Evaluation of polymethyl-methacrylate and acetal denture base resins processed by two different techniques before and after nano-chlorohexidine surface treatment.

BACKGROUND: Flexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a concern. Consequently, this study aimed to evaluate surface roughness and biofilm formation tendency of two types of denture base resins manufactured with two techniques before and after surface coating with chlorohexidine (CHX) NPs. MATERIALS AND METHODS: Acetal (AC) and Polymethyl-methacrylate (PMMA) resins manufactured by conventional and CAD/CAM methods were shaped into disk (10 X 10 X 1 mm). They were dipped for 8 h and 24 h in colloidal suspension prepared by mixing aqueous solution of CHX digluconate and hexa-metaphosphate (0.01 M). Surface roughness, optical density (OD) of microbial growth media and biofilm formation tendency were evaluated directly after coating. Elutes concentrations of released CHX were evaluated for 19 days using spectrophotometer. Three-way ANOVA and Tukey's post-hoc statistical analysis were used to assess the outcomes. RESULTS: AC CAD/CAM groups showed statistically significant higher roughness before and after coating (54.703 ± 4.32 and 77.58 ± 6.07 nm, respectively). All groups showed significant reduction in OD and biofilm formation tendency after surface coating even after 19 days of CHX NPs release. CONCLUSIONS: Biofilm formation tendency was highly relevant to surface roughness of tested resins before coating. After CHX NPs coating all tested groups showed significant impact on microbial growth and reduction in biofilm formation tendency with no relation to surface roughness. Significant antimicrobial effect remained even after 19 days of NPs release and specimens storage.

Exploring the biomedical potential of a novel modified glass ionomer cement against the pandrug-resistant oral pathogen Candida albicans SYN-01.

Dental caries is an infectious disease that is a major concern for dentists. Streptococci and Lactobacilli were long thought to be the primary etiology responsible for caries. Candida albicans with acidogenic and aciduric characteristics has recently been implicated in the onset and progression of cariogenic lesions. Moreover, due to the increased resistance to common antimicrobials, the discovery of innovative candidates is in high demand. Therefore, our study might be the first report that explores the efficacy of glass ionomer cement (GIC) incorporated with a newly modified carboxylated chitosan derivative (CS-MC) against multidrug-resistant (MDR) and/or pandrug resistant (PDR) C. albicans isolated from the oral cavity. In this work, four CS-MC-GIC groups with different concentrations were formulated. Group four (CS-MC-GIC-4) gave a significant performance as an anticandidal agent against selected PDR Candida strain, with an obvious decrease in its cell viability and high antibiofilm activity. It also, enhanced all the mechanical properties and supports cell viability of Vero cells as a nontoxic compound. Moreover, CS-MC-GIC-4 inhibited neuraminidases completely, which might provide a novel mechanism to prevent dental/oral infections. Thus, findings in this study open up new prospect of the utilization of CS-MC-GIC as a novel dental filling material against oral drug-resistant Candida.

Microhardness and Fluoride Release of Glass Ionomer Cement Modified with a Novel Al+3 Complex to Enhance Its Antimicrobial Activity.

OBJECTIVES: To synthesize and characterize a novel Al+3 complex with 2-(2-hydroxyphenyl)-1H-benzimidazole (HL) to be added to a restorative glass ionomer cement (GIC) to enhance its antimicrobial activities and to evaluate the Vickers microhardness (HV) and fluoride release (FR) of the modified GIC. MATERIALS AND METHODS: Al+3 complex was synthesized by the addition of 1 mmol (0.210 g) of HL to 1 mmol (0.342 g) of aluminum sulfate in ethanol. The resulting solution was then refluxed under stirring for 24 h and then collected by filtration and dried in a vacuum desiccator over an anhydrous CaCl2. Characterization of Al+3 complex was carried out by Fourier transform infrared spectroscopy (FTIR), elemental microanalysis, thermal gravimetric analysis (TGA), molar conductance, 1H NMR spectra, and electron impact-mass spectrometry. The antimicrobial activity of Al+3 complex-modified GIC (Al-GIC) was studied by the "cut plug method" against Gram-negative bacteria (Acinetobacter baumannii) and Gram-positive bacteria (Staphylococcus aureus, Enterococcus, and Streptococcus mutants) and fungi (Candida albicans). HV was evaluated by a digital microhardness tester (Zwick/Roell, Indentec, ZHVµ-S, West Midlands, England). Fluoride levels in ppm were obtained using the ion-selective electrode connected to a digital meter. A one-way ANOVA and Bonferroni test were used to analyze the data with the significance level established at p ≤ 0.05. RESULTS: Synthesis of Al+3 complex was confirmed by FTIR, elemental microanalysis TGA, molar conductance, 1H NMR spectra, and electron impact-mass spectrometry. Al-GICs exhibited an enhanced antibacterial activity against all studied microorganisms as confirmed by the growth of inhibition zones compared to control GIC (C-GIC). Though there was a slight reduction in HV and FR with increasing the added percent of Al+3 complex, no significant differences were found between the studied groups. CONCLUSIONS: Addition of Al+3 complex to GIC powder enhanced the antimicrobial activity of GIC materials. As there was a negligible insignificant reduction in HV and FR upon the addition of Al+3 complex, Al-GICs can be used with a guaranteed degree of clinical success.

