I'd "retopologise" the scan, a word that subdivision modellers use to describe returning subD models, which become progressively more triangular-faced as they're developed, to a quad-dominant approximation. Approximation because they appear very similar, but the vertices of the quad model lie on the faces of the subD model, so none of the surfaces actually coincide, and the quad structure is less busy with fewer points, and more amenable to smoothing and rebuilding with subdivision, or conversion to nurbs if you want to try that. Scanned surfaces are great guides to proportion and relative position of features, but they're random triangulated meshes, and I've never had a scanned surface that was actual usable geometry out of the box, after using Meshlab to remove "outliers" and refilling the resulting holes, improving smoothness, or any other way.
TC's good for building new surfaces over a scanned mesh, but I don't know of a way of making scans really usable as geometry in TC, or any other general CAD app.
