Thesis (M. Sc.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 92-93).

Tèse - Geneva. / "Bibliographie": p. 46-47.

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Orientadores: Marcelo Giannini, Cinthia Pereira Machado Tabchoury / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-16T09:10:08Z (GMT). No. of bitstreams: 1 Berger_SandrineBittencourt_D.pdf: 2055436 bytes, checksum: 7fb4b7b2c3d494b9ad94c29793baf2d4 (MD5) Previous issue date: 2010 / Resumo: O objetivo geral deste estudo foi avaliar o efeito de géis clareadores contendo cálcio ou fosfato de cálcio amorfo (ACP) no módulo de elasticidade da dentina bovina desmineralizada e desmineralização do esmalte hígido ou com lesão inicial de cárie artificial. Capítulo 1: Este estudo avaliou o efeito de agentes clareadores no módulo de elasticidade (ME) da matriz orgânica da dentina bovina. Oitenta e cinco fatias foram obtidas de dentes bovinos e separadas em 5 grupos: grupo controle - sem tratamento (GC), peróxido de hidrogênio 4% (PH4), PH4+0,05% Ca (HP4/Ca), PH 7,5% + ACP (PH7,5) e peróxido de carbamida 10% (PC10). Os grupos PH4, PH4/Ca e PC10 foram tratados com os géis clareadores por 8 horas / dia durante 14 dias, enquanto as amostras do grupo PH7,5 foi submetida ao clareador por 30 minutos, 2 vezes ao dia, durante 14 dias. O esmalte das amostras foi removido e foram preparados 17 espécimes (0,5 x 1,7 x 7,0 mm) por grupo. Em seguida, estas foram desmineralizados em solução de ácido fosfórico 10% por 5 horas e o ME foi mensurado: 24 horas, 7 e 14 dias após o clareamento, utilizando o teste de micro-flexão de 3 pontos. Os dados foram submetidos a ANOVA e teste de Fisher (p<0,05). As amostras clareadas após 24 horas e 7 dias mostram menor ME que o GC. Os grupos clareados foram similares ao GC após 14 dias, exceto o grupo PH7,5. O uso de peróxidos pode promover diminuição do módulo de elasticidade da matriz orgânica da dentina bovina. Capítulo 2: O propósito nesta parte da tese foi avaliar o efeito de um clareador experimental e um comercial no esmalte sadio (ES) ou esmalte com lesão inicial de cárie artificial (LC), utilizando microscópio confocal laser de varredura (CLSM). Oitenta blocos (4 x 5 x 5 mm) de esmalte bovino foram usados, sendo que quarenta destes foram desmineralizados com ciclagem de pH para induzir a lesão inicial de cárie artificial. Oito grupos experimentais foram formados a partir dos produtos clareadores e a condição do esmalte dental (ES ou LC), com n=10: Grupos ES: G1 - sem tratamento (controle); G2 - peróxido de hidrogênio 4% (PH4); G3: PH4 contendo 0,05%Ca (Ca); G4 - peróxido de hidrogênio 7,5% (PH7,5) contendo fosfato de cálcio amorfo (ACP). Grupos LC: G5 - não clareado; G6 - PH4; G7 - PH4 contendo Ca; G8 - PH7,5 contendo ACP. Os grupos G2, G3, G6 e G7 foram tratados com o gel clareador por 8 horas/dia durante 14 dias, enquanto as amostras dos grupos G4 e G8 foram submetidas ao clareador por 30 minutos/duas vezes ao dia, durante 14 dias. Os blocos de esmalte foram corados com solução de rodamina e área fluorescente de desmineralização foi quantificada utilizando CLSM. Os dados foram submetidos a ANOVA e teste de Fisher (p<0,05). Para ES, os tratamentos clareadores aumentaram significativamente a área de desmineralização quanto comparado com os grupos não clareados, entretanto, para LC não foi observado diferença estatística significante entre os grupos. A adição de ACP e Ca na composição dos géis clareadores não resultou em redução da desmineralização promovida pelos tratamentos clareadores / Abstract: The aim of this study was to evaluate the effect of bleaching agents containing calcium or amorphous calcium phosphate (ACP) on the elastic modulus of demineralized bovine dentin and demineralization in sound enamel or early artificial caries lesion. Chapter 1: This study evaluated the effect of tooth whitening agents on the elastic modulus (EM) of bovine dentin organic matrix. Eighty?five slices were obtained from bovine teeth and divided into five groups: unbleached control group (CG), 4% hydrogen peroxide (4HP), 4HP+0.05% Ca (4HP/Ca), 7.5% HP (7.5HP) and 10% carbamide peroxide (10CP). The 4HP, 4HP/Ca and 10CP groups were treated with the whitening agents for 8 hours/day during 14 days, while the samples of 7.5HP group were exposed to peroxides for 30 minutes twice a day during 14 days. The enamel of the samples was removed and 17 dentin specimens (0.5 x 1.7 x 7.0 mm) were prepared per group. The specimens were demineralized in 10% phosphoric acid solution for 5 hours and E was assessed using a micro-flexural three-point bend method at 24 hours, 7 and 14 days post-bleaching. The mean values of EM for each group were statistically analyzed using ANOVA and Fisher's test (p<0.05). Bleached specimens tested after 24 hours and 7 days showed lower EM than CG. The bleached groups were similar to CG after 14 days, except for the 7.5HP group. The use of peroxides can promoted decrease of EM of bovine dentin organic matrix. Whitening agents can significantly affect of the dentin organic matrix and irreversible damage is observed for selected agents. Chapter 2: The purpose of this study was evaluated to effect of experimental and one commercial bleaching agents on the sound enamel (SE) and with early artificial caries lesions (CL) enamel using confocal laser scanning microscopy (CLSM). Eighty blocks (4 mm thickness x 5 wide x 5 length) of bovine enamel were used and half of them were demineralized with a pH cycling to induce artificial caries lesions. Eight experimental groups were investigated following the bleaching treatments or not and SE or CL (n=10): SE groups: G1 - unbleached (control); G2 - 4% hydrogen peroxide (4HP); G3 - 4HP containing 0.05% Ca (Ca); G4 - 7.5% hydrogen peroxide (7.5HP) containing amorphous calcium phosphate (ACP). CL groups: G5 - unbleached; G6 - 4HP; G7 ? 4HP containing Ca; G8 ? 7.5HP containing ACP. The G2, G3, G6, G7 groups were treated with the bleaching agents for 8 hours/day during 14 days, while the samples of G4 and G8 groups were exposed to bleaching agent for 30 minutes twice a day during 14 days. The enamel blocks were stained with rhodamine solution and the quantification of fluorescence demineralization areas of the samples were evaluated using a CLSM. Data were analyzed using ANOVA and Fisher's tests (p<0.05). For the SE, the bleaching treatments significantly increased the demineralization area when compared to unbleached group, however, in CL no statistically significant difference was observed among the groups. The addition of ACP or Ca in the composition of the whitening products did not result in the decreasing of the enamel demineralization promoted by bleaching treatments / Doutorado / Materiais Dentarios / Doutor em Materiais Dentários

Indiana University-Purdue University Indianapolis (IUPUI) / This study evaluated the effectiveness of bleaching tetracycline-stained teeth by measuring the loss of fluorescent intensity from teeth that were bleached. Nineteen male New Zealand white rabbits, with 58 incisors stained with oxytetracycline and 16 incisors as unstained controls, were used. Three rabbits were sacrificed to determine whether the tetracycline stain was comparable between incisors in the same jaw. Of the remaining 16 animals, 6 were bleached once and 10 were bleached twice. One maxillary and one mandibular incisor were bleached in each jaw with 30 percent hydrogen peroxide and heat for ten minutes per tooth; the other incisors were protected with a rubber dam. The animals were sacrificed 24 hours after the last bleach. The fluorescent intensity of 374 select ground sections 100 ± 5 microns thick from the incisal, middle and gingival thirds of the teeth were measured with an ultraviolet light microscope coupled to a television electronic measurement system. These measurements were statistically analyzed by t-test, and observations correlated. The dentin of tetracycline-stained maxillary incisors which were bleached twice and the dentin in the incisal one-third of the mandibular incisors which were bleached twice had a significantly (P ≤ 0.001, P ≤ 0.005) lower tetracycline fluorescent intensity than the dentin of unbleached tetracycline-stained teeth. The greatest loss of fluorescent intensity of tetracycline occurred in dentin closest to the dentino-enamel junction and varied from about 150 to 350 microns from the outer enamel surface. Clinical Kodachromes indicate that the loss of tetracycline pigment is associated with the loss of tetracycline fluorescence; The ground sections showed that the tetracycline fluorescence was never totally removed by two bleaches.

