Orientadora: Profa. Dra. Patrícia Aparecida da Ana / Coorientadora: Profa. Dra. Ilka Tiemy Kato Prates / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Biomédica, São Bernardo do Campo, 2018. / Lasers de erbio podem ser usados para prevencao de carie radicular, o que e de suma importancia para os idosos. Contudo, parametros seguros e eficazes de irradiacao para a dentina radicular ainda nao foram determinados empregando-se o laser de Er,Cr:YSGG para tal finalidade. Esse estudo tem por objetivo avaliar os aumentos de temperatura pulpar e superficial, assim como as alteracoes morfologicas, decorrentes da irradiacao da dentina radicular com laser de Er,Cr:YSGG quando empregado com finalidade preventiva, e avaliar os efeitos de um dos parametros estabelecidos na composicao e resistencia a desmineralizacao da dentina radicular. O estudo foi dividido em duas fases experimentais. Na primeira, os efeitos morfologicos e de variacao de temperatura pulpar e superficial foram avaliados a partir de tres potencias medias do laser de Er,Cr:YSGG, enquanto que, na segunda, um dos parametros selecionados foi avaliado quanto as mudancas composicionais, morfologicas e opticas promovidas na dentina radicular. Na primeira fase experimental, 30 dentes unirradiculares humanos e 30 blocos de dentina radicular bovina foram aleatoriamente distribuidos em tres grupos experimentais para irradiacao com laser de Er,Cr:YSGG (2,78 £gm, 600 £gm, 20 Hz, 60 £gs, sem refrigeracao): G1a ¡Vpotencia media de 0,10W; G1b - potencia media de 0,25W; G1c - potencia media de 0,50W. Foram determinadas as variacoes de temperatura intrapulpar empregando-se termopares, variacoes de temperatura superficial com termografia e alteracoes morfologicas por microscopia eletronica de varredura (MEV). Na segunda fase experimental, 75 blocos de dentina radicular bovina foram aleatoriamente distribuidos em 5 grupos experimentais: G1b: sem tratamento; G2b: tratamento com fluor fosfato acidulado (FFA, 1,23% F-, pH= 3,6 = 3,9); G3b: irradiacao com potencia media de 0,25W; G4b: irradiacao laser seguida de aplicacao de FFA; G5b: aplicacao de FFA seguida da irradiacao laser. Foram efetuadas avaliacao composicional por espectroscopia de absorcao no infravermelho por transformada de Fourier (FTIR), optica por tomografia por coerenca optica (OCT) e morfologica por MEV. Em seguida, as amostras foram submetidas a ciclagem de pH por 8 dias e, no fim, foi avaliado o coeficiente de atenuacao optco obtido por nova avaliacao por OCT. A analise estatistica foi efetuada individualmente para cada variavel resposta, sendo adotado o nivel de significancia estatistica de 5%. Todos os parametros laser promoveram alteracoes de temperatura inferior ao limiar para danos pulpares; contudo, apenas o grupo tratado com 0,50 W promoveu aumentos de temperatura superficial superiores a 100o C, indicativos de alteracoes quimicas na dentina. Os grupos irradiados com 0,25W e 0,50 W promoveram microablacoes na dentina, observados pelo MEV. Na segunda fase experimental,
observou-se pelo FTIR que a irradiacao laser isoladamente nao altera a composicao da dentina, mas a aplicacao previa de FFA seguida da irradiacao laser diminuiu significativamente o conteudo de ¿Þ3¿Þ4 carbonato da dentina. Da mesma forma, este tratamento tambem promove maior alteracao morfologica e de coeficiente de atenuacao optica quando comparado aos tratamentos isoladamente. Apos desmineralizacao, observou-se que tanto a irradiacao laser isoladamente, quanto a aplicacao de FFA previamente a irradiacao, promoveram aumento significativo do coeficiente de atenuacao optico, indicando menor desmineralizacao das amostras para este grupo. Desta forma, foi possivel concluir que o laser de Er,Cr:YSGG apresenta potencial para uso em prevencao da desmineralizacao da dentina radicular, sendo segura sua aplicacao com potencia media de 0,25W e mais eficiente quando precedido da aplicacao de FFA. / Erbium lasers can be used to prevent root caries, which is imporant for the elderly. However, safe and effective irradiation parameters have not yet been determined for root dentin using the