• Assessing Fracture Toughness and Impact Strength of PMMA Reinforced with Nano-Particles and Fibre as Advanced Denture Base Materials

      Alhotan, Abdulaziz; email: aalhotan@ksu.edu.sa; Yates, Julian; email: julian.yates@manchester.ac.uk; Zidan, Saleh; email: saleh_0072002@yahoo.co.uk; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk; Silikas, Nikolaos; orcid: 0000-0003-4576-4584; email: nikolaos.silikas@manchester.ac.uk (MDPI, 2021-07-24)
      Statement of Problem: Polymethyl methacrylate (PMMA) denture resins commonly fracture as a result of the denture being dropped or when in use due to heavy occlusal forces. Purpose: To investigate the effects of E-glass fibre, ZrO2 and TiO2 nanoparticles at different concentrations on the fracture toughness and impact strength of PMMA denture base. Materials and Methods: To evaluate fracture toughness (dimensions: 40 × 8 × 4 mm3; n = 10/group) and impact strength (dimensions: 80 × 10 × 4 mm3; n = 12/group), 286 rectangular tested specimens were prepared and divided into four groups. Group C consisted of the PMMA specimens without any filler (control group), while the specimens in the remaining three groups varied according to the concentration of three filler materials by weight of PMMA resin: 1.5%, 3%, 5%, and 7%. Three-point bending and Charpy impact tests were conducted to measure the fracture toughness and impact strength respectively. Scanning Electron Microscope (SEM) was utilised to examine the fractured surfaces of the specimens after the fracture toughness test. One-way analysis of variance (ANOVA) followed by Tukey post-hoc tests were employed to analyse the results at a p ≤ 0.05 significance level. Results: Fracture toughness of groups with 1.5 and 3 wt.% ZrO2, 1.5 wt.% TiO2, and all E-glass fibre concentrations were significantly higher (p 0.05) than the control group. The samples reinforced with 3 wt.% ZrO2 exhibited the highest fracture toughness. Those reinforced with a 3 wt.%, 5 wt.%, and 7 wt.% of E-glass fibres had a significantly (p 0.05) higher impact strength than the specimens in the control group. The heat-cured PMMA modified with either ZrO2 or TiO2 nanoparticles did not exhibit a statistically significant difference in impact strength (p > 0.05) in comparison to the control group. Conclusions: 1.5 wt.%, 3 wt.% of ZrO2; 1.5 wt.% ratios of TiO2; and 1.5 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% of E-glass fibre can effectively enhance the fracture toughness of PMMA. The inclusion of E-glass fibres does significantly improve impact strength, while ZrO2 or TiO2 nanoparticles did not.
    • Chemical Characterisation of Silanised Zirconia Nanoparticles and Their Effects on the Properties of PMMA-Zirconia Nanocomposites

      Zidan, Saleh; email: sal.zidan@sebhau.edu.ly; Silikas, Nikolaos; orcid: 0000-0003-4576-4584; email: nikolaos.silikas@manchester.ac.uk; Al-Nasrawi, Suhad; orcid: 0000-0003-3045-7389; email: suhad.alnasrawi@uokufa.edu.iq; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk; Alshabib, Abdulrahman; email: Abdalshabib@ksu.edu.sa; Alshame, Alshame; email: Als.alshame@sebhau.edu.ly; Yates, Julian; email: julian.yates@manchester.ac.uk (MDPI, 2021-06-10)
      Objectives: The objective of this study was to investigate the mechanical properties of high-impact (HI) heat-cured acrylic resin (PMMA) reinforced with silane-treated zirconia nanoparticles. Methods: Forty-five PMMA specimens reinforced with zirconia were fabricated and divided into three groups: Pure HI PMMA (control group), PMMA reinforced with 3 wt.% of non-silanised zirconia nanoparticles and PMMA reinforced with 3 wt.% of silanised zirconia nanoparticles. Silanised and non-silanised zirconia nanoparticles were analysed with Fourier Transform Infrared (FTIR) Spectroscopy. For measuring the flexural modulus and strength, a Zwick universal tester was used, and for surface hardness, a Vickers hardness tester were used. Furthermore, raw materials and fractured surfaces were analysed using Scanning Electron Microscopy (SEM). A one-way ANOVA test followed by a post-hoc Bonferroni test was employed to analyse the data. Results: The results showed that the mean values for flexural strength (83.5 ± 6.2 MPa) and surface hardness (20.1 ± 2.3 kg/mm2) of the group containing 3 wt.% treated zirconia increased significantly (p 0.05) in comparison to the specimens in the group containing non-treated zirconia (59.9 ± 7.1 MPa; 15.0 ± 0.2 kg/mm2) and the control group (72.4 ± 8.6 MPa; 17.1 ± 0.9 kg/mm2). However, the group with silanised zirconia showed an increase in flexural modulus (2313 ± 161 MPa) but was not significantly different (p > 0.05) from the non-silanised group (2207 ± 252 MPa) and the control group (1971 ± 235 MPa). Conclusion: Silane-treated zirconia nano-filler improves the surface hardness and flexural strength of HI PMMA-zirconia nanocomposites, giving a potentially longer service life of the denture base.
    • Evaluating Polishability of Zirconia Impregnated PMMA Nanocomposite for Denture Base Application

