Effect of Anatase Titanium Dioxide Nanoparticles on the Flexural Strength of Heat Cured Poly Methyl Methacrylate Resins: An In-Vitro Study

Abstract

Poly methyl methacrylate (PMMA) resin is the most widely used material for fabrication of dentures since 1937 as it exhibits adequate physical, mechanical and esthetic properties. But one of the major problems faced using this material is that, it is highly prone to plaque accumulation due to surface porosities and its food retentive properties. This in turn increases the bacterial activity causing denture stomatitis. In efforts to impart antimicrobial property to these resins, various nanoparticles (NP) have been incorporated viz. Silver, Zirconia oxide, Titanium dioxide (TiO2), Silica dioxide (SiO2) etc. However, as additives they can affect the mechanical properties of the final product. Therefore, the aim of the present study was to evaluate and compare the effect of different concentration of TiO2 NP on the flexural strength of PMMA resins. Specimens made from heat polymerizing resin (DPI) without NP were used as a control group (Group A). The two experimental groups, (Group B and Group C) had 0.5 and 1 % concentration of TiO2 NP respectively. The specimens were stored in 37 °C distilled water for 50 ± 2 h. A three-point bending test for flexural strength measurement was conducted following ADA specification no. 12. The maximum mean flexural strength (90.65 MPa) belonged to the control group; and acrylic resin with 1 % TiO2 NP demonstrated the minimum mean flexural strength (76.38 MPa). But, the values of all the three groups exceeded the ADA Specification level of 65 MPa. Conclusion may be drawn from the present study that addition of TiO2 NP into acrylic resin can adversely affect the flexural strength of the final product and is directly proportional to the concentration of NP.

Evaluation of Flexural Strength of Different Denture Base Materials Reinforced with Different Nanoparticles

“…Ahmed et al added 1% and 5% 40 nm TiO 2 nanoparticles to traditional heat‐polymerized and high resistance heat‐polymerized acrylic resin powder and reported a decrease in flexural strength values. Nazirkar et al examined the flexural strength values of heat‐polymerized acrylic resin specimens in which 0.5% and 1% 7 nm TiO 2 nanoparticles were added and suggested that flexural strength decreased with the addition of the nanoparticles. In contrast to the aforementioned studies, Harini et al added TiO 2 nanoparticles (1%, 2%, and 5%) to PMMA and revealed that the highest flexural strength values were observed in the group with 5% nanoparticles added.…”

“…Mechanical or chemical methods such as melt mixing, mixing in solution, mixing with shear force and high shear force during mechanical mixing, and mixing with ultrasonic mixer are used . Although some investigators have added nanoparticles into the monomer (liquid), some researchers have also mixed them into acrylic resin polymers . In addition, Mc Nally et al explained that SiO 2 cannot be mixed homogeneously with more than 1% using manual mixing.…”

Comparison of mechanical properties of heat‐polymerized acrylic resin with silver nanoparticles added at different concentrations and sizes

“…Powders containing AgNPs of different sizes and concentrations were prepared and mixed with a heat‐polymerizing acrylic (Meliodent, Bayer Dental, Berkshire, UK) monomer liquid (3:1 vol/vol), sonicated (Confident dental equipments Ltd., Bangalore, India) for 1 h at room temperature to achieve proper dispersion, and then poured into 65 mm × 10 mm × 3.3 mm (according to ADA specification no. 12) molds to create 42 heat‐polymerized acrylic resin specimens.…”

“…In order to address these issues, manufacturers have recently begun incorporating antimicrobial agents into denture‐base materials, with much focus given to silver nanoparticles (AgNPs) . However, while improving the anti‐infective properties of acrylic dentures is essential, antibacterial agents can have a negative effect on the physical properties of the acrylic substrate, which, when used as a denture base must be able to withstand masticatory forces …”

New Trends for the Processing of Poly(Methyl Methacrylate) Biomaterial for Dental Prosthodontics

“…It was observed that by increasing the concentration of nanoparticles, the flexural strength of PMMA value increases. In some cases, better flexural strength value was found in comparison with PMMA alone [72,73]. Studies on the improvement of tensile strength concluded that increasing the TiO 2 nanoparticle concentration provided better tensile strength up to some concentration and then the strength decreases [74].…”