 Clinical Recordings Clinical parameters were assessed using the cemento-enamel junction CEJ or, when applicable, another defined landmark, as a fixed reference point. All measurements were recorded using an UNC 15 periodontal probe PCP-UNC 15, Hu-Friedy, Chicago, IL, USA by a blinded, trained and calibrated examiner CMMS, unaware of the treatment provided at baseline and one year after treatment. Measurements were recorded to the nearest mm. Full mouth plaque score FMPS was recorded dichotomously as the percentage of total surfaces four sites per tooth OLeary et al. 1972. BOP was also assessed dichotomously at the same sites, and a full mouth bleeding score was calculated. Recession REC was measured as the distance from the CEJ to the gingival margin GM. Probing depth PD was measured as the distance from the GM to the bottom of the gingival sulcus. PD and REC were used to calculate the vertical clinical attachment level PAL. Under local anesthesia, transgingival probing was performed and the distance between the CEJ and the bottom of the defect distance CEJ-BD was also recorded. Clinical measurements obtained at baseline immediately before surgery and at twelve months are reported. After debridement of the surgical site, the bottom of the defect BD was defined as the distance between cemento-enamel junction and base of the defect. Bone crest level BC was measured as the distance between the cementoenamel junction and crest of the defect and the intra-bony defect depth INTRA was measured as the subtraction of BC from BD measurements BD-BC. Moreover, the depth of the three, two and one-wall sub-components of the bony defect were also measured. The primary and secondary outcome variables of the present study were, respectively, change in PAL and bone gain change in distance CEJ-BD. 