Is Willems method universal for age estimation: A systematic review and meta-analysis.

Dental age (DA) has been widely accepted as a way to evaluate chronological age (CA) in recent years. However, the applicability of Willems method, as one of the most popular radiographic ways, still remains controversial in different areas. The aim of this study is to assess the difference between DA and CA with Willems method. Relevant studies published up to February 28th, 2017 were selected via PubMed, Embase, the Cochrane Library, CNKI, CBM and manual search. Studies that examined Willems dental age and chronological age were selected. 11 articles with 9347 individuals whose age ranged from 3.0 to 18.9 years old were ultimately included in this study. The general polled data indicated that Willems method overestimated CA by 0.18 years and 0.06 years for males and females respectively. Subgroup analysis for ethnicity showed significant difference for different ethnicities. Our aggregated data demonstrated that Willems method may not be an overall applicable tool to estimate chronological age for the reason of the difference of ethnicity and rational validity is suggested when necessary.