ABSTRACTAimTo evaluate and compare the retention ability, anticaries effect and marginal discoloration when sealed with a glass ionomer-based sealant (Fusion i-seal) and a resin-based fissure sealant (Helioseal-F) on permanent first molars.Materials and methodsCaries free, fully erupted permanent first molars of 50 children between 6 years and 8 years were sealed with pit and fissure sealants under rubber dam isolation. Glass ionomer-based sealant was applied on a permanent first molar and the contralateral molar with resin-based sealant. The sealants were evaluated at regular intervals for a period of 1 year. Statistical analysis was done by Chi-square test.ResultsHigher retention rates were noted for resin-based sealant (88%) compared to glass ionomer-based sealant (78%). None of the teeth sealed with resin sealant developed caries whereas 2% of teeth sealed with glass ionomer sealant developed caries. Marginal discoloration was not noted in teeth sealed with glass ionomer sealant whereas slight marginal discoloration was noted for 6% of teeth sealed with resin sealant.ConclusionClinically a difference was noted in the retention rate, anticaries effect and marginal discoloration whereas statistically no significant difference was noted for the two sealants after 1 year.Clinical significancePit and fissure sealants are highly effective and economical in preventing occlusal caries in young permanent tooth with low failure rate.How to cite this articleMathew SR, Narayanan RK, Vadekkepurayil K, et al. One-year Clinical Evaluation of Retention Ability and Anticaries Effect of a Glass Ionomer-based and a Resin-based Fissure Sealant on Permanent First Molars: An In Vivo Study. Int J Clin Pediatr Dent 2019;12(6):553–559.