BACKGROUND:The combination of platelet-rich fibrin and autogenous bone has achieved good results in the treatment of periodontal bone defects,but the study of the combination of the two in the treatment of severe alveolar bone defects is scarce. OBJECTIVE:To observe the effect of autologous bone transplantation plus platelet-rich fibrin on the repair of severe alveolar bone defects. METHODS:A total of 102 patients with severe alveolar bone defects in Hengshui People's Hospital from April 2022 to February 2023 were selected and divided into control and observation groups(n=51 per group)by random number table method.Guided tissue regeneration was performed in both groups.The bone defect was filled with autogenous bone in the control group,and the observation group underwent platelet-rich fibrin+autogenous bone filling for bone defects during the operation.The clinical efficacy,changes in tooth mobility,periodontal microecological environment(probing depth,clinical attachment loss,and bleeding index),height and density of alveolar bone,gingival crevicular fluid indicators(transforming growth factor-β,serine protease inhibitor,and matrix metalloproteinase-3)before and after surgery,as well as adverse reactions were observed between the two groups. RESULTS AND CONCLUSION:Six months after operation,there was no significant difference in treatment efficacy rate between the two groups(P>0.05).At 3 and 6 months after surgery,the levels of tooth mobility,probing depth,clinical attachment loss,and bleeding index in the observation group were lower than those in the control group(P<0.05).At 6 months after surgery,the height of alveolar bone in the observation group was higher than that in the control group(P<0.05).At 3 and 6 months after surgery,the levels of transforming growth factor-β in gingival crevicular fluid in the observation group were higher than those in the control group(P<0.05).At 3 and 6 months after surgery,the levels of serine protease inhibitor and matrix metalloproteinase-3 in the observation group were lower than those in the control group(P<0.05).The results suggest that using platelet-rich fibrin+autogenous bone filling in guided tissue regeneration treatment of patients with severe alveolar bone defects can improve the periodontal microenvironment,reduce gingival tissue inflammation,promote alveolar bone tissue regeneration and repair,and reduce tooth mobility.