The ability of different formulations of artificial saliva to protect dentin from erosive wear / Ação protetora de diferentes formulações de saliva artificial no desgaste erosivo

Objective: Evaluate the protective effect of artificial saliva formulations associated or not with mucin on dentin. Materials and Methods: Bovine dentin specimens were randomly allocated to 10 groups (n = 20) according to the artificial saliva tested and the presence or absence of mucin: Amaechi et al. (1998); Klimek et al. (1982); Vieira et al. (2005) and Eisenburger et al. (2001) and deionized water (control). Samples were submitted to an erosive cycle consisting of two immersions of 120 min in the saliva, followed by 1 min in hydrochloric acid solution, and new storage in saliva for 120 min. Surface loss (µm) was measured before and after the cycle. Data were analyzed using 2-way ANOVA and Tukey's test (p < 0.05). Results: A significant difference was observed for the saliva formulation but not for the presence of mucin. The deionized water provided the highest surface loss and the Eisenburger's saliva formulation the lowest. The groups testing the Amaechi, Klimek, and Vieira saliva did not present significant differences. Conclusion: Eisenburger's saliva formulation provides a higher protective effect against dentin erosion. The presence of mucin did not increase the erosion-preventive effect of artificial saliva formulations. (AU)

Objetivo: Avaliar o efeito protetor de formulações de saliva artificial associadas ou não à mucina sobre a dentina submetida a erosão. Material e Métodos: Espécimes de dentina bovina foram alocados em 10 grupos (n = 20) de acordo com a saliva testada e a presença ou ausência de mucina: . Amaechi et al. (1998); Klimek et al. (1982); Vieira e cols. (2005), Eisenburger et al (2001) e agua deionizada (controle). As amostras foram submetidas a um ciclo erosivo composto por duas imersões de 120 min na saliva, seguidas de 1 min em solução de ácido clorídrico e novo armazenamento na saliva por 120 min. A perda de superfície (µm) foi medida antes e depois do ciclo. Os dados foram analisados usando ANOVA 2 fatores e teste de Tukey (p <0,05). Resultados: Foi observada diferença significativa para a formulação de saliva, mas não para a presença de mucina. A água deionizada proporcionou a maior perda de superfície e a formulação de saliva de Eisenburger a menor. Os grupos que testaram a saliva Amaechi, Klimek e Vieira não apresentaram diferenças significativas entre si. Conclusão: A formulação de saliva de Eisenburger fornece o maior efeito protetor contra a erosão dentinária e a presença de mucina não aumentou o efeito preventivo de erosão de formulações de saliva artificial (AU).

Comparative of flexural strength, hardness, and fluoride release of two bioactive restorative materials with RMGI and composite resin

Aim: This study was fulfilled to evaluate the flexural strength, micro-hardness, and release of two fluoride ions of bioactive restorative materials (Cention N and Activa Bioactive), a resin modified glass ionomer (Fuji II LC), and a resin composite (Filtek z250). Methods: Forty samples from four restorative materials (Activa Bioactive, Fuji II LC, Cention N, and Filtek Z250) were provided according to the current standards of ISO 4049/2000 guide lines. Subsequently, the samples were stored for 24 hours and 6 months in artificial saliva, and successively, flexural strength and micro-hardness of the samples were measured. For each studied groups the pH was decreased from 6.8 to 4 in storage solution. The rate of changes in fluoride ion release was measured after three different storage periods of 24 hours, 48 hours, and 6 months in distilled water, according to the previous studies' method. Two-way ANOVA, One-way ANOVA, Tukey HSD Pair wise comparisons, and independent t-tests were used to analyze data (α= 0.05). Results: The highest flexural strength and surface micro-hardness after 24 hours and also after 6 month were observed for Cention N(p<0.001).Flexural strength of all samples stored for 6 months was significantly lower than the samples stored for 24 hours(p<0.001). The accumulative amount of the released fluoride ion in RMGI, after six-month storage period in distilled water was considerably higher (p<0.001) than 24 hours and 48 hours storage. The amount of fluoride ion release with increasing acidity of the environment (from pH 6.8 to 4) in Fuji II LC glass ionomer was higher than the bioactive materials (p<0.05). Conclusion: The flexural strength of RMGI was increased after storage against the Activa Bioactive,Cention N and Z250 composite. Storage of restorative materials in artificial saliva leads to a significant reduction in micro hardness. The behavior and amount of released fluoride ions in these restorative materials, which are stored in an acidic environment, were dependent on the type of restorative material

