| Background and Objection:In the1980s, surface structure of dental implant was identified as one of the six factors which were very important for implant incorporation into bone, So far,30years had been past, the studies of the implant surface topography and physicochemical properties are still very popular. Today, they are the hot topic in the field of Oral Implantology yet! The implant surface treatment methods are still studied by a large number of scholars, because the physical and chemical characteristics, the morphology of implant surface can not only determine the bone tissue cell attachment, proliferation and differentiation,even the speed of healing rate between bone and implant were determined by it in a large extent. It was one of the important criterions for assessment of an implant system merits. Although the planting surface treatment method had reached an good effect in osseointegration, but each significant change in oral Implantology areas would usual be happed followed the discovery of surface treatment. It was endless in academic study of implant surface treatments. Shorten the implant healing time and reduced pains in dentition defect patients in futher are still a pursuit and expectations of basic and clinical researchers. In the methods of implant surface treatment, they mainly divided into coated and uncoated processings, but many researches show that the non-coated implant surface treatment was better than the coated one, it has become the the main stream of implant surface treatment. Of course, adding the active substances in the non-coated surface has also appeared in the treatment study in recent years, but these are still in preliminary study stage. Non-coating surface treatment was frequently used with physics, chemistry and electrochemical methods such as Sand blasting, Anodizing and Etching to roughened titanium implant surface directly, so as to further improve the quantity and quality of the implant osseointegration.In recent years, the Sandblasted and Acid-etched (SLA) surface has been widely used in implant surface treatment, it’s mechanical biocompatibility has been recognized. The holes with diameter10-30μm in the implant surface can be obtained by the large particles blasting, these holes were good for the bone formation. Meanwhile, a large number of pores (size at about1-3μm) were formed by the acid-etched method. To some extent, titanium implant surface was also cleaned, that would increase their surface hydrophilicity,so it had primary and secondly roughness. It could be said that, the primary roughness was helpful to the osteoblasts adhesion, and proliferation and differentiation of osteoblasts could be stimulate by secondly roughness. In addition, the fact that sandblasting plus etching could increase the the implant torque values significantly had been confirmed. Therefore, from some famous implant systems in the world, we found that they dealed the surface with a sandblasted etching method, such as Switzerland straumman implant system (SLA/SLActive), Ankylos system in Germany. All these systems had the good osseointegration in clinical and the clinical treatment time was further shorten. Although the sandblasted and acid-etched surface had so many advantages, but it also had some certain disadvantages:such as sandblasting was out of control, the size of the holes directly affected osteogenic performance of implant surface. The size of the holes was mainly affected by the particle size, pressure and sandblasting distance. SLA surface treatment technology failed to meet the real pollution prevention and surface purification. The sandblasting particle such as Al2O3embedded in the surface was harmful for osseointegration, these inadequacies prompted scholars to do continue in-depth study!In recent years, with the continuous advancement of laser science and oral implantology, laser surface treatment as a new technology was gradually being introduced to the field of implant surface treatment Laser used in material processing and medicine had a long history, but officially applied to etched and roughened implant surface just began nearly10years. Different from the above-described conventional surface treatment technology, The laser surface treatment was a non-contact technique, having accurately controllable, highly reproducible and efficient and other characteristics. It could produce unique surface morphology and surface material and increase corrosion resistance of the titanium surface. Using different laser surface treatment technology for treating titanium alloys could achieve the purpose of improving the titanium alloy surface properties, or could add the bioactive, such as the laser alloying surface (LSA), Pulsed laser deposition (PID) and laser cladding ceramic coatings and other technology had been widely used. Shan-hui was successed in using the laser irradiation for sterilizating and cleaning the implant surface. Through the vitro and vivo experiments, they found that it can increase the adsorption of osteoblasts and bone formation on implant surface significantly. Recently, the Nd:YAG laser was used to increase the surface areas