J Periodontol • November 2003 In Vivo Effectiveness of a Glycerol- Compounded Demineralized Freeze-Dried Bone Xenograft in the Rat Calvarium Scott A. Matzenbacher,* Jason M. Mailhot, † James C. McPherson III, ‡ Michael F. Cuenin, § Steven D. Hokett,  Mohamed Sharawy, ¶ and Mark E. Peacock  1641 Background: Demineralized freeze-dried bone (DFDB) is com- monly hydrated with sterile water into a paste-like consistency for improved clinical handling or reconstituted with biodegradable barriers, such as glycerol, to promote handling and wound sta- bility following human periodontal surgery. The purpose of this study was to evaluate the in vivo effects of glycerol-compounded human DFDB on bone formation in the rat calvarial critical-sized defect (CSD) model. Methods: Forty-eight adult male Harland Sprague-Dawley rats were assigned to one of four treatment groups: glycerol, DFDB, DFDB plus glycerol, or a non-grafted control, and placed into 8 mm calvarial CSDs. DFDB (particle size 0.106 to 0.5 mm), glycerol, and their combination were from identical sources. Calvaria were har- vested at 8 weeks postsurgery and evaluated histomorphometrically. Results: A statistically significant increased percentage of total bone fill was detected in the glycerol plus DFDB group and DFDB group as compared to glycerol group or the control. How- ever, no significant difference was noted between the DFDB plus glycerol group and the DFDB group. Conclusion: The addition of glycerol to DFDB results in com- parable osseous regeneration in the rat calvarium defect model versus DFDB alone; however, based upon clinical judgment, han- dling characteristics of DFDB were greatly improved. J Periodontol 2003;74:1641-1646. KEY WORDS Animal studies; bone, demineralized; bone, freeze-dried; glycerol; grafts, bone; wound healing. * United States Army, Seoul Korea. † Medical College of Georgia, Department of Periodontics, Augusta, GA. ‡ United States Army, Department of Clinical Investigation, Ft. Gordon, GA. § United States Army, Wuerzburg, Germany.  United States Army, Ft. Gordon, GA. ¶ Medical College of Georgia, Department of Oral Biology. The opinions expressed in this article do not represent the views of the United States Department of Defense, the Department of the Army, or the United States Army Dental Corps. Use of any commercial products in this project does not imply endorsement by the United States Government. P eriodontitis is a disease process lead- ing to periodontal attachment loss subsequent to the inflammation of tooth supporting tissues. This disease usu- ally involves a progressive, destructive change leading to loss of alveolar bone and periodontal ligament attachment. Epi- demiological reports indicate that 5% to 20% of the United States adult population has a severe form of this disease. 1,2 The major objectives of periodontal therapy include pocket reduction, regeneration of a functional attachment apparatus, and restoration of lost alveolar bone. The ideal therapeutic goal should be the complete restoration of the periodontium to within previously existing, normal physiologic limits. 3 Bone is one of the most frequently transplanted tissues in humans because of its remarkable regenerative ability. Senn first used demineralized bovine bone as a vehicle for delivery of anti- septics (iodoform) to treat osteomyelitis. 4 Demineralized bone matrix was initially described as inducing bone formation in muscle. 5 Bone grafts are routinely used for repair of skeletal defects caused by trauma, neoplasia, and infection. 6 When large amounts of alveolar bone are lost due to periodontal disease, the resulting osseous defects may require regenera- tive therapy with some type of bone grafting material. An inadequate quan- tity of autogenous bone may limit peri- odontal therapy results and may dictate the use of alternative graft materials.