Saglam 2003.

Study characteristics
Methods	Study design: RCT (split‐mouth) Conducted in: Department of Oral and Maxillofacial Surgery, School of Dentistry at Suleyman Demirel University, Isparta, Turkey
Participants	Inclusion criteria: healthy, co‐operative patients aged 15 to 39 years who had bilateral fully impacted mandibular third molars, partly or completely covered by bone Exclusion criteria: patients with significant medical diseases or history of bleeding problems. Pregnant women and patients with signs of pericoronitis were also excluded. Number randomised: 13 Number evaluated: unclear ‐ no mention of withdrawals, but numbers evaluated not stated
Interventions	Tube drain versus no drain Group A (n = 13 teeth): small surgical tube drain applied via a stab incision in buccal fold between first and second molars; drain was removed 3 days postoperation Group B (n = 13 teeth): no drain used; flap approximated without tension All procedures performed by 1 surgeon, and all participants received the same antimicrobial and analgesic drugs. Seems likely that procedures performed on 2 separate visits, but timing unclear. All procedures performed under local anaesthetic. Follow‐up: 7 days
Outcomes	Swelling by measuring distance from commissures to ear lobe and distance from outer canthus of eye to angulus mandibulae. Maximum mouth opening measured between edges of maxillary and mandibular central incisors.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "...the teeth were assigned [...] by random selection and in a crossover pattern" Comment: method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Unclear
Blinding (performance bias and detection bias) patient	Unclear risk	Not mentioned, and it is not possible to blind participants to the presence of an intraoral surgical drain
Blinding (performance bias and detection bias) assessor	High risk	Quote: "...the patients were examined by the same surgeon immediately preoperatively, and on the first, second, third and seventh post‐operative days." Comment: unclear whether the outcome assessor was the surgeon who performed the procedure. Probably obvious whether drain was used
Incomplete outcome data (attrition bias) All outcomes	Low risk	No mention of withdrawals. It is likely that all 26 were included in evaluation.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes reported on.
Other bias	Low risk	No other sources of bias identified.