Procedure: The study will use 2 groups, a control group and a test group with 16 patients in each group, with severe chronic periodontitis having clinical or radiographic evidence of Class II furcation defects in the buccal or lingual of the mandibular molars or Class II furcation defects on the buccal of maxillary molars. 16 patients will serve as the control group and open flap debridement with bioresorbable collagen membrane will be the mode of treatment. Group 2: 16 patients will serve as the test group and will undergo open flap debridement in conjunction with Er, Cr: YSGG laser irradiation and a bioresorbable collagen membrane will be used.