Hi all,
I’ve got some pieces of mesh in my model that i wasnt able to lay flush with other parts, I need a simular tool thats avalable in Maya, where i can extrude an edge in order to bridge the gap. The model is already very high polyl so its a difficult one. 
Hi there Alex.
Trying to fuse meshes with high poly, decimated or triangular geometry together on a polygon by polygon basis is indeed going to be prohibitively difficult, and slightly outside the focus of the Zbrush toolset.
If I understand what you want to do correctly, this would generally be achieved in Zbrush by simply fusing the meshes together with Dynamesh or Live Boolean, then re-meshing the resulting mesh to clean up the geometry.
So you have what appears to be some sort of wrap around mesh that you would like to fuse to the underlying mesh to remove any gaps? If the wrap is planar without any thickness, you may need to first give it some thickness in order to work with. You could do this with the Mesh Extract feature. Triangular geometry can be difficult to sculpt on–you may find the mesh needs to be put through dynamesh just to close any holes and improve the quality of the surface for sculpting.
I would use something like the Clay or Inflat brush on that wrap to extend that mesh towards (and into) the underlying object. Make sure to only use it on the interior facing side if you dont wish any outward inflation–Backface Masking may be useful to only work on one side and not the other. Failing that you may have to hide the outward facing geometry–polygroups would be helpful here. Dynamesh or Live Boolean to fuse together.
This will result in a medium to medium-high density mesh with quadratic geometry, that can then be remeshed with ZRemesher or otherwise to clean up and simplify. Or you could decimate if if triangular geometry is not an issue.
Hi there,
Apologies for the late reply. Dynamesh wasn’t working as I intended at first, but you where right, inflating the face behind the mesh and then dynameshing it did the trick.
Thank you very much for your reply, its looking great now!