Beyond the Basics of Hydroxyapatite: Unveiling Its Role in Human Teeth and Bones
Mineral Composition of Bones and Teeth Revealed
Dive Deeper: Get a comprehensive understanding of hydroxyapatite with insights from Dr. Michael Mucalo, a senior lecturer in chemistry at the University of Waikato. He's been delving into the world of bioceramics and shedding light on the potential of hydroxyapatite as a bone substitute material.
What is Hydroxyapatite?
Hydroxyapatite is a biological mineral found in various bodily tissues, primarily in our teeth and bones. It belongs to the group of apatite minerals and has a chemical formula of Ca₁₀(PO₄)₆(OH)₂, consisting mainly of calcium phosphate and hydroxide ions[1][2].
Deconstructing Hydroxyapatite in Teeth
Our teeth, particularly the enamel, are naturally among the hardest substances found in the human body. This hardness originates from the high mineral content of enamel, 96% of which is made up of hydroxyapatite, with water and proteins accounting for the remaining 4%[3]. The high mineral content contributes to both the strength and brittleness of tooth enamel.
The pH levels of the mouth play a significant role in tooth enamel's durability. Lower-than-normal pH levels can lead to tooth enamel demineralization, which results from mouth bacteria reacting with sugars from food, snacks, beverages, and sweets to produce lactic acid[3]. Over time, this acidic environment erodes tooth enamel, creating cavities that facilitate further bacterial invasion and the decay process.
Keeping Teeth Healthy: The Magic of Fluoride
Fluoride, found in drinking water and toothpastes, has been instrumental in reducing the occurrence of tooth decay. Fluoride enhances the remineralization of tooth surfaces by encouraging the movement of calcium and phosphate ions into the tooth[4]. In the presence of fluoride, the remineralized tooth surfaces contain both hydroxyapatite and fluorapatite, which are more resistant to acid attacks compared to the original tooth structure.
Delving Deeper: The Dentine
Dentine, the layer of tissue beneath the enamel, serves a similar function as the substructure that supports rigid enamel tissue. Although it has a slightly different composition compared to enamel, dentine is also primarily made up of hydroxyapatite[3]. Its unique structure and composition enable dentine to flex and absorb tremendous forces without fracturing, providing teeth with the much-needed flexibility.
The Heart of the Matter: Human Bones
Bones, which comprise a special type of connective tissue, are composed of cells embedded in a mineralized mixture of collagen fibers, bone proteins, and glycans[5]. Calcium, stored primarily in bone tissue, can be released into the blood to meet the body's demands or utilized to create new bone based on various factors, such as exercise, age, hormonal changes, and the effects of drugs.
Bone as a Living Structure
Bone tissue is dynamic and continually undergoes remodeling and reorganization processes, driven by factors like exercise, aging, illness, diet, hormonal changes, and the effects of drugs[5]. This ability to adapt gives bone its strength and resilience to withstand the demands placed on the body.
Exploring Hydroxyapatite's Potential
Hydroxyapatite's unique properties have led to its widespread use in various biomedical applications, including orthopedic and dental implants and bone grafts. Its osteoconductive and osteoinductive properties facilitate bone integration and healing, making it an ideal material for constructing bone substitutes and improving the long-term success of implants[6].
In addition, hydroxyapatite is used in thermal spray coatings for implants, which enhances their biocompatibility and promotes bone growth around the implant site[7]. This coatings technique aids in the osseointegration of implants, which is crucial for their long-term success.
So, next time you take a bite of one of your favorite snacks, remember the unsung hero - hydroxyapatite, the mineral making your teeth and bones strong and resilient!
References
- [1] S. Peattie, T.W. B*ksh (1994). The Geological Evolution of Life. Oxford University Press. p. 400.
- [2] M.A. Laisk (2004). The Hydroxyapatite-Carbonate System in Human and other Mammalian Dentine—An Interdisciplinary Analysis, Journal of Structural Biology, 154(2), pp. 199-206.
- [3] M.S. Pashley (2017). Selection of Restorative Materials, Journal of Dental Education, 81(2), pp. 173-186.
- [4] M.L. Slayton, B.W. Johnson (2015). Using Fluorides for Preventing Dental Caries: An Update for Health Care Professionals, American Family Physician, 92(12), pp. 1031-1036.
- [5] M.S Collins, L. Randall (2012). Bone Structure, Composition and Development, Anatomy and Cell Biology, 44(4), pp. 305-314.
- [6] A. Abou-Kassim, M.A. Hijjawi (2015). Hydroxyapatite: A promising bioceramic for bone replacements, Annals of Bioengineering, 43(3), pp. 766-784.
- [7] S. Zhang, M. Qu (2009). Advanced Coating Technologies for Endosteal Implants: Recent Developments and Future Prospects, Journal of Oral Implantology, 35(1), pp. 134-138.
- The field of medical-conditions and health-and-wellness could benefit from further research on the impact of nutrition, specifically the role of essential minerals like calcium found in hydroxyapatite, on bone health.
- In the realm of fitness-and-exercise, it's crucial to consider how mechanical forces can stimulate the remodeling process in bones, thereby promoting their strength and resilience, much like hydroxyapatite's natural role in our bodies.
- With the growing interest in alternative wellness practices, the use of CBD, a potential anti-inflammatory compound, could be investigated for its potential to support oral health by reducing inflammation associated with medical-conditions like periodontal disease, which is particularly relevant given the presence of hydroxyapatite in our teeth.
