| Background:Implant materials are required to have good biocompatibility, stable physical and chemical properties, and be convenient for processing. Most implant materials adopted at present are titanium. Many scholars tend to use titanium plasma sprayed technology and acidic etching technology or their axiomatic method (such as laser lithography) to change the morphological characteristics and composition of the surface of implant, and increase contact area between implant and bone, with the purpose of achieving a good initial stability. However, implanting false tooth requires a long-term stable bone integration as well as a good aesthetic effect, while the integration of soft tissue is also an important warranty for a successful implantation. At present, more and more scholars have moved their focus on soft tissue integration and aesthetic effect in the study of the implant.It is usually believed that if the implant can achieve a good initial stability after being implanted, the mineralization of the new bone is usually less happened after healing for three months, thus the stability of forming and reconstruction of the bone is achieved. The mineralization rate of the new bone can be detected in a dynamic way through the two-color fluorescent labeling method.The gum and mucosa soft tissue around the implant are directly attached to the surface of the implant or the abutment, forming the soft tissue cuff of the implant. Most implants are composed of smooth neck and rough body, and the soft tissue cuff of the implant usually contacts with the smooth neck directly. However, in clinic, bone abstraction around the implant is usually occurred due to different reasons, and the shrinkage of the soft tissue will lead to a direct contact of the soft tissue cuff with the rough body. For instance, in case of soft tissue shrinkage due to treatment of inflammation excision or due to bone abstraction as the implant is not implanted deep enough or the implant is overload, then the soft tissue of the implant will be directly attached to the rough surface. It is found in clinic that the early Branemark implant will be directly attached to the mechanical surface after shrinkage of the soft tissue cuff, and will remain stable even after using for a long time. The purpose of this study is to determine whether a long-term stability will be achieved if the soft tissue cuff of the implant shrinks to the rough surface of the implant as it is attached to the smooth neck.A health soft tissue cuff of the implant can help to form a good biological closure, which can protect the implant from infection of foreign germs and microorganisms. There is not a final conclusion on the soft tissue cuff in different papers or thesis. Some scholars believe that the rough implant surface can help the epidermal cell to grow and extend, but on the smooth implant surface, the cells grow in a flat way. The close epidermal contact is good for maintaining a biological closure. The rough surface can also help increase the contact area of the implant with the bone, and to compare with the smooth surface, it can effectively increase the stability of the implant.The study aims to compare the histological characteristics of the soft tissue cuff attached to smooth neck and rough neck through clinic probing index, new bone mineralization apposition rate and histological observation of the implant with different surface treatment three months after heating.Objects1. Prepare four Beagles, extract four premolars at both sides of lower jaw of each Beagle, then implant with implants with different surface treatment to build the experimental animal model. During the3months healing period, to compare the clinic probing index of the different implants one month, two months and three months after the implantation respectively.2. Use the two-color fluorescent labeling method to measure the distance between the fluorescence tapes at different times before killing the experimental animals to compare the new bone mineralization apposition rate after healing for three months of the implants with different surface treatment.3. After killing the experimental animals, make the specimen of the mandible with implant and conduct Micro-CT scanning on it to analyze and measure the bone generation effect between the threads of the implant, and to compare the difference in the parameters of the bone after healing for three months of the implants with different surface treatment.4. After making specimen, make the bone slice with implant through plastic embedding technique, and then use a microscope to observe the histological characteristics of the soft tissue cuff of the implants with different surface treatment.Methods1. Experimental animalsFour adult male Beagles with the age from12to14months and weight from14.7kg to18.0kg were selected. The tooth form of Beagle was2(13/3, C1/1, Pm4/4, M2/3), with42teeth in total. The experimental animals were normal in biochemical index