Glass ionomer heated or not to identify bone defect created in rat calvaria / Ionômero de vidro aquecido ou não para identificação de defeitos ósseos criados em calvárias de ratos

Introduction: Some experimental models have been used to evaluate the use of biomaterials in bone regeneration. Among them are the critical size defects (CSD) created in rat calvaria. An experimental model has been described in the literature, in which "L" markings are performed on the margins of the bone defects in order to assist in the precise identification of these defects during laboratory processing and analysis of the results. In the proposed model, the "L" markings are filled with amalgam. Objective: The purpose of the present study was to evaluate the amalgam replacement of an experimental bony defect model in rat calvaria by heated or unheated glass ionomer. Material and method: 24 rats were used. A 5 mm CSD was created at each animal calvaria. Two "L" shaped markings were made 2 mm from the margins of the bone defect, filled with amalgam (Group AM), heated glass ionomer cement (Group GIh) or not (Group GI). The animals were euthanized 15 days postoperatively. The areas of the surgical defect and the L-shaped marking were histomorphometrically analyzed and the data were analyzed statistically (p <0.05). Result: There were no significant clinical, histological or methodological differences among the experimental groups. Conclusion: It can be concluded that GI can replace AM in the proposed experimental model and GI heating did not promote additional benefits.

Introdução: Alguns modelos experimentais têm sido usados para avaliar o uso de biomateriais na regeneração óssea. Entre eles estão os defeitos de tamanho crítico (DTC) criados em calvárias de ratos. Um modelo experimental foi descrito na literatura onde marcações em L são realizadas nas margens do defeito ósseo para auxiliar na identificação precisa desses defeitos durante o processamento laboratorial e análise dos resultados. No modelo experimental proposto, as marcações em "L" são preenchidas com amálgama. Objetivo: Avaliar a substituição do amálgama por ionômero de vidro aquecido ou não em um modelo experimental para identificação de defeito ósseo criado em calvária de ratos. Material e método: Foram utilizados 24 ratos. Um DTC de 5 mm de diâmetro foi criado na calvária de cada animal. Duas marcações em "L" foram realizadas a 2 mm das margens do defeito ósseo, preenchidas com amálgama (Grupo AM), ionômero de vidro aquecido (Grupo CIVaq) ou não (Grupo CIV). Os animais foram eutanasiados aos 15 dias pós-operatórios. A área do defeito cirúrgico e das marcações em "L" foram histomorfometricamente avaliadas e os dados estatisticamente analisados (p<0,05). Resultado: Não houve diferença estatisticamente significativa entre os grupos experimentais para as análises metodológicas, clínicas ou histomorfométrica realizadas. Conclusão: Dentro dos limites deste estudo, pode-se concluir que CIV pode substituir o AM no modelo experimental proposto e o aquecimento do CIV não promoveu benefícios adicionais.

Effect of Spondias mombin L. extract on the wettability, roughness, color and morphology of bovine enamel

Although Spondias mombin L. extract has an excellent antimicrobial effect against oral microorganisms, it should be clarified how it affects enamel surface properties. Aim: To evaluate the color change, wettability/contact angle, surface roughness and morphology of bovine enamel submitted to the Spondias mombin L. extract. Methods: Thirty bovine teeth were distributed into the following groups: 0.12% chlorhexidine digluconate, 1:32 Spondias mombin L. extract and distilled water. Color change (CC) was evaluated after immerging specimens into the solutions for 14 days. Surface roughness (Ra) was measured using a roughness meter; wettability/contact angles (CA) were determined by the sessile drop method, and scanning electron microscopy images were obtained to characterize the morphology (SMA). The pH of the solutions was evaluated using a pHmeter. The Ra, CA, and CC data were parametric (Kolmogorov-Smirnov; p>0.05). Two-way ANOVA (for Ra and CA) and one-way ANOVA (for CC) with Tukey's posthoc tests at a significance level of 5% were used. SMA was analyzed descriptively. Results: The Spondias mombin L. extract revealed an acidic pH, and when in contact with the bovine teeth, it increased the wettability, but it did not cause statistically significant differences in the Ra. Spondias mombin L. extract caused the highest color change. The SEM images showed differences in the specimens' surface submitted to the extract compared to the other groups. Conclusion: Spondias mombin L. extract provided negative effects on bovine enamel's surface, including a high color change and a more wettable substrate

Effect of bleaching agents on hardness, surface roughness and color parameters of dental enamel.