Magister Scientiae Dentium - MSc(Dent) / Tooth discoloration has increased the demand by patients to pursue aesthetic treatment options. Bleaching is considered a conservative approach in performing an aesthetic treatment for discolored teeth; however colour rebound and post-operative sensitivity are among the adverse effects associated with vital bleaching. In-office bleaching systems employ the use of high hydrogen peroxide concentrations. The effects of in-office bleaching agents on the degree of colour change and the gender differences in relation to bleaching outcomes are questionable. Post-operative sensitivity can be considered a bleaching side effect and the number of patients that experience it is unknown.Aim: The aim of this study was to assess the outcome of an in-office vital bleaching technique. Objectives: The objectives of this study were to evaluate the degree of colour change after vital tooth bleaching using a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain), using a spectrophotometer (CM-2600d Konica, Minolta) to measure the colour change at each intervention during the bleaching process, to assess the post-operative sensitivity during the first week of the intervention, to evaluate the patients' perception of the colour change and to compare it to the colour change (ΔE) expressed in numeric values and to investigate whether gender differences exist in relation to the outcome of the bleaching procedure. Materials and Methods: The maxillary anterior teeth of 22 patients comprising of 11 males and 11 females were bleached with a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain). Pre-treatment readings of the two maxillary central incisors using a spectrophotometer (CM-2600d Konica, Minolta) were obtained. Subsequent readings were obtained after scaling and polishing, before bleaching (which was used as a baseline reading), immediately after bleaching, one week and one month post-operatively. Patients were requested to complete a form regarding post-operative tooth sensitivity and their colour perception toward the bleaching treatment. Results: The quantitative effect of the bleaching material on tooth colour showed an increase in L* values and a decrease in a* and b* values, the changes were significant (p values ≤ 0.05) except for the mean value of b* one month after bleaching which was only significant between five and ten percent.The mean values of colour change measured as ΔE between baseline and after bleaching was found to be 3.4 which did not exceed the visible colour change perceptible clinically at a difference of 3.7 units according to the literature. However nine patients exceeded the visible clinical colour change immediately after bleaching. There was no gender difference in the ΔE values in the entire bleaching process. Tooth sensitivity is considered a bleaching side effect and in this study sensitivity was traced until the fifth day after bleaching. The mean value of patients' tooth sensitivity was found to be 1.73 in the first day on a 4 point visual analog scale. The mean value of patients' colour perception was found to be 2.14 immediately after bleaching on a 3 point visual analog scale. Spearman correlation tests showed a positive relationship between ΔE values immediately and one week after bleaching and a weak relationship one week and one month after bleaching. There was significant consistency in the patients‟ colour perception data immediately and one week after the bleaching process and a weak relationship between ΔE values and patients' colour perception one month after bleaching. Conclusion: Yotuel® Special, Biocosmetics Laboratories, (Spain) an in-office bleaching material consisting of 35% hydrogen peroxide was able to bleach patients' teeth with a perceptible colour change however the chalky white teeth desired were not obtained for all the patients. Tooth sensitivity was a temporary side effect.

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