The study evaluated secular trends in dental development during a period of 30 years, correlation between dental and chronological age in Istria and the littoral region of Croatia. The sample consisted of 1000 panoramic radiographs of children, aged 6–16 years (mean 10.0 ± 1.8), taken in the period 1977–1979 (N = 500; 243 females) and 2007–2009 (N = 500; 299 females). Dental age was assessed according to Demirjian's method. Correlation between chronological and dental age was linear, positive, high, and statistically significant in both periods and genders, ranging from 0.73 to 0.86. Dental age was underestimated when compared to chronological age by 1 year on average, more 30 years ago (−1.35 ± 1.17) than today (−0.63 ± 1.09), less for girls (−0.80 ± 1.22) than boys (−1.21 ± 1.10). A statistically significant positive secular trend in acceleration of dental development was present of 0.72 years during the 30-year period and was more significant in girls than boys (0.83- and 0.51-year acceleration).