Graduate Student from the Branch of Medical and Industrial Materials Science Earns a Master’s Degree for Research on Enhancing Denture Base Properties Using Nanoparticles

The Branch of Medical and Industrial Materials Science awarded a Master’s degree to the graduate student Iman Alwan Arhim for her thesis titled:

“Improvement of Mechanical and Antimicrobial Properties of Denture Base by Adding Nanoparticle Materials”

The defence was held in the late Professor Dr Abdul-Muttalib Ibrahim Al-Sheikh Hall at the department building.

In this study, the effect of incorporating nanoparticles (silver, titanium oxide, and zirconium oxide) on certain mechanical properties (flexural strength, impact strength, surface hardness, compressive strength, and surface roughness) of polymethyl methacrylate (PMMA) used in denture fabrication was investigated. Additionally, the effect of nanoparticle incorporation on antimicrobial properties was examined.

The samples were divided into three groups based on the ratio of added nanoparticles (silver: titanium oxide and silver: zirconium oxide). A fixed weight percentage of 0.3% silver nanoparticles was added, while titanium oxide and zirconium oxide were added at weight percentages of (0.1%, 0.3%, 0.5%). Furthermore, a third group of samples was prepared with 0.3% silver and (0.05%, 0.15%, 0.25%) of both titanium oxide and zirconium oxide to study the combined effect of nanoparticles on the properties of PMMA.

The structural properties of the nanoparticles were examined using X-ray diffraction (XRD), and surface morphology was analyzed using field emission scanning electron microscopy (FESEM). Surface roughness was evaluated using an atomic force microscope (AFM).

Key Findings

• The incorporation of silver and titanium oxide nanoparticles increased the flexural strength, with the highest value recorded at (76.62 MPa) for 0.3% Ag + 0.3% TiO₂. Meanwhile, adding ZrO₂ resulted in a slight improvement, reaching (71.83 MPa) at 0.5% ZrO₂. The highest flexural strength was achieved when combining nanoparticles, reaching (89.35 MPa) at 0.3% Ag + 0.15% (TiO₂-ZrO₂).
• Surface hardness increased for all samples upon nanoparticle addition, reaching the highest values of (85.3) and (85.5) at 0.3% Ag + 0.3% TiO₂ and 0.3% Ag + 0.5% ZrO₂, respectively, compared to (81.2) for pure PMMA.
• The impact strength was enhanced by silver and titanium oxide nanoparticles, reaching a maximum of (7.54 kJ/m²) at 0.3% Ag + 0.3% TiO₂, compared to (6.81 kJ/m²) for PMMA. A similar effect was observed with the combined nanoparticles, with the highest value of (7.14 kJ/m²) at 0.3% Ag + 0.15% (TiO₂-ZrO₂). However, the addition of zirconium oxide decreased impact strength, with the lowest value recorded at (5.49 kJ/m²) for 0.1% ZrO₂.
• Compressive strength increased with nanoparticle addition, with the highest value of (147.07 MPa) at 0.3% Ag + 0.5% ZrO₂, followed by (132.3 MPa) at 0.3% Ag + 0.5% TiO₂, compared to (98.01 MPa) for pure PMMA.
• Young’s modulus decreased with increasing nanoparticle concentrations, with the lowest value recorded at (415.18 MPa) for 0.3% Ag + 0.25% (TiO₂-ZrO₂), compared to (616.44 MPa) for PMMA.
• Surface roughness significantly improved with nanoparticle incorporation, with the best value recorded at 0.3% Ag + 0.3% TiO₂ (0.2917 µm) compared to (0.7556 µm) for PMMA, followed by (0.3453 µm) at 0.3% Ag + 0.3% ZrO₂.
• Antimicrobial activity results showed that 0.3% Ag + 0.25% (TiO₂-ZrO₂) exhibited the highest microbial inhibition. Additionally, the antimicrobial effect was more pronounced against Streptococcus mutans compared to Escherichia coli at all concentrations.

Examination Committee

• Prof. Dr. Ali Abadi Al-Taif
  Department of Applied Sciences / Medical and Industrial Materials Science Branch – Chair
• Asst. Prof. Dr. Athraa Ali Mahmoud
  Al-Mustansiriya University / College of Dentistry – Member
• Lect. Dr. Mohammed Salman Kazem
  Department of Applied Sciences / Laser Science and Technology Branch – Member
• Lect. Dr. Manal Abdulwahid Aboud
  Department of Applied Sciences / Medical and Industrial Materials Science Branch – Member & Supervisor
• Dr. Halima Thajeel Halboos
  Ministry of Science and Technology / Materials Research Directorate – Member & Supervisor