Modified Cerium Oxide Nanoparticles Have Influences On The Performance Of Denture Acrylic Resin And The Degree Of Dispersion

Objective Thermosetting resin base material which is also called polymethyl methacrylate?PMMA?is an important raw material for denture repairing,because of its good biological properties,mechanical properties and high clinical workability,and other advantages make it get widely use in denture repairing.But after the denture wearing a period of time in the clinical,because the tissue surface of the base plate and the polished surfaces have different degrees of wear and oxidation,resulting in different regional base thinning,coupled with aging,making it brittle and easily broken.Therefore,base breaking has become a problem facing the oral medical.Denture fracture forcied the patient to repeated trimming,and even re-make,not only to increase the economic and psychological burden of patients,but also result patients being in distress of toothless for a Long-term,has serious implications on the beauty,pronunciation and chewing function of patients.Therefore,to improve and enhance the mechanical properties of denture has become one of international explore hot spot[1].In this study,through modified nano-cerium oxide by stearate added polymethyl methacrylate?PMMA?,detecting its effect on the mechanical properties of the base material,and to analyze the optimum filling amount according to the test results.It aims to provide the appropriate reference materials for clinical application.Methods Put modified nano-cerium oxide by stearate into drying,crushed and set aside.Regard the base material adding various concentrations of modified nano Ce O2 as experimental groups,without adding modified nano Ce O2 as a control group.Production?50 ± 2?mm ×?10 ± 2?mm ×?3 ± 0.5?mm standard wax.The modified nano Ce O2 which at a mass ratio of 1%,2%,3%,4%,5% is added to polymethyl methacrylate monomers ultrasonic dispersion,and obtain the suspension of the two liquid after mixing for 30 minutes.Then the powder is mixed in accordance with the ratio?23 g:10 m L?given by the manufacturer,hand box and cook box conventionally.Each gruop made six denture base resin specimens,then polished conventionally with 600 grit sandpaper water.Finally,the specimens were stored in 37 ? saline and detected after 24 h.Performed on universal material testing machine,testing the corresponding mechanical strength of each gruop,and observed the degree of dispersion of fracture surface by scanning electron microscopy.Results After the addition of modified nano cerium oxide powder through stearic,the mechanical strength of the thermosetting base resin has increased,the results show the following trends:microhardness increased gradually;bending strength is increased after first reduced;tensile strength,impact strength and flexural modulus are all first increasing and then decreasing trend,while the the indicators of control group are the smallest.Wherein 3% is the the best ratio to achieve the overall performance of material.Scanning electron microscope shows that when the added amount of inorganic nanoparticles is less than 4%,inorganic nanoparticles can well dispersed.when the added amount is 4%,the agglomeration occurs,then increases inorganic additive content,molecular agglomeration became clear,agglomerated particles increased and larger.Analysis found that only the impact strength of 2% and 3% experiment group have statistically meaning,the other groups were not statistically meaning;bending test that except 2%,3%and 4% experimental group have statistically meaning,the rest were not statistically meaning;but experiments in flexural modulus,added 3%,4% and 5%experimental group have statistically meaning,the rest were not statistically meaning.Microhardness measurements show 1% group was not statistically meaning.Tensile test shows 1% and 4% group have significant meaning and the rest have.Conclusion The added amount of modified nano CeO₂ affects the hardness,tensile strength and other mechanical properties of denture base.In this study,different amounts of modified nano-Ce O2 add into PMMA compared with those did not add.Draw someconclusions:1.The five groups specimens of containing the modified nano-Ce O2 is slightly higher than the control group;2.When the proportion is 3%,the overall performance of materials is their best,but there is no significant difference when the proportion is 1%;3.Scanning electron microscope shows that when the added amount of inorganic nanoparticles is less than 4%,inorganic nanoparticles can well dispersed.when the added amount is 4%,the agglomeration occurs,then increases inorganic additive content,molecular agglomeration became clear,agglomerated particles increased and larger.