Objective To explore the effect of microscopic resin layered build-up technique on marginal adaptation and aesthetic scores of restorations for anterior Class Ⅲ cavities. Methods A total of 86 patients with anterior Class Ⅲ cavities admitted to our hospital from April 2023 to September 2025 were selected as the research subjects, and they were divided into the control group and the study group by the random number table method, with 43 patients in each group. The control group received conventional restoration technique, and the study group received microscopic resin layered build-up technique. The marginal adaptation of restorations, aesthetic scores, restoration effect and periodontal indicators were compared between the two groups. Results The marginal adaptation of restorations in the study group after treatment was higher than that in the control group (P<0.05). The scores of WES and PES in the study group after treatment were higher than those in the control group (P<0.05). The total effective rate of restoration in the study group (95.35%) was higher than that in the control group (81.40%) (P<0.05). The plaque index, probing depth of periodontal pockets and gingival index of the study group after treatment were lower than those of the control group (P<0.05). Conclusion The application of microscopic resin layered build-up technique in the restoration of anterior Class Ⅲ cavities can improve marginal adaptation and aesthetic scores of restorations, ameliorate periodontal conditions, and achieve favorable restoration outcomes.