Objective To evaluate the clinical efficacy of erbium laser pretreatment combined with fiber-reinforced composite resin in the restoration of tooth defects.Methods A total of 84 patients with deep caries at the First Affiliated Hospital of Anhui Medical University North District from January 2021 to December 2023 were selected. They were divided into the observation group and the control group by the random number table method, with 50 affected teeth from 42 patients in each group. Both groups received erbium laser pretreatment on the tooth surfaces. The observation group was treated with fiber-reinforced composite resin restoration, while the control group received 3M P60 resin restoration. After a one-year follow-up, the two groups were compared in terms of microleakage scores (lateral wall and gingival wall), restoration satisfaction (surface morphology, restoration stability, and color coordination), gingival index (GI), plaque index (PLI), sulcus bleeding index (SBI), and the overall incidence of complications (secondary caries, food impaction, root fracture).Results The observation group showed lower scores for both lateral wall and gingival wall microleakage compared to the control group (P < 0.05). The observation group achieved higher satisfaction levels in all three aspects including surface morphology, restoration stability, and color coordination compared to the control group (P < 0.05). The observation group exhibited greater improvements in GI, PLI, and SBI before and after treatment than those in the control group (P < 0.05). The observation group had a lower overall incidence of complications than the control group (P < 0.05).Conclusion Erbium laser pretreatment combined with fiber-reinforced composite resin restoration demonstrates significantly superior efficacy in repairing tooth defects compared to conventional resin restoration. This approach reduces microleakage, enhances restoration satisfaction and periodontal health, minimizes complications, and holds high clinical application value.