I've seen that before... It is indeed the most accurate aging method. It's basically the same way Icthyologists age fish with their otoliths. I've never sent anything in to have the cementum rings counted... But here's my opinion on it: In Ohio, I don't really see much use for it. Unless you're hunting large properties where the deer are confined to your land, it's very rare to kill a deer that's older than 5.5 in Ohio. Tooth-wear aging is fairly accurate up to 4.5 years old. The DNR actually breaks it down into 6 mo, 1.5 yrs, 2.5 yrs, 3.5 yrs, 4.5 yrs, and 4.5+ years... because once a deer gets older than 4.5, it's very difficult to distinguish between older age classes by tooth wear alone. The percentage of deer that get classified as 4.5+ years old is EXTREMELY rare during harvest surveys. In the rare instance that you think you've killed the Father Time of bucks and he's got no molars left in his jaw, then yea it'd be worth it to send the teeth out to a lab. More often than not, tooth-wear aging will get you damn close.