Aim: The treatment and long-term retention of mandibular molar teeth with furcation involvement have always been a challenge in periodontal therapy. Root resection has been used successfully to retain teeth with furcation involvement. The term root resection refers to the resection and removal of either of theroots of mandibular molar, which may be affected by periodontal, endodontic, structural deformity. There should be __ampersandsigngt;50% bone support of the remaining roots at the time of the root resection in treating periodontally diseased mandibular molars, which acts as an important factor to obtain good results. In addition, a careful prosthetic plan should be designed to avoid a fracture of resected molars related to biomechanic impairment. Case Report: This case report of a 23 year old female provides an overview of the feasibility of mesial root resection and bone grafting along with CGF membrane of mandibular right first molar severely affected by perio-endo lesion thus maintaining the function of the teeth. Discussion: Root resection represents a form of conservative procedure that aims at retaining as much of the original tooth structure as possible thus acting as an alternative to extraction. Root resection of the affected tooth allows the preservation of tooth structure, alveolar bone and maintains the normal function thus being advantageous over other treatment options. Conclusion: With the results of this case report, the suggested treatment of periodontal abscess with Grade-III furcation by root canal treatment followed by root resection and periodontal flap procedure with bone graft placement along with Concentrated Growth Factor in the furcation defect of the involved tooth could result in successful resolution of infection and excellent healing in the residual defect of furcation which was considered hopeless thus maintaining the function of the dentition.