Browsing by Author "Zhang, Shengmiao"

Now showing 1 - 5 of 5
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    Bio-Active Nano-Diamond Designer Materials and Dentures: From Design to Application
    (Dentistry, 2015) Perchyonok, V. Tamara; Souza, John; Zhang, Shengmiao; Moodley, Desigar; Grobler, Sias
    Objective: The present study aims to design functional biomaterials and evaluate performance of nano-diamond: chitosan based bio-active containing PMMA (polymethyl methacrylate) materials towards application in treatment and prevention of denture stomatitis and associated conditions in denture wearers. Methods: The bio-active nano-diamond modified PMMA were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan gelling agent. The release behaviors at physiological pH and also under acidic conditions and stability of the antioxidant-chitosan-nano-diamond were also evaluated. Mechanical performance such as tensile strength and compressive strength were measured as well bio-adhesive studies were investigated in order to assess the suitability of these designer materials. Results: The bio-active nano-diamond modified PMMA materials showed a high adhesive force and they only swelled slightly in the aqueous medium. Bioactive release suggested prolonged release of the therapeutic agent from the hydrogels. The hydrogels also had significant free radical defense capability. Conclusion: In this study we demonstrated that the newly prepared bio-active modified PMMA resins are suitable novel bio-active materials capable of comparable performance with the conventional PMMA materials with additional benefit of therapeutic bioactive release as well as potential antimicrobial properties to be demonstrated in vitro. Our findings might be thus a step forward towards the development of alternative non antibiotic based strategies targeting bacterial infections.
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    Insights into chitosan hydrogels on dentine bond strength and cytotoxicity
    (Scientific Research Publishing, 2013) Perchyonok, Tamara; Grobler, Sias Renier; Zhang, Shengmiao; Olivier, Annette; Oberholzer, Theunis
    Contemporary dental adhesives show favorable im- mediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. Materials and Methods: Preparation of 3 chitosan-antioxidant hydrogels was achieved us- ing modified hydrogel preparation method. Their effect on the bond strength to dentine both short term (after 24 hours) and long term (after 6 months) were evaluated using shear bond strength measurements using Instron Universal Testing Mascine). The SEM was used to study the surface of the hydrogels. The cell survival rate (cytotoxicity) of the antioxidants re- sveratrol, β-carotene and propolis towards Balb/c 3T3 mouse fibroblast cells was also assessed using the standard MTT assay. Results: It was found that chi- tosan-H treated dentine gives significantly (p < 0.05; Non-parametric ANOVA test) higher shear bond va- lues than dentine treated or not treated with phos- phoric acid. The anti-oxidants chitosan hydrogels improved the shear bond strength. Overall, there was a relapse in the shear bond strength after 6 months. The SEM study showed that the hydrogel formula- tions have a uniform distribution of drug content, homogenous texture and yellow color. The pH of the growth medium adjusted to relevant values had a highly significant influence (Tukey-Kramer Multiple- Comparison Test; p < 0.01) on the cell survival rate of Balb/c mouse 3T3 fibroblast cells and therefore most probably also to tooth pulp fibroblast cells. The lower the pH value the higher the negative influence. Fur- thermore, the sequence of survival rate was found to be: β-carotene (92%) > propolis (68%) > resveratrol (33%). Conclusion: the antioxidant-chitosan hydro- gels significantly improved bonding to dentine with or without phosphoric acid treatment. The pH of the growth medium had a high influence on the cell survival rate of Balb/c mouse 3T3 fibroblast cells. The release of the antioxidant β-carotene would not have an influence on the pulp cells. These materials might address the current perspectives for improving bond durability.
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    Temporomandibular Joint Dysfunctions and Bio-Materials: Design, Free Radical Defense and Mechanism In Vitro
    (EC Dental Science, 2015) Perchyonok, V Tamara; Souza, Tatiana; Moodley, Desigar; Basson, Nickolas; Zhang, Shengmiao; Grobler, Sias
    The aim of this investigation is to evaluate the suitability and flexibility of the bio-active containing designer materials to act as an “in vitro” probe to gain insights into molecular origin of TMJ. The hydroxyapatite/chitosan containing hydrogels represent a reliable biocompatible scaffold and allowed to evaluate the defense “build in” free radical defense mechanism of the functionalized bio-scaffolds on the molecular level, compare the effectiveness of the designer materials with the earlier reported capabilities of N-acetyl cysteine and apply the newly developed materials for the evaluation of new therapeutic treatment modalities in the TMJ therapy in vitro. Materials and Methods: The hydrogels were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan: hydroxyapatite as a molecular scaffold. The surface morphology (SEM), release behaviors (physiological pH and also in acidic conditions), stability of the antioxidant-chitosan were also evaluated. Structural investigations of the reactive surface of the hydrogel are reported. Bio-adhesive studies and mechanical properties of newly prepared materials were conducted to assess the suitability of these designer materials. Ability of the materials to release the phenolic components as potential therapeutic agents was assessed. Results: The sustained release of total phenolic component as a potential therapeutic agent confirms the added benefit of synergistic action of a functional therapeutic delivery when comparing the newly designed chitosan/HA-based hydrogel molecular scaffold. The hydrogel formulations have a uniform distribution of drug content. The bio-adhesive capacity, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and quantified. Conclusion: The added benefits of the chitosan hydroxyapatite treated hydrogels involved positive influence on the phenolic component release, sustainable bio-adhesion, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and demonstrated in vitro “build in” free radical defense mechanism.
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    Towards Bio-active Restorative Materials with Copaiba Oil and Oblepicha Oil: In vitro
    (J Dent Oral Disord Ther, 2015) Perchyonok, V. Tamara; Moodley, Desigar; Grobler, Sias; Souza, Tatiana; Augusto de Souza, Joane; Zhang, Shengmiao
    We developed and evaluated chitosan - fucoidan bio-composites with additional bioactive components of oblepicha oil and copaiba oil for bioactive restorative material as intra-dental and wound healing applications such as bioadhesion to soft and hard tissue in vitro, dentin bond strength and free radical defense mechanism for the compounds in the oral environment.
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    Towards bioactive containing restorative materials: from design to testing in vitro approach
    (Symbiosis, 2015) Perchyonok, Tamara; Mulder, Riaan; Grobler, Sias Renier; Zhang, Shengmiao
    In any repair of a tooth with permanent restorative materials, the interface is always a sensitive region. The appearance of adhesive materials was a great step forward in dealing with the problems of this region and improving the overall performance of the restorations. However, contemporary adhesive materials do have a major disadvantage, namely that their durability is limited, a limitation which often arises due to their inadequate marginal adaptation. Restorative materials in the new era aim to be “bio-active” and long lasting. As part of our continuous interest in developing the novel bioactive containing restorative materials, we evaluated the effect of the additional bio-actives (such as chitosan, β-carotene, guar gum resin and the combination of the materials) to the commercially available flowable restorative materials such as Premise on the volumetric shrinkage, flexural strength, compressive strength, the surface hardness of the “bio-active” containing composite