Fluoridated Hydroxyapatite Solubility and Caries Formation

Moreno, E.C.; Kresak, M.; Zahradnik, R.T.

doi:10.1038/247064a0

Cited by 323 publications

(221 citation statements)

References 10 publications

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“…2 can be expected (28). Similar with the Mg(OH) 2 , as pH increases, the thermodynamic driving force leading to formation of solid precipitates increases as well.…”

Section: Discussionsupporting

confidence: 52%

Long-term clinical study and multiscale analysis of in vivo biodegradation mechanism of Mg alloy

Lee

Han

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

384

236

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There has been a tremendous amount of research in the past decade to optimize the mechanical properties and degradation behavior of the biodegradable Mg alloy for orthopedic implant. Despite the feasibility of degrading implant, the lack of fundamental understanding about biocompatibility and underlying bone formation mechanism is currently limiting the use in clinical applications. Herein, we report the result of long-term clinical study and systematic investigation of bone formation mechanism of the biodegradable Mg-5wt%Ca-1wt%Zn alloy implant through simultaneous observation of changes in element composition and crystallinity within degrading interface at hierarchical levels. Controlled degradation of Mg-5wt%Ca-1wt%Zn alloy results in the formation of biomimicking calcification matrix at the degrading interface to initiate the bone formation process. This process facilitates early bone healing and allows the complete replacement of biodegradable Mg implant by the new bone within 1 y of implantation, as demonstrated in 53 cases of successful long-term clinical study.biodegradable implant | bone formation | clinical application T he century-old concept of the fixation device that holds the fractured bones in place to allow repair through the natural bone remodeling process is still being practiced today without alteration (1-5). The recent rapid growth of the elderly demographic of physically active adults has tremendously intensified the occurrence of bone trauma cases, highlighting once again the major drawbacks of current surgical approaches and osteosynthesis systems, such as inevitable secondary surgery to remove the inert fixation devices after complete bone healing and inflammatory response due to the release of metal ions. In the past decade, countless studies have been performed to control and optimize the mechanical and corrosion properties of magnesium-based alloys (6-9), which, thanks to their degradation in the physiological environment, could overcome the limitations of inert implant materials and shift the paradigm of conventional bone fixation devices toward new horizons. Driven by these new possibilities, important findings regarding, among others, the degradation mechanism of Mg-based alloys (10, 11), the formation of corrosion protective layers by degradation products (12, 13), and the osteogenetic properties of Mg ions (14, 15) have been reported in the literature. However, such findings are based on the observation of degradation products and of bone healing at the macroscale level. Due to lack of fundamental understanding on biocompatibility and underlying bone formation mechanism of the degradation product, there is so far only one known case of statistically insignificant clinical study result (16) with a short-term follow-up. In our previous study, we reported successful development and long-term in vivo study of uniformly slowly degrading Mg-5wt%Ca-1wt%Zn alloy system (SI Appendix, Figs. S1 and S2) featuring adequate mechanical strength [ultimate tensile strength (UTS) ∼250 MPa] (17) a...

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“…2 can be expected (28). Similar with the Mg(OH) 2 , as pH increases, the thermodynamic driving force leading to formation of solid precipitates increases as well.…”

Section: Discussionsupporting

confidence: 52%

Long-term clinical study and multiscale analysis of in vivo biodegradation mechanism of Mg alloy

Lee

Han

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

384

236

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“…Perhaps more significant, fluorination is well established to decrease the solubility of apatite in water by several orders of magnitude 32,33 , resulting in its extensive incorporation in the jaws of aggressive marine predators such as sharks 34,35 . Likewise, the impact surface of stomatopod dactyl segments must be shielded from chemical dissolution to fulfil their function, and thus it is not surprising that FAP is chemically favored over HAP.…”

Section: Discussionmentioning

confidence: 99%

Textured fluorapatite bonded to calcium sulphate strengthen stomatopod raptorial appendages

et al. 2014

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Stomatopods are shallow-water crustaceans that employ powerful dactyl appendages to hunt their prey. Deployed at high velocities, these hammer-like clubs or spear-like devices are able to inflict substantial impact forces. Here we demonstrate that dactyl impact surfaces consist of a finely-tuned mineral gradient, with fluorapatite substituting amorphous apatite towards the outer surface. Raman spectroscopy measurements show that calcium sulphate, previously not reported in mechanically active biotools, is co-localized with fluorapatite. Ab initio computations suggest that fluorapatite/calcium sulphate interfaces provide binding stability and promote the disordered-to-ordered transition of fluorapatite. Nanomechanical measurements show that fluorapatite crystalline orientation correlates with an anisotropic stiffness response and indicate significant differences in the fracture tolerance between the two types of appendages. Our findings shed new light on the crystallochemical and microstructural strategies allowing these intriguing biotools to optimize impact forces, providing physicochemical information that could be translated towards the synthesis of impact-resistant functional materials and coatings.

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“…In practice, the fluorine ion itself has been studied widely in dental restoration areas, due to its advantages over other ions in that it prevents the formation of caries in bacteria-existing environments and promotes mineralization and crystallization of calcium phosphates in the formation of bone. 9,10 Nevertheless, there have been few reports concerning the fabrication or characterization of the FA or FHA materials. [11][12][13][14][15] Most studies discussed the possible fabrication of FA powders by precipitation methods or films by thermal spraying techniques.…”

Section: Introductionmentioning

confidence: 99%

“…7 On the other hand, pure fluorapatite (FA, Ca 10 (PO 4 ) 6 F 2 ) is known to have a much lower solubility than HA, because FA possesses a greater stability than HA, both chemically and structurally. 8,9 Moreover, the FA forms fluor-hydroxyapatite (FHA, Ca 10 (PO 4 ) 6 (OH,F) 2 ) solid solutions with HA through the replacement of OH Ϫ by F Ϫ . Hence, modulation of the extent of fluoride substitution provides an effective way of controlling the solubility of the apatite.…”

Section: Introductionmentioning

confidence: 99%

Sol–Gel Preparation and Properties of Fluoride‐Substituted Hydroxyapatite Powders

Kim

Koh

et al. 2004

Journal of the American Ceramic Society

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Fluoridated Hydroxyapatite Solubility and Caries Formation

Cited by 323 publications

References 10 publications

Long-term clinical study and multiscale analysis of in vivo biodegradation mechanism of Mg alloy

Long-term clinical study and multiscale analysis of in vivo biodegradation mechanism of Mg alloy

Textured fluorapatite bonded to calcium sulphate strengthen stomatopod raptorial appendages

Sol–Gel Preparation and Properties of Fluoride‐Substituted Hydroxyapatite Powders

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