Objective To compare the effect of all-ceramic onlay and all-ceramic crown restoration on aesthetic effect and masticatory function in the repair of tooth defect. Methods A total of 100 patients with tooth defect admitted to our hospital from June 2021 to March 2024 were selected, and they were divided into group A and group B according to different restoration schemes, with 50 patients in each group. Group A was treated with all-ceramic onlay restoration, and group B was treated with allceramic crown restoration. The clinical efficacy, aesthetic effect and stability, masticatory function and subjective satisfaction with restorations were compared between the two groups. Results The total effective rate of group B (94.00%) was higher than that of group A (90.00%), but the difference was not statistically significant (P >0.05). The scores of surface and marginal discoloration, marginal fitness and proximal anatomical morphology in group B were higher than those in group A (P <0.05). There was no statistically significant difference in the scores of fracture and retention between the two groups (P >0.05). The masticatory efficiency and occlusal force of group B at the 12th month after restorations were better than those of group A (P <0.05). The subjective satisfaction with restoration in group B (96.00%) was higher than that in group A (92.00%), but the difference was not statistically significant (P >0.05). Conclusion Both all-ceramic onlay and all-ceramic crown restoration have definite clinical effects and good fracture resistance and retention in the repair of tooth defect. However, all-ceramic crown restoration has better aesthetic effect and stability, and can effectively improve masticatory efficiency, occlusal force and subjective satisfaction with restorations.