Srinivas 2006.

Study characteristics
Methods	Study design: split‐mouth RCT Conducted in: Bangalore, India Number of centres: 1 Recruitment period: not stated
Participants	Inclusion criteria: patients aged 15 to 39 years willing to participate in the study. No significant medical history, non‐smokers, non‐alcoholics with bilateral and symmetrically positioned impacted lower third molars that were completely covered by mucosa/partially or completely covered by bone Exclusion criteria: none stated Number randomised: 14 Number evaluated: 14
Interventions	Tube drain versus no drain Group A (n = 14): mucoperiosteal flap raised following envelope incision, flap was reflected and bone removed with a bur. Tooth was removed and socket was irrigated with saline. Small surgical drain was placed via stab incision in buccal fold between first and second molar and closed. Tube was removed on postoperative day 3. Group B (n = 14): mucoperiosteal flap raised following envelope incision, flap was reflected and bone removed with a bur. Tooth was removed and socket was irrigated with saline. Flap was approximated, closed with interrupted 3‐0 silk sutures. All surgical procedures were performed by the same surgeon under local anaesthetic. Second extraction was performed after 2 months.
Outcomes	Pain (present/absent), swelling (vertical/horizontal measurements), trismus (MMO)
Notes	No sample size calculation reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomly chosen" Comment: method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding (performance bias and detection bias) patient	Unclear risk	Not mentioned
Blinding (performance bias and detection bias) assessor	High risk	Not mentioned. Likely that the same operator performed the procedures and assessed the outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	All randomised participants included in outcomes.
Selective reporting (reporting bias)	Low risk	All planned outcomes reported.
Other bias	Low risk	No other sources of bias identified.