Melbourne Dental School - Theses
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ItemInfluence of the addition of microencapsulated phytoncide to a denture base resin on mechanical properties and antimicrobial activity( 2017)Background: Resins such as a polymethyl methacrylate (PMMA) are the most commonly used in denture base material (DBR) because it possesses the advantage of adequate physical, mechanical, and aesthetic properties. However, research regarding the antimicrobial properties of PMMA still remains an area of interest that requires further investigation. Objectives: The aim of this project was to fabricate a denture base resin (DBR) containing phytoncide microcapsules (PTMCs) at various concentrations and investigate its influence on the mechanical properties of DBR. It also aimed to evaluate the antibacterial effects against Porphyromonas gingivalis and determine the antifungal activity of the microencapsulated phytoncide against Candida albicans. Methods: A total of 54 rectangular shaped (64 x 10 x 3.3 mm) specimens were fabricated using the heat cure polymerisation processing method for the mechanical property testing of the DBR. The samples were divided into nine groups; 0% (control), 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 4.0%, and 5.0% (dry wt/wt%) according to the incorporation percentage. The flexural strength test was conducted by using a three-point bending test in a universal testing machine. A scanning electron microscopy (SEM) investigation was performed and evaluated the fractured surface morphology of specimens. A total of 30 disc-shaped (10 mm x 3 mm) specimens were fabricated using the heat cure polymerisation processing method for the antibacterial test. The samples were divided into two groups (0% control, 2.5% dry wt/wt%) according to the incorporation percentage of phytoncide. The disc resin samples containing PTMCs were incubated at 37°C for 76 h and the inhibition of the growth of P. gingivalis W50 in a 24 well plate set-up was observed using the turbidity method with a spectrophotometer. A turbidometric antifungal test was conducted to determine if the phytoncide plant essential oils (PPEOs) in microcapsule could produce an antifungal effect against C. albicans, under a pH 5.5 acidic environment in a 96 well plate assay. Liquid yeast peptone glucose (YPG) broth and a solid agar growth medium were used for biofilm growth. The solution was incubated at 37°C for 24 h and the optical density (OD) was observed. Results: The flexural strength decreased as more PTMCs were added to DBR; 0% (97.58 ± 4.79 MPa), 0.5% (83.55 ± 2.95 MPa), 1.0% (78.62 ± 1.45 MPa), 1.5% (69.49 ± 1.84 MPa), 2.0% (77.06 ± 3.43 MPa), 2.5% (65.72 ± 1.03 MPa), 3.0% (64.78 ± 1.53 MPa), 4.0% (56.13 ± 2.10 MPa), and 5.0% (53.66 ± 2.46 MPa). DBR containing 2.5% of PTMCs was the maximum acceptable concentration (65.72 MPa) to comply with the ISO strength requirements. The one-way ANOVA was F8, 45 = 165.99; P<0.001. For the antimicrobial test, there was no antibacterial effect against P. gingivalis. However, the antifungal test showed a dose-dependent effect on C. albicans as the phytoncide percentage increased from 0.5% to 5.0%, the OD of the culture decreased from 0.908 to -0.071. At a 2.5% concentration, the phytoncide had effectively stopped C. albicans growth. Conclusion: Fabrication of DBR containing the PTMCs was successful at 2.5% level and below without affecting the mechanical properties. This could lead to an investigation of the antimicrobial effect of DBR containing the PTMCs against oral microorganisms such as P. gingivalis or C. albicans for clinical applications. Further research on a new non-toxic carrier shell material, such as a biodegradable or semi-perishable polymer, needs to be investigated.