RESUMO
This study evaluated the effect of microabrasion and polishing on the microhardness and roughness of bovine enamel, and the effect of artificial saliva on the hardness of enamel. Bovine enamel blocks were used, forming the groups (n = 48): GI-37% phosphoric acid and pumice, GII--Opalustre, and GIII--Whiteness RM. The groups were divided into different subgroups: (a) diamond paste, (b) fluoride prophylactic paste, and (c) without polishing. Hardness tests were carried out at the following set times: (T1) initial, (T2) after microabrasion and polishing, (T3) after immersion in artificial saliva for 24 h; and (T4) after seven days of immersion. Surface roughness tests were performed. The obtained data were analyzed by two-factor ANOVA and Tukey's test with significance of 5%. Microhardness increased in T2; without polishing, only groups GII and GIII showed an increased microhardness. T3 did not differ from T4; GI, GII and GIII did not provide surface roughness that differed from each other; and all microabrasive systems followed by polishing showed a higher surface smoothness compared with the control groups. It is concluded that microabrasion followed by polishing provided higher hardness and better surface smoothness of the enamel. However, immersion in artificial saliva was not able to increase the enamel hardness.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Dentifrícios/farmacologia , Análise de Variância , Animais , Compostos Inorgânicos de Carbono/química , Bovinos , Misturas Complexas/química , Esmalte Dentário/química , Dureza , Ácido Clorídrico/química , Microscopia Eletrônica de Varredura/métodos , Ácidos Fosfóricos/química , Propilenoglicol/química , Saliva Artificial/farmacologia , Silicatos/química , Compostos de Silício/química , Propriedades de Superfície , Fatores de TempoRESUMO
This in vitro study evaluated microleakage in Class II cavities restored with dental composite and varying light-curing units and the temperature of the composite when subjected to a thermocycling test. Ninety cavities were prepared on the proximal surfaces of bovine teeth and randomly divided according to the light-curing mode (QTH-420 mW/cm2, LED 2nd generation-1100 mW/cm2, or LED 3rd generation-700 mW/cm2) and temperature of the resin composite (23°C, 54°C and 60°C). Following the restorative procedures and thermocycling, the samples were immersed in methylene blue for 12 hours. The samples were ground and the powder prepared for analysis in an absorbance spectrophotometer. All the results were statistically analyzed using the nonparametric tests of Kruskal-Wallis and Dunn (p ≤ 0.05). The results showed that there was no statistical difference between the light-curing modes at a temperature of 23°C. For 54°C, QTH showed a microleakage mean that was significantly lower than those of the LED groups, and for 60°C, QTH had a microleakage mean significantly lower than that of the LED 2nd generation group. There was no statistical difference between the temperatures of the resin composite when LEDs were used. For QTH, 54°C showed statistically lower microleakage than 23°C. The group preheated to 60°C showed no difference when compared to the group heated to 23°C. Preheating the resin composite (54°C and 60°C) did not improve the microleakage means when high-irradiance LED was used; however, it decreased the microleakage means when a QTH with low irradiance was used.
Assuntos
Resinas Compostas/química , Lâmpadas de Polimerização Dentária , Infiltração Dentária/prevenção & controle , Restauração Dentária Permanente/métodos , Calefação , Cura Luminosa de Adesivos Dentários/instrumentação , Animais , Bovinos , Resinas Compostas/efeitos da radiação , Restauração Dentária Permanente/classificação , Análise do Estresse Dentário , Halogênios , Semicondutores , Estatísticas não ParamétricasRESUMO
This in vitro study evaluated the marginal leakage of two light-cured resin composites used for posterior restorations using two filling techniques. Standardized Class V cavities were made on the enamel vestibular surface of 30 freshly extracted sound inferior bovine incisors. The teeth were randomly restored according to three experimental groups (Group 1--Z250 with 1 mm vertical increments; Group 2--Z250 with 1 mm horizontal increments; Group 3--SureFil with 1 mm horizontal increments). All samples were thermocycled (3000 cycles at 5 degrees C and 55 degrees C) with a dwell time of one minute at each temperature and immersed in a dye solution for 12 hours. After being ground into powder, the samples were individually immersed into glass tubes with absolute alcohol. The solution was centrifuged and the supernatant was analyzed using a spectrophotometer to quantify its dye concentration. Results showed that Group 2 exhibited the lowest leakage means, which was significantly different from Groups 1 and 3 (p<0.05). It was concluded that despite the lower leakage means exhibited by medium viscosity composites, no restorative material or filling technique was able to avoid leakage.
Assuntos
Resinas Compostas , Infiltração Dentária , Restauração Dentária Permanente/métodos , Análise de Variância , Animais , Bovinos , Infiltração Dentária/prevenção & controle , Teste de Materiais , Dente Molar , Distribuição Aleatória , Estatísticas não Paramétricas , ViscosidadeRESUMO
PURPOSE: To evaluate the surface roughness and staining of a glass ionomer cement when subjected to different finishing procedures. MATERIALS AND METHODS: Sixty-four discs of Chem-Fil II glass ionomer cement were submitted to staining test with methylene blue by spectrophotometry and roughness test by profilometry. Four groups were evaluated: Mylar matrix (control). Sof-Lex discs, Enhance points, and diamond bur. RESULTS: Staining and roughness test, analyzed by ANOVA and Tukey's test, showed that the best surface was obtained when the material cured in contact with the Mylar matrix strip or when treated with Sof-Lex discs. The poorest results were obtained after using the diamond bur.