Pradeep 2015.

Methods	Trial design: randomised, longitudinal, triple‐masked, parallel trial Location: Department of Periodontics, Government Dental College and Research Institute, Bangalore, India Number of centres: 1 Recruitment period: November 2013 to July 2014 Source of funding: not stated Ethical approval: Institutional Ethical Committee and Review Board of the Government Dental College and Research Institute, Bangalore, India Number of surgeons: 1
Participants	Inclusion criteria: presence of intrabony defect ≥ 3 mm deep (distance between alveolar crest and base of the defect on an intraoral periapical radiograph (IOPA)) along with an interproximal PD ≥ 5 mm after phase I therapy (scaling and root planing) in asymptomatic maxillary/mandibular molar teeth Exclusion criteria: aggressive periodontitis patients; patients with systemic conditions known to affect the periodontal status; medications known to affect the outcomes of periodontal therapy; haematological disorders and insufficient platelet count (< 200,000/mm3); pregnancy/lactation; smoking and tobacco use in any form; and immunocompromised individuals. Those having unacceptable oral hygiene (PI > 1.5) after re‐evaluation of phase I therapy were also excluded. In addition, teeth with furcation defects, non‐vital teeth, carious teeth warranting restorations and mobility of at least grade II were also excluded Age at baseline: mean = 41 years Gender: F 68/M 68 (for all 4 groups) Smokers: excluded Teeth treated: maxillary and mandibular molar Number randomised (participants/teeth): 64/64 (126/126 for all 4 groups; 136 eligible but 10 excluded at time of surgery) Number evaluated (participants/teeth): 60/60 (120/120 for all 4 groups)
Interventions	Comparison: OFD alone versus OFD + PRF Group 1: OFD alone (n = 30) Group 2: OFD + PRF (n = 30) Surgical technique: in group 1, only OFD was done, without addition of any regenerative material into the bone defect; in group 2, PRF of the required size was filled into the intrabony defect after OFD Follow‐up duration: 9 months
Outcomes	Clinical: site specific PI, modified sulcus bleeding index, relative attachment level, gingival marginal level Radiographic: radiographic intrabony defect depth Other: none
Notes	Sample size calculation: reported Radiographs were taken with a bite block for ensuring reproducibility Comparability at baseline: yes, assessed Complications reported: yes Dropouts: reported, 4 dropouts (6 for all 4 groups) 3rd and 4th group data (OFD + 1% metformin and OFD + PRF + 1% metformin) not included in this review
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "These patients were divided randomly (computer generated tables) into 4 groups" Comment: random sequence generation properly done
Allocation concealment (selection bias)	Unclear risk	Insufficient information provided for allocation concealment method
Blinding of participants and personnel (performance bias) All outcomes	High risk	Impossible to blind the operator given the surgical nature of the treatment. For the same reason, blinding of the patient, even though it was done, does not influence the outcome of the treatment
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quotes: "This was a randomized, single‐centre, longitudinal, triple‐masked (investigators, individuals and statistician), parallel arm design study" and "One operator (KN) performed all the surgeries, whereas another operator (ARP) performed all the clinical and radiographic measurements without knowledge of the groups" Comment: blinding of outcome assessment properly done
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 dropouts (6 for all 4 groups)
Selective reporting (reporting bias)	Low risk	All outcomes properly reported