Qualitative Characterization of the Abrasive Component of Charcoal-Containing Toothpastes and the Effect on Dentin Roughness / Caracterización Cualitativa del Componente Abrasivo de las Pastas Dentales que Contienen Carbón Vegetal y la Rugosidad de la Dentina

This study investigated the effect of commercially available whitening toothpastes containing charcoal on dentin. Nine charcoal-containing toothpastes were compared with 3 whitening toothpastes (positive control) and distilled water (negative control). Periodontally hopeless molars were cleaned and washed and the occlusal table removed to expose dentin. The teeth were mounted in auto-polymerizing resin and exposed dentine surfaces polished with water-cooled decreasing grits of silica carbide paper up to 1500 grit. Baseline average roughness (Ra) measurements were taken. Specimens were then mounted in an automatic tooth-brushing machine and brushed for 5000 cycles. Repeat Ra measurements were taken. Specimens were brushed in 5000-cycle increments up to 25,000 cycles with Ra measurements being taken at each time point. Between abrasive challenges specimens were stored in distilled water. All toothpaste samples were sputter coated and examined under a scanning electron microscope to qualify the shape and size of the abrasive components of the formulations. Data were analyzed using a two-way analysis of variance with post hoc Bonferroni. The results demonstrated that the abrasive effect, in terms of increasing Ra, on dentin was noted as early as 5000 cycles for all the tested toothpastes (p<0.05). The effect of continued brushing showed an overall cumulative effect on dentine roughness up to 25000 cycles. When toothpastes were compared between groups at each time-point, dentin specimens brushed with Pursito were statistically similar to the control group. At 25,000 cycles all dentin samples were significantly rougher compared to Pursito and the control groups. It may be concluded that all the tested toothpastes have an abrasive effect on dentin surfaces.

Este estudio investigó el efecto sobre la dentina de las pastas dentales blanqueadoras disponibles en el mercado que contienen carbón vegetal. Se compararon nueve dentífricos que contenían carbón vegetal con 3 dentífricos blanqueadores (control positivo) y agua destilada (control negativo). Los molares sin material periodontal se limpiaron y lavaron y se retiró la tabla oclusal para exponer la dentina. Los dientes se montaron en resina autopolimerizable y las superficies expuestas de la dentina se pulieron con papel de carburo de sílice de grano decreciente enfriado con agua hasta grano 1500. Se tomaron medidas de rugosidad promedio (Ra) de referencia. Luego, las muestras se montaron en una máquina automática de cepillado de dientes y se cepillaron durante 5000 ciclos. Se tomaron medidas repetidas de Ra. Las muestras se cepillaron en incrementos de 5000 ciclos hasta 25 000 ciclos y se tomaron medidas de Ra en cada punto de tiempo. Entre periodos abrasivos, las muestras se almacenaron en agua destilada. Todas las muestras de pasta de dientes se recubrieron por pulverización catódica y se examinaron bajo un microscopio electrónico de barrido para calificar la forma y el tamaño de los componentes abrasivos de las formulaciones. Los datos se analizaron utilizando un análisis de varianza de dos vías de Bonferroni post hoc. Los resultados demostraron que el efecto abrasivo, en términos de aumento de Ra, sobre la dentina se notó ya en 5000 ciclos para todas las pastas dentales probadas (p<0,05). El efecto del cepillado continuo mostró un efecto acumulativo general sobre la rugosidad de la dentina hasta 25.000 ciclos. Cuando se compararon las pastas dentales entre los grupos en cada momento, las muestras de dentina cepilladas con Pursito fueron estadísticamente similares al grupo de control. A los 25.000 ciclos, todas las muestras de dentina eran significativamente más ásperas en comparación con Pursito y los grupos controles. Se puede concluir que todas las pastas dentales probadas tienen un efecto abrasivo sobre las superficies dentinarias.

The long-term effect of sparkling flavored water on human tooth enamel determined by gravimetric analysis: a preliminary evaluation / O efeito a longo prazo da água aromatizada com gás no esmalte dental humano determinado por análise gravimétrica: uma avaliação preliminar

Objetivo: O objetivo deste estudo foi avaliar o efeito in vitro de águas aromatizadas no esmalte dental humano utilizando um método gravimétrico. Material e Métodos: As superfícies linguais dos molares inferiores foram utilizadas para obter amostras de esmalte. O esmalte (n = 3) foi lavado, seco, e posteriormente imerso em 6 diferentes águas aromatizadas com gás disponíveis na região, e avaliado periodicamente por até 9 dias através de análise gravimétrica. Além disso, as medições de pH das águas aromatizadas foram registradas. Resultados: Todas as águas aromatizadas testadas apresentaram valores de pH abaixo do pH crítico. Os testes t pareados demonstraram reduções significativas na massa média do grupo para todas as amostras de esmalte desde o primeiro dia após a imersão em água com sabor, em comparação com as medições de referência. Reduções adicionais na massa média continuaram até o nono dia de imersão. Conclusão: As águas aromatizadas são potencialmente erosivas para as amostras de esmalte humano, sendo o efeito erosivo cumulativo ao longo do tempo. (AU)

