Evaluation the effect of modified nano-fillers addition on some properties of heat cured acrylic denture base material


Background: The poly(methylmethacrylate) (PMMA) shown to be lacking two properties which are strength and
radio-opacity. The aim of this study was to evaluate the effect of addition of modified nano-zirconium oxide (ZrO2)on
some properties of heat cured acrylic denture base material .
Material and method: (ZrO2) nanofillers were incorporated into (PMMA) denture base by free radical bulk
polymerization. (PMMA) nanoparticales were coated with a layer of trimethoxysilypropylmethacrylate (TMSPM)
before dispersed and sonicated in monomer (MMA) in different percentages 2%, 3%, 5% and 7% by weight. Then
mixed with acrylic powder as general conventional method. Two hundred fifty five (255) specimens were prepared
for this study they were divided into (6) groups according to the test used. The tests were impact strength,
indentation hardness, surface roughness, transverse strength, radio-opacity and microscope test, for each test five
subgroups (one control and four for nano-ZrO2). The size and shape distribution of nano-ZrO2 particles were
estimated using scanning electron microscope (SEM) and atomic force microscope (AFM) .
Result: Highly significant increase in impact and transverse strength occur in acrylic reinforced with 5wt%, but non
significant increase was observed at 7wt% when compared to control group. Non-significant increases in indentation
hardness and surface roughness appear with addition of modified nano-ZrO2 at different percentages. For radioopacity
a highly significant increase had occurred with the addition of modified nano-ZrO2.
Conclusion: The maximum increase in impact strength, transverse strength and radio-opacity was observed in
denture base nano composite containing 5wt% of nano-ZrO2.
Key words: poly (methylmethacrylate), nano composite. (J Bagh Coll Dentistry 2011;23(3): 23-29).