Effect of the use of bromelain associated with bioactive glass-ceramic on dentin/adhesive interface.

OBJECTIVES: To evaluate the effect of bromelain associated with Biosilicate on the bond strength (BS) of a universal adhesive system to sound (SD) and caries-affected dentin (CAD), and on the proteolytic activity. MATERIALS AND METHODS: Cavities were prepared in 360 molars, half submitted to cariogenic challenge. Teeth were separated into groups (n=20): Control-No treatment; CHX-0.12% chlorhexidine; NaOCl-5% sodium hypochlorite; Br5%-5% bromelain; Br10%-10% bromelain; Bio-10% Biosilicate; NaOClBio-NaOCl+Bio; Br5%Bio-Br5%+Bio; Br10%Bio-Br10%+Bio. Following treatments, the adhesive system was applied, and cavities were restored. Samples were sectioned into sticks and stored at 37 °C for 24 h, 6 months, and 1 year. Microtensile BS (2-way ANOVA, Bonferroni's test, α=0.05), fracture patterns (SEM), and adhesive interfaces (TEM) were evaluated. Bacterial collagenase assay and in situ zymography were performed. RESULTS: In CAD, Br10% presented higher BS (p=0.0208) than Br5%Bio. Br5% presented higher BS (p=0.0033) after 6 months than after 24 h; and association of treatments, higher BS (p<0.05) after aging than after 24 h. Mixed fractures were the most prevalent. Association of treatments promoted a more uniform hybrid layer with embedded Bio particles. Experimental groups presented lower (p<0.0001) relative fluorescence units than Control. Bromelain, associated or not with Bio, showed collagenolytic degradation. CONCLUSIONS: Bromelain associated with Biosilicate did not affect the BS to SD. In CAD, Br5%Bio decreased immediate BS but had no long-term influence. This association decreased the proteolytic activity. CLINICAL RELEVANCE: Bromelain and Biosilicate may enhance the longevity of adhesive restorations by inhibiting endogenous proteases.

O uso do gel de glicerina melhora a estabilidade de cor de resinas compostas? / Does the use of glycerin gel improve the color stability of composite resins?

Introdução: A camada superficial de resina composta não polimerizada, em função da presença do oxigênio, ocasiona problemas clínicos, como alteração de cor por absorção de pigmentos. Objetivo: Determinar o efeito de diferentes técnicas usadas no controle da formação da camada de dispersão sobre as propriedades ópticas de uma resina composta comercial. Material e método: Espécimes foram produzidos com a resina composta Estelite Sigma. A fotoativação foi conduzida com uma fonte de luz LED Bluephase G2 (1.200 mW/cm2 por 40 s). Os grupos foram determinados em função de três técnicas distintas: 1) sem tratamento (controle); 2) fotoativação com gel de glicerina; 3) polimento com lixa abrasiva após a fotoativação. A estabilidade de cor (ΔE) e o parâmetro de translucidez foram determinados pelo método de espectroscopia de reflectância (Easyshade Compac, Vita) empregando o parâmetro CIELab. As análises foram realizadas imediatamente após a fotoativação e repetidas após 7 dias de armazenamento em água ou em café. Os resultados foram submetidos à análise de variância e ao teste de Tukey (α = 0,05). Resultado: Não houve diferença para ΔE nos grupos envelhecidos em água. Quando armazenados em café, o grupo controle apresentou o maior valor de ΔE, enquanto o grupo polido gerou a menor alteração de cor. A aplicação do gel de glicerina produziu resultados intermediários. O parâmetro de translucidez não foi afetado pelos tratamentos testados. Conclusão: O uso do gel de glicerina minimiza a alteração de cor nas regiões de difícil acesso aos instrumentos de acabamento e de polimento.

