A Histomorphometric Comparison of the Bone Graft-Titanium Interface Between Interpositional and Onlay/Inlay Bone Grafting Techniques

Purpose: To analyze the bone graft-implant interface of titanium microimplants (MIs) placed at the time of bone grafting or after a healing period of 6 months and retrieved after another 6 to 14 months of healing. Integration of MIs placed in interpositional bone grafts (IBGs) in conjunction with a Le Fort I osteotomy was compared with the integration of those placed in onlay/inlay bone grafts (OBGs). Materials and Methods: The severely atrophied edentulous maxillae of 23 patients (14 women, 9 men) were restored with autogenous bone grafts (either IBG [n = 8] or OBG [n = 15]) and titanium implants. Six-month periods were allowed between grafting, implant placement, and abutment connection. The bone-implant interface was studied histologically with the use of unloaded titanium MIs. Results: Sixty-eight MIs were either (1) placed simultaneously with grafting and retrieved after 6, 12, or 14 months or (2) placed after 6 months of healing and retrieved after another 6 to 8 months. Histomorphometry indicated equal degrees of osseointegration for the 2 intraoral reconstruction techniques when looking at bone-implant contact, bone area in threads, and newly formed bone (NFB) (Student t test for unpaired observations). There was a significant difference between simultaneous and delayed implant placement with respect to BIC and NFB (Student t test for paired observations). Three additional MIs placed in the nongrafted residual alveolar ridge and retrieved after 6 months showed significantly more bone in threads and NFB (Student t test for paired observations; P = .003 and P = .009, respectively) compared to MIs placed at graft placement (6 months' healing). Discussion: Timing of implant placement appeared more important than healing time or surgical technique. The delayed approach resulted in better implant integration, probably because of the initial revascularization of the graft. Conclusions: Implant integration was similar in the IBG and OBG groups. Placement of MIs after an initial healing period of 6 months resulted in better integration than placement simultaneously with grafting. Keywords: autogenous bone grafts, atrophic maxilla, edentulous maxilla, interpositional bone graft, microimplants, onlay/inlay bone grafting