A Thermosensitive Chitosan-based Hydrogel For Sealing And Lubricating Purposes In Dental Implant System

Background: With the improvement of people's consumption level and the maturity of the dental implant technology,dental implantation are becoming the main way to repair missing teeth because of its greater biocompatibility,better stability and higher chewing efficiency.Though the dental implant has a lot of advantages compared with traditional repaired methods,there are still some complications happening in the clinic owing to the special mechanical structure of implant system,including mechanical complications such as the retained screw loosening,screw fracture,implant fracture and so on,and the biological complications such as mucositis,peri-implantitis and marginal bone resorption and so on.These complications would cause some inconvenience to patients' lives and bring some trouble to clinicians,and even lead to the implant failure.Therefore,it is necessary to prevent these complications for the purpose of raising the success rate of implantation.Purpose: This study aimed to develop a chitosan(CS)-based thermosensitive hydrogel to be utilized as sealant and lubricant in dental implant system,which intended to reduce the incidence of the mechanical and biological complications associated with implant system in clinic.Materials and Methods: In this study,a thermosensitive hydrogel made up of CS,?-glycerophosphate pentahydrate(?-GP)and povidone-iodine(PVP-I),called CS/?-GP/PVP-I thermosensitive hydrogel,was fabricated.Three experimental groups with different volume ratios of CS to ?-GP were prepared,namely 16/4,13/7 and 10/10 groups.The surface topography of the different groups and their physicochemical characteristics were examined by Scanning Electron Microscope(SEM),X-ray diffraction(XRD)and Attenuated total reflectanceFourier transform infrared spectrometry(ATR-FTIR).The cytotoxicity of the hydrogel was examined by CCK-8 test with rat bone mesenchymal stem cells(BMSCs)and human gingival fibroblast cells(h GFCs).In vitro antibacterial efficiency was analyzed by the spread plate method with Escherichia coli,Staphylococcus aureus and Porphyromonas gingivalis.Sealing ability of the hydrogel was detected by incubating two-piece implants in Escherichia coli suspension.Lubricating ability of the hydrogel was evaluated by the removal torque test with a calibrated digital torque meter.Results: The CS/?-GP/PVP-I thermosensitive hydrogel was fabricated successfully and showed a highly porous structure under SEM.An in vitro cytotoxicity test demonstrated that 13/7 group displayed no cytotoxicity to BMSCs and h GFCs.Furthermore,all three groups showed obviously antibacterial effects to Escherichia coli,Staphylococcus aureus and Porphyromonas gingivalis.In the sealing ability test,the three experimental groups all showed better sealing effect than control group and 16/4 group displayed the best sealing ability,which even could reach 60 days.In addition,the removal torque of 16/4 group and 13/7 group was significantly greater than control group.Conclusions: Based on our findings and within the limitations of the research,it could be concluded that the thermosensitive and antibacterial CS/?-GP/PVP-I hydrogel with sealing and lubricating ability was successfully prepared.The hydrogel had better sealing and lubricating effects when the volume ratio of CS to ?-GP was 16/4.