Performance of nitric acid and mineral enriched system versus phosphoric acid and universal adhesive in cervical carious lesions: a randomized clinical trial

Abstract Objective To evaluate the clinical performance of nitric acid associated with a mineral-enriched adhesive system compared to the conventional approach of phosphoric acid and a universal adhesive in cervical carious lesion restorations. Materials and methods Twenty-six individuals with 44 cervical anterior carious lesions were randomized into two equal parallel groups. The intervention group received a nitric acid etch (Clean and Boost dentin enamel cleanser, Vista Apex, USA) in conjunction with a mineral-enriched adhesive and a flowable composite liner (RE-GEN, Vista Apex, USA). Control group treated with phosphoric acid (Scotchbond Universal Etchant, 3 M ESPE), a universal adhesive (Single Bond Universal Adhesive, 3 M ESPE), and a standard liner (Filtek Supreme, 3 M ESPE). All cavities were restored using nanohybrid resin composite (Filtek Z350XT, 3 M ESPE). Postoperative sensitivity was assessed both qualitatively, using the modified USPHS criteria, and quantitatively, using a visual analog scale (VAS), as the primary outcome. In addition, clinical performance regarding marginal discoloration, adaptation, secondary caries, and retention was evaluated as secondary outcomes using modified USPHS criteria. Outcomes were assessed at 24 h, 6, 12, and 18 months. The data was statistically analyzed using intention-to-treat analysis. Intergroup comparisons were performed using the Chi-Squared test with a significance level (p ≤ 0.05), and intragroup comparisons were analyzed using Cochran’s Q test with a confidence level of 95% and a study power of 80%. Relative risk was used to assess clinical significance. The survival rate was analyzed using the Kaplan-Meier and Log-rank tests. The study was conducted following the CONSORT 2025 guidelines. Results Both groups demonstrated similar performance in terms of postoperative sensitivity, retention, secondary caries, and marginal adaptation, as assessed using modified USPHS criteria. However, there was a significant increase in marginal discoloration within the phosphoric acid groups after 18 months. There was 50% less risk of sensitivity with nitric acid compared to phosphoric acid using the VAS scale (CI (0.2512 to 0.9953); p = 0.0485). The tested groups showed an equal survival rate (p = 0.3771). Conclusion Combining nitric acid with a mineral-enriched system is a promising approach for restoring cervical carious lesions.