The Preliminary Research On The Preparation And Performance Of Polyvinyl Alcohol

Due to the aging population and living conditions,the number of patients with tooth loss who need incremental soft tissue repair is as high as hundreds of millions of people every year.It is a long way to go.It is very important to promote the research of incremental soft tissue repair.Polyvinyl alcohol hydrogel(PVA)is considered as an ideal material for incremental soft tissue repair because of its good biocompatibility,high water content,similar structure and mechanical properties to natural cartilage.However,the PVA hydrogel was soft and irregular after drying,and the PVA hydrogel extract could inhibit the proliferation of mouse fibroblast L929 significantly.These problems limit the application of PVA hydrogel in soft tissue increment.In this paper,Methyl sulfonyl methane(MSM)was introduced to improve PVA hydrogel property.In this paper,MSM/PVA hydrogels prepared by crosslinking have excellent water swelling,stable biodegradability and certain chemical properities.It has broad application prospects in cartilage,cornea,nucleus pulposus,skin and other tissues transplanation,repacement,repair and reconstruction.However,the appication of MSM/PVA hydrogel needs further study,in the matter of oral soft tissue increment,especially in the study of biocompatibility and feasibility of expanding soft tissue increment.In this study,we will lay a theoretical foundation for the application of MSM/PVA hydrogel in clinical oral soft tissue increment.Part ? Preparation and swelling properties of MSM/PVAObjective:The present study aimed to prepare MSM/PVA hydrogels by repeated freeze-thaw physical crosslinking method and study the swelling properties of MSM/PVA hydrogels.Methods:The power of polyvinyl alcohol was dissolved by deionized water in high temperature,to blend into different concentration,10%,12%and 15%.Various experim-ental results show that,the concentration of 12%polyvinyl alcohol has the better physical and chemical properties.Adding different amounts of methyl sulfonyl methane into polyvinyl alcohol,the concentration of methyl sulfonyl methane are 0.01%,0.1%,1%and 10%.The statistics results of various tests show that the properties of polyvinyl alcohol and methyl sulfonyl methane-polyvinyl alcohol have no difference.It illustrats the property will not be changed when adding methyl sulfonyl methane.The different concentrations of MSM/PVA were analyzed by electron microscope,mechanical property,water content and swelling.RESULT:The prepared hydrogel was hard and uniform,and smooth surface.In simulated body fluid at 37?,the volume of prepared hydrogel was increased by three times.The hydrogel of 15%has the faster water absorption,10%hydrogel has the slower in inital stage.After immersed 8 days,the volume of all the samples reached 95%of the maximum volume.The volume of the sample tends to be stable about 10 days.There is no obvious dissolution in 60 days.CONCLUSION:The above test results show that,prepared hydrogel have the best physical and biological properties.Part II Study on biocompatibility of MSM/PVAObjective:MSM/PVA hydrogel was co-cultured with osteoblasts to investigate the biocompatibility of MSM/PVA hydrogel with osteoblasts.Methods:After freeze-drying,MSM/PVA was immersed in simulated physiological body fluid.With the prolongation of observation time,the re-swelling of MSM/PVA occurred regularly.The swelling MSM/PVA was co-cultured with osteoblasts to detect the cytotoxicity of osteoblasts.The properties of MSM/PVA prepared was analysed by toxicity test,material preparation methods,material performance testing and biological evaluation.MTT(Methyl Thiazolyl Tetrazolium)method was used to detect the cytotoxicity of MSM/PVA,that was the toxicity of osteoblasts.Results:The results of cytotoxicity test showed that the relative proliferation rate of osteoblasts in direct contact with MSM/PVA hydrogel on the first day was above 99%,and the toxicity was classified as 0;the relative proliferation rate on the second day was above 95%,and the toxicity was classified as 1;the relative proliferation rate on the fifth day was above 99%,the toxicity was classified as 0,and the relative proliferation rate on the eighth and tenth days was above 90%,toxicity grade was 1.Conclusion:MSM/PVA hydrogel has no toxicity to osteoblasts,and MSM/PVA hydrogel has good biocompatibility.Part III Animal experimental study of MSM/PVA hydrogel expanding oral mucosaObjective:The feasibility of MSM/PVA hydrogel expanding mucoperiosteal by water absorption volume expansion was verified by histometrology and histology,which pr-ovided experimental basis for exploring new oral mucoperiosteal expanding materials.Methods:Alveolar bony periosteum in the maxillary of rabbit have interdental space,no teeth.Implantation of hydrogel into the periosteum of the alveolar bone,observed cell number in implant area,the number of periosteal fibers,cross section length,the number of blood vessels amd osteoclasts in tissue section by Olympus microscopes and Nikon cameras at first week,second week,third week and forth week time point after euthanized rabbit The results were statistically analyzed.Results:At the initial stage of implantation,perpared hydrogel caused normal cellular immune response owing to surgical trauma.Cross section length of periosteum increased with the increase of post implantation time,which are observed and measured by microscope.The length increased 1.8 times when compared to the innitial time.The amount of collagen fiber was 5 times compared to initial time at the fourth week.The number of periosteal vessels reached the peak in third weeks.Around the 4th week,with the complete healing of the periosteum,the number of the blood vessels was the same as that of the periosteal vessels before expansion.Conclusion:The feasibility of expanding the periosteum was verified by histomorph-ometry and histology.It can provide experimental evidence for exploring new oral periosteal expansion materials.