Pozos‐Guillen 2007.

Methods	Study design: parallel‐group randomized controlled trial Sample size: 60 Country: Mexico Setting: secondary care hospital Dates conducted: not reported Postoperative opioid used and delivery: N/A Pain score collection: in clinic‐submitted pain evaluations Concurrent postoperative analgesics: dexamethasone 4 mg intramuscular before procedure, paracetamol 500 mg to 1000 mg or ketorolac 10 mg (or intramuscular 30 mg) depending on pain
Participants	Inclusion criteria Between the ages of 19 and 27 years Undergoing elective removal of an impacted mandibular third molar surgery with local anaesthesia Exclusion criteria Use of analgesics 12 hours before the treatment History of seizure disorders Pregnancy Lactation
Interventions	Group A (20 participants): intramuscular tramadol 100 mg 1 hour before surgery Group B (20 participants): intramuscular tramadol 100 mg after surgery Group C (20 participants): saline placebo
Outcomes	Postoperative pain (0‐to‐10‐centimetre VAS at 6 and 24 hours) Relief of pain (0‐to‐4 scale at 24 hours) Analgesic consumption (mg ketorolac and mg paracetamol at 24 hours)
Notes	Funding: funded by Universidad Autónoma San Luis Potosí; C0‐FAI‐04‐3.4 and C04‐FAI‐10‐10.53 Declarations of interest: not reported Authors contacted: we contacted authors for further information but received no response. Other: extracted from graphs using computer software. Unclear what errors bars represent
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Unclear details. Quote: "participants were randomized"
Allocation concealment (selection bias)	Unclear risk	No mention
Blinding of participants and personnel (performance bias) All outcomes	High risk	No double‐dummy placebo
Blinding of outcome assessment (detection bias) All outcomes	High risk	No double‐dummy placebo
Incomplete outcome data (attrition bias) All outcomes	Low risk	It appears that all participants were followed up.
Selective reporting (reporting bias)	High risk	Adverse events not fully reported.
Other bias	Low risk	Similar groups and no industry funding. Quote: "demographic characteristics of the sample were similar between groups for age and gender"