2.5 to 3.5 Years
Deer older than yearlings are aged through wear of the cusps closest to the tongue on the cheek teeth. For 2.5 year olds, the third tooth is bicuspid and stained. The fourth tooth shows little wear, having a defined point, and the brown dentine is thinner than the white enamel.
The enamel on the fourth tooth has worn away so that the dentine is now as wide or wider than the enamel. The fifth tooth doesn't have as much wear, and the dentine on that tooth is not as wide as the enamel.