| Background:Dental caries, periodontal disease and trauma contribute for the defect and missing of the teeth in everyday life. In different degrees, the missing teeth affect the aesthetics, chewing, pronunciation and other functions. What’s more, the long-term missing tooth should affect the muscles and joints, which would make severe stomatognathic system disorders. Implants, because of its retention, strong chewing efficiency, aesthetics and comfort, have become an indispensable method for Stomatology. Two scholars, Andre Schroeder of the Sweden Gothenburg University and Perlngvar Branemark of the Switzerland Bern University, completed the basis of experimental studies with their groups, dental implants replacing some or all of the missing teeth have been accepted by the scientific treatment programs. They published some landmark papers in the late1960s and1970s, two research groups described the titanium bone implants osseointegration phenomenon, which is characterized as an active bone deposited directly on the titanium surface. Modern dental implantology research goal is to promote wound healing bone implants with good primary stability, it can afford immediate or early load. Therefore, scholars who worked on how to get the best and the stability of the implant osseointegration interface, tried their best to preserve the surrounding bone, in order to improve the long-term success rate of implant denture. The micro-arc oxidation (Micro-arc Oxidation referred, MAO) belongs to one of the electrochemical methods, combined with strength film and that has been used to the implant surface modification crystalline phase apatite content, it reflects the advantage. In the late1990s of the last century, the surface treatment of titanium by micro-arc oxidation technology has become a popular method. The research confirmed that titanium implant material surface by micro-arc oxidation treatment has no toxic effect on the growth and proliferation, cells with better than pure titanium planting material biocompatibility, and exhibits a good bone-inducing ability, thereby promot the growth of new bone tissue around implants, and shorten the time of osseointegration.However, it is reported the area of bone-implant after early osseointegration formed is only (45±16)%, up to50%-75%. Of the micro-arc oxidation treatment of early implant bone-implant contact (BIC) is only (49±12)%, far less than100%. Implant surface activity of micro-arc oxidation treatment to be further improved to make it more conducive to early new bone formation around the implant, and enhance the implant success rate.1972, A.Fujishima and K.Honda found the water photoelectrocatalysis (photocatajytic reaction) was found in the n-type semiconductor TiO2electrode decomposition, as an opportunity to start a new era in the study of heterogeneous photocatalytic. Photocatalysis is the photon excitation which can play a catalytic role collectively the basic nanotechnology and was born in the1970s. In1997, A.Fujishima published in Nature that TiO2also has photo-induced superhydrophilic phenomenon. TiO2oxide film on titanium implant osseointegration film after UV irradiation can induce high hydrophilic properties of the surface of TiO2oxide film because of organic pollution, while reduce the oxide film on the surface of carbohydrate, so that in recent years, people began to explore of modified TiO2oxide film of UV irradiation method and applied it in the oral implant surface modification of materials. Present study shows that TiO2surface of the super-hydrophilicity originates from the changes of light-induced:TiO2is a n-type semiconductor, the difference in energy between the corresponding to the forbidden band width of the anatase (valence band and the conduction band Eg) was3.2eV, and its maxmum wavelength is about380nm. After ultraviolet irradiation, under the wave length of380nm, TiO2valence band (filled with the highest electron with valence band, VB) electron is excited into the conduction band (and is not filled with electrons lowest band that is the conduction band, CB), the electron and hole to migrate to the surface, and the electronic and Ti4+reaction, the hole with the surface of the oxygen ion reaction, respectively, Ti3+and oxygen vacancy is formed. At this time, the air in the hydrolysis from the adsorption in the oxygen vacancy as a chemical adsorbed water (i.e. hydroxyl group of OH" is a hydrophilic group, forming hydrogen bonds easily physically adsorbed water, the material surface hydrophilicity), chemical adsorption the water can be further adsorbed moisture in the air, the formation of physically adsorbed layer. Then formed around the Ti3+defects highly hydrophilic micro-area, and the remaining region on the surface remained hydrophobic, thus constitutes