Age assessment using the second molar maturation index (I2M): A systematic review.

Age estimation plays a crucial role in forensic sciences, being necessary for deceased and living individuals. In adolescents, it is often used to estimate whether an individual is above or below legal age thresholds, which vary across countries. In 2018, Cameriere et al. introduced the Second Molar Maturation Index (I2M), a method based on measuring apical openings and tooth height of the second molar to estimate whether an individual is older or younger than 14 or 16 years. Since then, some studies have sought to validate this method, with varying outcomes. This systematic review aimed to assess the applicability of the I2M method for estimating age thresholds of 12, 14, 15, and 16 years in forensic contexts. A systematic search was conducted in six databases (PubMed/MEDLINE, Embase, Scopus, Web of Science, LILACS, and SciELO), using keywords in Portuguese, Spanish, and English. Studies were selected based on predefined inclusion and exclusion criteria. The methodological quality and risk of bias were assessed. Seven eligible studies were identified, all using orthopantomographs of individuals aged 7-22 years. Validations were performed in seven countries: Brazil, Chile, China, Croatia, India, Portugal, and Turkey. All included studies showed a low risk of bias. The findings indicate that the I2M method is applicable for estimating age thresholds of 12, 14, 15, and 16 years in forensic practice, with satisfactory results across diverse populations. However, further primary research is necessary to strengthen the evidence base and improve the method's reliability.