Avaliação in vitro e in situ da eficácia de diferentes lasers no aumento da resistência ácida do esmalte em regiões de sulcos e fissuras / In vitro and in situ assessment of lasers to increase enamel acid resistance on the pits and fissures surface.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The aim of this study was to assess in vitro and in situ the lasers Er:YAG, Nd:YAG e CO2 in preventing enamel demineralization on the pits and fissures surface. For the in vitro study 45 occlusal enamel blocks were randomly divided into 3 groups in according with the treatment: G1 - Er:YAG; G2 - Nd:YAG; G3 - CO2. Treatments were made only on a half of the specimen and the remaining part was considered as a control. The samples were submitted to an in vitro pH cycles. For the microhardness test the specimens were seccioned in the middle and the seccioned wall received the test. The other halves were analyzed using polarized light microscopy for the measurement of the caries-lesion areas and morphological SEM analyses. Wilcoxon test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) and caries-lesion area measurements (mm2) (α= 5%) when each groups was compared with its control. Variance analysis were performed for the difference in means of microhardness data and Kruskal Wallis test were performed for the difference in means of caries-lesion area measurements (α= 5%). For the microhardness data the G3 was statically different from its control area and the others groups presented statistical similarity among the experimental and control areas. For the caries-lesion area measurements statistical difference was observed for the groups G2 and G3 presenting smaller caries-lesion area when compared with their respective control areas. In the SEM analysis the G3 showed uniform surface without enamel-prism exposure. For the in situ study 60 occlusal enamel blocks were randomly divided into 4 groups in according with the treatment: G1 - Control (no treatment); G2 - Er:YAG; G3 - Nd:YAG; G4 - CO2 (n=15). The specimens were fixed in intra oral appliances and worn by the volunteers for 14d. Sucrose solution (20%) was applied to each specimen 6 times/d. As the in vitro study the samples were removed, sectioned and examined for microhardness, caries-lesion area measurements on the polarized light microcopy and morphological analyses on SEM. Variance analysis and the Fisher test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) (α= 5%). The control group was statically different from G3 and G4, which present higher microhardness values and were statistical similar between them. The data of microhardness from the depth of surface were greater in proportion of distance from the surface, as 20µm <30µm <40µm <50µm. Wilcoxon test were performed for the statistical analysis of the data obtained from the caries-lesion area measurements (mm2) (= 5%) and all the groups were statically similar. Considering the results obtained from the both of studies can be concluded that the laser CO2 and Nd:YAG were able to increase the enamel acid resistance on the surface of pits and fissures.

ASSUNTO(S)

oclusal laser nd:yag laser nd:yag fissures. laser co2 occlusal caries laser er:yag pits fissuras laser co2 cáries laser er:yag

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