BACKGROUND: In this study was evaluated the effect of carbamide peroxide (CP) and hydrogen peroxide (HP) in different concentrations on hardness, roughness, and color parameters (color change - ΔE, lightness - ΔL, and yellow-blue axis - Δb) of bovine teeth. MATERIAL AND METHODS: Fifty square dental blocks (7 x 7 x 2 mm) were submitted to initial readings of Knoop hardness, surface roughness (Ra), and color parameters. Specimens were divided into 5 groups (n = 10): control group was kept in artificial saliva during the experimental period; CP 20% was bleached for 2 h daily for 14 days, HP 9.5% was bleached for 30 min daily for 14 days, HP 38% the bleaching gel was applied for 15 min, gel was removed and it was reapplied for two more times, the bleaching session was repeated for another 2 times every 7 days, totaling three sessions, and in CP 45% three sessions of 30 min each were performed of 7 in 7 days. All groups after the bleaching procedures had the bleaching gel removed, washed, and kept in artificial saliva. At the end of bleaching treatment, the hardness, roughness, and color parameters (ΔE, ΔL, and Δb) were re-evaluated. Data were analyzed by ANOVA, Tukey, and Dunnett tests (α = 0.05). RESULTS: Bleaching promoted a reduction in hardness, the CP 45% showed the lowest hardness and the CP 20% the highest, the HP 9.5% and HP 38% showed intermediate values of hardness. Bleaching agents did not affect the roughness. CP 20% and HP 38% promoted the highest values of ΔE and higher reduction of yellowish tone of tooth. Lightness increase after bleaching treatment for all groups. CONCLUSIONS: All the bleaching agents tested showed effectiveness, but with reduced hardness. Key words:Carbamide peroxide, hydrogen peroxide, tooth whitening, hardness, roughness.

Evaluation of the Fluorescence of Composite Resins Under an Ultraviolet Light Source / Evaluación de la Fluorescencia de Resinas Compuestas Bajo una Fuente de Luz Ultravioleta

ABSTRACT: The aim of this research is to compare the fluorescence of different trademarks of composite resins under ultraviolet light, indicating through the optical characteristics the restorative materials that best mimic the properties of dental fluorescence. In this study, nine composite resin trademarks of EA2 color were evaluated, and ten test samples were prepared for each material, totalizing ninety specimens. The specimens were produced from a bipartite aluminium matrix (10x2 mm), and then stored for 24 h in tubes of radiographic films, immersed in distilled water and after 48 h it were polished. A blind-type study (four evaluators) was used and the samples were analyzed in a dark wooden chamber where it was coupled two black lamps. In the data collection phase, the Kolmogorov-Smirnov normality test, ANOVA and Post Hoc of Tukey were used (adopting a significance level of 0.05). It was noted that the composite resin of the trademark Ultrafill was more fluorescent and Luna was statistically less fluorescent than all other materials, while Opallis and Tetric were superior to Glacier. There was no significant statistical difference among the composite resins Premissa, Point 4, Llis and Premium.

RESUMEN: El objetivo de esta investigación es comparar la fluorescencia de diferentes marcas registradas de resinas compuestas bajo luz ultravioleta, indicando a través de las características ópticas los materiales de restauración que mejor imitan las propiedades de la fluorescencia dental. En este estudio, se evaluaron nueve marcas registradas de resina de color EA2, y se prepararon diez muestras de prueba para cada material, totalizando noventa especímenes. Las muestras se produjeron a partir de una matriz de aluminio bipartita (10x2 mm), y luego se almacenaron durante 24 h en tubos de películas radiográficas, se sumergieron en agua destilada y después de 48 h se pulieron. Se utilizó un estudio de tipo ciego (cuatro evaluadores) y las muestras se analizaron en una cámara de madera oscura donde se acoplaron dos lámparas negras. En la fase de recolección de datos, se utilizaron las pruebas de normalidad KolmogorovSmirnov, ANOVA y Post Hoc de Tukey (adoptaron un nivel de significancia de 0,05). Se observó que la resina compuesta de la marca registrada Ultrafill era más fluorescente y la marca Luna fue estadísticamente menos fluorescente que todos los demás materiales, mientras que Opallis y Tetric eran superiores a Glacier. No hubo diferencias estadísticamente significativas entre las resinas compuestas Premissa, Point 4, Llis y Premium.

Dental adhesives and strategies for displacement of water/solvents from collagen fibrils.

OBJECTIVES: To evaluate the influence of temperature of evaporation in adhesive systems with different solvents on the apparent modulus of elasticity and mass change of macro-hybrid layers modified by proanthocyanidins (PACs). METHODS: Adhesive resin beams (A) from Single Bond Plus (SB), Excite (EX) and One Step Plus (OS) were prepared after solvent evaporation at 23°C or 40°C (n=12). Macro-hybrid layers (M) (n=12) were prepared using demineralized dentin beams sectioned from extracted human third molars. The demineralized dentin specimens were infiltrated with each one of the three adhesive systems at 23°C or 40°C; with or without prior dentin treatment with PACs for 10min. The apparent modulus of elasticity (E) and mass change (Wmc, %) of adhesives beams and resin-infiltrated specimens were assessed in dry and wet conditions after immersion in water (24h, 1, 3 and 6 months). The E was statistically analyzed by Tukey-Kramer test and the Wmc, % by Kruskal Wallis, and Dunn (α=0.05). RESULTS: Solvent evaporation at 40°C resulted in higher E values for adhesive resin beams at all storage conditions, regardless of the adhesive system (p<0.05). Increased mass loss (3 months: -0.01%; 6 months: -0.05%) was observed in One Step resin beams (p≤0.05). In the macro-hybrid layer models the pretreatment with PACs along with solvent evaporation at 40°C increased E and decreased the Wmc, % (3 months: -2.5; 6 months: 2.75%) for adhesives evaluated over time (p<0.05). No significant differences in ratio (resin/dentin) were found for the macro-hybrid layers (p>0.05). SIGNIFICANCE: Improved solvent evaporation at higher temperature, and increased collagen cross-linking induced by PACs, enhanced the mechanical properties resulting in highly stable macro-hybrid layers over 6 months storage.