Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Odontologia. / Made available in DSpace on 2012-10-22T16:04:02Z (GMT). No. of bitstreams: 1 235673.pdf: 10801675 bytes, checksum: 12cb9960ede56e2d3157106247732d52 (MD5) / This in situ/ex vivo study aimed to investigate the effects of two non-fluoridated dentifrices with calcium carbonate (CaCO3) and silica (SiO2) on human permanent enamel eroded by a carbonated soft drink. During two phases over 5 days, 12 volunteers (mean age 28) used a palatal appliance with 6 enamel blocks. In each period, the appliances were immersed in the soft drink for 5 min, 4 times a day. In two moments of the erosive challenge, 2 enamel blocks were not additional treatment, 2 blocks were brushed either with a CaCO3 or SiO2 dentifrices, immediately after the erosive treatment and 2 blocks 1 h later. Brushing was made for 30 s. Between phases a 2 day washout period was followed. An in vitro study was also conducted to investigate artificial and natural saliva influence on the erosion variation. The results were expressed in enamel roughness (Ra, ìm) and morphology analysis. The eroded and abrasioned enamel blocks showed superficial roughness changes significant higher than the eroded blocks (p<0.05). Blocks submitted to immediate abrasion or 1 h later did not show significant statistical difference. Both dentifrices had a similar abrasive effect on the eroded blocks. There was no significant difference in roughness between the enamel blocks from the experimental group (in vitro) and blocks from the in situ/ex vivo groups (CaCO3 and SiO2 control). Data showed that independently of the abrasive used, surface roughness is increased when erosion is associated to dental abrasion. It also did not have a 12 higher effect when comparing natural with artificial saliva in relation to dental

[pt] A madeira é o material biológico mais conhecido e utilizado como matéria-prima desde os primórdios da humanidade até os dias atuais. Como um compósito natural e renovável, seu tempo de vida útil é limitado pela degradação de seus elementos básicos. Essa degradação pode ser ocasionada por reações químicas ou por agentes biológicos capazes de acelerar o processo de deterioração. Esse trabalho teve como objetivo avaliar, sob condições laboratoriais, características mecânicas, térmicas, microestruturais e de biodeterioração em sistemas estáticos de 3 espécies de madeiras - Pupunha (Bactris gasipaes, Kunth), Pau-Brasil (Caesalpinia echinata) e Imbuia (Ocotea porosa) - com o objetivo de utilizá-las em projetos de design de jóias. Como resultado, foi observado que a pupunha obteve menor perda de massa após ensaio de abrasão, menor teor de umidade absorvida e mostrou resistência a degradação em temperaturas mais elevadas. O pau-brasil apresentou melhor desempenho visual quando analisado no MEV após ensaio de abrasão, maior índice de cristalinidade e menores valores referentes a ataques de fungos, formação de biofilme e/ou qualquer variação causada por substâncias agressivas. A imbuia foi a espécie que sofreu visualmente maiores alterações microestruturais, apresentou elevados valores quanto ao teor de umidade, aumento da rugosidade após ensaio de abrasão, maior contaminação por fungos e crescimento bacteriano; provavelmente por ser a espécie mais porosa dentre as analisadas. / [en] Wood is the best-known and biological material used as raw material since the dawn of mankind until the present day. As a natural and renewable composite, its lifetime is limited by the degradation of its basic elements. This degradation can be caused by chemical reactions or by biological agents capable of accelerating the process of deterioration. In this work, mechanical, thermal, micro-structural characteristics and bio-degradation characteristics in static systems of 3 species of woods - Pupunha (Bactris gasipaes), Pau-Brazil (Caesalpinia echinata) and Imbuia (Ocotea porosa) - were studied under laboratory conditions in order to use these woods in jewelry design. The results obtained show that pupunha had less loss in mass after abrasion test, less absorbed moisture content and showed higher resistance to thermal degradation. Pau-brazil showed better visual performance when analyzed in SEM after the abrasion test, the highest crystallinity and lower values for fungus attacks, bio-film formation and/or any variation caused by aggressive substances. Imbuia was the species that suffered visually major micro-structural changes; presented higher values for the moisture content and increase of roughness after abrasion test and greater contamination by fungi and bacterial growth. This behavior was probably due because Imbuia is the most porous species among the analyzed ones.