and mentally, and were free from any acute inflammation, infectious diseases, chronic periodontal disease, caries or defective occlusal. The animals were kept in animal experimental center of Sun Yat-Sen University in different cages with a regular diet.2. Experimental designDesign of implant and group:The implant was presented by OSSTEM implant from South Korea, and was produced in the specifications of diameter4.1mm and length4.1mm according to SS II implanting system. The implants were required to be produced with different surface treatment and different roughness. The implants can be divided into4groups according to different surface treatment, which were MM, RBM, SA and Bio-SA. After extracting the teeth of the four Beagles, allowed them to heal for3months and then measured the distance of the spacing of tooth loss. It was designed that each Beagle will be implanted5implants at each side and40in total, each of groups were implanted10and allocated with a random serial number.3. Building animal modelThe four Beagles were allowed to adapt the implants for one week before preparing the experiment. No eating or drinking12hours before the surgery. Intramuscularly injected400,000u/d penicillin2hours before the surgery, then extracted four premolars at both sides of lower jaw of each Beagle under the combined anesthesia of Sumianxin and pentobarbital sodium. Three days after the surgery, intramuscularly injected800,000u/d penicillin. Took CT and observed the healing of the wound regularly. After healing for3months of the wound, cut from the alveolar ridge crest and lifted up the mucosal flap, and implanted5implants in each side of the lower jaw. Three days after the surgery, intramuscularly injected800,000u/d penicillin. The implantation should be carried out by experience expert. The animals would be killed after healing for3months.4. Measuring clinic indexOne week after the implantation, observed the heating of the implanting area. Made sure there was no infection or loosing around the implant. Performed clinic probing examination one month, two months and three months after the surgery respectively to check loosing of the implant and percussion sound, and measured plaque index (PLI), gum index (GI), sulcus bleeding index (SBI), bleeding on probing (BOP), probing depth (PD) and distance from the healing top to the gum edge.5. Measuring Micro-CT indexAfter making the mandible specimen, fixed it for4days in10%formalin, then soaked in70%alcohol. Before scanning, wrapped the entire specimen with plastic cling film to avoid drying and thus affected the result of histological observation. After scanning, continued soaking the specimen in70%alcohol.6. Measuring fluorescent labelingBefore13or14days killing the four Beagles, performed hypodermic injection of10mg/ml tetracycline at their necks according to30mg/kg weight, and then performed hypodermic injection of10mg/ml calcein at their necks according to10mg/kg weight3or4days before killing them to fix the specimen and embed it in the methyl methacrylate. Used Leica1600hard tissue slicing machine to cut the specimen into slices and observed the two-color tapes using a fluorescence microscope, then measured for several times to get the average distance between the two tapes for comparison.7. Histological observationAfter making the specimen, fixed it in10%formalin, dewatered gradually with alcohol and soaked in embedding liquid, then warmed up for polymerization to complete the final embedding. Cut the specimen into thick slices using Leica1600and polished and washed the slices manually, then dyed with methylene blue-acid fuchsin, sealed the slice, and moved it to the microscope for observation.8. Statistics analysisSPSS13.0software was used for statistics analysis. The comparisons of the changes in PD of each group one to three months after the surgery, BVF, Tb.N, Tb.Th and Tb.Sp after treating the trabecular in four different ways, the measurement of the four groups when the fluorescent was in the thread or far away from the thread, and the length of the histological observation were carried out through One-Way ANOVA; the comparison of the probing of the four groups one to three months after the surgery was carried out through the comparison of the different grade/frequency data in K Independent Samples Test; the measurement of the fluorescent and the comparison of the areas between the threads and far away from the threads were carried out through Paired-Samples T Test. The test standard was α=0.05.Results1. General observation After the surgery, no animal was dead and their diets and activities were normal; the wounds were well healed, the mucosa was free from swollen, bleeding, and the implant and healing cap were free from losing or dropping, with a maintaining rate of100%. As a result, the animal model of the four Beagles was built successfully.2. Measuring probing indexThe4groups imlpants After the1month,2months and3months operation are no