the TiO2surface with a uniform distribution of nano-size separation of hydrophilic and hydrophobic regions, similar to the two-dimensional capillary phenomenon. As the water droplet size is much larger than the hydrophilic area, the macroscopic performance of the water contact angle on its surface is smaller. It has been reported that using the UVC band treat etching surface of pure titanium produced a super-hydrophilic, which promoted adhesion, proliferation and differentiation of osteoblast in the etching titanium surface and animal experiments BIC fourth week increased by51.7%to98.2%. UVC band ultraviolet processing micro-arc oxidation of titanium little studied. Our group early experiments using UVC and UVA band ultraviolet respectively process micro-arc oxidation of titanium surface, relative to without irradiating but micro-arc oxidation treatment group and the UVA band ultraviolet micro-arc oxidation treatment group, comparing the terms of UVA band, the UVC treatment group can significantly increase the protein adsorption, enhance the adhesion, stretching, proliferation and ALP activity to the MG-63cells. However, There is still not any report about osteogenesis state in vivo of the implant ater the UVC band ultraviolet irradiate micro-arc oxidation implants.Therefore, the purpose of this experiment is to use the UVC band ultraviolet process micro-arc oxidation of pure titanium implant surfaces, and implant in the tibia of New Zealand white rabbits,and observe bone integration at the early stage, in order to explore a new method of implant surface treatment.Object:To investigate the osteogenesis state at early period and the condition of bone integration after ultraviolet irradiation of micro-arc oxidation surface of implants, in order to achieve early contaction of bone tissue to the implant surface, and improve the osseointegration rate period.Methods:1. Implant group and surface treatmentImplant divided into two groups:the control group is micro-arc oxidation (MAO group), and the experiment group is micro-arc oxidation after UVC band ultraviolet irradiation (UVC+MAO group). Using commercial two grade titanium rod to make certain specifications of the particular implant, which has a ring of the two bone ring cavity, after the surface treatment, bone formation can be highlight,then using ultrasonic cleaning with anhydrous acetone, ethanol, and deionized water. Implants were treatrd in an aqueous electrolyte containing glycerophosphate disodium salt and calcium acetate at a low temperature. The processing parameters such as:voltage350V, frequency800HZ,20%duty cycle, the oxidation time30S, and ultrasonic cleaning with deionized water; We use some of the MAO implants to irradiated by15W UVC germicidal lamp in a sterile environment,5cm close to the material surface, and irradiated48h. Both groups were stored in deionized water, after the backup we use the y-ray sterilization.2. Selection and grouping of animals:We selected26healthy female New Zealand White rabbits with the general level. The rabbit aged5-6months, weight is2.7to3.2kg.26rabbits, we choose one randomly as a surgery model model, and been sacrified after a week, using the same kind of treatment at the same surgery site. We choose the other one randomly to be a surgery model as the treatment group and it was sacrified after4weeks. Remaining24rabbits were divided into three groups (2,4,6weeks),8rabbits of each group.3. Experimental procedure: Surgical procedures:experimental rabbit anesthesia under supine epiphyseal line of the left and right tibia, respectively, in the rabbit tibia proximal end of the preparation osteotomy, we randomly choose the rabbit left leg tibial implanting MAO group and the right leg tibial implanting UVC+MAO group, implantation sites in the tibial metaphyseal line bias near the heart end, which is rich in cancellous bone,and far away from the bone marrow cavity.Implant in the cancellous bone within the unified implant and surrounding bone relative growth environment, to facilitate future histological observation and comparison. The implant depth need flush with the bone surface.We start the operation of establishing the animal models according to the schedule. After3days of the surgery, we use intramuscular gentamicin to prevent infection. At the13th,14th day before sacrified, the animals (4W,6W) injected subcutaneous of tetracycline hydrochloride (30mg/kg),4th,3th days prior to sacrifice, the rabbits (2W,4W,6W) injected subcutaneous of calcein (lOmg/kg). Rabbits were sacrified according to the schedule, the separation of the tibia to obtain bone specimens with implants, dental CT scan implantation site and placed in10%formalin4℃generally osteogenesis fixed one week, and washed with running water24h. The specimen is divided