published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

In recent years bleaching of vital teeth has become popular among both dentist and patients. Different bleaching agents were used for this purpose. They are either applied professionally at high dose (office bleaching) or by patient at lower dose (home bleaching). In the present work we studied the effects of a high concentration bleaching agent (35% hydrogen peroxide), and a low concentration bleaching agent (17% carbamide peroxide) on human enamel and dentin using Fourier Transform Infrared (FTIR) Spectroscopic Technique. The OH stretching band of hydroxyapatite at 3567 cm-1 appeared in the spectra of enamel tissue which was absent in dentin. Carbamide peroxide and hydrogen peroxide treatment induced some differences in enamel and dentin spectra according to control group spectra. While the treatment of hydrogen peroxide leaded to significant decrease in mineral to matrix ratio, carbamide peroxide treatment did not cause decrease in this level. In addition, organic components of the teeth were changed after the treatment of bleaching agents. The frequency of the Amide A and Amide I bands were significantly changed for enamel tissue after the treatment of high concentration bleaching agent. However, it is observed that these changes result from two different bleaching methods are negligible in dentin tissue. In conclusion it can be stated that hydrogen peroxide treatment caused dramatic changes in enamel structure according to carbamide peroxide treatment, but two methods did not cause significant changes in dentin tissue.

Thesis (Ph. D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 217-247).

The aim of this study was to evaluate the impact of in-office tooth bleaching with 37% carbamide peroxide on patients' perceptions regarding the change in the satisfaction with their smile and on the bleaching procedures and their dental color change results and postoperative sensitivity when compared to 35% hydrogen peroxide. Forty patients were allocated to receive two sessions of in-office tooth bleaching using either 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP) (n=20). The perception of the smile itself was indicated through a visual analogue scale (VAS), and the procedures of tooth bleaching and its results were evaluated by means of a questionnaire applied 1 week after the first session and 30 days after the last one. Patients' sensitivity level was recorded during and up to 24 hours after bleaching procedure. Dental sensitivity was assessed using the verbal and EVA scales. It was calculated the absolute and relative risks to tooth sensitivity. The efficacy of bleaching procedures was evaluated with a spectrophotometer one week after each session and 30 days after the last one. Data from color evaluation (ΔL*, Δa*, Δb* and ΔE) were individually submitted to 2-way repeated measures ANOVA followed by Tukey’s post hoc test. Data from the level of sensitivity were analyzed by test Mann- Whitney. Absolute and relative risks were compared by the Fisher Exact test. It was observed a lower risk and level of tooth sensitivity for CP, while the difference between the bleaching agents disappeared after 24 hours. An increased bleaching effect was observed for HP, mainly due to an improved reduction of redness and yellowness. Participants perceived improved tooth bleaching for HP and reduced sensitivity for CP, but no differences regarding the comfort of the techniques were noted. An improved bleaching effect was observed for HP. CP resulted in reduced tooth sensitivity but also reduced the tooth bleaching efficacy. However, both bleaching agents resulted in high levels of patient satisfaction. / O objetivo deste estudo foi avaliar o impacto do clareamento dental de consultório com peróxido de carbamida a 37% na percepção dos pacientes em relação à mudança da satisfação com o seu sorriso, e sobre os procedimentos de clareamento e seus resultados de alteração de cor dental e sensibilidade pós-operatória, quando comparado ao peróxido de hidrogênio a 35%. Quarenta pacientes foram alocados para receber duas sessões de clareamento dental de consultório, utilizando peróxido de hidrogênio a 35% (PH) ou peróxido de carbamida a 37% (PC) (n = 20). A percepção do próprio sorriso foi indicada por meio de uma escala visual analógica (EVA), e os procedimentos de clareamento e seus resultados foram avaliados por meio de um questionário aplicado 1 semana após a primeira sessão e 30 dias após a última. O nível de sensibilidade dos pacientes foi registrado durante e até 24 horas após o clareamento. A sensibilidade dentária foi avaliada por meio das escalas verbal e EVA. Foram calculados os riscos absoluto e relativo à sensibilidade. A eficácia dos procedimentos clareadores foi medida com um espectrofotômetro uma semana após cada sessão e 30 dias após a última. Os dados da avaliação da cor (ΔL*, Δa*, Δb* e ΔE) foram individualmente submetidos à ANOVA de 2 fatores para medidas repetidas seguido pelo Teste de comparações múltiplas de Tukey. Os dados sobre o nível da sensibilidade foram analisados pelo teste Mann-Whitney. Riscos absoluto e relativo foram comparados pelo teste Exato de Fisher. Foi observado um menor risco e nível de sensibilidade dentária para o PC, apresentando valores próximos à zero, enquanto que a diferença entre os agentes clareadores desapareceu após 24 horas. Um maior efeito clareador foi observado para o PH, principalmente devido a maior redução do vermelho e amarelo. Os participantes perceberam melhor clareamento dental para o PH e menor sensibilidade para o PC, mas não foram observadas diferenças quanto ao conforto das técnicas. Concluiu-se que o PC resultou em menor sensibilidade dentária, mas também menor eficácia do clareamento dentário. No entanto, ambos os agentes clareadores resultaram em altos níveis de satisfação dos pacientes. / Aracaju

