关键词: 下颌磨牙, 牙槽嵴保存术, 牙种植, 牙周牙髓联合病变

Abstract: Implant therapy is an ideal restoration option for partial edentulousness. Sufficient amounts of soft and hard tissues are necessary for successful implant therapy. The mandibular molar area is closely related to the mandibular canal，and it is necessary to keep a safe distance to avoid nerve injury during implant therapy. Following extraction of mandibular molars with severe periodontal lesions，inadequate bone mass will greatly increase the difficulty and risk of subsequent implant therapy. Ridge preservation can achieve preservation or augmentation for alveolar ridge，thus creating good soft and hard tissue conditions for implant therapy. This article illustrates a case of the mandibular second molar with the periodontal and endodontic lesions undergoing ridge preservation after extraction and receiving implant treatment 6 months later，which increases the safety of implant therapy，and achieves good therapeutic effect and provides experience for clinical management of such cases. 

Key words: mandibular molars, alveolar ridge preservation, dental implantation, periodontal and endodontic lesions