 Two defects were selected from each patient, and were randomly assigned, immediately before each surgical appointment, by computer generated random sequence allocation to one of the two treatment modalities employed: a Control: open instrumentation of the root surfaces and bone defects via flap modified papilla preservation flap; b Test: open instrumentation of the root surfaces and bone defects via flap modified papilla preservation flap and application of a rhFGF-2HA in the intrabony defect. Treatment allocation was registered in an allocation table sheet that was unavailable to the clinical examiner throughout the study. Both the control and test sites were treated at the same surgical appointment and no information on treatment allocation was provided to the patient. All surgical procedures were performed by a single operator, which became aware of the site allocation only after completed root planning and conditioning, and immediately before the application of the growth factor in the test sites. A strict surgical protocol emphasizing careful hard- and soft-tissue management, root debridement, wound stability and infection control was employed Santana et al 2009; Miranda et al 2013. Nonsurgical infection control was performed in the context of cause- related periodontal therapy and consisted of oral hygiene instructions, scaling and root planing, tooth polishing and plaque control measures performed six months prior to regenerative surgery. Patients were re-evaluated three and six months after the completion of the non-surgical cause-related periodontal therapy and enrolled following the later evaluation appointment. 