The objective of the present study provides further data comparing retention, marginal integrity and caries preventive effects of two fissure sealants (glass ionomer based; GC Fuji VII Capsule [Fuji VIP and ormocer based; Admira Seal [AS]) in children. This study was designed as a randomized single-blind clinical trial. The permanent first molars (PFMs) of 50 children, 7-13 years of age (mean age: 8.9 +/- 1.3 years), were sealed with a split-mouth design. Fissure sealants applied to the PFMs according to the manufacturer's recommendations by one pediatric dentist. Clinical evaluation of the sealants was carried out to record retention, marginal integrity and presence of caries at 6, 12, 18 and 24 months after placement by the other pediatric dentist. Kaplan-Meier survival analysis and Cox's regression models were used to estimate the probability of two sealants success. Results: Alpha and Bravo retention rates at the end of follow-up were 13% and 80% for Fuji VII and 3% and 83% for AS, respectively. For retention and marginal integrity between fissure sealants was found similar survival rates (p > 0.05). After 24 months, presence of caries was 16% for Fuji VII and 32% for AS (p < 0.05). Conclusion: Fuji VII and AS exhibited similar retention and marginal integrity during 24 months. However, Fuji VII was showed better results than AS for caries preventive effect. Consequently, Fuji VII sealants may be a better choice for preventing occlusal caries.