Cerqueira 2004.

Study characteristics
Methods	Study design: RCT split‐mouth Conducted in: Pernambuco, Brazil Number of centres: 1 Recruitment period: not stated
Participants	Inclusion criteria: patients aged 14 to 30 years, with bilateral impacted third molars in similar positions on each side of the mouth Exclusion criteria: patients using medications that could interfere with healing or those with systemic disease Number invited: 5 patients underwent surgery "with the purpose of calibration", and a further 12 were excluded because they "proved to be unsuitable" Number randomised: 53 Number evaluated: 53
Interventions	Drain versus no drain Group A (n = 53): 1 side of the mouth, chosen at random, had a silicon tube drain inserted into the buccal fold. Drain in situ for 4 days Group B (n = 53): on the opposing side the wound was sutured with no drain All participants received preoperative antibiotic prophylaxis (amoxicillin) and postoperative cetoprophen for 4 days. All procedures performed under local anaesthesia.
Outcomes	Pain (0‐to‐10 VAS), maximal mouth opening, swelling (% of preoperative) on postoperative days 1, 3, 7, and 15
Notes	Sample size calculation: not reported E‐mail sent to Dr Vasconcelos at belmiroc@terra.com.br on 6 March 2012 requesting further information. No reply received.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The choice of treatment "was made randomly".
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding (performance bias and detection bias) patient	Unclear risk	Not mentioned and probably not possible
Blinding (performance bias and detection bias) assessor	High risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	All 53 participants were evaluated.
Selective reporting (reporting bias)	Low risk	Planned outcomes of pain, swelling, and trismus reported.
Other bias	Low risk	No other sources of bias identified.