Hydroxyapatite: Raw MaterialHydroxyapatite is chemically same as the main material of the bones and hard tissues of the human body. Thus, it is bioactive which means it can support bone growth and integration. Due to this nature, the material is mainly used as bone fillers as well as bone coatings. For bone coatings, this material will be coated onto the metallic implants usually by plasma spraying to ensure the implants can react and respond with other body tissues efficiently. This condition makes this material be classified as bioactive. The coating will act as an osteophilic surface which will secure the implant, allow bone atrophy as well as transfer the load to the bone. While, as bone fillers, this material will be used to fill any bone defects or voids in the form of beads, powders or bead blocks. As this material is chemically similar to the natural human bones, it will acts as a scaffold and supports the voids by naturally forming bone. It also acts as an alternative to the bone grafts. Eventually, the filler will become part of the original bone structure.
Bone Assimilation with New Synthetic Bone
Hydroxyapatite is bioactive and biocompatible material which makes it as the main advantages to be selected as the material for synthetic bone. In spite of its nature being biologically inert and degradation resistant, hydroxyapatite supports the bone ingrowth as well as osseointegration. For bone ingrowth, the material is readily bonded to the bone as it is chemically similar to the original bone material which then allows further bone growth. On the other hand, osseointegration is a direct functional and structural connection between natural bones and the artificial bones. This material support osseointegration which then can be applied as dental implants and also other synthetic bones. These material characteristics of promoting bone ingrowth and osseointegration allow the material to be used in orthopaedic, dental and maxillofacial applications.
However, in spite of having advantages as the main material for synthetic bone, it also has several disadvantages. Among the major one is it has lack of mechanical strength in which the Mohs Hardness is 5 (Apatite). In addition, it is brittle. Therefore, in human body application, hydroxyapatite is not suitable to be used in bulk form for load bearing applications such as in orthopaedics. One of the reasons why it is lack in mechanical strength is due to the fact that it is very porous. However, for bone ingrowth sense, this porosity allows relatively rapid bone ingrowth. Even though the material can be stated as thermally unstable compound as it decomposes at the range of temperature of 800 to 1200 °C, it is thermally stable being inside the human body as the average temperature will be around 36.9 °C and may up to 38 °C during high fever.
Bone Assimilation with New Synthetic BoneHydroxyapatite is bioactive and biocompatible material which makes it as the main advantages to be selected as the material for synthetic bone. In spite of its nature being biologically inert and degradation resistant, hydroxyapatite supports the bone ingrowth as well as osseointegration. For bone ingrowth, the material is readily bonded to the bone as it is chemically similar to the original bone material which then allows further bone growth. On the other hand, osseointegration is a direct functional and structural connection between natural bones and the artificial bones. This material support osseointegration which then can be applied as dental implants and also other synthetic bones. These material characteristics of promoting bone ingrowth and osseointegration allow the material to be used in orthopaedic, dental and maxillofacial applications.
However, in spite of having advantages as the main material for synthetic bone, it also has several disadvantages. Among the major one is it has lack of mechanical strength in which the Mohs Hardness is 5 (Apatite). In addition, it is brittle. Therefore, in human body application, hydroxyapatite is not suitable to be used in bulk form for load bearing applications such as in orthopaedics. One of the reasons why it is lack in mechanical strength is due to the fact that it is very porous. However, for bone ingrowth sense, this porosity allows relatively rapid bone ingrowth. Even though the material can be stated as thermally unstable compound as it decomposes at the range of temperature of 800 to 1200 °C, it is thermally stable being inside the human body as the average temperature will be around 36.9 °C and may up to 38 °C during high fever.
REFERENCES
Mindat.org. Apatite-(CaOH). 2009. http://www.mindat.org/min-1992.html (accessed on May 5, 2009)
AZoM.com. Hydroxyapatite – Hydroxyapatite Coatings An Overview. 2002. http://www.azom.com/Details.asp?ArticleID=1405 (accessed on May 5, 2009)
AZoM.com. Hydroxyapatite – Properties and Application. 2001. http://www.azom.com/Details.asp?ArticleID=107 (accessed on May 5, 2009)
Extracted from Personal School Project
Copyright Bento 2009
Copyright Bento 2009
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