The study aimed to estimate the prevalence, severity, and inequality in the distribution of dental caries in schoolchildren from Florianópolis, Santa Catarina, Brazil, in 2011, and to compare the results with data from previous studies carried out since 1971. All 12- and 13-year-old schoolchildren enrolled in a public school were eligible. Dental caries were assessed according to the World Health Organisation diagnostic criteria. Decayed, missing and filled surfaces and teeth (DMFS/DMFT) indexes, the Significant Caries Index (SiC) and the Gini coefficient (to assess inequalities in the distribution of dental caries) were estimated. The response rate was 82.3% (n = 130). The prevalence of dental caries decreased from 98.0% (95% CI 96.0–100.0) in 1971 to 36.9% (95% CI 28.5–45.3) in 2011. The mean DMFT ranged from 9.2 in 1971 to 0.7 in 2011. The mean DMFS index was 1.2 (95% CI 0.8–1.6) in 2011. The Gini coefficient was 0.624 in 2002 but increased to 0.725 in 2011; the Lorenz curve showed that 70–75% of dental caries attacks was restricted to 20% of the population in 2011. A reduction of 41.2% in the mean SiC index was observed between 2002 (3.4, 95% CI 3.0–3.8) and 2011 (1.9, 95% CI 1.6–2.1). An effective decline in the prevalence and severity of dental caries in schoolchildren was observed throughout 40 years of monitoring. However, a small proportion of the population has experienced most of the caries burden in the recent years studied.