Background <p>In the clinic, it is crucial to be aware of the long-term clinical efficacy of restoration techniques, such as direct and indirect, when restoring molar teeth. This randomized controlled trial aimed to evaluate the clinical performance of direct and indirect restorations in Class I cavities in molar teeth. Randomization was achieved by flipping a coin to determine which tooth would receive the direct restoration, with the other tooth receiving an indirect restoration.</p> Methods <p>The study was comprised of 27 patients, with an average age of 34.16 (range, 24–54) years. A total of 54 class I restorations were made, 27 of which were direct restorations and 27 were indirect restorations. One direct and one indirect Class I restoration was performed on each patient. A microhybrid universal composite (Aelite All-Purpose Body, Bisco) was used for direct restorations, and a reinforced microfill composite system (Tescera Indirect Composite System Body, Bisco) was used for indirect restorations. The restorations were assessed at baseline and at 1, 2, and 10-year recalls using the modified USPHS criteria. The results were analyzed statistically using the Friedman test, Mann-Whitney U test, and Dunn’s post hoc test.</p> Results <p>After 10 years, the success rate was 85.2% for direct restorations (<i>p</i> = 0.007) and 96.3% for indirect restorations (<i>p</i> = 0.39). Four direct restorations failed because of caries (<i>p</i> = 0.007), and one indirect restoration failed due to the need for crown restoration (<i>p</i> = 0.39). The failure rate of direct restorations was higher than that of indirect restorations (<i>p</i> = 0.043). Except for caries, for any evaluation criterion, no statistically significant difference (<i>p</i> &gt; 0.05) was detected between indirect and direct restorations among all evaluation periods.</p> Conclusions <p>Both direct and indirect restorations have demonstrated satisfactory success rates after 10 years. The primary cause of restoration failure in direct restorations was caries. Although indirect restoration options give excellent results for Class I cavities at the end of 10 years, direct restorations may be a suitable alternative for Class I cavities due to their several advantages.</p> Clinical Significance <p>At the end of 10 years, it can be said that both direct and indirect restorations may be preferred in Class I cavities.</p> Trial registration <p>ClinicalTrials.gov identifier NCT07081529. Registered on July 22, 2025. Retrospectively registered.</p>