Valoración del grado de pigmentación en dientes acrílicos sometidos a humo del cigarrillo / Assessment of the degree of pigmentation in acrylic teeth subjected to cigarette smoke

INTRODUCCIÓN. Los cambios de color en los dientes acrílicos dependen de varios factores, con el humo de cigarrillo como uno de los principales agentes de igmentación de las prótesis. OBJETIVO. Valorar el grado de pigmentación en dientes acrílicos sometidos al humo del cigarrillo, mediante espectrofotometría digital. MATERIALES Y MÉTODOS. Estudio observacional, analítico, de caso y control. Muestra de 60 dientes acrílicos divididos en dos grupos: A (resina acrílica de 3 capas) y B (resina acrílica de 4 capas). Se subdividió en: grupo 1: dientes sometidos a humo de cigarrillo estándar con filtro de carbón; grupo 2: dientes sometidos a humo de cigarrillo estándar sin filtro; y, grupo 3: grupo control. Cada uno de éstos se expuso a 150 cigarrillos, 5 diarios durante 30 días y el grupo control fue mantenido a 37ºC en saliva artificial durante 30 días sin aplicación de humo de cigarrillo. Para la toma de color se empleó espectrofotómetro Vita Easyshade®. Los análisis se realizaron en el programa estadístico International Business Machines Statistical Package for the Social Sciences mediante la prueba de Kruskal-Wallis y comparaciones de Dunn. RESULTADOS. Se determinó que la pigmentación del grupo B fue mayor a la del grupo A, con una diferencia significativa entre ellos (p< 0,05). No se encontró datos estadísticamente significativos entre cigarrillos (con filtro - sin filtro). CONCLUSIÓN. La exposición al humo de cigarrillo pigmentó los dientes acrílicos de ambas propiedades siendo mayor en los dientes de resina acrílica de 4 capas.

INTRODUCTION. Color changes in acrylic teeth depend on several factors, with cigarette smoke as one of the main agents of denture pigmentation. OBJECTIVE. To assess the degree of pigmentation in acrylic teeth subjected to cigarette smoke, using digital spectrophotometry. MATERIALS AND METHODS. Observational, analytical, case-control study. Sample of 60 acrylic teeth divided into two groups: A (3-layer acrylic resin) and B (4-layer acrylic resin). It was subdivided into: group 1: teeth subjected to standard cigarette smoke with charcoal filter; group 2: teeth subjected to standard cigarette smoke without filter; and, group 3: control group. Each of these was exposed to 150 cigarettes, 5 daily for 30 days and the control group was maintained at 37ºC in artificial saliva for 30 days without application of cigarette smoke. Vita Easyshade® spectrophotometer was used for color determination. The analyses were performed in the statistical program International Business Machines Statistical Package for the Social Sciences using the Kruskal-Wallis test and Dunn's comparisons. RESULTS. It was determined that the pigmentation of group B was greater than that of group A, with a significant difference between them (p< 0,05). No statistically significant data was found between cigarettes (filtered - unfiltered). CONCLUSION. Cigarette smoke exposure pigmented acrylic teeth of both properties being higher in 4-layer acrylic resin teeth.

Saliva substitute mouthwash in nasopharyngeal cancer survivors with xerostomia: a randomized controlled trial.

OBJECTIVES: Xerostomia is a prevalent sequelae among nasopharyngeal cancer (NPC) survivors; yet, effective treatment protocols have been elusive. This study was a prospective randomized clinical trial to compare the effects of saliva substitute mouthwash in nasopharyngeal cancer survivors with xerostomia, between two treatment arms, conducted in a tertiary center. MATERIALS AND METHODS: This study measured the effects within 4 weeks in relation to summated xerostomia inventory (SXI) and unstimulated whole saliva (UWS). Patients randomized into the interventional arm were prescribed an immunologically active saliva substitute (IASS), while patients in the control arm were prescribed a non-immunologically active mouthwash as placebo. RESULTS: The study population consisted of 94 patients. There was a significant difference in SXI difference (p < 0.0001) and UWS difference (p < 0.0001) between control and interventional arms. No harmful side effects associated with the use of either mouthwash encountered throughout the study duration. CONCLUSION: IASS mouthwash significantly reduces subjective xerostomia scores measured using SXI and improves objective measurement of salivary flow using UWS among nasopharyngeal cancer survivors with xerostomia. CLINICAL RELEVANCE: IASS is significantly more effective in improving subjective and objective xerostomia measurements compared to non-immunologically active mouthwash. Additionally, this treatment is very safe, with superior side effect profiles. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04491435.

