Bennett 1999.

Methods	Design: blind, prospective randomized controlled trial Country: USA Multisite: no International: no Treatment timing: preoperative period Follow‐up: 24 hours postoperatively Operative procedure(s): extraction of at least 2 impacted third molars Randomization unit: participants Analysis unit: individual
Participants	90 participants enrolled ASA I to II male and females aged 18 to 43 undergoing extraction of at least 2 impacted third molars under deep sedation or general anaesthesia Screened participants were excluded: if they had taken any medication or consumed alcohol in the 48 hours preceding surgery; if they had cardiovascular, cerebrovascular, pulmonary, renal, or hepatic disease. Randomized to: high‐volume fluid (n = 38, 42.2%); low‐volume fluid (n = 39 43.3%); 13 participants (14.4%) did not complete the study. Their allocation group was not stated. These participants were excluded from the analysis because their data collection was incomplete. Main characteristics of participants: age (mean, range): high‐volume group 22 years, 18 to 37; low‐volume group 21 years, 18 to 43; number of females/males: 39/38.
Interventions	Supplemental fluid group (intervention): preoperative bolus of 15 mL/kg normal saline with an additional 1 to 2 mL/kg perioperatively Conservative fluid group (control): no preoperative bolus, only 1 to 2 mL/kg perioperatively Co‐interventions: none stated
Outcomes	Nausea/vomiting, headache, dizziness, drowsiness, fatigue, ambulation, thirst, postoperative urgency to void, and overall well‐being/recovery were assessed using 5‐point Likert scales on questionnaires completed "just before discharge", on the evening of surgery, and 24 hours after surgery Outcomes were reported for these outcomes at these time intervals.
Notes	Trial registration: not found Funder: none stated A priori sample size estimation: not completed Conducted: dates not stated Declared conflicts of interest: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Paper states (quote) "patients were randomly allocated" but no further information on methodology provided.
Allocation concealment (selection bias)	Unclear risk	Paper states (quote) "patients were randomly allocated" but no further information on methodology provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	It is stated that the trial is (quote) "double‐blind" but no further information on fluid administration is provided.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants complete questionnaires, and would be aware of whether or not they received the (preoperative) fluid intervention
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	13 participants are excluded, but they appear to be evenly distributed between the intervention and control groups.
Selective reporting (reporting bias)	High risk	All outcomes are reported, but an intention‐to‐treat analysis is not completed.
Other bias	Low risk	There were no other sources of bias.