Introduction: The resin composite superficial layer not polymerized due to the presence of oxygen leads to clinical problems as color alteration by the absorption of pigments. Objective: Evaluate the effect of different techniques to control the formation of the composite resin dispersion layer on the optical properties of a commercial composite. Material and method Resin composite Estelite Sigma specimens were made. The specimens were light-cured with the LED Bluephase G2 device (1200 mW/cm2 - 40 s). The groups were determined according to three different techniques: 1) no treatment (control); 2) light-curing through a glycerin gel layer on the surface; 3) polishing with abrasive discs after light-curing. The color stability (ΔE) and the translucency parameter were determined by the spectroscopy method (Easyshade Compact Vita) as a function of the CIELab parameter. The analyzes were performed immediately after photoactivation and repeated after 7 days of storage in water or 7 days in coffee. The results were submitted to ANOVA and Tukey test (α = 0.05). Result : No difference was found for ΔE in groups aged in water. When stored in coffee, the control group had the highest value of ΔE while the polished group generated the lowest color change. The glycerin gel groups promoted intermediated results. The translucency parameter was not affected by the treatments tested. Conclusion: The glycerin-based gel layer minimizes the color change in those regions that the finishing and polishing instruments are difficult to access.

Effect of chemical and microwave disinfection on the surface microhardness of acrylic resin denture teeth.

PURPOSE: The purpose of this study was to evaluate the effect of simulated disinfections (2% glutaraldehyde, 1% sodium hypochlorite, and microwave energy) on the surface hardness of Trilux, Biocler, Biotone, New Ace, and Magister commercial artificial teeth. MATERIALS AND METHODS: Specimens (n = 10) were made with the teeth included individually in circular blocks of acrylic resin, leaving the labial surface exposed. Cycles of simulated chemical disinfection were accomplished with the specimens immersed in the solutions at room temperature for 10 minutes, followed by tap water washing for 30 seconds and storage in distilled water at room temperature for 7 days until the next disinfection. Simulated disinfection by microwave energy was carried out in a domestic oven with 1300 W at a potency of 50% for 3 minutes with the specimens individually immersed in 150 ml of distilled water. Control (no disinfection) and the experimental groups (first and third disinfection cycles) were submitted to Knoop hardness measurements with indentations at the center of the labial tooth surface. Data were submitted to repeated measure two-way ANOVA and Tukey's test (α = 0.05). RESULTS: Biocler, Magister, and Trilux showed lower surface microhardness when submitted to microwave. Lower microhardness for Biotone was promoted by hypochlorite, while no significant difference was shown for New Ace. The third disinfection cycle significantly decreased the tooth surface hardness only for microwave. CONCLUSIONS: Different disinfection methods promoted different effects on the microhardness of different types of artificial teeth. Surface microhardness of the teeth was less affected by the simulated chemical disinfections when compared to microwaved specimens.

Effect of aluminium oxide particle sandblasting on the artificial tooth-resin bond.

AIM: The influence of tooth ridge-lap surface sandblasting with aluminium oxide particles was evaluated on the adhesion of artificial teeth to acrylic resins. METHODS: Specimens were made with the acrylic resin adhered to teeth (BioCler GII), according to an unmodified surface, glossy surface sandblasted with 50-µm particles and conventional (Classico) or microwaved (Onda Cryl) resin, and a glossy surface sandblasted with 100-µm particles and Classico or Onda Cryl resin. The shear bond test was performed in an Instron machine using a 500-N load cell and cross-speed of 1 mm/min. RESULTS: The analysis of variance revealed significant difference in the tooth-resin shear bond strength for resin, surface treatment, and interaction. For conventional resin, control, 50-, and 100-µm particles showed statistically-different values; for microwaved resin, the control showed less statistical difference when compared to 50- and 100-µm particle treatments; for between resins, only the 100-µm particle treatment showed statistically-different values, with lower values for the microwaved resin. Mixed failures (cohesive in the resin and adhesive) were predominantly observed in all groups. Mixed (cohesive in the tooth and adhesive) or adhesive failures were not observed. CONCLUSIONS: Sandblasting with different aluminium oxide particle sizes produced different effects on the shear strength values of the tooth-resin bond.

