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Author: search.filters.author.Onwubu, Stanley ChibuzorHas files: Yes

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    The development of a nano-sized eggshell and titanium dioxide desensitising paste to re-mineralise teeth
    (2019) Onwubu, Stanley Chibuzor; Mdluli, Phumlane Selby; Singh, Shenuka
    Dentin hypersensitivity [DH] is a common occurrence and notable painful condition among dental patients. Clinically, the pain associated with DH is caused by external stimuli such as thermal, tactile, osmotic or chemical changes from open dentinal tubules. Traditionally, the treatment of DH is the use of at-home desensitising toothpaste. While there is a variety of desensitising paste such as Sensodyne® and Colgate sensitive Pro-Relief TM to treat DH, the dentin tubule remineralising characteristics of these paste are, however, limited in an acidic environment which could result in DH relapse. The limiting abilities of these desensitising paste prompt this study to develop a desensitising agent using nano-sized eggshell-titanium dioxide (EB@TiO2) as an active ingredient in the management of DH. A quantitative research design and an experimental research strategy were adopted. The research design included three phases. In phase one of this study, different characterisation techniques such as Fourier Transform Infrared Spectroscopy (FTIR); X-ray Diffraction (XRD); Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscope (SEM); High Transmission Electron Microscopy (HRTEM); and Thermo-Gravimetric were used to confirm the modification of EB@TiO2. Phase two, on the other hand, assesses the suitability of the EB@TiO2 as an oral healthcare product by examining its cytotoxicity and antibacterial properties. By contrast, phase three investigated the quality of the EB@TiO2 as a new approach to the management of DH. Particularly, the acid resistant, abrasivity, and remineralisation characteristics of EB@TiO2 were studied using bovine and eggshell model, respectively. Different analytical technique such as pressure sensor, gas displacement test, Atomic Force Microscope, Raman Spectroscopy, SEM, and EDX were used to examine the product quality of EB@TiO2 in comparison with some commercially available paste. In addition, a mathematical model was used to predict the duration and rate of remineralisation of EB@TiO2. Both descriptive and inferential statistics were used to present the data (P=0.05). The validity of the study was achieved following SANS 1302 (2008) requirement for preparation, developing, and testing toothpaste. The reliability was determined via reproducibility and repeatability of tests. Paper I and II examines the effectiveness of commercially available toothpaste in the prevention of tooth decay, using eggshell powder as a substitute for the human tooth. Paper I established that eggshell model can be used as a substitute for the human tooth to study the acid resistant properties of toothpaste. The salient point of the paper is that all the tested toothpaste were effective against erosive attacks. However, the eggshell alone without the protective covering of toothpaste showed limited acidic resistance. Paper II established that acid resistance properties of EB@TiO2 were significantly better than eggshell alone. The paper confirmed that modifying eggshell with titanium dioxide improved its acidic resistance characteristics. Paper III and IV evaluate the acidic resistance of EB@TiO2 using a bovine model. Paper III and IV established that the protective effects of EB@TiO2 were superior to the tested commercially available toothpaste. The FESEM, AFM, and Raman test further confirmed that EB@TiO2 offer better protection on the tooth enamel. Paper V and VI assess the occluding capabilities of EB@TiO2 and eggshell alone in comparison with other desensitising toothpaste. Paper V confirmed that there was complete remineralisation of the dentin tubules in the samples treated with EB@TiO2. At higher magnification, the particles of EB@TiO2 were very much evident. The EDX spectrum reveals that the Ti peaks observe before and after post acidic treatment were comparable. Paper VI established that occlusion of EB@TiO2 was highly effective in an acidic environment, as occluded tubules remained intact post-acidic treatment. In addition, the cytotoxicity study identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100μg/ml. Manuscript I assess the occluding capabilities of EB@TiO2 in comparison with a known occluding desensitising agent (Pro-Argin and NovaMin). Manuscript I established that as the brushing days increase the remineralisation or dentin tubule occluded by each respective desensitising agent improved. It was found that the occluding capabilities of EB@TiO2 were more superior to both Pro-argin and NovaMin products in both saliva and without saliva. Manuscript II described the use of the logistic equation to predict the remineralisation of the EB@TiO2. Manuscript II established that the logistic equation effectively predicted the remineralisation trends of EB@TiO2 and Pro-argin toothpaste (Colgate Pro-relief). Manuscript III assesses the abrasivity of EB@TiO2 in comparison with calcium carbonate, and hydrated silica containing toothpaste. Bovine enamel specimen was used for the in vitro experiment. Manuscript III established that enamel loss from the brushed surface, regardless of the sample group, were statistically different when compared to the covered surface. The study found that the abrasivity of EB@TiO2 were comparable with the calcium carbonate toothpaste. It was also established that EB@TiO2 was less abrasive when compared against hydrated silica containing toothpaste. In conclusion, the experimental finding has exhaustively provided evidence on the suitability of EB@TiO2 as an active ingredient in toothpaste formulation. The study, therefore, provides new evidence and approach for the management of DH, particularly in low-income countries where the cost of oral healthcare may be too high.