Boca Seca em Idosos: Proposta de um Novo Substituto Salivar à Base de Própolis / Dry mouth in elderly people: proposal of a new salivary substitute based on propolis

Introdução: O idoso tem tendência à secura da cavidade oral, a qual está ligada à atrofia da mucosa oral e das glândulas salivares. Objetivo: O presente estudo objetiva, por meio de uma revisão de literatura, estudar a xerostomia e os substitutos artificiais atualmente utilizados para a saliva. Revisão de literatura: Os benefícios na área da saúde das propriedades farmacológicas com produtos apícolas estão sendo estudados devido à sua eficiência, para o crescente desenvolvimento de nutracêuticos e alimentos funcionais. Própolis e seus extratos têm inúmeras aplicações no tratamento de várias doenças devido ao seu efeito antisséptico, anti-inflamatório, antioxidante, antibacteriano, antifúngico, antiúlcera, anticancerígeno, e propriedades imunomoduladoras. No campo odontológico tem atraído a atenção, reduzindo a inflamação resultante de procedimentos cirúrgicos e como agente antimicrobiano no controle da placa bacteriana. Considerações finais: Os sintomas da boca seca (xerostomia e hipossialia) incluem: distúrbios do paladar, mau hálito, intolerância a prótese dentária, com um risco aumentado para infecções, incluindo candidíase e lesões nas mucosas, doença periodontal, desmineralização dos dentes, susceptibilidade a cárie dentária e perda dentária, principalmente nos idosos. Por isso a importância em estudar um novo substituto salivar (APIS saliva) a base de própolis, para amenizar e substituir a falta de saliva na cavidade oral.

Introduction: The elderly tends to dry the oral cavity, and it is linked to the atrophy of the oral mucosa and salivary glands. Objective: This study aims, through a literature review, to study xerostomia and the artificial substitutes currently used for saliva. Literature review: The health benefits of pharmacological properties with bee products are being studied because of their efficiencies, for the growing development of nutraceuticals and functional foods. Propolis and its extracts have numerous applications in the treatment of various diseases due to their antiseptic, antiinflammatory, antioxidant, antibacterial, antifungal, anti-ulcer, anticancer, and immunomodulatory properties. In the dental field has attracted attention, reducing inflammation resulting from surgical procedures and as an antimicrobial agent in plaque control. Final considerations: Dry mouth symptoms (xerostomia and hyposialia) include taste disturbances, bad breath, intolerance to dental prostheses, increased risk of infection, including candidiasis and mucosal lesions, periodontal disease, tooth demineralization, tooth decay susceptibility and dental loss, especially in the elderly. Therefore, the importance in studying a new salivary substitute (APIS saliva) based on propolis, to soften and replace the lack of saliva in the oral cavity.

Potencial erosivo de doces azedos (sour candies) dissolvidos em água e saliva artificial

O consumo frequente de balas e doces ácidos está associado a etiologia da erosão dental. Objetivo: o objetivo deste estudo é mensurar o potencial erosivo de doces azedos (sour candies) dissolvidos em água e saliva artificial. Materiais e método: os doces Sour Tubes Ácido Fini® sabores: maçã verde, tutti frutti, morango e melancia foram selecionados e divididos em 2 grupos ‒ doces dissolvidos em água destilada (G-1) e doces dissolvidos em saliva artificial (G-2). O pH foi mensurado utilizando potenciômetro e eletrodo combinado de vidro, previamente calibrado com soluções padrão pH 7,0 e pH 4,0 antes de cada leitura. A acidez titulável foi mensurada adicionando-se alíquotas de 100 µL NaOH 1M, até alcançar o pH 5,5. Os resultados foram submetidos à Análise de Variância (Anova), e as comparações das médias foram realizadas pelo teste Tukey, em um nível de 5% de significância (p<0,05). Resultados: todas as balas apresentaram valores de pH abaixo de 5,5, quando dissolvidas em água (G-1) e saliva artificial (G-2). Na comparação entre os grupos, houve elevação significante do pH após dissolução em saliva artificial (G-2). A acidez titulável mostrou-se menor no grupo G-2. Conclusão: todos os doces ácidos dissolvidos em água e saliva artificial são potencialmente erosivos, podendo contribuir para a etiologia da erosão dental.

