Iray SSS gets applied to the whole material/multi-mesh -can't make 0 opacity on any specific part of the multi-mesh.
The host program shows the correct result in the view port with the opacity map. I've detected the problem by making the scatter map a png with an alpha channel. I erased a UV area/mesh part in the scatter map that contains the gums side of the teeth model and it changes the model part that I want to make completely faded from looking white to a wet transparent look but the problem is that its still visible. If there is no current way around this could you please add opacity features to Iray SSS option that connects to the opacity texture and settings from the Host app?? The included images show the problem. I haven't found any solution to this other than maybe separating the teeth in Zbrush and sending only the teeth back as cloth so it binds to the character and hide or delete the default teeth but this increases file size.
Overall there are other reasons to fix this. SSS gets applied to the whole material and if that material is connected to a multimesh then it's not fully possible to have 0 opacity on any specific part of the mesh.