The effect of preoperative neutrophil-to-lymphocyte ratio on pain, swelling, trismus, and healing following mandibular third molar surgery

Background: The ratio of neutrophils to lymphocytes (NLR) has been suggested as an inflammatory biomarker that could potentially predict complications after surgery. Methods: A prospective cohort study comprised 150 patients aged between 18 and 35 yr undergoing surgical removal of impacted mandibular third molars. Patients were stratified into high NLR (≥2.8) and low NLR (<2.8) groups based on preoperative complete blood count results. Primary outcomes included pain measured by the Visual Analog Scale, swelling through facial measurements, trismus assessed through maximum interincisal distance, and healing indices measured at predetermined intervals up to 14 days postoperatively. Results: The high NLR group had significantly higher pain scores at 6 h (6.8 ± 1.4 vs. 5.2 ± 1.6; p <0.001), at 24 h (5.9 ± 1.5 vs. 4.3 ± 1.7; p <0.001), and at 48 h (4.7 ± 1.3 vs. 3.5 ± 1.4; p <0.001) in comparison to the low NLR group. Maximum swelling was more in the high NLR group at 48 h with results of a difference found to be significant between groups: mean difference was 12.3 ± 3.2 mm for the former and 9.1 ± 2.8 mm for the latter (p <0.001). Trismus was more severe in high NLR patients at 48 h with a mean difference of 21.4 ± 56 mm versus 26.8 ± 4.9 mm among low-NLR patients (p <0.001). Delayed healing occurred in 28% of high-NLR patients compared to only 12% among low-NLR patients (p = 0..024). Conclusion: Increased preoperative NLR is associated with increased postoperative pain, swelling, trismus, and delayed healing after extraction of mandibular third molars; hence it could be an important predictor for risk stratification and improved perioperative management.