Background The objective of this retrospective survey was to evaluate after one year, the conditions and impacts of a dental sealant intervention conducted in New Caledonia, within a health promotion program. A greater or at least equivalent quality and impact of the intervention was expected for children living in socially deprived regions with the greatest health needs. Methods The study population was the schoolchildren, aged 6 years in 2016, who benefited from the dental sealant program (n = 2532). The study sample was randomly selected in 2017 from that population (n = 550). The children's dental status was evaluated at school in 2017 and compared with that recorded in 2016 during the sealant intervention allowing the calculation of the retention rates and one-year carious increment on first permanent molars. Sociodemographic variables (gender, public/private school) and conditions of sealant placement (school/dental office, presence of a dental assistant) were recorded. The carious increment was explained using a mixed multiple random-effects regression. A mediation analysis was conducted to assess the respective contributions of the retention rates and the region of origin on caries increment. Results The participation rate was very high (89%) and on average, children had 83% of their dental sealants present after one year, 31% fully and 52% partially present. Caries increment varied depending on the sealant retention rate as well as on the region (North, South, Islands).