IADR Abstract Archives
Fluorapatite and Hydroxyapatite Dental Implant Coatings: Interfacial Properties and Degradation
Objectives: Hydroxyapatite (HA) coated dental implants may fail due to coating dissolution and delamination. Fluorapatite (FA) is more stable, with proven ability to enhance osseointegration and with promising antibacterial properties. This study aimed to perform detailed physical and mechanical surface analysis to explore the role of sintering on surface properties and degradation of each implant coating.
Methods: FA or HA coatings were deposited onto in-house prepared cpTi discs using a mild hydrothermal method. Half of the coated discs were sintered at 800°C for 180min, to give 4 groups (N=5). A morphological characterisation was performed using Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS). Coating crystallinity was investigated by X-Ray Diffraction (XRD). Surface roughness (Sa) and thickness were analysed using Laser Profilometry. A diamond stylus scratch test (ST) was used to determine coatings’ adhesion. Daily fluoride release at pH 4.0 was evaluated using a fluoride ion selective electrode for 8 weeks.
Results: Mild hydrothermal synthesis produced ordered FA coatings composed of well-aligned hexagonal crystals, and disordered HA coatings with randomly aligned spindle shape crystals. XRD confirmed FA and HA coatings’ crystallinity. EDS analysis showed Ca/P for FA (1.78±0.02) and HA (1.72±0.06). FA presented with less roughness 3.88µm±0.9 and thickness 9.43µm±0.7 compared to HA 13.4µm±1.4 and 340µm±20 respectively, these were significantly reduced after sintering. ST showed a significantly higher FA delamination force compared to HA, this was significantly increased after sintering. Unsintered FA coatings showed daily F- release ranging 4.7-12ppm which was entirely lost on the 14th day whilst sintered FA coatings maintained stable release for 8 weeks. HA coatings had completely degraded by the 3rd day.
Conclusions: The proposed hydrothermal method is effective in producing stable FA coatings. Sintering is effective in bringing about an enhancement in the surface morphology and stability of these coatings.
Methods: FA or HA coatings were deposited onto in-house prepared cpTi discs using a mild hydrothermal method. Half of the coated discs were sintered at 800°C for 180min, to give 4 groups (N=5). A morphological characterisation was performed using Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS). Coating crystallinity was investigated by X-Ray Diffraction (XRD). Surface roughness (Sa) and thickness were analysed using Laser Profilometry. A diamond stylus scratch test (ST) was used to determine coatings’ adhesion. Daily fluoride release at pH 4.0 was evaluated using a fluoride ion selective electrode for 8 weeks.
Results: Mild hydrothermal synthesis produced ordered FA coatings composed of well-aligned hexagonal crystals, and disordered HA coatings with randomly aligned spindle shape crystals. XRD confirmed FA and HA coatings’ crystallinity. EDS analysis showed Ca/P for FA (1.78±0.02) and HA (1.72±0.06). FA presented with less roughness 3.88µm±0.9 and thickness 9.43µm±0.7 compared to HA 13.4µm±1.4 and 340µm±20 respectively, these were significantly reduced after sintering. ST showed a significantly higher FA delamination force compared to HA, this was significantly increased after sintering. Unsintered FA coatings showed daily F- release ranging 4.7-12ppm which was entirely lost on the 14th day whilst sintered FA coatings maintained stable release for 8 weeks. HA coatings had completely degraded by the 3rd day.
Conclusions: The proposed hydrothermal method is effective in producing stable FA coatings. Sintering is effective in bringing about an enhancement in the surface morphology and stability of these coatings.