Forensic age estimation has recently become an important topic due to a steady increase of cross border migration. Dental age assessment is one pillar of the forensic age estimation in living persons. Currently it is done by evaluating an orthopantomogram, which is generated using ionizing radiation. Nevertheless, the use of X-ray without medical indication is ethically questionable. Therefore, the aim of the study was to provide reference values for dental MRI to have an alternative radiation-free method for the assessment of dental age. In this cross-sectional study, 316 adolescent, male individuals were investigated. Two dentists evaluated the stage of mineralization and eruption of the third molars of the upper and lower jaws, according to the staging systems established by Demirjian and Olze. Following data analysis and the creation of reference tables, the likelihood ratios to be over specific age limits were calculated. In the mineralization evaluation mainly stages D-H were seen (range A-H); regarding eruption, all four stages (A-D) appeared. A significant difference between the teeth was only found for eruption stage A. However, the evaluation of participants who had all four third molars, showed partly different stages for the individual teeth as well for mineralization as for the eruption. Therefore, it seems to be important to include all available teeth in the age estimation. The likelihood ratios showed about 99% probability to be 18 years or older for stage H (mineralization), but only about 93% for stage D (eruption). In summary, it can be concluded that dental MRI holds promise as an alternative to conventional orthopantomogram based age assessment.