# 2D vs. 3D Radiological Methods for Dental Age Determination around 18 Years: A Systematic Review
## 3 Results
All these methods are based on maxillofacial structures that are easily visualized with a CBCT, but compared to dental methods, they normally require a bigger FOV and they are also closer, especially in young subjects, to radiologic sensible developing structures: they should then be considered as secondary exams in the case of wide incertitude when utilizing a dental method for age estimation. [PERSON] et al. [58] focused on the structural changes of teeth and buccal alveolar bone level described by [PERSON] [59]; namely, attrition, secondary dentine formation, and periodontal recession, which occur progressively during the aging process, and therefore, are less useful compared with other methods when analyzing young subjects. This is also partially true for studies focusing on pulp-tooth volume ratio evaluation. [PERSON] et al. [60], for example, found that their original method, based on the geometric approximation of the different parts of the tooth (the root and the pulp were assimilated to elliptical based cones and the crown to an elliptical based truncated cone), showed the highest accuracy in age prediction for the age cohorts between 30 to 59 years, while for other age cohorts, the estimation error was similar to what was reported by applying other dental methods. [PERSON] et al. [61] found that the volumetric analysis of the pulp chamber/crown ratio (up to cemento-enamel junction) is a valuable gender-independent technique for age evaluation, and it is quicker and equally reliable compared to the analysis of pulp cavity/tooth ratio. [PERSON] et al. [62] confirmed the ratio of pulp volume to tooth volume is not gender-dependent, and they also found that it is more reliable when measured on maxillary central incisors than on other teeth. Of course, in all these studies, teeth with caries, filling or crown restorations, periapical pathologies or pulps that could not be identified were excluded, because they interfere with the physiological processes normally occurring in healthy teeth. Dealing with dental maturation evaluation, [PERSON] et al. [63] found that third molar evaluation on CT images is clinically useful for the accurate and reliable estimation of dental ages of children and youth. Findings by [PERSON] et al. [64] confirmed these results. Furthermore, they also compared the CT images to conventional radiographs to assess the developmental scoring agreement between the two and they found that the agreement of Demirjian [65] scores between the two imaging modalities was excellent and that the third molar is not a precise tool for age estimation in the ranges of 3-8 years; however, it is a useful tool for discriminating the adult/child transition age of 18 years. Opposite results were obtained by [PERSON] et al. [66] after applying the Kvaal [67] method, based on pulp and root width measurement, to bucco-lingual and mesio-distal CBCT sections of a tooth. They found that it was outside an acceptable range for forensic application (\(\pm\)10.00 years), and that it was also more time consuming than the original approach based on dental radiographs [68; 69; 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85]. A final consideration must be made taking into account opinions that do not support the radiological age estimation methods due to radiation exposure, even if the ALARA (As Low As Reasonably Achievable) or ALADA (As Low As Diagntically Acceptable) radioprotection principles are followed [86]. Any radiological exposure is free from stochastic effects, such as, for example, cancer induction and radiation-induced hereditary effects, which occur by chance. Nevertheless, in some situations--as discussed above--the benefit of obtaining a more precise age estimation overweight this kind of risk, which must be individually evaluated, case by case, following general rules and guidelines. Theoretically, a 2D method should be preferred and a 3D method should be used only in difficult or uncertain cases, due to anatomical or tooth morphological reasons.