This might help you out a bit, Dan. Jaw bone on the left is a 3.5 yr old... jaw bone on the right is a 2.5 yr old. I know, they look the same, but they're not. Pay special attention to the first molar (4th tooth from the top)... lingual crest (inside half of tooth, next to tongue) is where you want to compare the wear. 2.5 yr old, the dentine (dark stuff) on the lingual crest is slightly less the width of the enamel. 3.5 yr old, the dentine is slightly wider or just as wide as the width of the enamel. One other thing that gives it away, that you can't really see from this picture, is the back cusp of the last molar... it's cupped and worn down farther on the 3.5 yr old tooth than on the 2.5 yr old. Also, when you run your finger down the lingual crests of a 2.5 yr old, they're gonna feel pretty sharp. They start to get dull when they hit 3.5 and above.
Sorry for hijacking the thread, man. Just thought this could be some useful information to you in the future. Again, great story and a great buck.