Effect of propolis gel on the in vitro reduction of dentin permeability

OBJECTIVE: The aim of this study was to evaluate the capacity of potassium oxalate, fluoride gel and two kinds of propolis gel to reduce the hydraulic conductance of dentin, in vitro. MATERIAL AND METHODS: The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on a model proposed in literature. Thirty-six 1-mm-thick dentin discs, obtained from extracted human third molars were divided into 4 groups (n=9). The groups corresponded to the following experimental materials: GI-10 percent propolis gel, pH 4.1; GII-30 percent propolis gel; GIII-3 percent potassium oxalate gel, pH 4,1; and GIV-1.23 percent fluoride gel, pH 4.1, applied to the dentin under the following surface conditions: after 37 percent phosphoric acid and before 6 percent citric acid application. The occluding capacity of the dentin tubules was evaluated using scanning electron microscopy (SEM) at ×500, ×1,000 and ×2,000 magnifications. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5 percent significance level. RESULTS: Groups I, II, III, IV did not differ significantly from the others in any conditions by reducing in hydraulic conductance. The active agents reduced dentin permeability; however they produced the smallest reduction in hydraulic conductance when compared to the presence of smear layer (P<0.05). The effectiveness in reducing dentin permeability did not differ significantly from 10 percent or 30 percent propolis gels. SEM micrographs revealed that dentin tubules were partially occluded after treatment with propolis. CONCLUSIONS: Under the conditions of this study, the application of 10 percent and 30 percent propolis gels did not seem to reduce the hydraulic conductance of dentin in vitro, but it showed capacity of partially obliterating the dentin tubules. Propolis is used in the treatment of different oral problems without causing significant great collateral effects, and can be a good option in the treatment of patients with dentin sensitivity.

Effect of deproteinization and tubular occlusion on microtensile bond strength and marginal microleakage of resin composite restorations

Dentin adhesion procedure presents limitations, especially regarding to lifetime stability of formed hybrid layer. Alternative procedures have been studied in order to improve adhesion to dentin. OBJECTIVE: The aim of this study was to evaluate in vitro the influence of deproteinization or dentin tubular occlusion, as well as the combination of both techniques, on microtensile bond strength (µTBS) and marginal microleakage of composite resin restorations. MATERIAL AND METHODS: Extracted erupted human third molars were randomly divided into 4 groups. Dentin surfaces were treated with one of the following procedures: (A) 35 percent phosphoric acid gel (PA) + adhesive system (AS); (B) PA + 10 percent NaOCl + AS; (C) PA + oxalate + AS and (D) PA + oxalate + 10 percent NaOCl + AS. Bond strength data were analyzed statistically by two-way ANOVA and Tukey's test. The microleakage scores were analyzed using Kruskal-Wallis and Mann-Whitney non-parametric tests. Significance level was set at 0.05 for all analyses. RESULTS: µTBS data presented statistically lower values for groups D and B, ranking data as A>C>B>D. The use of oxalic acid resulted in microleakage reduction along the tooth/restoration interface, being significant when used alone. On the other hand, the use of 10 percent NaOCl alone or in combination with oxalic acid, resulted in increased microleakage. CONCLUSIONS: Dentin deproteinization with 10 percent NaOCl or in combination with oxalate significantly compromised both the adhesive bond strength and the microleakage at interface. Tubular occlusion prior to adhesive system application seems to be a useful technique to reduce marginal microleakage.

Avaliaçäo da efetividade de agentes condicionadores ácidos em diferentes tempos de observaçäo, com e sem contaminaçäo pela saliva / Effectiveness of etching agents to enamel in different observation times, with and without saliva contamination

Verificou-se, por meio de testes de resistência ao cisalhamento, a efetividade de retençäo da resina composta Herculite XR ao esmalte dental, conseguida pelo condicionamento ácido, e a influência da contaminaçäo pela saliva durante 1 minuto. Cento e quarenta dentes permanentes humanos extraídos foram condicionados durante 15, 30 e 60 segundos com ácido fosfórico a 37 por cento em gel e durante 1 e 2 minutos com o oxalato de potássio a 3 por cento em gel e em soluçäo. Dos resultados obtidos e com base na análise estatística aplicada, pôde-se concluir que: o ácido fosfórico a 37 por cento apresentou melhor comportamento, com valores de resistência ao cisalhamneto significativamente maiores que o oxalato de potássio a 3 por cento; o tempo de aplicaçäo de 60 segundos do ácido fosfórico a 37 por cento, dentre todos os grupos, foi o que melhor resultado apresentou; dentre as formulaçöes, as que melhor se comportaram foram o ácido fosfórico a 37 por cento em gel, e o oxalato de potássio a 3 por cento, em soluçäo; a contaminaçäo salivar dos espécimes interferiu no poder de uniäo da resina composta ao esmalte, embora näo determinando significância estatística; o teste de Tukey-Kramer demonstrou que os valores médios, em MPa, foram menores quando se usou o oxalato de potássio a 3 por cento