Degradation of hydroxylapatite, fluorapatite, and fluorhydroxyapatite coatings of dental implants in dogs

Abstract

Calcium phosphate coatings on dental implants enhance integration of the material. Resorption of the ceramic coatings has raised some concern about the behavior of the bone-implant interfaces after the coating disappearance. Substitution of the OH- ions by fluoride in the hydroxylapatite (HA) lattice makes the calcium phosphate more stable. We investigated the degradation rate of dental implants with 50- and 100-microm coatings of HA, fluorapatite (FA), or fluorhydroxylapatite (FHA). The implants were inserted in dog jaws and retrieved for histological analysis after 3, 6, and 12 months. The thickness of the calcium phosphate coatings was evaluated using an image analysis device. A relative resorption index and its standard deviation were studied. HA and FA coatings (even at 100-microm thickness) were almost totally degraded within the implantation period. In contrast, the FHA coatings did not show significant degradation during the same period. The standard deviation showed that the resorption process for FHA with thicknesses of 50 or 100 microm was the same. Such a difference was not observed between the 50- and 100-microm thick coatings of FA and HA. In conclusion, the FHA coatings showed good integration in the bone tissue and lasted much longer than classic calcium phosphate coatings.

Fluoride‐Based Bioceramics

“…However, several drawbacks still limit the quality of the interface and the implant biointegration: the poor adhesion of the coating on the titanium surface and its scaling either during implantation or in the long run, and the decomposition of the HA during the plasma spray process (formation of an amorphous phase), which consequently has a negative effect as it initiates the degradation of the coating [149,150] . Fluorapat ite-based coa tings have been studi ed wi th a v iew to partly solve these problems due to the higher stability of fluor-containing well-crystallised apatites, which can lead to coatings with greater resistance to dissolution and biodeg radation [151][152][153][154][155]. Howe ver, the main challen ge is to im prove the quality and the biological function of the coatings through the modification of their chemical composition at the lowest cost.…”

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…In addition, the outer layers might tend to detach from the inner ones, which in time can result in implant mobility. On the contrary, if they are too thin, the deposits are easy to dissolve, because resorbability of HA, which is the second least soluble CaPO 4 (Table 1), is about 15 -30 μm per year under the physiological conditions [761]. Needless to explain, that except of FA, dissolution of other CaPO 4 would be faster.…”

“…On the other hand, there are cases [761,[821][822][823], in which the biodegradation kinetics of CaPO 4 deposits appeared to be correlated imperfectly with their solubility values, mentioned in Table 1. For example, three types of CaPO 4 (HA, ACP and β-TCP) deposited by the laser ablation technique were immersed in SBF in order to determine their behavior.…”

“…Additionally, degradation rates of dental implants with 50-and 100-micron thick coatings of HA, FA and fluorhydroxylapatite (FHA) were studied [761]. The implants were inserted in dog jaws and retrieved for histological analysis after 3, 6, and 12 months.…”

Porous apatite biocompatible scaffolds for cell technology for the repair of tissue defects in surgery

“…The introduction of fluoride ions (2 and 10 wt %) instead of the OH groups did not improve the properties of materials as scaffolds for cell growth. However, fluorine ions are known to increase the stability of apatite ceramics against resorption by extracellular fluids, which may be useful in some cases [9]. Presumably, the ceramic granules, which have a much higher surface area for cell expansion than the reference material, change the initial inoculation density per unit of the potential growth surface.…”