This study determined the differences in clinical performance between materials for indirect composite restorations based on Ormocer (Admira) and nano-hybrid resin composite (Grandio), both at baseline and 36 months after placement. Modified USPHS criteria were used to analyze the degree of quality. Marginal integrity was assessed 36 months after placement, whereupon, the restorations fabricated from Grandio achieved an Alpha 1 score of 70.7% and an Alpha 2 score of 29.3%. The Wilcoxon test revealed a statistically significant difference in the evaluation of marginal integrity (p = 0.003), anatomic form of the marginal step (p = 0.025) and discoloration of the margins (p = 0.014) at baseline and after 36 months. For Admira, the Wilcoxon test showed statistically significant differences in the evaluation of surface texture (p = 0.025), anatomic form of the complete surface (p = 0.034), anatomic form of the marginal step (p = 0.008), marginal integrity (p = 0.002) and discoloration of the margins (p = 0.008) at baseline and after 36 months. According to the number of restorations awarded the Alpha 1 score (excellent), the overall success rates for marginal integrity were 70.7% for Grandio and 71.8% for Admira; both were evaluated 36 months after placement. The results have shown that the indirect restorations were acceptable after 36 months, which indicates a 100% success rate. Over 36 months, no statistically significant differences were noted between the two materials. Indirect resin composite restorations represent a good therapy choice for severely damaged teeth.