UE4 - Dark artifacts over highly detailed meshes, why?

Hi, Every time i import a higly detailed mesh to unreal, with very tinny details like scales or lines (image attached), light causes dark artifacts between these details, like weird shadows or black spots, i guess maybe because of Dynamic light, right now the only thing that has worked for hidding this issues is using Temporal AA, because MSAA and FXAA make this problem to increase drasticaly, but since UE4.21 artifact problems are worst, not any idea how to fix it.

Please help