Early osseointegration of implants with cortex-like TiO2 coatings formed by micro-arc oxidation: A histomorphometric study in rabbits.

In our previous studies, a novel cortex-like TiO2 coating was prepared on Ti surface through micro-arc oxidation (MAO) by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching (SLA) coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.

Early Osseointegration of Implants with Cortex-like TiO2 Coatings Formed by Micro-arc Oxidation: A Histomorphometric Study in Rabbits / 华中科技大学学报（医学）（英德文版）

In our previous studies,a novel cortex-like TiO2 coating was prepared on Ti surface through micro-arc oxidation (MAO) by using sodium tetraborate as electrolyte,and the effects of the coating on cell attachment were testified.This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration.A sand-blasting and acid-etching (SLA) coating that has been widely used in clinical practice served as control.Topographical and chemical characterizations were conducted by scanning electron microscopy,energy dispersive X-ray spectrometer,X-ray diffraction,contact angle meter,and step profiler.Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic,whereas the SLA surface was hydrophobic.The roughness of MAO was similar to that of SLA.The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT,histological analysis,and fluorescent labeling at the bone-implant interface four weeks after surgery.The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation.Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces.It was suggested that with micro/nanostructure and superhydrophilicity,the cortex-like MAO coating causes excellent osseointegration,holding a promise of an application to implant modification.

Effects of fluoride-ion-implanted titanium surface on the cytocompatibility in vitro and osseointegatation in vivo for dental implant applications.

As an attractive technique for the improvement of biomaterials, Plasma immersion ion implantation (PIII) has been applied to modifying the titanium material for dental implant application. The present study investigated the cytocompatibility and early osseointegration of fluoride-ion-implanted titanium (F-Ti) surface and implants, both characterizing in their composition of titanium oxide and titanium fluoride. The cytocompatibility of F-Ti was evaluated in vitro by using scanning electron microscope, Cell Counting Kit-8 assay, alkaline phosphatase activity assay, and quantitative real-time polymerase chain reaction. The results showed that the F-Ti weakened the effects that Porphyromonas gingivalis exerted on the MG-63 cells in terms of morphology, proliferation, differentiation, and genetic expression when MG-63 cells and Porphyromonas gingivalis were co-cultured on the surface of F-Ti. Meanwhile, the osteogenic activity of F-Ti implants was assessed in vivo via evaluating the histological morphology and estimating histomorphometric parameters. The analysis of toluidine blue staining indicated that the new bone was more mature in subjects with F-Ti group, which exhibited the Haversian system, and the mean bone-implant contact value of F-Ti group was slightly higher than that of cp-Ti group (p>0.05). Fluorescence bands were wider and brighter in the F-Ti group, and the intensity of fluorochromes deposited at the sites of mineralized bone formation was significantly higher for F-Ti surfaces than for cp-Ti surfaces, within the 2nd, 3rd and 4th weeks (p<0.05). An indication is that the fluoride modified titanium can promote cytocompatibility and early osseointegration, thus providing a promising alternative for clinical use.

High in vitro antibacterial activity of Pac-525 against Porphyromonas gingivalis biofilms cultured on titanium.

In order to investigate the potential of short antimicrobial peptides (AMPs) as alternative antibacterial agents during the treatment of peri-implantitis, the cytotoxic activity of three short AMPs, that is, Pac-525, KSL-W, and KSL, was determined using the MTT assay. The antimicrobial activity of these AMPs, ranging in concentration from 0.0039 mg/mL to 0.5 mg/mL, against the predominant planktonic pathogens, including Streptococcus sanguis, Fusobacterium nucleatum, and Porphyromonas gingivalis, involved in peri-implantitis was investigated. Furthermore, 2-day-old P. gingivalis biofilms cultured on titanium surfaces were treated with Pac-525 and subsequently observed and analysed using confocal laser scanning microscopy (CLSM). The average cell proliferation curve indicated that there was no cytotoxicity due to the three short AMPs. The minimum inhibitory concentration and minimum bactericidal concentration values of Pac-525 were 0.0625 mg/mL and 0.125 mg/mL, respectively, for P. gingivalis and 0.0078 mg/mL and 0.0156 mg/mL, respectively, for F. nucleatum. Using CLSM, we confirmed that compared to 0.1% chlorhexidine, 0.5 mg/mL of Pac-525 caused a significant decrease in biofilm thickness and a decline in the percentage of live bacteria. These data indicate that Pac-525 has unique properties that might make it suitable for the inhibition the growth of pathogenic bacteria around dental implants.

