Bijani) on 28 August 2014. No response by date of submission of update Sponsor: Babol University of Medical Sciences, Iran