Inclusion Criteria:  no systemic diseases a good level of oral hygiene presence of a 2-, 3-, or combined 2-3-wall intrabony defect with a defect angle of 20-40 (+/- 5) degrees with a minimum PPD of 6 mm and intrabony component of a minimum 4 mm as detected on radiographs no smoking  Exclusion Criteria:  systemic diseases that could influence the outcome of the therapy poor oral hygiene smoking horizontal bone loss