into a size of1.0cm×1.0cm×1.0cm. The specimen was gradient dehydration with ethanol, chloroform transparent and then using methacrylic resin embedding. Using the Leica SP1600hard tissue slicer cut the specimen into150-200μm thick. And use a fluorescence microscope to observe the fluorescent effect, measurement of new bone mineral apposition rate. Then we use hand-grinding to produce bone grinding with thickness about50-70μm, and then use methylene blue-acid fuchsin staining with an inverted microscope line. Histological observation and measurement of implant-bone combined length of the implant into the range of the two sets of bone concave bone area.Results:1. General observationAll animals are in good growth and recovery after experimental, the animals in each group had no deaths, wound inflammation and without dehiscence. Each rabbit implanted two implants, a total of26rabbit,52implant, and found no implant fall off. Incision of skin, muscle and tibia near the knee joints periosteum, we can see in the6w group have all of the bone tissue implant surface covery. In4w group, there is some bone implant surface covery, and2w group with a slightly small bone implant surface covery or completely leveled bone exposed, both the group have no obvious difference.2. Observed by fluorescence microscopy and calculated bone mineral apposition rate (MAR, μm/d)New bone was adhered fluorescence issued with green (calcein) and yellow (tetracycline).2W two groups was no significant difference in the total fluorescence, we can easily observed the green fluorescent as reticular.UVC+MAO group can be obviously found significant fluorescence close to the bone cavity and the MAO group the fluorescence multi distance implant bone ring cavity have a certain distance. The4W group tetracycline amount of yellow phosphor is increased significantly, and green fluorescent calcein reticulation two fluorescently labeled smaller spacing. The amount of fluorescence emitted by the UVC+MAO group is slightly much more than MAO group. Visibly of UVC+MAO group,the fluorescent basic thread attached to the bone ring cavity surface, and part of the fluorescence from the surrounding bone tissue to the implant-bone ring cavity secrete new bone (MAR:4.50±1.80μm/d). MAO group fluorescence from the implant-bone ring cavity distance to a certain irregular, most of the fluorescence from the surrounding bone tissue to the implant-bone ring cavity secrete new bone (MAR:2.75±0.67μm/d). According to independent variance t value, and correction of the degrees of freedom, the test results: t=-4.98, the v=36.769, P＜0.001;4W experimental group and control group difference was significant.6W group fluorescence emitted is relatively wide, and the yellow-green fluorescence labeled interwoven annular flaky, of linear or mesh the spacing of two fluorescent-labeled width than4weeks, new bone formation active. Total fluorescence emitted by the UVC+MAO group (MAR:6.91±2.36μm/d) than MAO (MAR:4.42±1.21μm/d) group and more. The two groups of fluorescent display new bone growth of new bone and the bone around the wall to the implant surface secretion close to the implant surface together into one, no boundaries. The test results:t=-5.13,v=43.311, P<0.001; six weeks experimental group and control group difference was significant.3Histological observation and calculation Implants-osseointegration (BIC%) and new bone area (BA%)Optical microscope observation methylene blue-acid fuchsin chip,2w, less the amount of new bone, slightly more new bone is located in the UVC+MAO group near the surface of the cortical bone ring cavity than in cancellous bone into bone mass. No significant chunk of osteoblasts, mostly for small amounts of trabecular bone, and slightly slender bone small visible close to the implant surface, while the surrounding bone tissue convex new bone to bone ring cavity. And the MAO group of bone ring cavity full of deep blue osteoblasts, osteoid, fibrous tissue or muscle tissue, and a certain distance from these organizations and the implant surface. Part of the secretion of new bone is protruding from the surrounding mature bone tissue to the ring cavity deposition. Between the two groups of cortical bone area implants-osseointegration percentage difference was statistically significant (F=7.285, P <0.001), and the experimental group BIC%(48.156±19.058) was significantly higher than that of the control group (10.452±8.080). Between the two groups of cancellous bone area implant-osseointegration rate difference was statistically significant (F=5.57, P＜0.001), the experimental group BIC%(31.009±16.714) was significantly higher than that of the control group (6.815±4.750). The difference was statistically significant (F=5.415, P＜0.001) between the two groups implant cortical