Inclusion Criteria:  Healthy adult patients aged between 18 and 65 years Moderate to severe pain (4-10) according to a visual analogue scale (VAS) Mandibular molar teeth diagnosed with symptomatic apical periodontitis (a painful response during mastication and/or percussion or palpation)  Exclusion Criteria:  Pregnancy or lactation Taking analgesics or anti-inflammatory drugs 12 hours before the treatment Taking antibiotics in the month prior to the treatment Teeth with calcified root canals, greater than grade I mobility and a 4 mm pocket depth, non-restorable damage, occlusal trauma and previous root canal treatment or an open apex Allergy to articaine or non-steroid anti-inflammatory drugs