Bone Substitutes and Validation

Abstract

This chapter will focus on the review of the various bone grafting materials in the market for implant dentistry with much emphasis on the fact that they are all second-hand bones (bone substitutes) when compared with the autogeneous bone graft which is the gold standard to which all bone substitutes are compared. Bone grafting implies to the application of autogenous bone or other bone substitute obtained from natural or synthetic source to an area of with boney defect. Bone grafting is a procedure and should not be confused with bone regeneration which is the actual formation of new bone in the grafted defect. Bone grafting does not necessarily lead to bone regeneration. It is so important that the clinician and the patient are aware of the difference in terminology because of the clinical, scientific and medicolegal implications. The use of bone substitutes or bone replacement source has increased tremendously in implant dentistry today and will continue to be so because of the unavailability of autogenous bone from the intra-oral site in most situation and patients are becoming more and more tolerant to clinicians harvesting bone from the extra-oral site such as the iliac crest or the tibial tuberosity. The mechanisms available for bone regeneration will be fully described and classification of bone substitutes under these mechanisms will be attempted so as to assist the surgeon make a decision regarding which bone substitute to be used for pre-implant, intra-implant surgery and post-implant bone grafting and regeneration. Theses previously mentioned bone regeneration mechanisms are actually positive mechanisms (osteogenesis, osteoinduction and osteoconduction). The author will introduce a newly discovered mechanism called the osteo-obstructive mechanism as a negative bone regeneration mechanism. This osteoobstructive mechanism was accidentally discovered by the author on single photon emission computerized tomography (SPECT) with histologic correlation during animal experiment to validate bone grafting technique and substitutes in the Ogunsalu sandwich bone regeneration technique. This osteoobstuctive mechanism has been histologically confirmed to be due to foreign body reaction. In this chapter bone grafting will be mentioned distinctly from bone regeneration, similarly bone substitute (second -hand bone) will be distinctly separated from autogeneous bone graft.