Performance of Nitric acid and Mineral Enriched System Versus Phosphoric Acid and Universal Adhesive in cervical carious lesions: a randomized clinical trial

Background: Phosphoric acid is considered the most commonly used acid for the pretreatment of tooth structures prior to resin composite restoration. However, its use on dentin substrates is frequently associated with postoperative sensitivity. Therefore, this study aimed to evaluate the clinical performance of a multifunctional protocol comprising a nitric acid etch, mineral-enriched adhesive, and flowable composite liner compared with a conventional protocol using phosphoric acid, a universal adhesive, and a regular flowable composite liner in cervical carious anterior cavities. Methods: A total of 26 individuals presenting with 44 cervical anterior carious lesions were recruited and randomized into two equal groups. One group received treatment with 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). The other group received treatment with phosphoric acid (Scotchbond Universal Etchant, 3M ESPE), a universal adhesive (Single Bond Universal Adhesive, 3M ESPE) , and a regular flowable composite liner (Filtek Supreme, 3M ESPE) . Both groups received a final restoration using a packable nanohybrid resin composite (Filtek Z350XT, 3M ESPE) . Postoperative sensitivity was evaluated using a visual analog scale at baseline, 6, and 12 months. The data was statistically analyzed using the Chi-Squared test with a statistical significance level set at (P ≤ 0.05). Intragroup comparisons for each intervention were performed using Cochran's Q test, with a statistical significance level set at (P ≤ 0.0083) after Bonferroni correction. Success rates were compared using the Z test for independent proportions, and relative risk was calculated to assess clinical significance. All tests were two-tailed, with a confidence level of 95% and a study power of 80%. Results: After 12 months, the risk of postoperative sensitivity was 44% lower in the nitric acid group compared to the phosphoric acid group (RR= 0.5625, 95%CI (0.3201 to 0.9884); P = 0.0454). The success rate for the phosphoric acid protocol was 27.3%, whereas the nitric acid protocol achieved a success rate of 59.1%, with a statistically significant difference (P = 0.0353). Conclusion: The use of nitric acid combined with mineral-enriched adhesive and a flowable composite liner system is a promising approach to reducing postoperative sensitivity. Trial registration: This study was registered at www.clinicaltrials.gov under the identification number NCT05928533 on 26/06/2023.