Objectives: Comparing the effects of submucosal dexamethasone injection, Twin Mix injection, and drain placement on the surgical removal of impacted mandibular third molar regarding postoperative edema, trismus, and pain.

Material and Methods: 64 patients were selected randomly from Oral and Maxillofacial Surgery Department at Mansoura University. They were divided into four equal groups according to the surgical technique and its modifications. 16 patients were included in each group: The submucosal injection group received dexamethasone injection in the buccal vestibule preoperatively, the Twinmix group received Twin Mix solution injection in the pterygomandibular space preoperatively, the drain group received a tube drain placed submucosally at the buccal vestibule while the control group; had a conventional surgical technique applied. The participants were assessed for pain using visual analog scale (VAS), swelling using facial edema lines, and trismus by a maximum interocclusal opening (MIO) measurement at immediate postoperative period, two days and seven days follow up periods.

Results: The analysis of pain using VAS showed significant statistical differences in values recorded at all time intervals. Meanwhile,evaluation of edema revealed that there was a significant statistical difference between the groups at values recorded at the second day follow up (P=0.005). Furthermore, no statistically significant difference was showed regarding MIO between all groups at all time intervals
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Conclusions: Submucosal and Twinmix groups had a better pain control than the drain and control groups. The submucosal group showed the best outcome with regards to swelling. None of the studied groups showed a significant difference concerning trismus.