Topic 10 biomaterial complications Flashcards
How are tumors formed and what is neoplasia?
Neoplasia is the excessive and uncontrolled cell proliferation - resulting in tumors.
What is a tumor?
Comprised of proliferating neoplastic cells surrounding connective tissue and blood vessels. Can be benign or malignant.
What is a carcinogen?
a stimulus that causes malignant transformation in cells due to many cumulative mutations in DNA of normal cells.
What 3 phases comprises the formation of a tumor?
Initiation phase: cells are transformed
latency period: no tumor and can be several years
Promotion stage: obvious tumor growth observed
Which two ways can the malignant transformation happen?
Chemical and foreign body carcinogenesis
What is chemical carcinogenesis?
Caused by chemicals or substances leached from implants
What is foreign body carcinogenesis?
Tumor formation by a solid material, not caused by chemical activity. Not fully understood but usually seen together with a thick fibrous capsule formation.
What the process of foreign body carcinogenesis?
In theory: Process begins during foreign body reaction to implant. High proliferation of cells due to high concentrations of growth factors, pre-neoplastic cells may be present and also proliferate. Inflammation dies down as fibrous capsule is formed, but pre-neoplastic cells are trapped between implant and capsule and malignant transformation occur, tumor grows in “protected space”.
Risk increases with size of implant.
How are abestos fibers carcinogenic?
They cause a foreing body tumorigenesis as they penetrate the cell membrane and cause direct damage to the nucleus - resulting in DNA mutations
Why are materials being degraded in our bodies and how?
Our bodies are not an easy environment as we are 37 C hot, saline solution, dissolved dioxide, cells, enzymes, reactive oxidative species etc. This can cause metallic corrosion as well as oxidation or hydrolysis of polymers as well as dissolve ceramics (if low pH).
What’s calcification?
The deposition of calcium-containing minerals on the surface of biomaterials after implantation.
What is stenosis?
The hardening, calcification/accumulation of connective tissue on the aortic valve or in the blood vessels. It also becomes heavier so takes more pressure to open it up.
How does calcification occur?
Calcium ions bind to adsorbed negatively charged proteins on biomaterials. Ruptured cells from wound healing process can also expose negatively charged membrane phospholipids that nucleate mineralization. Rupture of cells can also be caused by moving biomaterial components.
