Objective To investigate the long-term efficacy of CEREC chairside CAD/CAM inlay/onlay on the restoration of dental defect. Methods A total of 120 patients with dental defect admitted to the Second People's Hospital of Jimo District, Qingdao from February 2019 to September 2022 were selected as the research objects. They were divided into control group and observation group by random number table method, with 60 patients in each group. The control group was treated with conventional impression making inlay/onlay repair, and the observation group was treated with CEREC chairside CAD/CAM inlay/onlay repair. The repair effect, periodontal health status and complications were compared between the two groups. Results The success rate of repair in the observation group was higher than that in the control group at 3, 10 and 18 months after treatment, and the difference was statistically significant (P <0.05). The SBI, GI, TM and PLI of the observation group were lower than those of the control group, and the differences were statistically significant (P <0.05). The incidence of complications in the observation group was 6.67%, which was lower than 23.33% in the control group, and the difference was statistically significant (P <0.05). Conclusion CEREC chairside CAD/CAM inlay/onlay has a good long-term effect on the repair of dental defect, with fewer complications after treatment, and can improve the periodontal status of patients. The comprehensive effect is good.