**7.1 Background**

Flap design in periapical surgery should be adequate for the planned surgical procedure, offering good access to the zone surrounding the affected apexes without altering the soft-tissue circulation. The flap should be a firm continuous incision and not cross an underlying bony defect. If a vertical incision is needed, it should be in the concavities between bone eminences. The vertical incision should not extend into the mesiobuccal fold, and its termination of the gingival crest must be at the mesial or distal line angle of the tooth. Additionally, the base of the flap must be at least equal to the width of its free end. The most frequently used flap in periapical surgery is the Luebke-Ochsenbein flap involving submarginal incision, with semilunar or Partsch flap variants.
