Twin-mix injection reduces postoperative complications after lower third molar removal – A systematic review and meta-analysis of randomized controlled trials

ABSTRACT Background The aim of this systematic review and meta-analysis was to assess whether pain, swelling and trismus following surgical removal of the lower third molar could be reduced by twin-mix injection. Materials and Methods MEDLINE, Embase and Cochrane Trials were searched for randomized controlled trials (RCTs) until 17th November 2022. Eight RCTs were included in the systematic review, and seven in the meta-analysis. In this study, the twin-mix was compared with the conventional anesthetic solution. Outcomes were assessed on postoperative days 1, 3 and 7. Primary outcomes were swelling and trismus. Secondary outcomes were postoperative pain, pain score on local anesthetic injection, duration of soft tissue anesthesia, and latency of anesthesia. Risk of bias was assessed using the Cochrane ROB2 tool. Certainty of evidence was evaluated with the GRADE tool. Results On postoperative day 1, the twin-mix group showed significant reductions in facial swelling (MD: -3.51 mm; [-5.04 to -1.97]), trismus (MD: -1.7 mm; [-2.48 to -0.92]) and pain (MD: -1.07; [-1.49 – -0.65]). On day 3, swelling (MD: -4.64 mm; [-6.34 to -2.94]), trismus (MD: -1.08 mm; [-1.55 to -0.61]) and pain (MD: -0.62; [-1.09 to -0.15]) remained significantly reduced. On day 7, differences persisted for swelling (MD: -0.58 mm; [-0.76 to -0.40]) and trismus (MD: -0.42 mm; [-0.72 to -0.12]), but no significant difference was found in pain (MD: -0.29; [-0.65 to 0.07]). The twin-mix also significantly reduced pain under local anesthesia, shortened latency and prolonged duration of anesthesia. Conclusion In conclusion, the use of twin-mix is highly beneficial for pain relief, facial swelling and trismus following mandibular third molar surgical removal.