Analgesic efficacy of 0.75% ropivacaine versus 2% lidocaine after unilateral mandibular third molar extraction: a prospective observational cohort study

Abstract

This prospective observational cohort study aimed to evaluate the clinical efficacy of 0.75% ropivacaine in unilateral mandibular third molar extraction and to compare its postoperative analgesic outcomes with those of 2% lidocaine. A total of 128 patients undergoing unilateral mandibular third molar extraction were prospectively enrolled. According to the local anesthetic administered during routine clinical practice, patients were categorized into two exposure cohorts: 2% lidocaine (China Otsuka, Tianjin, China) and 0.75% ropivacaine (Shijiazhuang No.4 Pharmaceutical, Shijiazhuang, China). All patients received inferior alveolar nerve block anesthesia with the designated agent, supplemented with local infiltration anesthesia using articaine (Primacaine, Mérignac, France). Postoperative assessments were conducted at 24 h and 7 days using standardized electronic questionnaires. Key measures included: (1) onset of postoperative pain (primary endpoint); (2) duration of lower lip numbness; (3) time to first analgesic intake; (4) 10 cm Visual Analogue Scale (VAS) at 24 h and 7 days; (5) Postoperative Symptom Severity scale (PoSSe). The cohort included 41 males and 82 females, with a mean age of 28.5 ± 7.61 (ranging: 17‒65 years). In ropivacaine group, the Median (Quartile) of postoperative pain onset, durations for lower lip numbness, and time to first analgesic intake were 9.00 (6.00, 11.00) hours, 8.00 (6.00, 9.00) hours, and 7.00 (6.00, 10.00) hours respectively, compared to 3.00 (3.00, 4.00) hours, 3.00 (2.25, 3.00) and 3.00 (2.00, 5.00) hours in lidocaine group. No significant difference was found in both VAS scores at 24 h (24hVAS) and 7 days (7dVAS). No significant difference was found in PoSSe. Only the 24hVAS showed a positive correlation with the Pell & Gregory II classification in both lidocaine group and ropivacaine group. The 7dVAS only showed a positive correlation with the Pell & Gregory II classification in lidocaine group, and the PoSSe only showed a positive correlation with the Pell & Gregory I classification in ropivacaine group ( P < 0.05, r > 0). The results demonstrate that 0.75% ropivacaine delays pain onset and analgesic consumption, which may offer an advantageous option for prolonged surgical procedures and early postoperative pain management. However, all patients received supplementary articaine infiltration, which may limit the interpretation of the true analgesic efficacy of the tested agents. Besides, it requires confirmation in randomized trials.