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-12T13:18:59Z No. of bitstreams: 1 larissadutrabittencourtdeoliveira.pdf: 15789701 bytes, checksum: f26b4d361b2cff1c8d4d0f75c7aec47a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-02-26T12:14:22Z (GMT) No. of bitstreams: 1 larissadutrabittencourtdeoliveira.pdf: 15789701 bytes, checksum: f26b4d361b2cff1c8d4d0f75c7aec47a (MD5) / Made available in DSpace on 2016-02-26T12:14:22Z (GMT). No. of bitstreams: 1 larissadutrabittencourtdeoliveira.pdf: 15789701 bytes, checksum: f26b4d361b2cff1c8d4d0f75c7aec47a (MD5) Previous issue date: 2014-08-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As alterações químicas foram analisadas através do EDS no esmalte dentário bovino, submetido ao branqueamento com peróxido de carbamida contendo ACP nas concentrações de 10%, 16% e 22%, nos tempos de 21 dias, indicado e 35 dias, prolongado. Os grupos foram divididos em: G1 e G5-controle (isento de branqueamento); G2 e G6–PC a 10% com ACP; G3 e G7–PC a 16% com ACP e G4 e G8–PC a 22% com ACP. G2, G3 e G4 foram avaliados aos 21 dias e G6, G7 e G8 aos 35 dias no MEV para observar a morfologia dental e no EDS para a análise dos elementos químicos oxigênio, fósforo e cálcio. As imagens observadas no MEV apresentaram-se porosas, irregulares com erosões e perda de estrutura. Para análise dos resultados obtidos no EDS utilizou-se a ANOVA com o teste de Tukey e o teste t de Student com nível de significância de 5% e foram observadas alterações significantes aos 21 dias nos elementos químicos oxigênio entre G2 e G4 e para o cálcio entre os G1 e G3; G1 e G4 e entre G2 e G4. Aos 35 dias, para o oxigênio entre G5 e G6, G7 e G8; para o fósforo entre G6 e G8 e para o cálcio, entre G5 e G8. A adição de ACP nas fórmulas dos géis branqueadores exógenos em diferentes concentrações, pode promover um equilíbrio na composição mineral do esmalte dental, porém não anula completamente os efeitos nocivos do PC. / The chemical changes were analyzed by EDS in bovine enamel submitted to bleaching with carbamide peroxide ACP containing concentrations of 10%, 16% and 22%, in the time of 21 days, and 35 days indicated, prolonged. The groups were divided into G1 and G5-control (free bleaching); G2 and G6-10% CP with ACP; G3 and G7- CP to 16% with ACP and G4 and G8- CP to 22% with ACP. G2, G3 and G4 were evaluated at 21 days, G6, G7 and G8 at 35 days under SEM to observe the tooth and EDS analysis of the chemical elements oxygen, phosphorus and calcium morphology. Images observed under SEM were presented porous with irregular erosion and loss of structure. To analyze the results obtained in the EDS used the ANOVA with Tukey's test and Student's t test with significance level of 5% and significant changes were observed at 21 days in chemical oxygen between G2 and G4 elements and calcium between G1 and G3; G1 and from G4 and G2 and G4. At 35 days, for oxygen between G5 and G6, G7 and G8; for the match between G6 and G8 and calcium, between G5 and G8. The addition of ACP in the formulas of exogenous whitening gels at different concentrations, can promote a balance in the mineral composition of dental enamel, but not completely nullify the harmful effects of CP.

