Dental development, one of the most reliable indicators of chronological age (CA), has been believed to be fundamentally influenced by genetics rather than environmental factors. The study aims (i) to compare dental ages (DAs) in monozygotic (MZ) and dizygotic (DZ) twins using three different DA methods and determining the most appropriate method, and (ii) to determine the possible effects of genetics on DA by evaluating the differences in the estimated DAs of MZ and DZ twins. The study sample consisted of 171 twin pairs (47 monozygotic, 124 dizygotic) between the ages of 5.0 and 12.9. In order to estimate DA, Demirjian, Willems and Nolla methods were used. The mean CA of group was 8.42 (2.05) years. The Demirjian, Willems and Nolla methods overestimated the DAs by 0.69, 0.60 and 0.56 years, respectively. The estimated DAs in age groups were similar, and differences were not statistically significant for intrapair DZ and MZ twins. As a result, it was not correct to state that any method was more appropriate and better than others for studies of twins. All methods' standards were not suitable for any age groups of MZ and DZ twins, except for twins aged 12-12.9 years. Country-wide samples are needed to gather enough data to create valuable results and to establish the applicability of methods used.