Prolonged application time effects on universal adhesives in non-carious cervical lesions: An 18-month split mouth randomized clinical trial

Objective: This double-blind, split mouth randomized clinical trial aimed to assess the clinical performance of Clearfil Universal Bond Quick (CBUq) universal adhesive under different application times (no waiting and waiting) compared to Clearfil SE Bond adhesive in non-carious cervical lesions (NCCLs) over 18 months. Methods: One hundred and eighty-three restorations were distributed randomly into three groups based on the adhesive system and waiting time: CUBq without waiting time (CUBq-NW), CUBq with a 20 s waiting time (CUBq-W), and CSE with a 20 s waiting time. After placement, restorations were evaluated after 18 months using the International Dental Federation (FDI) and United States Public Health Service (USPHS) criteria. Statistical analyses involved Friedman repeated measures analysis of variance and Wilcoxon tests, with a significance level set at 5 %. Results: Over the 18-month period, no restorations were lost across the tested groups. Marginal adaptation evaluation indicated minor discrepancies in 21 restorations (8 CUBq-NW, 6 CUBq-W, and 7 CSE). There were no significant differences observed among the three groups following the 18-month clinical assessment (p > 0.05). Only two restorations showed marginal discoloration after 18 months (1 CUBq-NW and 1 CSE). Conclusions: The application of Clearfil Universal Bond Quick using either the "waiting" or "no-waiting" technique exhibited excellent clinical results in NCCLs during the 18-month follow-up period, demonstrating comparable performance to Clearfil SE Bond in all assessed outcomes. Clinical significance: The findings suggest that the new universal adhesive applied using the no-waiting technique demonstrates promising clinical performance when compared to conventional application methods. Trial registration: ClinicalTrials.gov identifer RBR-69p7mpr.