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    Using eggshell for the development of a quality alternative material to pumice in reducing the surface roughness of heat-cured acrylic resins.
    (2016) Onwubu, Stanley Chibuzor; Vahed, Anisa; Singh, Shalini; Kanny, Krishnan
    Pumice is used in the polishing of dental appliances to remove surface irregularities. It is usually used in a slurry form that is pumice powder mixed with water. In Nigeria, the increased cost of pumice as a result of its limited supply into the country has encouraged dental technicians to re-use pumice slurry for longer periods than advocated when polishing acrylic dentures, whether new or old dentures which have been worn in the mouth. Consequently, this is likely to increase cross-infection of communicable diseases in the dental technology laboratory. Although materials such as white sand, black sand and porcelnite can be used, literature documents that these materials are less effective in the polishing of acrylic dentures (Areeg 2011). The focus of this study was to use eggshells, a natural waste product, to develop and test the quality of an alternative material to reduce the surface roughness of heat-cured acrylic resins. A quantitative research paradigm and an experimental research strategy were adopted. The research design included two phases. In phase one of this study, different characterisation techniques such as Brunnae-Emmer Teller (BET); Fourier Transform Infrared Spectroscopy (FTIR); X-ray Diffraction (XRD); Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscope (SEM); Transmission Electron Microscopy (TEM); Laser Scattering Particle Size Distribution Analyser (PSA); Thermo-Gravimetric Analysis (TGA); and Induction-Coupling-Optical Emission Spectroscopy (ICP-OES) were used to assess the suitability of the new abrasive material (NAM). In addition, the level of microbial contamination of the NAM was assessed in line with the specified microbial limits for cosmetic products. In contrast, phase two investigated the product-based quality of the NAM as an abrasive material for removable dental appliances. There were two sample groups, that is, the NAM (test group) and Pumice (control), and each sample group had 50 PMMA acrylic specimens. The surface roughness (Ra) was measured using a Talysurf profilometer. An Independent Tukey test was used to analyse the Ra values (p=0.05). A Scanning Electron Microscope (SEM) and Optical Microscope (OEM) were further used to support the results of the profilometer in terms of the quality of surface finish and polish. Validity of the study was achieved following the ISO 20795-1 (2013) methods of preparation and fabrication of the acrylic specimens. The reliability was determined via reproducibility and repeatability of tests. The BET analysis showed that the NAM is predominantly a mesoporous powder. The FTIR and XRD analyses confirmed that the NAM is pure calcite with unique water absorbing characteristics, and is free of bacteria. The EDX and ICP-OES analyses revealed calcium, oxygen and carbon as the major elemental composition of the NAM. The SEM and TEM images revealed irregular shaped particles in the NAM. The PSA analysis of the particle distribution showed the NAM to be superfine (50nm to 0.3µm) and medium (44µm powder), respectively. The TGA analysis revealed a high-grade carbonate product in the NAM (>66.0 mass% of calcium carbonates). In addition, and in terms of in the qualities of the NAM in reducing the surface roughness of PMMA resins, the test group and the control group produced Ra values that were significant different (p<0.0001). The SEM and OEM analyses further confirmed the differences in the surfaces between the polished sample groups at different magnifications. Overall, the control showed the highest mean average (0.1056±0.03688µm), whereas the test group had the lowest Ra values (0.0476±0.01379). The lowest Ra values measured with the test group indicated that the NAM improves the surface smoothness of PMMA acrylic specimens. Notably, this study conclusively showed that the NAM effectively reduces the surface roughness to below the threshold limit value of 0.2µm. Significantly, and in associating the Ra values to the threshold limit value of 0.2µm, the NAM produced better results than pumice. Hence the use of the NAM as a polishing material for acrylic dentures is highly recommended. Finally and in line the NAM being a suitable alternative to pumice as it effectively reduces the surface roughness of PMMA specimens, future investigation into the use of eggshell nanoparticles to develop dental prophylaxes will be encouraged.