ortopdental (2)

Ortopedik ve Dental Malzemeler Yard. Do. Dr. Feride Sermin Utku

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Biocompatibility

Success of implant operation depends on the kind of tissue response to the surgical procedure and any interaction between tissues and implants.

Biocompatibility entails

mechanical,

chemical,

pharmacological and

surface compatibility.

Biocompatibility entails local and systemic response of tissues.

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Systemic Effects by Implants PMMA lowers blood pressure due to the reaction toward

MMA monomers.

Systemic effects of: biodegradable implants such as absorbable suture and surgical

adhesives,

biodegradable polymer scaffolds

large number of wear and corrosion particles released by metallic and polymeric implants. Various organs have different affinities for different metallic elements.

Corrosion-resistant metal alloys release some elements into the body. Interfere with physiologic activities.

Divalent ions may inhibit enzymes.

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Systemic Effects by Implants

Mammary augmentation with silicone gel in a

silicone rubber envelope. Median 16 years of use.

Rupture.

Autoimmune diseases, i.e. Systemic sclerosis and chronic connective tissue inflammation were claimed to have developed after mammary augmentation with silicon.

T cell memory to silica was observed in the off-spring of women after receiving silicone breast implants.

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Carcinogenicity

Chemical structure and function structural or pharmacological similarity to known carcinogenic agents (aromatic amines, polynuclear aromatic hydrocarbons with multiple ring structures, alkylating agents, aflatoxins, halogenated hydrocarbons, chloroform, polychlorinated biphenyls, pesticides, metallic nickel, cadmium and cobalt)

Carcinogenecity studies

Short-term

Long-term

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Response to Implants

Type of cell Description

metals (except noble metals) evoke a severe tissue reaction. Less reaction with Titanium due to oxide layer Co-cr and SS must be passivated

Ceramic, carbon Biocompatible, minimal tissue reaction, sometimes a thin layer of encapsulation

Glass-ceramic Some glass-ceramics showed direct bonding between implant and bone

polymers Quite inert if there are no unbound additives antioxidants, fillers, anti-discoloring agents, plasticizers, etc., and free monomers

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tissue response

implant : tissue

Minimal response Thin collagenous

membrane encapsulation

Chemically induced response

Physically Induced Response

Acute, mild inflammatory response

nflammatory response to particulate

Chronic, severely inflammatory response

Tissue growth into porous materials

Necrotic response

Layer of necrotic debris

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Biyomateryallerin Olas Etkileri

A) biyotolere etki

Uyguland blgede snrl fibrz bir doku ile evriliyorsa

B) biyoinert etki

Uygulanan kemik dokuyla arada snrl fibrz bir doku olmadan birleir. Dokuyla biyomateryal arasnda herhangi bir etkileim olmamaktadr.

C) Biyoaktif etki

Biyomateryal uyguland dokuda benzer hcrelerin oluumunu aktive etmektedir.

D) Toksik etki

Biyomalzemelerin alerjik, immn, nonimmn, mutajenik, karsinojenik ve enflamatuvar etkileri grlr.

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Biyouyumluluk

Baz aratrmaclar gerekten tam anlamyla biyouyumlu ve biyoinert malzeme olmadn sylemektedirler.

Bu yzden biyouyumluluk materyal seiminin en nemli parametresidir.

Biyolojik ortam iin malzeme tasarm, birbiriyle etkileen ayr dinamik unsurun varlndan dolay son derece zordur. Bunlar:

1. Biyomateryal yzeyinin kimyasal yaps

2. Aradaki pellikl (arayz) tabakas

3. Konak hcre yantdr.

Biyomateryale tutunan pellikl tabakas evreyle fizyolojik etkileime araclk eder. Bu yzden yzey kimyasnn, pellikl komponentlerinin ve adsorbsiyon mekanizmasnn tanmlanmas, oluacak yant kontrol etmede birincil neme sahiptir.

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The Defense System/Immune Response Immunity:

Resistance of the body to microbes

Elimination of worn-out or damaged body cells

Destruction of abnormal or mutant cell

The body reacts to foreign materials in ways to get rid of them.

Either moved, extruded or walled-off.

If particulate or fluid, it can be ingested by giant cells and removed.

Immune response is a stimulus-response sequence of events.

Immune response:

Non-specific defense (during the initial exposure to a foreign organism)

Specific defense

Humoral (antibodies)

Cell-mediated (sensitized lymphocytes).

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Effector cells of immune system White-blood cells (leukocytes colorless blood corpuscles capable of ameboid

movement)

Polymorphonuclear granulocytes

Neutrophils (50-70%) bone marrow- phagocytosis of bacteria, cell debris and antibody-primed foreign matter

Eosinophils (1-4 %) bone marrow. Unknown function

Basophils (0.1 %) bone marrow release of histamine and other chemicals (similar to tissue mast cells)

Lymphocytes (20-40%) bone marrow and lymphoid tissue. B cells: production of antibodies after transformation into plasma cells. T cells : responsible for cell-mediated immunity

Monocytes (2-8%) bone marrow. Transformed into tissue macrophages with phagocytic activity.

Macrophages - major function is phagocytosis of bacteria, cell debris and antibody-primed foreign matter. Found scattered throughout the tissues of the body. In liver, spleen, lymph nodes and bone marrow they form part of the lining of vascular and lymphatic channels.

Plasma cells - derived from B-lymphocytes in lymphoid tissue and are responsible for humoral immunity

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1. Neutrophils are short lived. They disintegrate and disappear after 24-48 hours.

2. Monocytes differentiate into macrophages and these cells are very long-lived. (up to months)

3. Monocytic emigration may continue for day to weeks, and

chemostatic factors are activated over longer periods of time.

Inflammation- clotting and provisional matrix formation

Injury to vascularized tissue in the implantation procedure: immediate development of provisional matrix at the implant site. occur early, in minutes to hours following implantation of a device.

Provisional matrix consists: fibrin, produced by activation of the coagulation and

thrombosis systems,

Inflammatory products released by the complement system, activated platelets, inflammatory cells and endothelial cells.

to provide structural and biochemical components to the process of wound healing. Provisional matrix may be viewed as a naturally derived, biodegradable, sustained release

system in which mitogens, chemo-attractants, cytokines and growth factors are released to control subsequent wound-healing processes.

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Acute inflammation Neutrophils (polymorphonuclear leukocytes, PMNs) and other motile white

cells emigrate or move from the blood vessels to the perivascular tissues and the injury site.

Specific receptors for chemostactic agents on the cell membranes of leukocytes are important in the emigration or movement of leukocytes.

Following the localization of leukocytes at the injury (implant) site, phagocytosis and the release of enzymes occurs following activation of neutrophils and macrophages.

The major role of the neutrophil in acute inflammation is to phagocytose microorganisms and foreign materials.

Acute inflammation normally resolves quickly, usually less than 1 week, depending on the extent of injury at the implant site.

The presence of acute inflammation (PMNs Polymorphonuclear Granulocytes) at the tissue/implant interface at time periods beyond 1 week suggests the presence of an infection. (fig 2)

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Acute inflammation

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Chronic inflammation

Persistent inflammatory stimuli lead to chronic inflammation.

Characterized by:

Presence of macrophage, monocytes and lymphocytes (production of antibodies)

Proliferation of blood vessels and connective tissue.

Factors:

Chemical and physical properties of the materials in themselves

Motion in the implant site by the materials

Infection

Short durat