Osseointegration ENT Theroy Question

Q: What is osseointegration ?

Osseointegration is process by which there is a connection between living bone and the surface of a artificial implant.

Define osseointegration. Describe indications and complications of Bone Anchored Hearing Aids. (2+4+4) Dec 2013 Just go through this video and images, understand the main context. It will come as a short note question upto 5 marks. What is osseointegration ? THE IMPLANT AND TISSUE INTERFACE1,2 The precise mechanism of osseointegration remains unknown, although the physiology of bone healing, with which it is intimately associated, is well documented. The implant material is important. Direct bone to implant contact, i.e. osseointegration, is not restricted to titanium or titanium alloys. Aluminium oxide ceramics, tantalum, stainless steel and cobalt and nickelbased alloys have all been shown to osseointegrate. It is a reactive metal that spontaneously forms a surface oxide layer on exposure to air. This titanium oxide is inert, practically insoluble and very resistant to body fluids. It can be easily machined into shapes that are small enough to be placed in the jaws and facial bones and yet it is strong enough to withstand functional loads. Mechanism of osseointegration Mechanism of osseointegration Osteoblasts cells will only adhere to and cover the surface of clean implants. The cells are seen to lie perpendicular to the implant’s titanium oxide surface in a characteristic pattern. The surgical placement of an implant into bone causes bleeding and an acute inflammatory response in the tissues immediately adjacent to the implant. A haematoma forms between the implant and the bone. The implant surface becomes coated with the products of acute inflammation, and macrophages remove bone debris. In order to create Osseointegration • A minimal amount of remaining bone should be removed • The basic topography of the region should not be changed • The retention of the original or transitional denture should be maintained during the healing period Mechanism of osseointegration surface Mechanism of osseointegration surface Undifferentiated mesenchymal cells migrate into the area and produce an extracellular matrix.2 Within one week of implant placement, these cells develop into osteoblasts and produce osteoid. The osteoblasts are responsive to both local and systemic factors. The osteoid gradually organizes into an increasingly dense procallus, with further mesenchymal cells differentiating into osteoblasts and fibroblasts. The osteoblasts produce fibres that have the potential to calcify. The fibrocartilagenous callus that develops matures into woven bone by the third week. The remodelling of woven bone involves the recruitment of osteoclasts into the area. After seven weeks, lamellar bone is being laid down. This is more mineralized and further stabilizes the implant. Any bone rendered nonvital by the surgery is gradually replaced by living bone. In effect, the body fails to recognize the implant as a foreign body and it becomes incoincorporated into bone as part of the wound healing process. Mechanism of osseointegration surface The fibres produced by osteoblasts are intimately associated with this glue. A very thin layer of proteoglycan exists between the bone and the implant surface of all osseointegrated implants. This layer is up to 500 nm thick. The final stages of healing involve maturation of the bone at the implant interface. There is an increase in bone hardness and density that is associated with loading and functional use, and which is ongoing even a year after implant placement. This correlates with Wolff ’s law, which states that bone tends to develop the structure best suited to resisting forces prevailing upon it. The soft tissue interface, between the skin or mucosa and the implant. is equally important. It consists of both epithelium and connective tissue. A rough implant surface has been demonstrated to promote connective tissue fibre attachment. The connective tissue fibres run parallel to Inflammation and excessive loading can cause bone resorption. Where peri-implant disease develops, the sulcal epithelium desquamates, exposing the underlying connective tissue, which becomes inflammed. This inflammation induces osteoclast activity and chemical mediator release from cells adjacent to the implant surface. Within the bone, premature loading or overload (as can occur in occlusal trauma, or the nonpassive fit of a bar linking implants) causes areas of pressure concentration, osteoclastic activity and angular bone loss at the implant site. This is particularly damaging during the healing phase when osseointegration has not fully developed and the bone resorbs easily. Overloading, even after several years, can cause micro-fractures in the bone that may heal with scar tissue and cause implant mobility to develop. The combination of inflammation and overload is particularly harmful, but separately or together, the end is the same as osseointegration is progressively lost and the implant fails. 1. Parithimarkalaignan S, Padmanabhan TV. Osseointegration: An Update. J Indian Prosthodont Soc. January 2013:2-6. doi:10.1007/s13191-013-0252-z 2. Dhinakarsamy V, Jayesh R. Osseointegration. J Pharm Bioall Sci. 2015:228. doi:10.4103/0975-7406.155917

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