and roughness, the study suggested that the surface was more suit for osteoblasts to grow and increased torque and implant-bone contact significantly. Itala’s experimental results suggest that the diameters of the hole in40or50μm were more more conducive to bone than the diameters of100μm; The different diameter and deep holes in the implant surface were studies by Davide Berardi, it concluded that a hole with a diameter of30μm, depth of20μm in the surface by the laser processing was more conducive to implant osseointegration; The holes on the implant surface by Sandblasting techniques were generally in the diameter of10to30μm. Recently, the pore size with the diameter of40μm, a depth of23μm treated by laser, Sang-Hwan Kang found that laser surface was more than the micro-arc surface can help increase the implant bone torque; According to the above literature, it can be speculated that the diameter of the holes of10-50μm is more conducive to bone ratio of greater than100pm diameter binding. In addition, the roughness values was an important indicator to affect the implant osseointegration of sandblasting and etching surface. Wihtout controllable, different diameter of spray particles and sandblasting time and other factors would have a different effect of sandblasting, Such as the SLA surface of ITI Straumann dental implants, the Ra value was2.93μm, the pit diameter was about2μm; the3i dental implant(USA) with the surface Ra value of0.86μm, the pit diameter of2μm; the Frialit-Xive with the surface Ra value of2.75μm, the main pit diameter was3to5μm, the pit depth was2to3μm. Thereby the biological activity of the generated surface of these methods could be inferred by the above will also vary, a uniform good value of Ra was not existed at the moment, just only one range. More and more studies implied the diameter of the pit from1to4μm,the roughness values from1to3.62μm implant were more conducive to bone cell adhesion, while the roughness values greater than3.62μm was not conducive to bone tissue attachment. What the value was more conducive to osseointegration needed further study.Lasers for implant surface treatment mainly included YAG laser and CO2laser, but the YAG laser was more suitable than the CO2laser in it[291, mainly reflected in the punch with high average output power, high repetition frequency, and having high brightness, high focusability, easy to achieve the fine processing characteristics. studies abroad have shown that:no cell toxicity on the titanium surface after the Nd:YAG laser irradiation, it was better than a smooth titanium surface to promote osteoblast attachment and osseointegration. In addition, compared with the blasting treatment, laser-treated was clean and controllable, the accurate formation of the desired hole size and uniform three-dimensional cavity could be created by it. Many scholars believe that:in viable surface treatment technology, only laser treatment had no contaminate to implant surface at the moment. The energy, pulse angle and wavelength of the laser irradiation had a close relationship with implant surface morphology and chemical changes. Fiber laser as the representative of the third generation of laser technology, with unparalleled technical superiority of other lasers: the advantages beam quality,1micron resolution, which was about10times than that of traditional products, the marking speed was3-5times higher than traditional products, and low power consumption. In addition, the price of fiber lasers was greatly reduced, which was possible for us to use. In recent time, Cho SA and Sang-Hwan used the fiber laser to obtain good implant surface morphology and better osseointegration. It was worth to mention that the implant surface treatment development trended to a combination of different methods, such as the recent reported in sandblasting etching and micro-arc oxidation, micro-arc containing silver and non containing silver and other integrated approach between the surfactant and bone effects1. For example, the implant surface treated with the Sandblasted/acid-etched firstly, and laser processing secondly to change surface morphology to seek better methods. This year, Prodanov’s study was the latest research in laser implant surface treatment reports, there was the comparative study of laser-treated with the Sandblasted/acid-etched. both of them obtained good osseointegration. It provided timely experimental basis and theoretical basis for further study in laser surface treatment.In summary, although there had been numerous studies about the laser-treated and the Sandblasted/acid-etched, but a comparative studies about the laser plus acid etching with sandblasting plus etching were not seen in reports. Whether the osseointegration of Laser-treated/acid-etched surface had the some effect as or better than the Sandblasted/acid-etched surface was to be determined yet. Some relative comparative study on the urgent need; In addition, our research group had been done comparative study about Laser-treated/acid-etched surface and the acid-etched surface, we found that Laser-treated/acid-etched surface had good biocompatibility and