Objective: The aim of this study was to assess the in vitro effect of flavored waters on human tooth enamel using a gravimetric method. Lingual surfaces of lower molars were used to obtain enamel specimens. Material and Methods: Enamel (n=3) was washed and dried, immersed in 6 flavors of locally available flavored sparkling water and assessed using gravimetric analysis, periodically for up to 9 days. Additionally, pH measurements of the flavored waters were recorded. Results: All the tested flavored waters showed pH values below that of critical pH. Paired t-tests demonstrated significant reductions in the mean group mass for all enamel specimens from as early as day 1 after immersion in flavored water, compared to baseline measurements. Further reductions in mean mass continued up to day 9 of immersion. Conclusion: Flavored waters are potentially erosive to human enamel specimens with the erosive effect being cumulative over time. (AU)

Comparison of the mechanical properties of two nano-filled composite materials / Comparação das propriedades mecânicas de dois materiais nanocompósitos

OBJETIVO: A finalidade deste estudo foi quantificar e comparar as propriedades mecanicas de dois materiais restauradores nanocompositos disponiveis comercialmente. MATERIAL E METODO: Especimes de dois nanocompositos, Z350TM e GrandioTM, foram polimerizados com luz LED por 30 segundos e submetidos a testes mecanicos. As propriedades testadas incluiram: resistencia flexural, resistencia tensil diametral, resistencia a fratura e microdureza (topo e fundo). RESULTADOS: O Grandio apresentou valores de resistencia flexural media maiores quando comparados com o Z350 (89.1 MPa vs 61.9 MPa). O Grandio demonstrou maior microdureza das superficies de topo de cada composito quando comparada com sua correspondente superficie de fundo. As propriedades de resistencia a fratura e forca tensil diametral nao foram fatores discerniveis neste estudo em particular. CONCLUSAO: Grandio possui maiores valores para propriedade de resistencia flexural e dureza quando comparado com o Z350. Nao houve diferencas entre os dois materiais em relacao a resistencia a fraturas e resistencia a forcas tenseis diametrais.

OBJECTIVE: The purpose of this study was to quantify and compare the mechanical properties of two commercially available nanocomposite restorative materials. MATERIAL AND METHODS: Specimens of two nanocomposites, Z350TM and GrandioTM, were polymerized with a LED light for 20 seconds and subjected to mechanical tests. Properties tested included: flexural strength, diametral tensile strength, fracture toughness and microhardness (top and bottom). RESULTS: Grandio exhibited significantly higher mean flexural strength values when compared to Z350 (89.1 MPa vs 61.9 MPa). Grandio exhibited significantly higher top microhardness values when compared to Z350. Additionally when microhardness for the top surfaces of each composite were compared with their corresponding bottom surfaces, the bottom surfaces demonstrated significantly lower readings. The properties of fracture toughness and diametral tensile strength were non-discerning factors in this particular study. CONCLUSION: Grandio has greater observed values for the properties of flexural strength and hardness when compared with Z350. There was no difference between the two materials with respect to their fracture toughness and diametral tensile strength.

Extreme lateral interbody fusion for degenerative scofiosis / 中华显微外科杂志

@#Objective To introduce extreme lateral interbody fusion (XLIF) as a new minimally inva-sire spinal surgery with established correction and fusion methods to assess its clinic use for degenerative scoliosis. It is emphasized the value and highlight of this technique in spinal surgery. Methods Surgical treatment of 8 patients with degenerative scoliosis were performed with XLIF between March 2006 and April 2008. In this group of patients, 5 cases provided an anterior cage in every disc space, and another 3 supplemented with vertebrae screw fixation. Blood loss was 50 ml every procedure. To observe the low back pain, corrective rate, achieving a balanced and complications. Results The low back pain have been relieved in all patienta after operations, the disc height can be restored, allowing more room at the foraminal level for nerve roots, and lumber lordosis can be maintained. Corrective rate was 64%, there wasn't neurologic and vascular injury, 2 case had correction loss a little postoperation 6-30 month. Conclusion The potential benefits of XLIF include safe, effective, less approach-related blood loss, improved cosmetic result with smaller incisions, and reduced hospital stay for degenerative scoliosis.