| BackgroundIn the study of intraosseous implants,enhancing bone formation ability and shortening the healing time has always been the direction that people must consider.However,some systemic diseases such as diabetes,osteoporosis,and blood diseases can adversely affect the biological performance of titanium implants,such as bone conduction ability.Moreover,the surface roughness,morphology,electrochemical properties,and charge of titanium implants have important effects on the biocompatibility and osseointegration of implants,so various technologies and researches are focused on improving these factors.In the surface modification of titanium,titanium dioxide nanotube columns(TNTs)are nanotube structures prepared by anodizing titanium(Ti).They are characterized by highly self-ordering oxide nanostructures and various shapes,such as hollow,cylindrical,and six.Angular shape and so on,and because of this it has many unique features,it shows the ability to accelerate the adhesion or proliferation of osteoblasts,induce the release of cytokines,and affect the biological activity,so that the drug can be released.In addition,the nanotube structure is an excellent biomaterial,with a high surface area to volume ratio and a controllable size range,which improves biocompatibility,so that different sizes of nanotubes can be used to enhance osteoblasts Function.As a new implant,TNTs-modified implants have begun to be extensively explored in the fields of osteogenesis,tumor therapy,and drug loading.Importantly,TNTs can also be used as a carrier for therapeutic drugs and antibacterial drugs,especially on the drug loading,and its "test tube"-like structure gives the drug installation site.Many studies have focused on the research of implanting antibiotics,osteogenic proteins,anticancer drugs or anti-inflammatory drugs.Although nanotube arrays have been shown to have an effect on the interaction of bone cells and materials,the biological performance of nanotube array structures in the delivery of drugs,compounds,and biomolecules from implants to bone still needs to be studied in order to be clinically Application and use in oral implants.ObjectiveBy implanting implants of different experimental groups into the jaw bone of rats,the bone formation and the formation of bone in the inflammatory state were analyzed after implanting antibacterial drugs on the surface of TNTs.To evaluate the effect of TNTs surface implants on osseointegration under the condition of inducing bacterial inflammation.To study the mechanism of the effect of TNTs-Pac525 implants on peri-implantitis in rat jawsMaterials and methods1?Preparation of Ti,Pac525-Ti,TNTs-Ti and TNTs-Pac525-Ti.Commercial pure titanium is anodized.The commercial pure titanium is placed in the electrolyte,using a 16V voltage and an oxidation reaction for 4 hour to prepare the surface nanotube structure.Under the scanning electron microscope,observe the surface morphology of the nanotubes and analyze the diameter,shape and length of the nanotubes.2?Measurement Of surface contact angleEvaluate the material's hydrophobicity and hydrophilicity.0.1ml of distilled water was dropped at 5cm from the surface,and the surface wettability was measured The shape of the water droplets was measured with a stereo microscope,and the contact angle was measured to prove the hydrophilic behavior.3?Drug release curve drawingThe amount of Pac-525 released from the P-Ti group and TNTs-P-Ti group implants was measured using a spectrophotometer.From the day of drug loading,each sample was immersed in 1 ml of high-temperature sterilized physiological saline at room temperature,and the sample solution was transferred to a 24-well plate every other day,and the amount of drug released was measured by 290 nm ultraviolet detection.Repeat the operation for 1 week to determine the unknown concentration using the known Pac-525 concentration absorbance curve.(Pure titanium group:Ti group;Pac-525 carrying pure Ti group:P-Ti group;nanotube Ti group:TNTs-Ti group;Pac-525 carrying nanotube Ti group:TNTs-P-Ti group)4?The surface implants of TNTs carried Pac-525 in rats.The first molar of the left mandible in the left SD of an eight-week-old male SD rat of about 250 g was removed.After the new bone in the extraction socket is formed,a hole is drilled with a drilling machine at 900r/min,washed with saline and implanted with a 5*0.8mm implant,and the resonance frequency analyzer analyzes the mechanical stability of the implant.Think the implant is successful.And the use of silk thread embolism to introduce subgingival plaque,to induce bacterial inflammation in the surrounding environment.Micro-CT was used to analyze the osteogenesis process and bone healing.5?Rat jaw specimens were used to study the molecular mechanism of experimental peri-implantitis.The experimental animals were sacrificed by air embolism under anesthesia four weeks after implantation.Remove the implant and dehydrate and grind the bone tissue around the implant.After dissolving and extracting the tissue proteins,the Western Blot method was used to study the differences in the expression of RANKL,BMP-2 and BMP-7 proteins.qRT-PCR was used to analyze the differences in TNF-?and IL-1? gene expression.Result1.Preparation of TiO2 nanotube structure on the surface of titanium.Observed under FE-SEM.The pore structure is about 50nm ±15nm and