I've just created a character and I've rendered the image in cycles and in Eevee. Point is that with EEvee I don't see any problem,but with Cycles I see that the face let see what's inside the mouth,that's the teeth. Also I see an odd gray coloring at the cheeks. Can u give a look at the pictures below ? thanks.
This is how looks the image rendered with cycles :
this is eevee :