Background: Persistent primary teeth (PPT) may occur due to various local factors, or it may develop due to general factors such as systemic diseases and syndromes. Since eruption and dental development are two different processes, it is important to investigate both processes to determine the actual cause of delayed tooth eruption. The study aimed to evaluate the dental development of a group of Turkish children with multiple PPT using the Willems dental age estimation method. Study Design: Digital panoramic radiographs of children and adolescents aged between 9 and 15 years were retrieved, assessed and categorized. A total of 80 radiographs of patients with more than one PPT were selected and matched with children without PPT. Dental age was calculated using the method of Willems et al. All analyses were conducted using the SPSS statistical software. The statistical significance was set at 0.05. Results: The permanent tooth development of children with multiple PPT could be delayed by 0.5–4 years compared to healthy ones. A strong positive correlation was found between the number of PPT and deviation for both females and males (p < 0.001). Conclusion: In conclusion, we found that permanent tooth development of children with multiple PPT could be delayed compared to healthy ones. In addition, as the number of PPT increased, the difference between chronological age and dental age also increased, especially in males.