Objective To compare the clinical application effects of bulk-fill flowable resin composite and nanofilled flowable resin composite in the restoration of wedge-shaped defect. Methods A total of 60 patients (142 affected teeth) who underwent wedge-shaped defect restoration in the Department of Stomatology, Xuzhou Xiahe Stomatological Hospital from June 2025 to June 2026 were selected, and they were divided into the control group and the observation group by the random number table method, with 30 patients (71 affected teeth) in each group. The control group was restored with bulk-fill flowable resin composite, and the observation group was restored with nanofilled flowable resin composite. The clinical efficacy, dentin hypersensitivity rate, wear loss of restorations, marginal microleakage depth and complication rate were compared between the two groups. Results The total effective rate of the observation group (94.37%) was higher than that of the control group (78.87%) (P <0.05). The postoperative dentin hypersensitivity rate, wear loss of restorations and marginal microleakage depth in the observation group were lower than those in the control group (P <0.05). The incidence of complications in the observation group (2.82%) was lower than that in the control group (12.68%) (P <0.05). Conclusion Compared with bulk-fill flowable resin composite, nanofilled flowable resin composite achieves better effects in the restoration of wedge-shaped defect. It can effectively reduce the incidence of postoperative dentin hypersensitivity, decrease restoration wear and marginal microleakage, and help to lower the risk of postoperative complications, presenting more stable restoration outcomes. It is worthy of clinical application.