Erdogan 2011.

Study characteristics
Methods	Study design: split‐mouth RCT Conducted in: Adana, Turkey Number of centres: 1 Recruitment period: January 2008 to June 2009
Participants	Inclusion criteria: participants were aged 20 to 32 years with bilateral symmetrically impacted mandibular third molars. Participants were free of systemic disease and had no history of pericoronal infection or recent anti‐inflammatory drug use. Included teeth were all class I or II and position A or B according to Pell and Gregory classification. Exclusion criteria: deeply impacted cases were not included in the study Age: mean 23.9 ± 4.3, 20 to 32 years Number randomised: 20 Number evaluated: 20
Interventions	Envelope flap versus triangular flap Group A (n = 20): sulcular incision extending from the lateral border of the  mandibular ramus to the second premolar with no releasing vertical incision Group B (n = 20): buccal releasing incision positioned on the mesial aspect of the second molar All participants had preoperative single dose of oral penicillin and rinsed with CHX. All surgical procedures were performed by the same surgeon under local anaesthetic, and incisions were closed with secondary wound closure. Second extraction was performed after 3 weeks.
Outcomes	Operating time, mouth opening, VAS (0 to 10) pain (resting and chewing), analgesic consumption
Notes	No sample size calculation reported. Probably underpowered. E‐mail sent 25 March 2013, and reply from authors provided additional information.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quotes: "...selected randomly to have their first operations on the left side…. For the first extraction the flap design was chosen randomly" "A coin toss was used to determine the flap type and surgical site at the day of the first surgery" (e‐mail communication)
Allocation concealment (selection bias)	Unclear risk	Quote: "Coin toss was conducted by junior surgeon, and an experienced surgeon performed the surgery" (e‐mail communication)
Blinding (performance bias and detection bias) patient	Low risk	Double‐blind
Blinding (performance bias and detection bias) assessor	Low risk	Quote: "A blinded surgeon who was not aware of the flap design, conducted the measurements"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data reported for all 40 procedures on all 20 participants.
Selective reporting (reporting bias)	Low risk	Planned outcomes reported.
Other bias	Low risk	No other sources of bias identified.