Degradation properties
Degradation
- Degradation refers to a chemical process resulting in the cleavage of covalent bonds due to hydrolysis, oxidation or enzymatic processes
- (Bio)degradation or resorption is chemical breakdown of an implant by a chemical agent (enzyme, cell, organism)
- Erosion refers to physical changes in size, shape or mass due to degradation, dissolution, ablation or wear
- Erosion can be distinguished into surface erosion and bulk erosion
Degradation/resorption has an effect on:
- Mechanical properties (impactability, strength, stiffnes, Young’s modulus)
- Biological properties (osteoconduction)
- Degradability speed
- Rules of thumb:
- TCP chemically less stable compared to HA due to high resolution characteristics
- TCP easily resorbed by osteoclasts compared to HA
- TCP faster degradation (12-18 months) compared to HA (2-10 years)
In vitro & in vivo dissolution of Ca-P materials depends on:
- Composition
- Crystallinity
- Ca/P ratio
- Interconnectivity
- Degradability / type and speed of resorption
- Mechanical properties
- Particle size
- Surface area
- Production process
- Patient characteristics: age, gender, health status, co-morbidities
Important:
Ca-P bone substitutes have to be intact long enough for bone ongrowth to occur and to maintain stability.