 Root conditioning and rhFGF-2 application After instrumentation, the root surfaces were washed with saline solution to remove any remaining detached fragments from the defect and surgical field. Then, a freshly prepared tetracycline hydrochloride paste in saline was applied with gentle circular movements on the instrumented and dried root surfaces of both test and control groups for three minutes. After that, the defect area was carefully rinsed with saline. Finally, on the experimental sites, 0.2ml of a gel containing 4mgml rhFGF-2 in sodium hyaluronate MW 1.3 x 106 was applied on the dried root surfaces and bone defect. The flaps were then repositioned and tension-free primary flap closure was obtained using internal mattress, and single interrupted sutures 5.0 Ethicon Sutures, Johnson Johnson, NJ, USA or Gore-tex Sutures, W.L Gore, AZ, USA. 