Influence of simplified, higher-concentrated sodium ascorbate application protocols on bond strength of bleached enamel

Bleaching procedures performed before restorative procedures, due to the oxygen released, affects the quality of bonding restorations. The application of an lower-concentrated antioxidant for one-hour or more can reversal the compromised bonding to bleached enamel, but it was not effective according to the bleaching concentrations applied. The aim of the present study was to evaluate simplified protocol of higher-concentrated sodium ascorbate (35%SA) in bond strength values of enamel bleached with 10%, 16%, 22% carbamide peroxide (CP) or 35% hydrogen peroxide (HP). Three hundred and forty enamel surfaces of 85 human third molars were used, divided into 17 groups (n=20), according to the following groups: control = no bleaching and no ascorbic acid application; bleaching (CP10%, CP16%, CP22% at-home and HP 35% in-office) and 35%SA application (no application; 35%SA applied twice for 1-min each [SA2×1], twice for 5-min each [SA2×5] and; twice for 10-min each [SA2×10]). After that, adhesive was applied and composite cylinders were made with Filtek Z350 composite. Microshear test was performed in a universal testing machine. BS values were statistically evaluated using ANOVA and Tukey?s and Dunnet?s (against control) tests, with 5% level of significance. All bleaching concentrations significantly decrease the enamel bond strength results when compared to control group (p<0.05). More concentrated PC (PC22% and PH35%) showed lower enamel bond strength results when compared to lower concentrated PC (PC10% and PC16%; p<0.05). A significant increase of the enamel bond strength results were only observed when SA2×5 and SA2×10 were applied (p<0.05). The application of 35% sodium ascorbate for twice 5- and 10-min each was an efficient protocol to reverse the bond strength in bleached enamel at the same level as the no bleaching enamel, independently of the bleaching concentration used

Factors associated with dental fluorosis in three zones of Ecuador

To determine the prevalence of dental fluorosis in 10-12 year-old school children, in three provinces of the inter-andean Region of Ecuador: Imbabura, Pichincha and Chimborazo, as well as the relationship between certain factors, considering that the latest studies go back to the year 2009. A cross-sectional and observational study was proposed. A sample of 599 was calculated at 95% of confidence considering population projections for children between 10 and 12 old of three zones of Ecuador. However, 608 school children, who had the acceptance and informed consent of their parents to participate, completed a survey about factors associated with dental fluorosis. Once the survey was completed, the vestibular surfaces of the upper and lower anterior teeth of the infant were photographed, following standardized distance and light procedures. Three evaluators, trained in the detection of fluorosis using the Thylstrup and Fejerskov index, analyzed the photographs. The Stata 13.0 software was used for the statistical analysis, with a level of significance of 5% and with a confidence interval of 95%. To relate the risk factor of fluorosis, a multinomial logistic model was used. The prevalence of dental fluorosis was of 89.96%, with a greater presence of grade 2 TF. A positive statistical relationship and statistical significance was detected between dental fluorosis and consumption of bottled beverages. Also the amount of toothpaste used and its ingestion during brushing (p = 0.000) were analyzed. The populations evaluated, that are related to the consumption of bottled beverages and involuntary toothpaste ingestion, and have a high prevalence of a mild level of fluorosis

Effect of the combination of materials for inclusion at different pressures on the mobility of artificial teeth during prosthetic processing

Objetivo: Comparar los cambios en la posición de los dientes artificiales en las prótesis totales maxilares al momento del prensado, mediante la medición en puntos de referencia pre determinados, bajo una fuerza de presión de 800, 1 000 y 1 250 kg, empleando yeso tipo III (Whip Mix, USA®) o silicona de condensación (Zhermack, Italia) como materiales de inclusión. Métodos: Fueron fabricadas 36 prótesis superiores obtenidas desde un modelo de yeso de un único paciente edéntulo total. Las réplicas fueron divididas de forma aleatoria en seis grupos, cada uno con seis repeticiones, considerando las variables involucradas, materiales y fuerza evaluada, tras el prensado y acrilizado. La diferencia entre los puntos referenciales fue establecida mediante Autocad (versión 21,2, Autodesk, España). Resultados: Se detectó una diferencia significativa entre la silicona y el yeso a 1 000 kg fuerza al 1% de nivel de significancia. Conclusiones: Existió mayor estabilidad en cuanto a movimiento cuando fue empleado como material de inclusión la silicona, con mejores resultados al emplear bajo 1 000 Kg fuerza de presión; independiente de la presión probada en todas las muestras existió movimiento en la posición original de los dientes artificiales.Objective: Compare the artificial teeth changes position in the maxillary total prosthesis at the time of pressing, by measuring at certain pre-determined reference points, under different types of pressure force of 800, 1 000 and 1 250 kg, using Type III gypsum (Whip Mix, USA®) and condensation silicone (Zhermack, Italy) as inclusion materials. Methods: 36 superior prostheses obtained from a plaster model of a single total edentulous patient were fabricated. The copies were randomly divided into 6 groups each with 6 repetitions, considering the involved variables, materials and evaluiated strength after press and process of being transformed in acrylic. The difference between the reference points was established by Autocad (21.2 version Autodesk, Spain). Results: significant difference was detected between silicone and gypsum at 1 000 force at 1% of significance level. Conclusions: Standing out more stability in terms of movement when used silicone as material for inclusion, with better results when using under 1 000 kg pressure force, independent of the pressure tested in all samples there was movement in the artificial teeth original positio