Degradable Materials

What are the two main types of biodegradable materials?

Bioerosion and Biodegradation

Bioerosion properties

physical change, bulk(hydrophilic, surface (hydrophobic)

Biodegradation properties

chemical process, by cells

Advantages of degradation materials

• no need for removal of the implant

• no long-term issues

• allows normal tissues to take over

Disadvantages of degradation materials

• degradation kinetics 

• has to be non-toxic 

• limited resources  

What polymers are examples of biodegradable materials?

Polylactic acid(PLA) and Polyglycolic acid(PGA) 

Polylactic acid(PLA)

Hydrophobic and lasts 1-2 years

Polyglycolic Acid (PGA)

More hydrophilic but only last 2-4 months

more ____——> more_____

hydrophilic, hydrolysis

Applications of degradable polymers

Tissue engineering, degradable sutures, degradable screws/ nails

Degradable ceramics

Hydroxyapatite, Tricalcium Phosphate

How do ceramics degrade?

hydrolysis and cells

Degradable metals

Magnesium alloys

Applications of degradable metals

Bone repair and biodegradable stents

Advantages of degradable metals

• Anti-platelet deposition and Low thrombogenicity (Biodegradable stents)

• Growth of bone cells and ideal mechanical properties( Bone repair)

Degradable applications

• Vascular Grafts/ Stents- blood compatibility is crucial

• Sutures: Earliest in medicine

• Fracture Fixation: Instead of classical metals

• Tissue regeneration: Biomaterials fills defect