Estratégias para o alívio da sede: revisão integrativa da literatura / Estrategias para el alivio de la sed: revision integrativa de la literatura / Strategies for thirst relief: integrative literature review

RESUMO Objetivo: analisar as estratégias utilizadas para minorar a sede do paciente hospitalizado. Método: revisão integrativa, para a qual as bases de dados PubMed, LILACS, CINAHL e o conjunto de referências organizadas pelo Grupo de Estudo e Pesquisa da Sede foram selecionadas para a busca dos estudos primários, com os descritores: thirst, ice, cold, intervention, nursingcare, artificialsaliva. Resultados: a amostra da revisão foi composta de 10 estudos primários. As estratégias encontradas foram: baixa temperatura utilizando gaze congelada, lascas de gelo e água fria, mentol associado a estratégias frias, goma de mascar, acupressão, uso de canudo fino, substituto salivar e ingestão precoce de líquidos. Conclusão: a temperatura apresentou-se como estratégia predominante e efetiva para minorar a sede de pacientes cirúrgicos, em cuidado intensivo e em tratamentos de hemodiálise.

RESUMEN Objetivo: analizar las estrategias utilizadas para saciar la sed del paciente hospitalizado. Método: revisión integrativa, sobre estudios primarios seleccionados de las bases de datos PubMed, LILACS, CINAHL y del conjunto de referencias elaboradas por el Grupo de Estudio e Investigación de la Sed, con los descriptores: thirst, ice, cold, intervention, nursing care, artificial saliva. Resultados: la muestra de la revisión se compuso de 10 estudios primarios. Las estrategias halladas fueron: baja temperatura utilizando gasa congelada, hielo molido y agua fría, mentol asociado a estrategias frías, goma de mascar, acupresión, uso de sorbete delgado, sustituto salival e ingestión precoz de líquidos. Conclusión: la temperatura se presentó como estrategia predominante y efectiva para saciar la sed en pacientes quirúrgicos, en cuidados intensivos y en tratamientos de hemodiálisis.

ABSTRACT Objective: to analyze the strategies used to relieve the thirst of hospitalized patients. Method: an integrative review, for which the databases PubMed, LILACS, CINAHL and the group of references organized by the Group for Study and Research of Thirst were selected for the search of primary studies, with the keywords: thirst, ice, cold, intervention, nursing care, artificial saliva. Results: the review sample was composed of ten primary studies. The strategies found were: low temperature using frozen gauze, ice chips, and cold water, menthol associated with cold strategies, chewing gum, acupressure, and the use of a thin straw, substitute saliva, and early fluid ingestion. Conclusion: the temperature was presented as a predominant and effective strategy to relieve the thirst for surgical patients in intensive care and hemodialysis treatment.

Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study.

BACKGROUND: The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. MATERIAL AND METHODS: Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. RESULTS: The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. CONCLUSION: In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested.

Mensuração do potencial erosivo de balas dissolvidas em água e saliva artificial / Measurement of erosive potential of candies dissolved in water and artificial saliva

Introdução: O consumo excessivo e frequente de balas ácidas pode estar associado à etiologia da erosão dental. Objetivo: Mensurar e comparar o pH e a acidez titulável de balas dissolvidas em água e saliva artificial. Material e método: Foram utilizadas as balas Tic Tac® sabores laranja, cereja/maracujá e morango, agrupadas em dois grupos: G-1: balas dissolvidas em água; G-2: balas dissolvidas em saliva artificial. As balas foram trituradas e, do pó resultante de cada sabor, foram pesadas duas amostras de 20 g, sendo então dissolvidas em 120 mL de água destilada ou 120 mL de saliva artificial. Destas soluções, obtiveram-se três amostras de 30 mL para cada um dos sabores, permitindo a leitura em triplicata do pH e da acidez titulável. O pH foi mensurado utilizando-se um potenciômetro e eletrodo combinado de vidro, previamente calibrado com soluções padrão pH 7,0 e pH 4,0. Para a verificação da acidez titulável, adicionaram-se alíquotas de 100 μL NaOH 1M, até o pH alcançar 5,5. Submeteram-se os resultados à Análise de Variância (ANOVA). As comparações das médias foram realizadas pelo Teste Tukey, em um nível de 5% de significância (p<0,05). Resultado: Todas as balas apresentaram pH abaixo do crítico para dissolução do esmalte, quando dissolvidas em água e saliva artificial. Na comparação entre os grupos, o G-2, mostrou um pH mais elevado e menor acidez titulável, diferindo significantemente do G-1. Conclusão: Todas as balas dissolvidas em água e saliva artificial mostraram-se potencialmente erosivas, podendo contribuir para a etiologia da erosão dental.

