A systematic review and meta-analysis of Gustafson's six dental variables for age estimation in adults

Dental age estimation (DAE) by means of direct visualisation remains a fundamental tool in forensic odontology, particularly for Disaster Victim Identification (DVI) in resource-limited settings. This systematic review and meta-analysis aimed to calculate the pooled correlation coefficient between chronological age (CA) and six Gustafson-derived dental variables in modern adults. Following PRISMA guidelines, five databases were searched until June 2025, resulting in 27 included studies, with 19 utilized in a three-level random-effects meta-analysis. The overall weighted correlation between CA and Gustafson-derived variables was moderate (r = 0.67, [Formula: see text] = 0.93), though significant heterogeneity was observed with low certainty due to method variability. Subgroup analyses indicated that the six variables do not contribute equally to age prediction; transparency of the root gives the highest correlation (r = 0.75), while root resorption showed the lowest correlation (r = 0.28). Additionally, sectioned teeth showed a higher correlation than intact teeth, although this difference was not statistically significant. In conclusion, while direct visualisation of Gustafson-derived variables shows utility for DAE, high between-study heterogeneity and low certainty of evidence dictate cautious application and interpretation of the current results. Furthermore, although tooth sectioning may improve correlation, using destructive methods requires balancing potential analytical benefits against ethical and legal constraints.