OBJECTIVETo assess the efficacy of Dexamethasone (DM) pericoronal injection for the control of swelling and trismus caused by impacted mandibular third molars extraction.

METHODSCochrane, PUBMED, EMBASE and CBM were searched for eligible studies. Hand-searching included references of the included studies and Chinese dental journals. Risk of bias of the included studies was assessed by two reviewers independently using Cochrane Collaboration's tool, and data extraction was done by them. Meta-analysis was delivered with Revman 5.1.

RESULTSSeven randomized controlled trials, involving 684 participants, were included. Six of them had moderate risk of bias and one had high risk of bias. Meta-analysis showed that DM pericoronal injection could relieve trismus by 6.77 mm (P=0.02) within 1-2 days after the surgery. It could also reduce 51% of the risk of moderate-severe trismus(P<0.000 01) and could significantly control facial swelling (P<0.05). There was no differences between 4 mg and 8 mg DM (P>0.05).

CONCLUSIONPeriodontal injection of 4-5 mg DM could control facial swelling and trismus following impacted mandibular third molar extraction. But more randomized controlled trials are needed.