Massachusetts Institute of Technology Harvard Medical School Brigham and Women’s Hospital VA Boston Healthcare System 2.79J/3.96J/BE.441/HST522J FORMATION OF SOFT TISSUE AND BONE AROUND IMPLANTS: The Chronic Response to Implants I.V. Yannas, Ph.D. and M. Spector, Ph.D. RESPONSE TO IMPLANTS: WOUND HEALING Surgical Implantation Vascular Response Clotting Phagocytosis Neovascularization New Collagen Synthesis Tissue of Labile and Stable Cells Tissue of Permanent Cells Framework Framework Scarring Intact Destroyed (fibrous encapsulation; synovium) Regen. Scarring Chronic Inflammation (incorp. (fibrous encapsulation; of implant) synovium) Chronic Inflammation Acute Inflammation Granulation Tissue Implant Movement Inc. time Photo removed due to copyright considerations. I. Metchnikoff In 1923 a piece of glass was removed from a patient’s back; it had been there for a year. It was surrounded by a minimal amount of fibrous tissue, lined by a glistening synovial sac, containing a few drops of clear yellow fluid. Photo removed due to copyright considerations. Smith-Peterson J. Bone Jt. Surg., 30-B:59 (1948) Four pages removed due to copyright considerations. I. Silver CHRONIC RESPONSE TO IMPLANTS ? Persistence of macrophages* at the implant surface ? Presence of fibroblasts* ? Proliferation and increased matrix synthesis of fibroblasts can result from mechanical perturbation by the implant or by agents released by the implant, leading to an increase in the thickness and density of the scar tissue. ? Fibroblast contraction can result in scar contracture. * Constituents of synovium MACROPHAGE AND FIBROBLAST INTERACTIONS IN SYNOVIUM Macrophage + Part. Sol. Part + Reg. Endocytosis Fibroblast + ECM + Reg. Fibroblast + ECM + Reg. Fibroblast + ECM + Reg. Fibroblast + ECM + Reg. Mitosis Migration Synthesis Contraction Ions Mechanical force RESPONSE TO IMPLANTS: WOUND HEALING Surgical Implantation Vascular Response Clotting Phagocytosis Neovascularization New Collagen Synthesis Tissue of Labile and Stable Cells Tissue of Permanent Cells Framework Framework Scarring Intact Destroyed (fibrous encapsulation; synovium) Regen. Scarring Chronic Inflammation (incorp. (fibrous encapsulation; of implant) synovium) Chronic Inflammation Acute Inflammation Granulation Tissue Implant Movement Inc. time IMPLANT MATERIALS/BIOMATERIALS TISSUE RESPONSE Soft Tissue (that does not regenerate) ? Fibrous capsule (scar) Synovium: fibrous tissue interspersed with macrophages Wound healing response of repair (scar formation) coupled with macrophage accretion at the “dead space” - chronic inflammation Bone ? Tissue integration and tissue bonding TISSUE INTEGRATION TISSUE BONDING ? Tissue Integration (Osseointegration) Apposition of tissue (bone) to the implant (contact of bone with the surface but not necessarily bonding); no macrophage layer? Regeneration of tissue up to the surface of the implant ? Tissue Bonding (Bone Bonding) Chemical bonding of tissue (viz., bone) to the surface Protein adsorption and cell adhesion Biomaterials: calcium phosphates and titanium (?) Dental Implant Designs and Materials Carbon Titanium Alumina Images removed due to copyright considerations. Alumina Alumina Carbon Blade Implant Photos removed due to copyright considerations. “Commercially pure” Titanium Two-Stage Design; to shield the artificial root from loading during the initial stage of healing Images removed due to copyright considerations. Osseointegration Images removed due to copyright considerations. T. Albrektsson, et al., Ann. Biomed. Engr., 11:1 (1983) T. Albrektsson, CRC Crit. Rev. Biocompat., 1:53 (1984) Osseointegration: Control of Surgical Trauma Image removed due to copyright considerations. T. Albrektsson, CRC Crit. Rev. Biocompat., 1:53 (1984) Implants with Porous Coatings in Bone Bone Metal stem Bone Beaded porous coating Image removed due to copyright considerations. Image removed due to copyright considerations. Image removed due to copyright considerations. Bone Hydroxyapatite-Coated Implants Images removed due to copyright considerations. Plasma-sprayed HA coating, 40 μm thick 3 hr Metal Image removed due to copyright considerations. Bone Image removed due to copyright considerations. Cylindrical implant in canine prox. femur 6 da Plasma-Sprayed Hydroxyapatite Coating Image removed due to copyright considerations. 14 da Image removed due to copyright considerations. Bone regeneration in the gap between the implant surface and surrounding bone. Plasma-Sprayed Hydroxyapatite Coating 14 days Photo removed due to copyright considerations.