the order is about 1.26?m.The densely arranged nano-scale tubular structure is ordered,but the surface of the untreated titanium implant shows Smooth surface.2.The average contact angle of distilled water on the Ti group surface is 46.3°,indicating that the surface is hydrophobic.The average contact angle on the surface of the TNTs-Ti group is 14.7°,and the average contact angle on the P-Ti group is 12.1°,indicating that TNTs-The Ti group and the P-Ti group have similar hydrophilicity.The TNTs-P-Ti group showed an average contact angle of 8.7°,and the TNTs-P-Ti group showed better hydrophilicity3.Perform Pac-525 mounting on pure titanium and nanotube Ti.Immerse the Ti surface in 10 ml Pac-525 solution.The result of spectrophotometric determination of Pac-525 release within 7 days of release was performed after the immersion step.Pac-525 refers to the concentration at 290 nm absorption peak.On the first day,the degree of Pac-525 released from the surface of the TNTs-P-Ti group was about 0.3 mM more than that of the P-Ti group.Two days after the release test,the P-Ti surface showed a significant decrease in the amount of Pac-525 released from the surface(<0.1 mM),while the surface of the TNTs-P-Ti group showed a continuously higher Pac-T until day 5.Pac-525 release volume and sustained release capacity.The results showed that Pac-525 was successfully loaded onto the surface of TNTs-Ti and could continue to be released from the nanotubes to the surrounding area for a longer period of time.4.The extraction process of the first mandibular molar of the left mandible of SD rats was smooth.Micro-CT imaging showed that there was no foreign body remaining in the extraction socket,and the surrounding bone was intact.See the clear alveolar space.5.After 4 weeks,the bone of the left mandibular first molar of SD rats observed by micro-CT healed well,and the bone density after healing was approximately the same as the surrounding tissue.6.Implanted into the first molar region on the left side of SD rats.The resonance frequency measured ISQ values were all greater than 75,and there was no statistical difference among the groups.One week later,the ISQ value of TNTs-P-Ti group was significantly greater than that of Ti group and P-Ti group,and greater than that of TNT-Ti group.After 7 and 4 weeks,micro-CT showed that the bone mass around the implant in TNTs-P-Ti group was significantly larger than that in Ti group.The BIC%value showed that the bone mass around the implants in the TNTs-P-Ti group was significantly greater than that in the Ti group,and greater than that in the P-Ti and TNT-Ti groups.8.Western Blot results of tissues around the implant showed that the expression level of RANKL protein in TNTs-P-Ti group was smaller than that in other groups.The protein expression levels of BMP-2 and BMP-7 in TNTs-P-Ti group and TNT-Ti group were greater than those in Ti group and P-Ti group.9.Analysis of qRT-PCR results showed that the expression levels of TNF-? and IL-1? in TNTs-P-Ti group and TNT-Ti group were lower than those in Ti group and P-Ti group.The TNTs-P-Ti group showed lower expression levels.Conclusions1.The nanotube structure can be prepared on the surface of pure Ti by anodizing reaction.In a stable reaction system,the structure of the prepared nanotube structure is dense and orderly.Measuring the surface contact angle is used to evaluate the hydrophobicity and hydrophilicity of different groups of implants.Distilled water has surface hydrophilic behavior in both TNTs-P-Ti group and TNT-Ti group.However,the TNTs-P-Ti group showed better hydrophilic properties.2.Pac-525 drug can be loaded on the surface of pure Ti and nanotube Ti,and both show the possibility of continuously releasing the loaded drug to the surroundings.But on the surface of pure Ti,the release of Pac-525 was significantly reduced after two days of drug release.The nanotube Ti surface showed a more sustained release process until the 7th day.These results indicate that Pac-525 loaded on nanotube Ti has the ability to continuously release drugs to surrounding tissues.3.The experimental implant can be smoothly implanted in the area of the first molar of the mandible of the rat,and all can obtain good stability.Through micro-CT evaluation of the new bone and bone density,it is analyzed that the first molar of the mandible of the rat is a suitable value to enter the site.4.Compared with other experimental groups,the nanotube Ti carried by Pac-525 showed the symptoms of reduced inflammatory bone destruction around the implant and enhanced bone formation ability.5.Through analysis of protein molecules,the nanotube Ti carried by Pac-525 has the ability to reduce the expression of RANKL and other inflammatory molecules.The structure of nanotube Ti has the ability to increase the expression of BMP-2 and BMP-7 proteins.It can stimulate bone formation to a certain extent.6.Through the analysis on the gene expression level,the expression of TNF-?and IL-1? inflammatory factor genes is obviously lower in the nanotube Ti group,while the nanotube implants with Pac-525 appear lower.It shows that the nanotube structure itself has a certain effect of inhibiting the development of inflammation,and sustained drug release also reduces the occurrence of peripheral inflammation to a greater extent. |
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