Ozgul 2015.

Study characteristics
Methods	Study design: randomised, multicentre, split‐mouth clinical trial Conducted in: Turkey
Participants	Inclusion criteria: bilateral, fully impacted third molars that have the same degree of surgical difficulty comparing 1 side with the other; no pre‐existing medical conditions or use of medication that would influence or alter wound healing; no active pathology associated with the third molars; no temporomandibular joint disorder history that would affect pain sensation after surgery Age: 18 to 28 years Number randomised: 56 (23 male, 33 female) Number evaluated: 56
Interventions	PRF versus none Group A (n = 56): PRF was placed in the socket Group B (n = 56): control; nothing placed in the socket
Outcomes	At 24 h, 72 h, and 7 days Evaluation of facial swelling was performed using a horizontal and vertical guide. Pain/comfort was evaluated in the postoperative period using a 0‐to‐100‐millimetre VAS.
Notes	Sample size calculation: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A coin toss technique was used for the study.
Allocation concealment (selection bias)	Unclear risk	Comment: unclear if the person making the allocations was separate to the operator
Blinding (performance bias and detection bias) patient	Low risk	Quote: "Patients were blind to the knowledge of PRF placed side" Comment: participants were reported as being blind to the intervention
Blinding (performance bias and detection bias) assessor	Low risk	Quote: "The postoperative evaluations were performed by surgeons that were blinded to the operative procedures, in order to eliminate unwanted bias." Comment: assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: it is not stated if outcomes were measured for all participants. No dropouts are mentioned.
Selective reporting (reporting bias)	Low risk	Comment: planned outcomes were reported
Other bias	Unclear risk	Comment: the recruitment process is unclear; patients were "selected"