The effect of addition nano particle ZrO2 on some properties of autoclave processed heat cure acrylic denture base material


Background: Polymethyl methacrylate (PMMA) is used in denture fabrication and considered as the most reliablematerial for the construction of removable prosthodontic appliances. The material is far from ideal in fulfilling themechanical requirements and the effect of autoclave processing has not been fully determined. The purpose of thisstudy was to evaluate the effect of addition of salinized (ZrO2) Nano fillers in percentages 3%, 5% and 7% by weighton some properties of heat cured acrylic processed the by autoclave and compare it with 0% (control) group .Materials and methods: The silanized(ZrO2) Nano-particles was added to PMMA powder by weight in three differentpercentages 3%, 5% and 7%, mixed by probe ultra-sonication machine.Two hundred specimens were constructedand processed by autoclave and divided into 5 groups according to the test (each group consist of 40 specimens )and each group was subdivided into 4 sub-groups according to the percentage of added (ZrO2) nano-particles(with 10 specimens for each subgroups) . The tests conducted were transverse strength, hardness (shore D), Impactstrength test, surface morphology and apparent porosity. AFM can provide 3D image of the specimen thehomogeneity of nanostructure film, roughness of surface and crystallite size. Scanning electron microscope SEM ofcontrol and salinized Nano ZrO2 reveal the Nano fillers distribution and it is shaped.Results: Highly significant increase in impact strength recorded when acrylic (vertex) mixed with 3%, 5% ZrO2 nanofiller, while a non-significant reduction was observed with 7% ZrO2 addition in comparison to control. Non-significantimprovement in transverse strength when 3% ZrO2 was added, 5% nano addition ZrO2 improved transverse strengthsignificantly while 7% nano addition showed anon significant reduce when these groups compared to the controlgroup .Anon significant reduction in the deformity was seen within 3% nano addition ZrO2 also 5% nano ZrO2 additionreduce the deformity significantly and significant increase was recorded when 7% nano addition ZrO2 was add andwhen these groups are compared to the control group. A significant increase in surface hardness was observed withthe addition of (ZrO2) nano-particles to (PMMA) at the percentage of 3%, highly significant increase at 5% and 7%with addition of modified nano-ZrO2. A non-significant decrease in apparent porosity at 3% and highly significantdecrease in apparent porosity at 5% and 7% with addition of modified nano-ZrO2 were observed. SEM results showeda good distribution of the modified nano-ZrO2 fillers at 3%, 5% and showed aggregation at 7% in the polymer matrix.Conclusion: The addition of modified nano-ZrO2 particles to acrylic resin cured by autoclave improved impact andtransverse strength of denture base nano composite containing 5% of nano-ZrO2. And this strength decreases withfurther increase of nano-ZrO2 filler content. Also addition of modified nano-ZrO2 slightly increaseshardness, thesurfaceroughness and the apparent porosity also decrease by addition of nano ZrO2 percentage increase