In a first broad aspect, there is provided herein a bioactive device and system for fusion between two bones, two parts of a bony joint, or a bony defect, such as of the spine. The fusion device includes a screw having a head and a threaded shaft. The fusion device also includes a bone dowel having an internal bore of which at least a distal portion is threaded to engage the threads of the screw shaft. The bone dowel is made of a bone-like, biocompatible, or allograft material to provide a layer of bone-like, biocompatible, or allograft material between the screw and the spinal bone. The device is generally coaxial and is further described in the drawings and description herein.