Atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to assess the 3D organization at molecular and structural resolution during the healing course of experimentally injured tibiae in unirradiated and irradiated rats. Rat tibiae were surgically injured and HeNe laser radiation was transcutaneously applied after surgery. Newly formed collagen fibrils at the injury site of the irradiated tibiae had acquired improved lamellar organization close to the spatial organization of mature intact bone. The HeNe laser doses accelerated bone neoformation. (c) 2005 Elsevier B.V. All rights reserved.