Okuda 2000.

Methods	1‐year follow‐up split‐mouth study including 16 patients. No drop outs at 1 year.
Participants	Patients in good general health and motivated for good oral hygiene. Teeth with PPD greater or equal to 6 mm and IBD greater or equal to 4 mm in presence of 2 mm of keratinized gingiva on the buccal aspect. Patients should not have been treated for periodontitis in the last 2 years. No antibiotics in the previous 6 months. Smokers were excluded. Age ranging between 45 and 67; 8 males and 8 females recruited at 1 university dental clinic.
Interventions	Emdogain versus flap surgery and placebo.
Outcomes	FMPS and FMBS. For experimental teeth only: vertical relative attachment gain, tooth mobility, PAL, PPD, REC, IBD on standardised intraoral radiographs measured as radiographic bone density at baseline and 1 year. Tooth loss, postoperative infections and adverse events. 1‐year data used.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The paired intrabony defects selected for treatment were randomly assigned to receive either the EMD treatment or the placebo treatment by a flip of a coin".
Allocation concealment (selection bias)	Low risk	Author's reply: "At first a surgeon operated open flap and debridement at both sites. After these procedures were finished, the surgeon was put a blindfold condition. At next stage, another person who was not involved in the surgery, applied EMD or placebo to the site determined by a flip of a coin. The surgeon again open eyes, sutured the flap".
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "The clinical examinations were performed by a single examiner (author KO), who was not involved in the surgical procedures". Also the author made it clear that the trial was triple blinded, i.e. patient, clinicians and evaluators had no information regarding the treatment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data are presented in Table 3: Mean clinical and radiographical (RBD) changes at 12 months (mean ± SD). Comment: No missing data. No drop outs.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes for PPD, PAL, REC and IBD are reported in Table 3: Mean clinical and radiographical (RBD) changes at 12 months (mean ± SD). No teeth were extracted and no adverse complications were reported. Aesthetics were not evaluated.
Other bias	Low risk	No other source of bias can be identified.