Prosthodontic Rehabilitation With Fixed Implant-Supported Prosthesis:Case Reports

PART I:Prosthodontic Rehabilitation with Fixed Implant-Supported Prosthesis:Case ReportsThe aim of this study was to discuss fixed implant-supported prosthesis as a prosthodontic treatment alternative to restore missing teeth in dental arch.Dental implant,with the advantages of not damaging the adjacent teeth and superior retention,is gradually replacing some of the conventional prosthodontic treatment modalities.Choosing the right retention method for implant superstructures plays a critical role in increasing the survival rate of dental implant.In this study,we selected 5 implant cases,in which all of them used cement-retained(or modified cement-retained)superstructures.These cases include a case of extracted tooth due to inflammatory root resorption,a partial edentulous case with dental fluorosis,a partial edentulous case with supra-erupted antagonist,a partial edentulous case with mesially inclined adjacent tooth,and a case with previous implant mobility.All the cases were completed with satisfactory results.PART 2:Modification of Silver Nanoparticles on the Surface of Dental Crown ProsthesesBackground:With the advancement of science and technology,active metals,bioceramics and polymer materials has been emerging and replacing some natural materials.Since 1980s,various dental alloy materials have been gradually utilized in the field of oral restoration,dental implant,and oral and maxillofacial surgery.Dental alloy materials,commonly used as prosthetic crown,have some adverse effects in clinical applications.There have been studies reporting that patients with metal crown tend to get marginal denture stomatitis around the crown characterized by gingival congestion and redness.Silver nanoparticles,as a noble nanomaterial,provided more possibility of applications in biomedical fields owing to its broad antibacterial spectrum,good endurance ability and thermal stability.There are three main methods for the synthesis of silver nanoparticles:physical method,chemical method and biosynthesis.Both chemical method and the biosynthesis method gain Ag the from AgNO3 solution through the reaction:AgNO3+NaBH4?Ag+1/2H2+1/2B2H6+NaNO3.However,it was reported that silver nanoparticles may inhabit DNA replication and mitochondrial function.Its concerning cytotoxicity limited its application in the field of biomedicine.Therefore,this research utilized physical method to synthesize silver nanoparticle in various size with physical method and aimed to search for a balance between cytotoxicity of silver nanoparticles and its antibacterial ability.Objective:The aim of this study was to attach silver nanoparticles on the surface of dental alloys and observe the changes in cytotoxicity and antibacterial properties.Methods:Silver nanoparticles were coated on 6 kinds of dental alloys including pure titanium through hydrothermal process.The antibacterial properties of dental alloys coated with three different concentrations of silver nanoparticles were tested on Staphylococcus aureus(S.Aureus)and Streptococcus mutans(S.Mutans).Mesenchymal stem cells(BMSC)from rats and osteogenic precursor cells(MC3T3-E1)from mice were used to test the cytotoxicity of the alloys by MTT assay.Results:Cytotoxicity of silver nanoparticles were observed on all dental alloys including the control groups.The addition of silver nanoparticles weakened cytotoxicity values of dental alloys.There is no difference on antibacterial effect against S.Aureus or S.Mutans among three concentrations of silver nanoparticles used in this study.Conclusion:The six dental alloys all showed cytotoxicity on BMSC and MC3T3-E1 cells.Cytotoxicity degraded after dental alloys were coated with silver nanoparticles.The mechanism remained unknown.No statistical differences were observed on cytotoxicity or antibacterial properties of silver nanoparticles among the three different concentrations.