Influence of temporary cement in the tensile strenght of fullcrowns cemented with resin cement / Influência do cimento temporário na resistência à tração de coroas totais cimentadas com cimento resinoso

Objetivo: Este estudo avaliou a influência do eugenol residual a resistência à tração na cimentação decoroas cerômero, usando cimento resinoso. Material e Métodos: Trinta e nove terceiros molares foram preparados para coroa total. Para cada dente preparado uma restauração provisória e uma coroa de cerômero foram feitas. Os dentes foram divididos em três grupos de acordo com o cimento provisório (n = 13): [GTB]Temp de Bond; [GTBNE] Temp NE Bond e [GDY] Dycal. Após a cimentação temporária, os dentes foram mantidos em água destilada por uma semana e, em seguida, submetidos ao teste de tração em uma máquina universal de ensaios (EMIC DL 500), usando uma célula de carga 200 kgf em 0,5 mm/min. Após o teste, os dentes foram limpos e receberam a cimentação adesiva final das coroas de cerômero. Em seguida, as amostras foram mantidas em água destilada (37 ºC) durante uma semana e, em seguida, foi realizado o teste de resistência à tração, também a 0,5 mm/ min. A comparação entre grupos foi realizada por análise de variância (ANOVA)seguida pelo teste de Tukey (p < 0,05). Resultados: Os resultados (kgf) de cimentação provisória para grupos GTB, GTBNE e GDY foram respectivamente: 2,75 ± (1.35b), 3,43 ± (1.66ab), e 4,48 ± (1.11a).Os resultados da cimentação adesiva (Kgf) eram respectivamente: 42,71 ± (15.33b), 57,59 ± (15.66a),e 54,75 ± (15.28ab). Conclusão: Concluiu-se que o cimento temporário, contendo eugenol apresentou influência negativa sobre a resistência à remoção de coroas cimentados com cimento de resinoso. Além disso, o dycal apresentou melhor resistência à remoção.

Objectives: This study evaluated the influenceof residual eugenol on the tensile strength in the ceromer crowns cementation, using resin cement. Material and Methods: Thirty-nine third molarswere prepared for a full crown. For each prepared tooth one provisional and one ceromer crown were made. The teeth were divided into three groups according the temporary cement (n = 13): [GT]Temp Bond; [GTBNE] Temp Bond NE and [GDY]Dycal. After temporary cementation, the teeth were kept in distilled water for one week and then submitted to traction test in a universal testing machine (EMIC DL 500), using a 200 Kgf loadcell at 0.5 mm/min. After the test, the teeth werecleaned and received the final adhesive cementationof ceromer crowns. Next, the specimens were keptin distilled water (37 0C) for a week and then the tensile strength test was performed, also at 0.5 mm/min. The comparison among groups was carriedout by variance analysis (ANOVA) followed by theTukey test (p ≤ 0.05). Results: The results (Kgf)of provisional cementation for groups GTB, GTBNEand GDY were respectively: 2.75 ± (1.35b), 3.43± (1.66ab), and 4.48 ± (1.11a). The results of the adhesive cementation (Kgf) were respectively:42.71 ± (15.33b), 57.59 ± (15.66a), and 54.75 ±(15.28ab). Conclusion: It was concluded that the temporary cement containing eugenol presented negative influence on the removal resistance of crowns cemented with resin cement. Furthermore,dycal presented best result for removal resistance.

Micro-sized erosions in a nanofilled composite after repeated acidic beverage exposures: consequences of clusters dislodgments

Objective: To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days. MATERIAL AND METHODS: Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey's test). Scanning electron microscopy (SEM) topographic analysis was also performed. RESULTS: In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis. CONCLUSIONS: The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution. .

Micro-sized erosions in a nanofilled composite after repeated acidic beverage exposures: consequences of clusters dislodgments.

OBJECTIVE: To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days. MATERIAL AND METHODS: Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37 ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey's test). Scanning electron microscopy (SEM) topographic analysis was also performed. RESULTS: In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis. CONCLUSIONS: The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution.