PURPOSE: Patterns of healing were investigated in mandibles reconstructed with three different techniques to assess their readiness for implant placement. PATIENTS AND METHODS: The subjects were 10 patients who had undergone mandibular reconstruction with either nonvascularized iliac block bone grafts (group 1; 3 patients), particulate cancellous bone and marrow (PCBM) grafts (group 2; 3 patients) for mandibular discontinuity, or PCBM grafts for mandibular marginal defects (group 3; 4 patients). Six (groups 2 and 3) or 12 months (group 1) after mandibular reconstruction, bone biopsy specimens were obtained for histologic examination with a trephine bur. As controls, bone specimens were obtained from ungrafted mandibles of patients undergoing dental implant placement. Undecalcified specimens were embedded in polyester resin and examined by routine light microscopy and microradiography. RESULTS: The morphology of the specimens from group 1 was similar to that of group 2, but not to that of the control subjects. However, the morphology of specimens from group 3 was generally similar to that of control subjects. CONCLUSION: These results suggest that mandibular reconstruction with PCBM grafts allows the placement of dental implants sooner than reconstruction with block bone grafts.