      Zidan, Saleh; email: sal.zidan@sebhau.edu.ly; Silikas, Nikolaos; orcid: 0000-0003-4576-4584; email: nikolaos.silikas@manchester.ac.uk; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk; Jahantigh, Javad; email: javad.jahantigh@mft.nhs.uk; Alhareb, Ahmed; email: ahmed_ahmed32710@yahoo.com; Yates, Julian; email: julian.yates@manchester.ac.uk (MDPI, 2021-05-31)
      Artificial biomaterials are being developed for use in denture base with symmetrical properties to restore the aesthetics and functionalities. The rough surface of denture base resin promotes the adhesion of microorganisms and plaque accumulation. This study aimed to explore the consequences of polishing times on the surface roughness of high-impact (HI) heat-polymerized PMMA denture base acrylic resin reinforced with zirconia nanoparticles (nanocomposite). Thirty specimens (25 ± 0.50 mm in diameter and 2 ± 0.10 mm thickness) were fabricated from HI PMMA by adding zirconia nanoparticles at different concentrations of (0 wt.%, 1.5 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, and 10 wt.%). Specimens were divided into six groups (n = 5) and surface roughness (Ra) was measured before and after polishing with a standard protocol for one and two minutes. The addition of zirconia in PMMA at low concentrations (1.5 wt.%, 3 wt.%, and 5 wt.%) did not negatively affect the surface finish of the denture base composites following conventional polishing and remained below the clinically acceptable limit (0.2 µm). After one minute of polishing, only the 10 wt.% zirconia (0.17 ± 0.03 µm) demonstrated a substantial rise in median surface roughness, in comparison with the control group (0.11 ± 0.01 µm). It is concluded that the group containing 3 wt.% (0.10 ± 0.01 µm) of zirconia is the optimum concentration to obtain the best symmetrical surface finish after two minutes of polishing.
    • Flexural Strength and Hardness of Filler-Reinforced PMMA Targeted for Denture Base Application

      Alhotan, Abdulaziz; email: abdulaziz.alhotan@postgrad.manchester.ac.uk; Yates, Julian; email: julian.yates@manchester.ac.uk; Zidan, Saleh; email: saleh_0072002@yahoo.co.uk; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk; Silikas, Nikolaos; orcid: 0000-0003-4576-4584; email: nikolaos.silikas@manchester.ac.uk (MDPI, 2021-05-19)
      The aim of this work was to evaluate the flexural strength and surface hardness of heat-cured Polymethyl methacrylate (PMMA) modified by the addition of ZrO2 nanoparticles, TiO2 nanoparticles, and E-glass fibre at different wt.% concentrations. Specimens were fabricated and separated into four groups (n = 10) to measure both flexural strength and surface hardness. Group C was the control group. The specimens in the remaining three groups differed according to the ratio of filler to weight of PMMA resin (1.5%, 3%, 5%, and 7%). A three-point bending test was performed to determine the flexural strength, while the surface hardness was measured using the Vickers hardness. Scanning Electron Microscope (SEM) was employed to observe the fractured surface of the specimens. The flexural strength was significantly improved in the groups filled with 3 wt.% ZrO2 and 5 and 7 wt.% E-glass fibre in comparison to Group C. All the groups displayed a significantly higher surface hardness than Group C, with the exception of the 1.5% TiO2 and 1.5% ZrO2 groups. The optimal filler concentrations to enhance the flexural strength of PMMA resin were between 3–5% ZrO2, 1.5% TiO2, and 3–7% E-glass fibre. Furthermore, for all composites, a filler concentration of 3 wt.% and above would significantly improve hardness.
    • Studying Effects of Calcium Oxide Nanoparticles on Dentinogenesis in Male Wistar Rats

      Academic Editor: Mallineni, Sreekanth Kumar; Al-Maula, Bushra Habeeb; orcid: 0000-0002-2293-4897; email: bushraalmaula@gmail.com; Wally, Zena Jehad; orcid: 0000-0002-0885-0179; email: zinah.alnuaimi@uokufa.edu.iq; Al-Magsoosi, Mohanad Jameel Najm; orcid: 0000-0002-9007-2870; email: muhanned72@yahoo.com; Dosh, Rasha Hatem; orcid: 0000-0002-2318-6608; email: rasha.dosh@uokufa.edu.iq; Mustafa, Ruba M.; orcid: 0000-0002-3425-459X; email: rmmustafa@just.edu.jo; Al-Nasrawi, Suhad Jabbar Hamed; orcid: 0000-0003-3045-7389; email: suhad.alnasrawi@uokufa.edu.iq; Alfutimie, Abdullatif; orcid: 0000-0002-2531-3762; email: abdullatif.alfutimie@manchester.ac.uk; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk (Hindawi, 2021-07-26)
      This study aimed to evaluate potential impacts of calcium oxide nanoparticles (CaO-NPs) at different dosages on predentin thickness, number of blood vessels, periodontal ligament thickness, and blood glucose level of Wistar rats. Twelve rats were randomly gathered into four groups, untreated (control) and CaO-NP-treated groups at three concentrations (25, 50, and 100 mg/kg of the body weight) over a period of 60 days. Histological investigation was performed on twenty-four lower incisor teeth extracted from all the tested groups under a light microscope, and an automatic Fujifilm was used to measure the blood glucose level. The results showed that regular nanoparticle treatment significantly increased predentin and periodontal ligament thicknesses, a gradual decrease in vascularization in the pulp tissue, and an increase in the blood glucose level as the dosages of nanoparticles administered to the rats increased. Administration of the CaO-NPs at low dosage (25 mg/kg) could be beneficial for the growth and integrity of teeth and dentinal tissues in rats.