Butler 1977.

Study characteristics
Methods	Study design: RCT (split‐mouth) Conducted in: Bethesda, Maryland, USA
Participants	Inclusion criteria: patients with bilaterally symmetrical impactions with regard to depth and angulation. Partial or complete impactions were also accepted. Exclusion criteria: patients with evidence of acute infection or severe pericoronitis around the wisdom teeth were excluded from the study Number randomised: 211 Number evaluated: 211 participants/422 teeth
Interventions	High‐volume irrigation versus low‐volume irrigation Group A (n = 211): postextraction irrigation with 175 mL sterile saline under IV sedation Group B (n = 211): postextraction irrigation with 25 mL sterile saline under IV sedation Follow‐up: at 4, 5, or 6 days All procedures performed under intravenous sedation.
Outcomes	Presence of alveolar osteitis at recall 4 to 6 days later
Notes	Sample size calculation: not reported In 32 cases a mechanical irrigation device was used for irrigation in the higher‐volume site.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "a random selection technique was used" Comment: method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding (performance bias and detection bias) patient	Unclear risk	As participants were sedated, they were highly unlikely to be aware of which volume of irrigant they received and where. However, this may be confounded by the 32 cases in which a mechanical irrigating device was used (see below).
Blinding (performance bias and detection bias) assessor	High risk	No mention of assessor blinding
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals
Selective reporting (reporting bias)	Unclear risk	The authors state that "patients were examined on the fourth, fifth, or sixth postoperative day for evidence of localised osteitis". However, they go on to mention that most "infections" occurred between the seventh and 10th postoperative days. The outcome of infection was not mentioned at the outset, regardless of the fact of a non‐significant result.
Other bias	High risk	Quote: "...most patients also had one or two maxillary third molars removed, but these operations were not included in the investigation" Comment: multiple extraction sites may influence the presence of alveolar osteitis and therefore should be considered as a confounding factor In 32 cases a mechanical irrigating device was used to provide the higher volume of irrigant, thus also confounding the results.