advice for simulation set up or suitable tutorial (3D stress distribution with multiple materials in contact)

Hi All,

I am trying to help my fellow Orthodontics to showcase COMSOL's ability to simulate one of his problem. But I am struck and getting inconsistent results. The simulation is very basic and therefore experts here are requested to advice or direct a suitable tutorial for us.

The problem is teeth embedded in bone. when bone is subjected to a force, we want to see the stress distribution that is all. My problem is inexperience in 3D and structural modelling handing multi materials in contact. The 2D cross sectional picture is attached. Some may kindly enlighten us to proceed further?

Thanks in advance