The aim of this study, thus, was to assess the effect of occlusal reduction on postendodontic pain after the first (post-instrumentation) and the second (post-obturation) visit in mandibular posterior teeth with symptomatic irreversible pulpitis and sensitivity to percussion treated in two visits.

The purpose of this randomized clinical trial was to evaluate the effect of occlusal reduction on post-instrumentation and post-obturation pain in mandibular posterior teeth with symptomatic irreversible pulpitis and sensitivity to percussion treated in two visits. Three hundred and eight patients were included in this study. Inclusion criteria were posterior mandibular teeth having symptomatic irreversible pulpitis with sensitivity to percussion. Patients were randomized into two equal groups. In the intervention group, occlusal reduction was done, while, in the control group, the occlusal surfaces were left intact. Conventional endodontic treatment was performed in two visits using a rotary nickel-titanium system followed by the lateral-condensation obturation technique. Post-instrumentation pain was assessed after 6, 12, 24 and 48 hours following the first visit, and post-obturation pain after 6 and 12 hours following the second visit. Each patient received a pain diary to record their pain levels and rescue medication intake.

Inclusion Criteria:

• Healthy adults 18-65 years old.
• The diagnosis of symptomatic irreversible pulpitis with sensitivity to percussion.
• Posterior mandibular teeth.

Exclusion Criteria:

• Pregnant women.
• Patients who reported bruxism or clenching.
• Patients who took analgesics during the last 12 hours before treatment start.
• Teeth with no occlusal contact.
• Unrestorable teeth.