Lets make a model, and I have done so on my computor, so you can see where the curves are. I tried to use the 123d site, and I DID make an account, but I dont not have google crome nor does my computor want it.
I have made a few models of these teeth but my camera fails to work today.
Step 1: Reading the "Pattern"
You can see from the birds eye view that there are four grooves, creating the top of a molar tooth.
Step 2: Creating the Object
First get a nice sized chunk and roll it in your hands to make a ball, then from that shape you can created a cylinder. Then with a pointy clay or scalpel like tool you must make a cross on the top and on the bottem of this cylinder.
You can see that the top is created by four mounds, the cross seperates the top into these four mounds, then what you must do is blend it together so you have smooth grooves, just as a real tooth would.
The bottom cross must be deaper, and they dont need to be blended as much, just make sure that there is a smooth point at the middle of these four tips. I call these ones tips because they are longer, and they end gradually in a tip, just like the roots of a real tooth.
You can shape the middle bit, but I tend not to.
There you go