osteoconduction. Based on some new developments of laser surface treatment, The study was intended to changed some conditions of the laser processing, narrowing the diameter of etching holes and combined with the acid-etched, and then made a comparative study with the sandblasted/acid-etched surface by animal experiments, so as to provid experimental basis and theoretical basis for in-depth study of the Laser-treated/acid-etched, to seek a better implant surface treatment technology eventually was also the experimental target.Methods and materials1. Preparation of laboratory samples:based on a large number of domestic and foreign literature and research purposes, using precision CNC machine tools to produce an experiment implant; By surface treatment method, according to pre-determined and related experimental parameters, prepared two good implant surfaces:the Laser-treated/acid-etched surface and the sandblasted/acid-etched surface. 2. The test of physical and chemical properties:measure the morphology, roughness, elemental composition with scanning electron microscopy, X-ray photoelectron spectroscopy and BMT Experi3D surface topography instrument, respectively, to assess the physical and chemical properties of SLA and LA surfaces.3. Animal model and implantation:New Zealand rabbits were used in the study of different implantation sites of the proximal tibia to osseointegration, implant were installed in3different sites-,4beagle dogs as experimental animals. According to the principle of random allocation, two different surface implants were installed into each side of the tibia, numbered them from the top to down with No.1to8, each treatment group had4implants in one tibia. At a certain time interval, made some subcutaneous injection with a hypodermic calcein and tetracycline color marker, experimental animals were sacrificed at2,4weeks,1-4implants were used to production of bone tissue slices,5-8implant for torque measurement.4. Making implant bone tissue sections and measurement of experimental:After decalcification, the anatomy of the rabbit tibia were made into paraffin section for HE staining observing; The bone tissues with implant were used to made sections of undecalcified, osseointegration growth rate and the BIC%was assessment and calculated by the fluorescence labeling and staining.5. The measurement recorded torque measurement value and BIC%data, statistical analysis obtained experimental results.Statistical analyses:The experimental data are expressed as mean±standard deviation (SD). Statistical analysis was carried out by SPSS±v13.0software (SPSS Inc., Chicago, USA). For the single factor data, when meet the normal distribution and homogeneity of variance, using two independent sample t test and single factor variance to the overall mean comparison; When the data not meet the normal distribution or variance not neat homogeneous, using two independent sample t’test or rank sum test; For two factors of single variable data with normal distribution and homogeneity of variance, to analyse the main effect and interaction by analysis of variance of factorial design. Hypothesis test for two-sided test, the test level was0.05, probabilities (P)>0.05was considered to be no statistically significant; Probabilities (P)<0.05was considered to be statistically significant.Results:1. Through access to a large number of domestic and foreign literatures and combined the purpose of the present study, using precision CNC machine tools produced some experimental implant. According to pre-set surface treatment methods and experimental parameters, two different implant surfaces were made: Laser-treated/acid-etched surface and Sandblasted/acid-etched surface.2. Results of the physical and chemical nature detecting:both of SLA and LA obtainted two rough structure, the surface roughnesses of LA was bigger than the SLA (LA:Ra=2.1μm; SLA:Ra=1.53μm)(P<0.01). Some melt was still obserted in LA surface, but the carbon material could been cleaned by the acid-etched; the sharp edge of the etching was visible on the surface of SLA, few oxide aluminum particles was still existed.3. The different implantation sites in the selected20mm area of rabbit’s tibias demonstrated different early osseointegration (P<0.05).4. No significant difference was found in torque measurement value and the BIC%in two and four weeks between two groups (P>0.05), both groups obtained good osseointegration. Conclusion:In the present study, the different implantation sites in the selected20mm area of rabbit’s tibias demonstrated different early osseointegration; the sites located7±1.5mm below the epiphyseal line were best suited for observing the effectiveness of early osseointegration among the3sites; The surface treatment methods of the Laser-treated/acid-etched and the Sandblasted/acid-etched could produce the rough surface, the former was more cleaner and more uniform than the latter, but both of them had good biocompatibility and promoted a good implant osseointegration, these two methods were feasible for implant surface treatment. Further studies were still needed. |
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