Omega-3 polyunsaturated fatty acids in large doses attenuate seizures, cognitive impairment, and hippocampal oxidative DNA damage in young kindled rats.

Omega-3 (OM3) dietary polyunsaturated fatty acids have promising seizure-protective effects, as well as enhancing effects of cognitive development and memory-related learning. This study aimed to explore the effect of large doses of OM3 on cognitive impairment and hippocampal oxidative DNA damage produced by seizures in epileptic children using a PTZ-kindled young rat model. Cognitive functions, biomarkers of oxidative stress, and DNA damage were assessed in PTZ-kindled young rats (30 mg/kg, i.p. once every other day for 13 injections) pretreated with OM3 (200-500 mg/kg, p.o.). Pretreatment with OM3 at the tested doses significantly attenuated PTZ-induced seizures and decreased cognitive impairment in both passive avoidance and elevated plus maze tests in the PTZ-kindled rats. Moreover, OM3 significantly attenuated the increase in hippocampal malondialdehyde and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, as well as the decrease in reduced glutathione (GSH) levels and GSH-peroxidase activity induced by PTZ kindling, in a dose-related manner. Relatively large dose levels of OM3 (200-500 mg/kg) effectively attenuated seizures and their associated cognitive deficits, and reduced oxidative stress and hippocampal DNA damage in PTZ-kindled young rats.

The influence of monomeric resin and filler characteristics on the performance of experimental resin-based composites (RBCs) derived from a commercial formulation.

OBJECTIVE: To explore experimental RBCs derived from a successful commercially available RBC (Grandio) to investigate resin monomer blend and filler parameters (volume fraction, density and diameter) on RBC performance. METHOD: Six experimental RBCs modified from a commercial RBC were tested. The three-point flexure strength (σ(3)) and modulus (E) data was determined for groups of 20 bar-shaped specimens, prepared in a custom-made knife-edge split aluminum mold and irradiated using a modification of the ISO 4049 protocol. The biaxial flexure strength (BFS) and top and bottom Vickers hardness number (VHN) determination was performed on disc-shaped specimens (n=20). Normal distribution of the σ(3), E, BFS and top and bottom VHN data was verified using the Shapiro-Wilk's test. Paired groups were compared using independent samples t-test for the individual tests investigated (σ(3), E, BFS and top and bottom VHN) at a significance level of P<0.05. RESULTS: A significant decrease in the mean σ(3) (P<0.011) and mean E (P<0.001) were identified on increasing the filler fraction (from 71.4 to 74.5 vol%) or increasing the mean filler diameter (from 1.5 to 2.5 µm). Increasing the filler density resulted in a significant increase in the mean σ(3) (P<0.001), mean E (P<0.001) and mean top VHN (P≤0.001). Replacing the monomeric blend with an ormocer blend significantly reduced the mean σ(3), E, BFS and top and bottom VHNs (all P<0.001). SIGNIFICANCE: For each RBC monomeric resin and filler (type, density and diameter) combination employed, a finite filler volume fraction exists. Operating at the finite filler volume fraction increases the difficulty in improving the mechanical properties of the RBCs tailored from a commercial product.