Sensory innervation around immediately vs. delayed loaded implants: a pilot study.

Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading is still lacking. For this randomized split-mouth study, six mongrel dogs randomly received one of four treatment protocols at 36 implant-recipient sites over 16 weeks (third maxillary incisor, third and fourth mandibular premolar): immediate implant placement and immediate loading (IIP+IL); delayed implant placement and delayed loading (DIP+DL); delayed implant placement and immediate loading (DIP+IL); and natural extraction socket healing (control). Histomorphometry was performed in the peri-implant bone and soft tissues within 300 µm around the implants. Immunocytochemistry and transmission electron microscopy were used to confirm the presence of neural structures and to reveal their ultrastructural characteristics, respectively. Myelinated nerve fibres densely populated the peri-implant crestal gingival and apical regions, although they were also identified in the woven bone and in the osteons near the implant threads. Compared with the control group in the mandible, the group that received IIP+IL showed a higher innervation (in N⋅mm⁻², 5.94 ± 1.12 vs. 3.15 ± 0.63, P<0.001) and smaller fibre diameter (in µm, 1.37 ± 0.05 vs. 1.64 ± 0.13, P=0.016), smaller axon diameter (in µm, 0.89 ± 0.05 vs. 1.24 ± 0.10, P=0.009) and g-ratio (0.64 ± 0.04 vs. 0.76 ± 0.05, P<0.001) in the middle region around the implants. Compared with DIP+IL in the mandible, IIP+IL had a higher nerve density (in N⋅mm⁻², 13.23 ± 2.54 vs. 9.64 ± 1.86, P=0.027), greater fibre diameter (in µm, 1.32 ± 0.02 vs. 1.20 ± 0.04, P=0.021), greater axon diameter (in µm, 0.92 ± 0.01 vs. 0.89 ± 0.03, P=0.035) and lower g-ratio (0.69 ± 0.01 vs. 0.74 ± 0.01, P=0.033) in the apical region around the implants. It may be assumed that the treatment protocol with IIP+IL is the preferred method to allow optimized peri-implant re-innervation, but further functional measurements are still required.

Bio-Oss(®) for delayed osseointegration of implants in dogs: a histological study.

We evaluated the effects of Bio-Oss® (a natural bone substitute derived from the mineral portion of bovine bone) on delayed osseointegration of implants. The bilateral third and fourth mandibular premolars of 4 adult, healthy, male and female dogs were extracted. We randomly selected 2 extraction sockets in each dog to be filled with Bio-Oss® (the experimental group); the other 2 extraction sockets, which were not treated, served as controls. Dental implants were inserted into the alveolar bone of the experimental group and the control group 3 months after insertion of the Bio-Oss®. The osteogenic activity in the bone around the implants was assessed by evaluating the histological morphology and estimating histomorphometric variables at 3 and 6 months after delayed implantation. After 3 months, Goldner's trichrome staining analysis showed that the rate of content between the bone and the implant and the mineralised area of bone around the implant were significantly higher in the experimental group (76%(9%) and 69.5% (9.6%), respectively) than those in the control group (56.1% (8.2%) and 52.8% (7.3%), respectively, p=0.003 and 0.000). However, the 2 groups did not differ significantly at 6 months. Fluorescence microscopy showed that the mean rates of mineralisation of the bony tissue around the implant in the experimental group at months 3 and 6 were 6.8 (0.4) µm and 8.4 (0.8) µm, respectively, which were significantly higher than those in the control group (p=0.000 and 0.03). These data indicate that putting Bio-Oss® into the extraction sockets can promote osseointegration after delayed implantation, and may be a promising option for clinical use.