The aim of this work is to contribute to the process development of the ECF light bleaching sequence Q(OP)D(PO) by providing a better understanding of the bleaching of softwood kraft pulp. There are few published studies on this type of sequence, and more knowledge is needed on how to reduce environmental impact, improve cost-effectiveness and ensure a high pulp quality. Firstly, this research showed that using a pH buffer to stabilize the pH at a near-neutral level during bleaching with chlorine dioxide can lower the formation of adsorbable organically bound halogens (AOX) without altering the bleaching efficiency. A near-neutral pH decreases the formation of strongly chlorinating species so that the AOX content in the bleaching effluents is reduced by up to 30%. The increased pH in the near-neutral pH D stage compared with the reference lowered the chlorine dioxide consumption, resulting in a higher kappa number and viscosity. A lower degradation of hexenuronic acid correlated well with a lower AOX content in the effluents, affirming earlier theories that hexenuronic acid has an important impact on AOX formation. Secondly, this research aimed at studying bleachability in (OO)Q(OP)D(PO). The bleachability was defined as delignifying and brightness gain bleachability, which is suited to ECF light bleaching sequences. The delignifying and brightness gain bleachability were used to evaluate the stages in (OO)Q(OP)D(PO) in regard to the unbleached kappa number. When comparing different stages, it is possible to distinguish the bleaching efficiency in each stage. For this ECF light sequence, the bleachability depends on the purpose of the stage. It was found that in the stages that are mainly delignifying (OO and D), a higher unbleached kappa number is beneficial for the delignifying bleachability, although the brightness gain is not improved. However, in the stages that are mainly brightness increasing (OP and PO), the brightness gain bleachability is improved by a lower unbleached kappa number. Thirdly, the bleaching of the pulp samples in this study with the ECF light sequence was most effective with a kappa number around 32 after cooking. Although an even higher kappa number resulted in a higher yield after cooking, it seemed that this bleaching sequence cannot preserve the yield gain. Kappa number 32 also gave the best results in regard to brightness ceiling and viscosity. On the other hand, kappa number 27 was the most favourable with regard to yellowing and chemical charge. / <p>Examinator: Helena Håkansson, lektor, Karlstads universitet</p>

