Preparation of dentin standard samples for age estimation based on increased aspartic acid racemization rate by heating

•Age estimation by aspartic acid racemization requires a wide age range of teeth.•Standard samples could be prepared by the racemization rate increased via heating.•The error ranges between actual and estimated ages were within ±5 years.•The stability of racemization rates in prepared powdered samples was high.•This technique would be useful when it is difficult to collect age-known teeth.