Summary
Despite the increasing number of studies in the field of implant dentistry investigating novel dental implant surfaces, biomaterials, and growth factors, comparatively very few have studied the biology and metabolism of bone healing and its implication in peri-implant tissue health. The aim of this chapter is to provide a thorough understanding of the biologic properties that impact bone formation and osseointegration, including the coupling mechanisms between immune cells and bone. This chapter focuses on the various bone cells in the body—osteocytes, bone lining cells (BLCs), osteoblasts, and osteoclasts—and their bone remodeling cycle. Furthermore, the importance of immune cells and their impact on biomaterial integration during bone formation and implant osseointegration is also discussed. Finally, the putative effects of cholesterol, hyperlipidemia, and vitamin D deficiency are addressed. Such factors should be monitored during patient care, and ultimately future research should focus on these avenues as well as meticulous maintenance programs to favor both early and long-term maintenance and stability of dental implants.
Objectives
▪ Understand how overall patient health directly affects dental implant osseointegration
▪ Understand the key cells involved in bone formation, maturation, and maintenance
▪ Understand the direct role of immune cells on biomaterial and dental implant integration
▪ Understand the essential role of optimizing the immune system prior to dental implant placement
▪ Investigate the relationship between vitamin D deficiency and early implant failure and how to avoid such pitfalls
Bone regeneration requires bone grafting materials that possess excellent biocompatibility and osteoinductivity without eliciting an antigenic effect. While companies that manufacture replacement biomaterials intended to mimic autogenous bone grafts often report on their osteoconductive, osteoinductive, or osteogenic potential, autogenous bone still favors the greatest bone regeneration compared to allografts, xenografts, and synthetic alternatives because it combines all three of these properties. Thus, despite the increasing number of new bone grafting materials brought to market as substitute replacement grafts, to date there is no true replacement for autogenous bone grafts.1 Autografts carry no risk of immunologic reaction or disease transmission and provide optimal conditions for the penetration of new blood vessels and migration of osteoprogenitor cells. In contrast, many bone grafting substitutes are osteoconductive but have limited osteoinductive potential.2
For bone regeneration to take place, especially with foreign-body biomaterials such as allografts and xenografts or dental implants, there is a great need to better understand the regulatory properties and integration process of these biomaterials. After all, no matter the biomaterial placed, bone formation relies on immune-related factors working at the cellular level. The aim of this chapter is therefore to provide the biologic background on the cells involved in graft consolidation and give a brief overview of fracture healing. This chapter focuses on the bone cells involved in bone formation and dental implant osseointegration, including osteocytes, BLCs, osteoblasts, and osteoclasts, and their bone remodeling cycle. The chapter also addresses the importance of immune cells and their impact on biomaterial integration, as well as the putative effects of cholesterol, hyperlipidemia, and low vitamin D levels.
Bone Cells: Osteoclasts, Osteoblasts, and Osteocytes
There are three main cell types in bone