An experiment was designed to test the hypothesis that each softwood pulp is unique and requires a specific, well defined mechanical treatment to derive its maximum strength potential. Three bleached softwood Kraft pulps and respective wood samples were sourced from both the Northern and Southern Hemispheres. The raw fibre characteristics of P. patula (Southern Hemisphere), P. menziesii (Northern Hemisphere) and P. mariana (Northern Hemisphere) were measured and compared. The raw pulp sheets were refined at different energies and intensities under controlled laboratory conditions using a 12” single disc pilot refiner. Results were assessed to determine the raw fibre characteristics, optimum refining conditions and the relative refined strength potential for each of the three samples. Results from anatomy measurements on the three wood samples differed significantly. P. patula exhibited a relatively high proportion of springwood growth in the early growing years. As the P. patula aged and formed mature wood there was a significant increase in the frequency of latewood formation. This was characterized by an abrupt and significant increase in the wall thickness, beyond that of the two Northern softwood samples. When the cell wall thickness increased, the lumen width and fibre diameter of the P. patula decreased significantly, yielding extremely coarse, stiff fibres. The Northern P .mariana and P. menziesii samples were characterized by a relatively consistent transition between high and low densities from the pith to the bark of the tree. The Southern P. patula had a unique density trend with an increasing frequency of high density peaks indicative of an increased latewood formation from the pith to the bark. The slower growing Northern P. menziesii and P. mariana samples did not have as clear a differentiation in fibre characteristics between juvenile and mature wood formation. The Northern samples did however contain a significantly higher proportion of juvenile latewood growth than the P. patula. However, the difference in fibre characteristics between earlywood and latewood formation was not as significant as that noted with the Southern P. patula Fibre morphology measurements on the unrefined bleached Kraft pulps also revealed significant differences between the three samples. The average MORFI LAB01 results on the P. patula defined fibres with a high coarseness and relatively low number of fibres per gram of pulp. The extremely coarse latewood fibres formed during mature wood growth being the most likely source. However, P. patula was also characterized with a high fibre flexibility and large lumen, characteristics consistent with earlywood fibres. The Pulmac Z-Span 3000 was used to define the individual fibre strength, when due consideration was given to the number of fibres per gram, the corrected Pulmac results suggested P. patula had the strongest fibres. When refined, using a standard disc refining programme, P. patula exhibited a fast freeness development. Conventional thinking would suggest that this was an indication of a weaker fibre. However, this species had a robust morphology compared to the Northern Hemisphere woods. The theory developed in this dissertation suggests that the effect of coarseness and the concomitant number of fibres per gram plays a significant role. These two parameters are not included in the “traditional” refining calculations. The applied refining load and intensity was calculated on the flow of the pulp passing through the refiner. The calculation did not consider the actual number of fibres present in that specific volume. The implication is that when a fixed refining load is applied to a pulp with coarse fibres there may be a higher effective load on those fewer fibres (resulting in fibre cutting and fines generation). In this case, the Northern samples have a comparatively low coarseness and more fibres per gram with each receiving a smaller portion of the total load and intensity. In terms of refined pulp properties, P. patula developed a relatively high bulk and tear index consistent with coarse, rigid fibres. The Northern P. mariana and P. menziesii samples produced a pulp with good tensile properties, consistent with a greater number of finer, collapsible fibres with a higher relative bonding area. P. patula fibres were extremely heterogeneous in nature containing the smallest relative lumen width during latewood formation and the largest lumen width during earlywood growth. As a result, P. patula contains extremes of both fine and coarse fibres in the same blend. It may be more beneficial for this species than the others to improve both the tear and tensile properties through fibre fractionation with appropriate development of the separate accepts and rejects streams. In terms of fibre development, low intensity refining parameters maximized the tensile strength of the Southern P. patula. The Northern P. mariana and P. menziesii samples had a greater number of fibres per gram of pulp requiring both a higher refining energy and intensity to develop the pulp to its maximum potential. To develop optimum tear results, high intensity refining, with a relatively low specific energy provided optimum results for all 3 samples. Results confirmed that there were significant differences in the fibre morphology both between the three different species and between the two Hemispheres. There was strong evidence that the fibre characteristics dictate the manner in which a fibre responds to refining which in turn determines the relative contribution to specific refined pulp properties. It may be possible to use fibre characteristics to determine the appropriate refining parameters for optimal fibre development which will enhance the value of the end product. To derive the maximum strength potential from P. patula pulp samples, it is recommended that further studies investigate Hydracyclone fractionation and the concomitant benefits of refining the separate streams. Furthermore, a separate study on fibre morphology and refining characteristics of the same species grown in both the Northern and Southern Hemisphere would provide valuable insight. / Thesis (M.Sc.Eng)-University of KwaZulu-Natal, Durban, 2009.

Cold pressed Hemp (Cannabis sativa L) seed oil, which contains a favorable ratio of omega-6/omega-3 and a considerable amount of vitamin E, is a high nutrition value product with various health benefits. However, the presence of a large amount of chlorophyll makes the oil highly susceptible to photo-oxidation and limits its applications. Chlorophyll and other pigments in edible oils are commonly reduced through oil bleaching process. The objective of this study was to reduce the chlorophyll content in cold pressed hemp seed oil using ultrasonic bleaching and evaluate the impacts on carotene content, peroxide value, conjugated diene, total phenolic content and oxidative stability. The bleaching efficiency increased significantly as the ultrasound power (0 to 60% pressure amplitude) and concentration of bleaching clay (20 to 40 g/kg) increased. At 20% ultrasound power, the chlorophyll reduction (%) of different clays was found to be 99.4% (industrial clay) > 97.8% (activated bentonite) > 82.7% (sepiolite) > 47.1% (non-activated bentonite). Ultrasonic bleaching significantly reduced (p<0.05) the total chlorophyll content, total carotene content and primary oxidation products of hemp seed oil. During accelerated oxidation tests (40 and 60 ℃), the developments of peroxide value and conjugated diene were significantly (p<0.05) slower for hemp seed oil treated with ultrasonic bleaching compared to the control oil. Enhanced oxidative stability was observed in hemp seed oil after ultrasonic bleaching. In addition, another objective of this study was to evaluate the impacts of solvent and heat treatment on phenolic profile and antioxidant activity of cold pressed canola and hemp meals. For canola meal, a solvent-mixture of aqueous methanol (70%) and aqueous acetone (70%) in a ratio of 1:1 (v/v) extracted (p<0.05) slightly higher total phenolic content (11.3 mg SAE/g), while aqueous methanol (70%) extracts exhibited higher DPPH scavenging effect (40.4%). For hemp meal, aqueous acetone (80%) extracts exhibited higher total phenolic content (6.0 mg GAE/g) and DPPH scavenging effect (12.5%). Total phenolic content and antioxidant activity in canola meal extracts were significantly higher (p<0.05) than those in hemp meal extracts. After heat treatments at temperature from 140 to 180 ℃, canola and hemp meal extracts showed equal or lower total phenolic content and DPPH scavenging effect. / May 2017

