Objective To explore the effect of root canal therapy combined with resin ceramic inlay indirect restoration on restoration aesthetics in patients with large molar defect. Methods A total of 90 patients with large molar defect admitted to our hospital from January to December 2024 were selected, and they were divided into the control group and the observation group by the random number table method, with 45 patients in each group. Both groups received root canal therapy. The control group received direct composite resin restoration, and the observation group received resin ceramic inlay indirect restoration. The restoration aesthetics, masticatory function and restoration defect rate were compared between the two groups. Results At 12 months after restoration, the grade A rates of restoration morphology, marginal adaptation, color matching and surface texture in the observation group were higher than those in the control group (P <0.05). The occlusal force and masticatory efficiency in the observation group at 3 months after restoration were higher than those in the control group (P <0.05). The restoration defect rate of the observation group (4.44%) was lower than that of the control group (24.44%) (P <0.05). Conclusion Root canal therapy combined with resin ceramic inlay for repairing large molar defect is superior to conventional direct composite resin filling in recovering masticatory function and improving aesthetic effect, and presents better long-term restoration stability.