Sweet 1976.

Study characteristics
Methods	Study design: RCT (split‐mouth) Conducted in: United States Public Health Service Hospital, New York, USA
Participants	Inclusion criteria: male patients from 17 to 27 years of age, who were in good health, and who required bilateral, similarly impacted wisdom teeth extracted. Medical health was ascertained by a "complete physical examination by a physician, normal hospital screening tests, a resident's admission examination, and a complete medical history". In addition, "only patients with soft‐tissue or osseous‐tissue impactions which were asymptomatic were accepted for the study". Exclusion criteria: "patients with a preoperative infection or pericoronitis were eliminated from the study" Number of participants randomised: 103 men, 206 teeth Number of participants evaluated: 99; no withdrawals, but 4 patients with infection excluded from other outcome assessments
Interventions	Mechanical irrigation versus manual irrigation Group A (n = 103 teeth): postextraction mechanical lavage (350 mL sterile saline) Group B (n = 103 teeth): conventional manual syringe lavage (350 mL sterile saline) Procedures performed under general anaesthetic, both teeth extracted in same session by same surgeon. Follow‐up: days 3 and 5
Outcomes	Alveolar osteitis, infection, pain (4‐point scale), swelling (4‐point scale)
Notes	Sample size calculation: not reported 4 participants who presented with alveolar osteitis or infection were excluded from other outcome assessments.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The type of irrigation [...] was predetermined by random selection technique, with the use of random sampling numbers, before the study was begun"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding (performance bias and detection bias) patient	Low risk	Blinding not mentioned, but it is likely that participants were unaware of lavage volume as they were sedated with pentobarbital.
Blinding (performance bias and detection bias) assessor	Low risk	Quotes: "These examinations were made by a dental surgeon who was not involved with the operation"; "the surgical sites were observed by a dental surgeon who was not involved with the operation, and who was unaware of the irrigation methods used" Comment: assessor blinding successful
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals, but 4 participants who had infections were excluded from wound healing outcome. However, in a split‐mouth study this is unlikely to have introduced bias. Quote: "once a patient was treated, he was then counted in the 'treated group', and was not evaluated for any healing results at the 3‐ or 5‐day levels"
Selective reporting (reporting bias)	Low risk	All planned outcomes reported.
Other bias	Low risk	No other sources of bias identified.