I take it you are meaning that you would put some sort of heating element onto the metal portion attached to the handle.
Firstly, what temperature are you talking about, and for how long (typical duty cycle in use)
Heat is transferred through metal relatively quickly, but if the toothed wheel is not making good thermal contact with the metal it is attached to, there may be considerable delay in the transfer. If the temperature is low enough, and the handle is made of a high thermal resistance material, and/or the device is not on for long during use (low duty cycle), then you may get away with it.
Look at a hot melt glue gun (the ones that take glue rods) design, the tip temperature is quite high, but the design keeps the handle at a low temperature, and they operate for long periods. You may be able to use a glue gun, just modify the toothed wheel support to fit to the nozzle, but as I said previously, you need to specify the temperature you require.
Otherwise the handle material would probably have to be some sort of ceramic or silica(think space shuttle tiles), you would need to check that out.
More details would be useful, not my area of expertise, but may give you some ideas,
cheers,
Richard
