Researchers in Orthodontics and Paediatric Dentistry

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Browsing by Author "Perchyonok, Tamara"

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    Bio-active restorative materials as alternative pit and fissure sealants in pediatric and preventative dentistry: In vitro investigation
    (MedCrave, 2017) Perchyonok, Tamara; Mulder, Riaan
    BACKGROUND: It has been more than 40 years since the pit and fissure sealants were first used clinically. During this time, pit and fissure sealants have been shown to be effective in reducing the risk of occlusal caries. AIM: The aim of the investigation is to further develop and evaluate a versatile designed chitosan based bio-active materials on for use as bonding free fissure sealant/fissure protectors on permanent dentition and evaluate remineralization/demineralization capacity of the materials through pH cycling, as well as shear bond strength etch and no etch prototype as well as measurement of Vickers hardness of the newly designed materials and compare the property with the commercially available standard. RESULTS: In general there was an increase in bond strength of the enamel treated with the modified Premise containing nanodiamond: chitosan materials compared to the bond strength of the conventionally bonded teeth. It is seen that release of phosphorus into the dematerializing solution (i.e. loss of phosphorus from the samples) showed larger amplitude (from 600.2mg to 101.3 mg) than the uptake of phosphorus by the samples from the re-mineralizing solution (from 125.2 mg to 66.1 mg). Therefore, the treatment with chitosan seems to act more on the demineralization of tooth enamel with little effect on the remineralization process. Regarding the net phosphorus loss (net P loss), it can be seen that net demineralization occurs in all cases. However, the net amount of phosphorous released by the control group samples was significantly higher than those groups treated with chitosan. The net P loss for the control group was 475 mg of P, whereas the groups containing chitosan had a net P loss in the range of 30-182 mg. When a 1mm layer is assessed all the materials including the Premise control indicated a conversion of above 96%, which is the upper limit of the conventional fissure sealant material which makes the newly designed bioactive materials suitable for the application as fissure sealant materials. The important aspect of any newly designed/ developed restorative material is cytotoxicity as Grobler et. al [1] investigated the cytotoxic effect of nanodiamonds and also the effect of the incorporation in a dental material (Premise), who found a higher shear bond strength (p < 5%) after 3 months of Premise treated with nanodiamonds, chitosan, cyclodextrin (CD) and combinations thereof than for the control Premise. The sequence for the Vickers hardness was: CD (32.5) < nano (34.8) < CD Nano (38.8) < Premise (39) < Chitosan Nano (42.2). Nanodiamonds (92%) and the combination of chitosan + nanodiamonds (93%) showed little cytotoxicity. The shrinkage was lower for all the additions than for Premise alone. CONCLUSION: All modified Flowable bio-active materials can be further developed in effective fissure sealant material based on the acceptable in vitro results and cytotoxicity data.
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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
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    Towards bioactive dental restorative materials with chitosan and nanodiamonds: evaluation and application
    (SciDoc Publishers, 2015) Mulder, Riaan; Grobler, Sias Renier; Moodley, Desi; Perchyonok, Tamara
    BACKGROUND/PURPOSES: Recently various articles showed beneficial effects of the addition of different the beneficial effect (bond strength and longevity) of the addition of different bioactive compounds towards dental materials. compounds towards dental materials. Therefore, the aim of this work was to evaluate the effect of the addition of bioactive materials and combination thereof (chitosan/nanodiamond or cyclodextrin/nanodiamond) to a dental composite. MATERIALS AND METHODS: The flowable composite Premise by Kerr was used as the standard control dental material. Premisewas also modified to contain: 10% nanodiamonds/Premise, 10% chitosan/nanodiamonds/Premise, 10% cyclodextrin/ nanodiamonds/Premise and 10% cyclodextrin/Premise and tested for their dentin bond strength, volumetric shrinkage, Vickers hardness and cytotoxicity. RESULTS AND CONCLUSION: Beneficial effects of the addition of different bioactive compounds towards dental materials were proved. A higher shear bond strength (p < 5%) was found after 3 months of Premise treated with nanodiamonds, chitosan, cyclodextrin (CD) and combinations thereof than the control Premise. The sequence for the Vickers hardness was: CD (32.5) < nano (34.8) < CD Nano (38.8) < Premise (39) < Chitosan Nano (42.2). Chitosan was found to increase the mouse 3T3 fibroblast cell survival rate (113%), while nanodiamonds (92%) and the combination of chitosan + nanodiamonds (93%) showed little cytotoxicity. The shrinkage was lower for all the additions than for Premise alone. Nanodiamonds and the combination chitosan + nanodiamonds showed little cytotoxicity towards mouse 3T3 fibroblast cells.