Histopathologic reaction of a calcium phosphate cement for alveolar ridge augmentation Akiyoshi Sugawara, 1 Kenji Fujikawa, 1 Kaoru Kusama, 2 Minoru Nishiyama, 1 Seidai Murai, 1 Shozo Takagi, 3 Laurence C. Chow 3 1 Nihon University School of Dentistry, 1-8-13, Kanda-surugadai, Chiyoda-ku, Tokyo, Japan 2 Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, Japan 3 American Dental Association Health Foundation Paffenbarger Research Center at National Institute of Standards and Technology, Gaithersburg, Maryland 20899 Received 28 June 2000; revised 11 July 2001; accepted 20 July 2001 Abstract: The objective of the present study was to evaluate the feasibility of using a calcium phosphate cement (CPC) in the reconstruction of a defective alveolar ridge in conjunc- tion with implant placement. The CPC consisted of an equimolar amount of tetracalcium phosphate and dicalcium phosphate anhydrous. At the beginning of the experiment, all mandibular premolar teeth of mature beagle dogs were extracted. After 1 month of healing, alveolar bone was re- duced to make a space for a CPC block that was prefabri- cated from a CPC mixed with water at a powder/liquid ratio of 5 g/mL. After an additional month, 8-mm long hy- droxyapatite-coated titanium implants were placed in such a way that the apical half was embedded into alveolar bone and the coronal half in the preformed CPC block. The dogs were sacrificed and biopsies were obtained at 1, 3, and 6 months after surgery. Sections that included implants were evaluated for integration of the CPC block to the alveolar bone and of the implant to the alveolar bone. Additional sections without the implants served as controls. The results obtained from this study show that the CPC ridge augmen- tation gradually is replaced by natural bone. Six months after surgery, histopathologic features of the augmentation area were quite similar to those of natural alveolar bone. The coronal half of the implants, previously surrounded by the CPC block, was firmly fixed by natural bone. Therefore, this method may be useful for increasing the height of the al- veolar ridge. © 2002 Wiley Periodicals, Inc.* J Biomed Mater Res 61: 47–52, 2002 Key words: histopathologic reaction; alveolar ridge aug- mentation; calcium phosphate cement (CPC); CPC block; implant INTRODUCTION The quality of alveolar bone at the desired location is one of the most important prerequisites for an ide- ally functional implant. Reconstructive surgery prior to an implant procedure usually is required if alveolar deficiencies are present. Reconstructive surgery can be performed with a number of techniques, including guided bone regeneration (GBR), 1–3 in which an oc- clusive barrier membrane is placed between the con- nective tissues and the residual alveolar bone to create a space for the formation of new bone. These osseous defects can be treated with either the barrier mem- brane alone or in combination with bone-graft mate- rials, such as autogenous bone, 4,5 allogenic bone ma- terials, 6 and calcium phosphate alloplastic materials. 7 In general, with the use of autogenous bone graft successful osseous regeneration occurs in a most pre- dictable manner. However, it would be quite difficult to reconstruct a large defect with intraoral autogenous bone-graft materials. 4,5 Implant placement should not be performed until there is normal bone formation at the surgical site. When autogenous bone successfully achieves ridge augmentation, it takes 6 to 8 months 8,9 for the necessary substantial reconstructive bone heal- Certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental pro- cedure. In no instance does such identification imply recom- mendation or endorsement by the National Institute of Stan- dards and Technology or the American Dental Association Heath Foundation or that the material or the equipment identified is necessarily the best available for the purpose. Correspondence to: A. Sugawara; e-mail: a-sugar@mx5. nisiq.net Contract grant sponsor: National Institutes of Health; con- tract grant number: DE11789 © 2002 Wiley Periodicals, Inc. *This article is a US Government work and, as such, is in the public domain in the United States of America.