Grau de conversão e densidade de ligações cruzadas de compósitos formulados com diferentes fotoiniciadores / Degree of conversion and cross-link density of resin composites formulated with different photoinitiators

O estudo verificou a influência da fonte de luz (FL) e do sistema fotoiniciador no grau de conversão (GC) e na densidade de ligações cruzadas (DLC) em compósitos com diferentes fotoiniciadores. Foram utilizadas as FLs XL2500® (3M/ESPE), Apollo95E® (DMD), UltraBlueIS® (DMC) e UltraLume5® (Ultradent), todas de acordo com as recomendações dos fabricantes e com 19J de energia aplicada, e os compósitos Pyramid-Bisco® (contendo fotoiniciador Lucirin TPO) e Filtek® Z250-3M/ESPE (fotoiniciador canforoquinona-CQ). O GC foi mensurado por espectroscopia de infra-vermelho transformada de Fourier. A DLC foi medida indiretamente por meio da leitura de dureza Knoop antes e após banho em etanol. Os dados foram submetidos à Anova e as médias, ao teste de Tukey (5%). Apollo 95E® produziu os maiores valores de GC para o compósito TPO (60,2%) quando a dose de energia foi mantida constante. A FL Ultra-BlueIS® não foi capaz de fotoativar o compósito TPO. Não existiram diferenças nos valores de GC para ocompósito CQ, a não ser quando Apollo 95E® foi usado pelo tempo recomendado pelo fabricante, levando a menor média (50,8%) de GC. Em geral, Ultra Lume5® produziu maior DLC, e Apollo 95E®, menor DLC para ocompósito TPO; para o compósito CQ não houve um padrão para os valores de DLC. Conclui-se que fontes de luz e fotoiniciadores influenciam as propriedades de compósitos dentais fotoativados.

Effects of 6 months of aging in water on hardness and surface roughness of two microhybrid dental composites.

PURPOSE: This study assessed the effect of 6 months of aging in water on surface roughness and surface/subsurface hardness of two microhybrid resin composites. MATERIALS AND METHODS: Filtek Z250 and Charisma were tested. Cylindrical specimens were obtained and stored in distilled water for 24 hours or 6 months, at 37 degrees C. For Knoop hardness evaluation, the specimens were transversely wet-flattened, and indentations were made on surface and subsurface layers. Data were submitted to three-way ANOVA and Tukey's test (alpha < or = 0.05). Surface roughness baseline measurements were made at 24 hours and repeated after 6 months of storage. Data were submitted to repeated measures ANOVA and Tukey's test (alpha < or = 0.05). RESULTS: Surface hardness (KHN, kg/mm(2)) means (+/- standard deviation) ranged from 55 +/- 1 to 49 +/- 4 for Z250 and from 50 +/- 2 to 41 +/- 3 for Charisma, at 24 hours and 6 months, respectively. Subsurface means ranged from 58 +/- 2 to 61 +/- 3 for Z250 and from 50 +/- 1 to 54 +/- 2 for Charisma, at 24 hours and 6 months. For both composites, the aged specimens presented significantly softer surfaces (p < 0.01). For the subsurface hardness, alteration after storage was detected only for Charisma, which presented a significant rise in hardness (p < 0.01). Z250 presented significantly harder surface and subsurface layers in comparison with Charisma. Surface roughness (Ra, mum) means ranged from 0.07 +/- 0.00 to 0.07 +/- 0.01 for Z250 and from 0.06 +/- 0.01 to 0.07 +/- 0.01 for Charisma, at 24 hours and 6 months, respectively. For both composites, no significant roughness alteration was detected during the study (p= 0.386). CONCLUSIONS: The 6-month period of storage in water presented a significant softening effect on the surfaces of the composites, although no significant deleterious alteration was detected for the subsurface hardness. In addition, the storage period had no significant effect on the surface roughness of the materials.