Objective To study the clinical value of multiple root canal fiber posts combined with zirconia all-ceramic crowns in the repair and treatment of patients with large-area tooth defects of molars, and to analyze their effects on periodontal health and masticatory efficiency. Methods From June 2021 to June 2024, 70 patients with large-area tooth defects of molars admitted to Licang District Licun Street Community Health Service Center, Qingdao City were selected as the research objects. They were divided into control group (35 patients) and observation group (35 patients) according to different repair treatment schemes. The control group was repaired with metal post cobalt chromium porcelain crown, and the observation group was repaired with multiple root canal fiber posts combined with zirconia all-ceramic crown. The repair effect, periodontal health, masticatory efficiency and complication rate were compared between the two groups. Results The proportions of complete restoration, suitable edge, color matching, good anatomical shape and surface, and gingival health in the observation group were higher than those in the control group, the difference was statistically significant (P <0.05). The probing depth (PD), gingival index (GI) and sulcus bleeding index (SBI) in the observation group were lower than those in the control group, the difference was statistically significant (P <0.05). The masticatory efficiency of the observation group was higher than that of the control group, the difference was statistically significant (P <0.05). The incidence of complications in the observation group was 5.71%, which was lower than 22.86% in the control group, the difference was statistically significant (P <0.05). Conclusion The effect of multiple root canal fiber posts combined with zirconia all-ceramic crown repair scheme for the repair and treatment of patients with large-area tooth defects of molars is better than that of traditional metal post cobalt-chromium porcelain crown repair. It can obtain better repair effect in terms of restoration integrity, color and edge adaptation, and gingival health, so as to further improve the periodontal status and reduce the occurrence of complications. It has high clinical value.