Er,Cr:YSGG laser for this purpose. The objective of this study was to evaluate the pulp and surface temperature increases, as well as the morphological alterations, due to Er,Cr:YSGG laser irradiation on root dentin when used for preventive purposes, and to evaluate the effects of one of the parameters in the composition and resistance to demineralization of root dentin. The study was split into two experimental phases. In the first one, the morphological and pulp and surface temperature variations were evaluated from three average powers of the Er,Cr:YSGG laser, while in the second phase, the compositional, morphological and optical properties promoted by one selected laser parameter were evaluated in root dentin. In the first experimental phase, 30 unirradicular human teeth and 30 bovine root dentin slabs were randomly distributed in three experimental groups for irradiation with Er,Cr:YSGG laser (2.78 £gm, 600 £gm, 20 Hz, 60 £gs, without refrigeration): G1a - average power of 0.10W; G1b - average power of 0.25W; G1c - average power of 0.50W. The pulpal temperature variations were determined using fast response thermocouples, the surface temperature variations were measured using infrared thermography and morphological changes were observed by scanning electron microscopy (SEM). In the second experimental phase, 75 slabs of bovine root dentin were randomly distributed in 5 experimental groups: G1b: without treatment; G2b: treatment with acidulated fluoride phosphate (APF, 1.23% F-, pH = 3.6 = 3.9); G3b: irradiation with average power of 0.25W; G4b: laser irradiation followed by APF application; G5b: application of APF followed by laser irradiation. The compositional evaluation was performed by Fourier transformed infrared spectroscopy (FTIR), the optical aspect was observed by optical coherence tomography (OCT) and morphology was evaluated by SEM. Afterwards, the samples were submitted to pH-cycling for 8 days and, finally, the optical attenuation coefficient was obtained by a new OCT evaluation. The statistical analysis was performed individually for each response variable, considering the level of significance of 5%. All the laser parameters promoted changes in temperature below the threshold for pulp damage; however, only the group treated with 0.50 W promoted surface temperature increases above 100 ¢XC, indicative of chemical changes in dentin. The groups irradiated with 0.25W and 0.50 W promoted microablation in dentin. In the second experimental phase, it was observed that the laser irradiation alone does not alter the composition of the dentin, but the previous application of APF followed by the laser irradiation significantly decreased the content of ¿Þ3¿Þ4 carbonate of the dentin. In the same way, this treatment also promotes greater morphological alterations when compared to treatments alone. After demineralization, it was observed that both the laser irradiation alone and the application of APF previously to the laser irradiation promoted a significant increase in the optical attenuation coefficient, indicating a lower demineralization of this group. In this way, it was possible to conclude that the Er,Cr:YSGG laser presents potential for use for preventing root dentin demineralization. Its application is safe with a mean power of 0.25W and more efficient when preceded by APF application.
| Identifer | oai:union.ndltd.org:IBICT/oai:BDTD:110517 |
| Date | January 2018 |
| Creators | Silva, Elizabete dos Santos Ferreira |
| Contributors | Ana, Patrícia Aparecida da, Prates, Ilka Tiemy Kato, Daghastanli, Nasser Ali, Zamataro, Claudia Bianchi |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf, 104 f. : il. |
| Source | reponame:Repositório Institucional da UFABC, instname:Universidade Federal do ABC, instacron:UFABC |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | http://biblioteca.ufabc.edu.br/index.php?codigo_sophia=110517&midiaext=76207, http://biblioteca.ufabc.edu.br/index.php?codigo_sophia=110517&midiaext=76208, Cover: http://biblioteca.ufabc.edu.brphp/capa.php?obra=110517 |
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