Attempts are made to smoothen the root furrow by the instrument and then the flap is gently raised but not more than necessary to obtain insight to the bony defect. The area is inspected carefully for remaining granulation tissue. If possible the flap should not be raised, on the buccal side, further than just apical to to the mucogingival line. The granulation tissue is removed. Note the thin bone ledge which border the defect.
All granulation tissue appears now to be removed.
The sharp bone edge prevents proper closer of the flap and also creates a deep one wall bony defect. It is therefore decided to remove this using a chisel. Gentle gradual removal of the bone reduces the risk of excessiv trauma from this procedure. Rotating instruments more easily generate heat and also create a risk of damage to the root surface. The gradual removal of the bone result in an elimination of the bony defect and on inspection a smooth junction between the bone and the tooth surface can be observed.