bone area percentage of new bone area (BA%), the experimental group BA%(42.890±21.061) was significantly higher than that of the control group (13.355±5.691). Between the two groups of cancellous bone implant area percentage of new bone area (BA%) difference was statistically significant (F=5.046, P＜0.001), the experimental group BA%(20.461±11.592) was significantly higher than that of the control group (5.102±3.723). Slightly more than the amount of new bone implant4weeks of the UVC+MAO group, part of the the bone ring cavity visible into new bone surrounding mature bone tissue is convex to the the bone ring cavity formed trabecular bone and implant surface new bone. Still most of the blue osteoid as well as a small amount of new bone trabecular the MAO group bone ring cavity. Between the two groups of cortical bone area implants-osseointegration percentage difference was statistically significant (F=3.282, P=0.003), and the experimental group BIC%(52.934±20.482) was significantly higher than that of the control group (31.288±16.622). Between the two groups of cancellous bone area implant-osseointegration rate difference was statistically significant (F=4.572, P<0.001), the experimental group BIC%(51.025±20.369) was significantly higher than that of the control group (25.061±10.059).Between the two groups implant cortical bone area percentage of new bone area (BA%) the difference was statistically significant (F=3.683, P=0.001), the experimental group BA%(53.160±21.831) was significantly higher than that of the control group (29.185±14.194). Between the two groups of cancellous bone implant area percentage of new bone area (BA%) difference was statistically significant (F=4.333, P＜0.001), and the experimental group BA%(41.931±15.445) was significantly higher than that of the control group (20.591q12.228).6weeks, the UVC+MAO group of fresh bone than MAO group. Where new bone tissue in the bone ring cavity together into a bone around mature, visible lamellar bone and haversian tube cancellous bone area part of the implant into the bone ring cavity slightly less bone, new bone is continuously deposited mineralization, better continuity of bony plates. The MAO group cortical bone closely integrated, new bone tissue is converted into lamellar bone. Between the two groups of cortical bone area implants-osseointegration percentage difference was statistically significant (F=7.067, P＜0.001), and the experimental group BIC%(63.011±7.024) was significantly higher than that of the control group (48.623±4.120). Between the two groups of cancellous bone area implant-bone contact ratio difference was not statistically significant (F=1.978, P=0.057), experimental group BIC%(53.648±9.535), control group (48.030±6.183). Between the two groups implant cortical bone area percentage of new bone area (BA%) the difference was statistically significant (F=6.336, P＜0.001), the experimental group BA%(71.640±6.605) was significantly higher than that of the control group (58.237±5.289). Significant difference between the two groups of cancellous bone implant area, percentage of new bone area (BA%) was significantly higher than that of the control group (F=2.866, P=0.008), the experimental group BA%(64.924±12.915) was significantly higher than that of the control group (53.396±9.597).Conclusion:1. Implant with annular bone cavity through the bone defect bone ring, comparison of different surface treatment methods on the osteogenic effects, including osteoblast mode in different time and bone.2. After UV treatment of micro-arc oxidation of titanium implants in animal in vivo, early can promote osseointegration. Cortical area BIC is4.8times more than MAO group; cancellous bone area is4.5times more than MAO group. With the passage of time, the effect of ultraviolet radiation is weaken, bone integration effection difference between them is reduction.3. After micro-arc oxidation of titanium implants with UV treatment, early osteoblast mode for bidirectional bone (on the one hand, bone ring at the bottom of a new bone grow to around, on the other hand, the peri-mature bone grow into bone ring). But MAO Group of early bone mostly is formation for distance bone. At2weeks, UV treatment group’s new bone formation area has reached43%, while only13%in group of MAO group.4. The early cortical bone formation rate is faster than the cancellous bone, which is2times than that of cancellous bone, as time goes by, the new bone in two groups of cortical bone and cancellous bone region formation rate difference is not obvious.5. After the UV irradiation,the mainly effect is for the osteogenic accelerated at early bone formation, but there was no obvious effect on osteogenesis in the bone mineralization rate. |
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