The pillar coral, Dendrogyra cylindrus, has been commonly described as widely distributed, but rare throughout its geographical range in the Caribbean. Having recently been listed as Threatened under the US Endangered Species Act, an understanding of population status is needed to promote species conservation and population recovery. Previous to this study the status of the pillar coral population in the state waters of Florida, U.S.A, was relatively unknown primarily due to few colonies being recorded and no comprehensive summary of population abundance, distribution or health being completed. Along with various environmental and anthropogenic factors affecting the pillar coral population on the Florida Reef Tract (FRT), it appears that reproductive limitations may also be contributing to species decline and limiting population recovery as evidenced by the lack of reported juvenile D. cylindrus colonies reported on the Florida Reef Tract (FRT) in the past 17 years. The factors contributing to this phenomenon are currently unknown, however are suspected to be derived from the pillar corals reproductive biology. Being described as a gonochoric, broadcast spawner, sexual reproduction relies on the synchronous release of gametes from colonies of separate sexes, and with low adult colony densities reported for the pillar coral on the FRT, gamete concentrations from both sexes may be too low for fertilization to occur. In 2014 submissions of pillar coral locations from the scientific and lay community were compiled and 610 D. cylindrus colonies along Florida Reef Tract were identified (Lunz et al. 2016). In my study, I describe the population structure of D. cylindrus for the southeast Florida region of the FRT which includes 65 of the total 610 colonies. For each of the 65 colonies, colony depth, demographic, and condition data were recorded including size (length, width, and height), percent of recent mortality, and presence and severity of disease and bleaching. Out of all locations identified in this region, about 50% contained only a single colony of D. cylindrus and the maximum number of colonies per site was 14. Throughout the duration of the study, devastating losses of live tissue were observed following the bleaching and disease events impacting the Florida Reef Tract in 2014, 2015, and 2016 and the status of the southeast Florida population of pillar coral is at serious risk of local extinction. To investigate the ability of colonies of D. cylindrus to sexually reproduce (referred to as sexual reproduction potential) tissue samples were collected from 95 colonies within 15 sites along the FRT and were prepared for histological analysis. The sex of each colony, sizes of gametes in mature developmental stages, the abundance of gametes per cm2 of tissue, and sex ratios for locations on the FRT were reported. All tissue samples from male and female colonies contained gametes that were ≥90% mature; however sex ratios were found to be skewed in all locations, deviating significantly from the 1:1 ratio expected for typical resource allocation in random mating. Hermaphroditic colonies of D. cylindrus are described for the first time throughout its geographical range in this study and comparisons to gonochoristic colonies confirmed that these hermaphrodites are sexually reproductive individuals. Results from this effort provide a more thorough understanding of the reproductive biology of D. cylindrus and essential data for the support of future conservation management and restoration strategies for this FRT population and comparative data for other Caribbean populations.

The aim was to evaluate whether a whitening system, when used during the final stages of orthodontics, would yield results comparable to whitening alone. Patients were assigned to either the control (n=20) or experimental (n=26) groups. At T1, patients were given a ten day supply of Trèswhite™ by Opalescence®, instructions on use, and initial shade determination was made and photographs were taken. At T2 and T3, shade determination was accomplished and updated photographs were taken. Whitening of the teeth occurred in both groups on average, but significantly more whitening was experienced in the experimental group (p < 0.004). An average of 87% of teeth whitened during orthodontic treatment compared to 97% of control teeth (p < 0.01) were judged to be uniform in appearance. In conclusion, the data do not contraindicate the concurrent accomplishment of teeth whitening during orthodontic treatment.