Demineralization of the Contacting Surfaces in Autologous Onlay Bone Grafts Improves Bone Formation and Bone Consolidation Maria L. Rezende,* Alberto Consolaro, † Adriana C. Sant’Ana,* Carla A. Damante,* Sebastia ˜o L. Greghi,* and Euloir Passanezi* Background: Autologous bone grafts are usually well con- solidated after 4 to 5 months but can be incompletely inter- locked with the native bone. This study investigated the effect of acid demineralization of the graft–bed interface on graft consolidation. Methods: Onlay bone grafts were performed on the cal- varia of 36 guinea pigs. Half of the animals had the graft– bed contacting surfaces demineralized with 50% citric acid (pH 1.0) for 3 minutes (test group). The other half received no demineralization (control group). The bone grafts were immobilized by a resorbable membrane glued to the recipi- ent bed with cyanoacrylate. After 7, 30, and 90 days, spec- imens (n = 6) were obtained for light microscopy. Data from qualitative analysis and computerized histomorphometry were statistically processed at a significance level of 5%. Results: Osteogenesis was not seen at the interface after 7 days. After 30 days, the test group showed 34.39% – 13.4% of the interface area filled with mineralized tissue, compared to 17.14% – 8.6% in the control group (P = 0.026). After 90 days, the mean percentages of mineralized tissue at the in- terface in the test and control specimens were 54.00% – 11.23% and 38.65% – 7.76% (P = 0.041), respectively. Within groups, a higher percentage of the area filled with mineralized tissue was seen at 90 days compared to 30 days (P = 0.004 for control and 0.041 for test). Conclusions: Demineralization of the contacting surfaces between autologous bone graft and bone bed improved new bone formation and bone consolidation. These data need to be confirmed in humans. J Periodontol 2014;85: e121-e129. KEY WORDS Bone transplantation; citric acid; guided tissue regeneration. A utologous onlay bone grafts are considered the gold standard to provide sufficient bone volume for implant placement in severely re- sorbed alveolar ridges. 1 Although these grafts usually take 4 to 5 months to be- come consolidated, 2 clinicians have ex- perienced detachment of the grafts during drilling and/or implant place- ment, 3 suggesting that bone grafts may be incompletely interlocked with the native bone. 2 The long-term outcome of onlay grafts may be influenced by the fol- lowing: 1) embryologic origin of the grafted tissue; 4,5 2) extent of its re- vascularization; 4 3) architectural fea- tures of the graft; 6 4) method for graft fixation; 7 and 5) treatments applied to the graft–bed interface. 8 Graft in- corporation seems to be enhanced when the bone marrow is exposed by perfo- rating or decorticating the host bed. 9-11 Perforations can provide access for blood vessels and progenitor cells from the endosteal compartment to the grafted area 12 and can also strengthen the physical bond between grafted bone and recipient surface. 9 Nevertheless, decortication and/or perforations present disadvantages: 1) longer operating time; 2) impaired visibility as a result of extra bleeding; 3) additional surgical trauma by overheating generated by the drilling * Division of Periodontics, Department of Prosthodontics, Faculty of Odontology of Bauru, University of Sa ˜o Paulo, Bauru, Sa ˜o Paulo, Brazil. † Department of Stomatology, Division of Pathology, Faculty of Odontology of Bauru, University of Sa ˜o Paulo. doi: 10.1902/jop.2013.130298 J Periodontol • May 2014 e121