Objective To explore the effect of 3M-Z350 nanocomposite resin material restoration on the incidence of pulp sensitivity in patients with vital pulp tooth defect. Methods A total of 128 patients with vital pulp tooth defect who visited the Department of Stomatology, the First People's Hospital of Guiyang from January 2022 to December 2023 were selected as the research subjects, and they were divided into the control group and the observation group by the random number table method, with 64 patients in each group. The control group was restored with traditional nanocomposite resin material, and the observation group was restored with 3M-Z350 nanocomposite resin material. The incidence of pulp sensitivity, aesthetic effect, complication rate and satisfaction were compared between the two groups. Results The incidence of pulp sensitivity in the observation group (1.56%) was lower than that in the control group (10.94%) (P<0.05). The scores of color matching, natural morphology and marginal adaptation in the observation group after restoration were higher than those in the control group (P<0.05). The incidence of complications in the observation group (4.69%) was lower than that in the control group (17.19%) (P<0.05). The satisfaction rate of the observation group (96.88%) was higher than that of the control group (82.81%) (P<0.05). Conclusion 3M-Z350 nanocomposite resin material can achieve ideal aesthetic effect in the restoration of vital pulp tooth defect. This material has fewer clinical complications, mild postoperative pulp response and high patient satisfaction.