Bone Tissue Response to Implant and Trauma

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Questions and Answers

What is the primary function of platelets in the hemostasis phase?

To release messenger substances for cell division
To stimulate cell adhesion on the implant surface
To form a provisional matrix on the implant surface
To aggregate and form a thrombus to stop bleeding (correct)

What is the effect of a hydrophilic implant surface on protein adsorption?

It preserves protein functions and allows for cell attachment (correct)
It denatures proteins and prevents cell attachment
It only allows for the adsorption of albumin
It has no effect on protein adsorption

What is the primary function of fibrin cross-links in the hemostasis phase?

To aggregate platelets and form a thrombus
To release messenger substances for platelet aggregation
To form a provisional matrix on the implant surface (correct)
To stimulate cell division of fibroblasts

Which protein is responsible for stimulating cell division of fibroblasts?

PDGF (D) Signup and view all the answers

What is the consequence of a hydrophobic implant surface on protein adsorption?

It denatures proteins and prevents cell attachment (B) Signup and view all the answers

Which protein is responsible for binding to cell adhesion molecules (integrins)?

Fibronectin (B) Signup and view all the answers

What is the effect of platelet aggregation on the implant surface?

It forms a provisional matrix on the implant surface (D) Signup and view all the answers

What is the primary function of vitronectin in the implant interaction with the surrounding tissues?

To bind more platelets and form a thrombus (B) Signup and view all the answers

What do macrophages secrete to antagonize the digestive enzymes and the growth factors stored in the tissue?

Angiogenic and fibrogenic growth factors (B) Signup and view all the answers

What is the prerequisite for osteogenesis?

Angiogenesis (A) Signup and view all the answers

What do pericytes detach from in response to VEGF expression by macrophages?

The outer wall of the blood vessel (D) Signup and view all the answers

What is the result of the arrangement of endothelial cells in angiogenesis?

Formation of holes (C) Signup and view all the answers

What is the role of macrophages in the protective mechanism of the extracellular matrix?

To protect the extracellular matrix (C) Signup and view all the answers

What is the result of the migration of fibroblasts from the surrounding tissue in response to FGF?

Formation of granulation tissue (B) Signup and view all the answers

What is released by platelets during the inflammatory phase?

TGF-b and Histamine (D) Signup and view all the answers

What is the role of Histamine during the inflammatory phase?

Increases vascular permeability to fluids (A) Signup and view all the answers

What is the result of prolonged presence of bacteria in the wound?

Tissue liquefaction and pus formation (B) Signup and view all the answers

What is the role of PMNs during the inflammatory phase?

Elimination of bacteria through active oxygen radicals (A) Signup and view all the answers

How can we limit the inflammatory phase?

By using antibiotics and local disinfection (C) Signup and view all the answers

What is the role of PDGF and TGF-b during the inflammatory phase?

Differentiation and proliferation of cells (D) Signup and view all the answers

What is the role of Macrophages during the inflammatory phase?

Elimination of bacteria by phagocytosis (B) Signup and view all the answers

What is the result of angiogenesis during the inflammatory phase?

Blood vessel formation (D) Signup and view all the answers

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Study Notes

Implant Interaction with Surrounding Tissue

Bleeding is stopped by the aggregation of blood platelets, forming a white thrombus
Mechanical crushing of bone (bone trauma) releases bone matrix proteins and growth factors

Bone Trauma

Bone matrix proteins (albumin, fibronectin, vitronectin) are released in high concentration
These proteins contain cell binding sites that interact with cell adhesion molecules (integrins)
They can bind more platelets, promoting further platelet aggregation

Implant Interaction with Surrounding Tissue (continued)

Hydrophobic implant surface leads to protein denaturation, loss of function, and platelet aggregation
Hydrophilic implant surface preserves protein function, allowing cells to attach to the implant surface

Hemostasis Phase

Platelets release messenger substances (thromboxane) that allow more platelets to aggregate
Platelets also release PDGF, which stimulates cell division of fibroblasts and fibrin cross-linking
Fibrin cross-links form a provisional matrix that adheres to the implant surface

Inflammatory Phase

Platelets release various messenger substances, including TGF-b, PDGF, FGF, histamine, and bradykinin
PDGF, TGF-b, and FGF play a significant role in blood vessel formation (angiogenesis)
Histamine increases vascular permeability, allowing fluid and serum proteins to flow into the site
Bradykinin increases blood flow and hyperemia
PMNs (neutrophils) are attracted to the site by chemotaxis, where they kill bacteria and release digestive enzymes

Limiting Inflammatory Phase

Clean surgical work, antibiotics, and local disinfection can limit the inflammatory phase
Macrophages eliminate bacteria by phagocytosis and remove tissue debris
Macrophages also secrete angiogenic and fibrogenic growth factors (PDGF, bFGF, VEGF)

Proliferative Phase

Formation of granulation tissue through angiogenesis and new extracellular matrix formation
Angiogenesis is a prerequisite for osteogenesis
Macrophages express VEGF, stimulating pericytes to detach from the outer wall of the vessel
Pericytes then stimulate the production of endothelial cell precursors, leading to angiogenesis