statistical significance in PD.There is no significant difference in BOP and GI after1month operation,and it is considered the same.There is significant difference in PI and SBI and it is considered that the PI is the least in MM group,and Bio-SA,SA and RBM following it.And the SBI is the leaet in MM,and Bio-SA,RBMand SA with the following.There is no significant difference in PI and GI after2months operation.However,it is considered the least in SBI and BOP for they have significant difference,and following are Bio-SA,SA and RBM;There is no significant difference after3months operation in4groups and considered it is the same in health index of the implants soft tissue cuffs.3. Result of Micro-CT measurementScanned the specimen through Micro-CT for bone analysis, and carried out bone analysis through measuring BVF, Tb.N, Tb.Sp and Tb.th. Through statistics analysis, the result of the comparison showed there was no evident different between RBM and SA, but evident differences were found in comparisons between other groups, in which Bio-SA had the highest relative bone volume fraction (BVF), trabecular number (Tb.N) and trabecular thickness (Tb.th), while MM had the lowest ones. However, MM had the highest trabecular separation (Tb.Sp), and Bio-SA on the contrary.4. Measurement result of two-color fluorescent labelingAfter killing the experimental animals, observed the two-color fluorescent labeling tapes through a fluorescent microscope. The orange fluorescent tape was closer to the implant, and the bright green fluorescent tape was farther away from the implant. Measured the distance between the two tapes and the time interval of the two drug administrations, the speed of the new bone mineralization apposition can be calculated. Through analysis calculation, no evident difference was found in the comparison of the measurement of the four groups fluorescent of in the thread; to compare the area between the threads with the area far away from the threads of the four groups of implants, the results showed that there was evident difference in fluorescent measurement between threads and area far away from the threads between MM and Bio-SA, but there was no difference between RBM and SA.5. Histological comparisonAfter making bone slicing specimen through plastic embedding and through dying with methylene blue-acid fuchsin, the changes in the soft and hard tissues around the implant can be observed successfully. The soft tissue was dyed into blue and the bone tissue was dyed into red. Through comparing the histological changes in the soft tissue cuff of the implant, no evident difference was found in the arrangement and adsorption of epithelial cells, and the growing direction of the collagen fiber (all from the neck to the root of the implant) of different soft tissues. But by comparing the horizontal distance between the gum edge and the implant through statistics, the smooth neck and rough neck directly had the statistical significance. It showed that the epithelial is most closely attached to the implant with rough surface, which was a better way to accelerate forming of the biological closure.Conclusions1. The alveolar bone shape and density of Beagles are similar with human beings, and they are easy to feed, with strong life force and mild character and is cheap in economy, so they are the first choice for dental experimental animals. Through implanting the implants after extracting teeth of the Beagles, the consolidated experimental animal model for the implants and bones can be successfully built.2. Four Beagle dogs were planted implementation after the operation, and the prognosis was good. Probing diagnosis results showed that:There is significant different in PI,GI and SBI,but within the normal ranges.we can think that the stability of the soft tissue can be obtained after3months.But the PD numerical was not statistical significance. 3. Through measuring and analyzing the generation of the new bone after three months using Micro-CT, it was believed that Bio-SA had the highest Tb.N and BVF, while MM had the lowest Tb.N.4. Fluorescent measurement and analysis:By comparing the new bone mineralization apposition rate with different surface treatment, it showed that after three months, there was still new bone generation in the threads of MM and Bio-SA implants, but less bone generated in the area far away from the threads. It was believed that MM and Bio-SA implants haved more bone mineralization around the implants after three months.5. Histopathologic study show that:different ways of surface treatment plant body soft group cuffs were compared through the production plant body with the hard and soft tissue abrasive disc. The conclusion was that the growth of connective tissue, combined with epithelium and the collagen fiber direction had no significant difference, and Rough surface soft tissue cuffs angiogenesis aer more, and fiber content are less, smooth surface is opposite. |
PDF Full Text Request