Retention and caries-preventive outcomes of glass ionomer–based fissure sealants in children: a 24-month split-mouth randomized controlled trial

This study aimed to comparatively evaluate the 24-month clinical retention performance and caries-preventive efficacy of three glass ionomer–based fissure sealants with different compositions. This randomized, controlled, double-blind clinical trial was conducted with ethical approval and registered at ClinicalTrials.gov (NCT07388472). A total of 400 sealants were applied to the two fully erupted mandibular first molars of each participant. Following randomization, one molar received GC Fuji Triage (high-fluoride containing/control) (GC Int., Tokyo, Japan), while the contralateral molar received either GC Fuji VII EP (CPP-ACP–containing) (GC Int., Tokyo, Japan) or GCP Glass Seal (nano-fluorohydroxyapatite–containing) (GCP Dental, Vianen, the Netherlands). Patients were evaluated at 3-, 6-, 12-, 18-, and 24-months. Retention, marginal integrity, marginal discoloration, and secondary caries were assessed using modified USPHS criteria. Occlusal caries progression was monitored via ICDAS-II codes and DIAGNOdent measurements. Data were analyzed using non-parametric tests (Friedman, Kruskal–Wallis, with Bonferroni adjustment), and retention survival was assessed by Kaplan–Meier analysis (p < 0.05). At 24 months, GC Fuji VII EP and GC Fuji Triage showed significantly higher retention than GCP Glass Seal (p < 0.001). The longest mean survival time was observed for GC Fuji VII EP (20.47 months), followed by GC Fuji Triage (19.53 months). No occlusal caries development or upward transitions in ICDAS-II scores were detected in any group. DIAGNOdent values decreased significantly over time across all materials (p < 0.001). Within the limitations of this study, no evidence of occlusal caries progression was observed over the 24-month period, while retention performance varied according to material composition and physicochemical properties. These findings support the potential of glass ionomer–based sealants to provide sustained caries-preventive effects beyond mechanical retention, possibly mediated by fluoride release and bioactive interactions related to their composition. Clinical Trial Registration The study was registered at ClinicalTrials.gov (Registration number: NCT07388472; Date of registration: 04/02/2026).