A Non-Inferiority Study Evaluating Fibroblast Growth Factor-2 (KCB-1D) to Enamel Matrix Derivative (Emdogain(R)Gel) for Periodontal Tissue Regeneration

INTERVENTION: KCB‐1D group Adequate volume of KCB‐1D will be administered to the lesion during flap surgery. EMD group Adequate volume of Emdogain(R)Gel will be administered to the lesion during flap surgery. FOP group Flap surgery only CONDITION: patients with periodontitis who require surgical intervention (flap surgery) PRIMARY OUTCOME: linear alveolar bone growth at 36 weeks after administration SECONDARY OUTCOME: change of clinical attachment level, probing pocket depth and gingival recession at 36 weeks after administration; ; adverse events and adverse drug reactions INCLUSION CRITERIA: 1.diagnosed as periodontitis requiring flap surgery after successful initial preparation 2.with vertical intrabony defect 4 mm or deeper on radiographs 3.with probing pocket depth 6 mm or deeper, with mobility of tooth 2 degree or less, and with width of keratinized gingiva for which flap surgery is considered appropriate