Introduction: Excessive and frequent consumption of acid candy is associated with the etiology of dental erosion. Objective: This study aimed to measure and compare the pH and titratable acidity of candies dissolved in water and artificial saliva. Material and method: Tic Tac® candies were used with the flavors: orange, cherry / passion fruit and strawberry, grouped into 2 groups. G-1: candies dissolved in water; G-2: candies dissolved in artificial saliva. The candies were crushed and, from the resulting powder of each flavor, two samples were weighed 20 g and dissolved in 120 ml of distilled water or 120 ml of artificial saliva. For these solutions were obtained 3 samples of 30 mL each flavor, allowing the determination of pH and titratable acidity in triplicate.. The pH was measured using a potentiometer and glass electrode calibrated with standard solutions pH 7.0 and pH 4.0. To check the titratable acidity, aliquots of 100 uL NaOH 1M were added until the pH reached 5.5. The results were submitted to the Analysis of Variance (ANOVA). Mean comparisons were performed by Tukey test at a 5% level of significance (p<0.05). Result: All candies had pH below the critical values for dissolution of enamel when dissolved in water and artificial saliva. Comparing the groups, the G-2, showed a pH higher and lower titratable acidity, significantly differing from the G-1. Conclusion: All acid candies dissolved in water and artificial saliva proved to be potentially erosive could contribute to the etiology of dental erosion.

Erosive potential of sugar-free hard candies dissolved in water and artificial saliva

Aim: To compare the acidity of sugar-free hard candies dissolved in water and artificial saliva.Methods: Sugar-free Flopi Florestal„¥ hard candies (grape, strawberry, cherry, orange, ginger, lemonbalm, fennel) were selected and grouped in 2 groups: G-1 (candies dissolved in distilled water)and G-2 (candies dissolved in artificial saliva). Candies were triturated with a porcelain pestle,yielding two samples of 20 g. Samples were dissolved in 120 mL distilled water (G-1) and 120 mLartificial saliva (20 mM NaHCO3, 3 mM NaH2PO4.H2O and 1 mM CaCl2.2H2O) (G-2), obtaining threesamples of 30 mL for each of the flavors and groups. pH was measured using potentiometer andcombined glass electrode. Titratable acidity was evaluated by adding 100 £gL 1M NaOH aliquotsuntil reaching pH 5.5. For statistical analysis, analysis of variance (ANOVA) was used. Means werecompared by the Tukey test at 5% significance level (p<0.05) Results: All flavors of G-1 showed pHvalues below 5.5. Comparison of groups in the same flavor showed a significant increase in pH inflavors of G-2. Comparison of the titratable acidity between G-1 and G-2, showed that fruit flavorswere significantly different from each other, with reduced acidity in G-2. Conclusions: All evaluatedcandies are acid, and dilution in artificial saliva raised their pH and lowered their titratable acidity,reducing their erosive potential.

Corrosion resistance of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires in different artificial saliva with different fluoride and pH / 中国组织工程研究

BACKGROUND:In the fluorine-containing acidic environment, it is unclear whether Damon copper- nickel-titanium arch wire can have a corrosion resistance similar to conventional nickel-titanium arch wire and whether copper ion wil affect its corrosion resistance. OBJECTIVE: To evaluate the corrosion resistance of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires in artificial saliva with different fluoride and pH. METHODS:Potentiodynamic polarization curves of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires were measured in four kinds of artificial saliva (pH=7; pH=7, 0.2% fluoride; pH=7, 0.5% fluoride; pH=5, 0.5% fluoride). Then, the corrosion potential, corrosion current density and polarization resistance were acquired, and scanning electron microscope was used for morphological observation after corrosion. RESULTS AND CONCLUSION: In neutral (pH=7) artificial saliva, 0.2% fluoride ions added could shift up the Damon specimen polarization curve, increase the corrosion cerrent density and reduce the polarization resistance (P 0.05), and no significant corrosion was produced. When fluoride concentration was increased to 0.5%, the polarization curves of two kinds of the specimens moved, the corrosion cerrent density increased, the polarization resistance decreased (P < 0.05), and there was significant presence of corrosion on the specimen surface. When pH=5, corrosion phenomenon was more pronounced. These findings suggest that low concentrations fluoride cannot affect corrosion resistance of 3M arch wire, but can reduce the corrosion resistance of Damon arch wire; high concentrations of fluoride and acid can both reduce their corrosion resistance. In addition, the corrosion resistance of 3M arch is stronger than that of Damon arch wire.

The influence of protective varnish on the integrity of orthodontic cements

OBJECTIVE: The aim of the present study was to assess the influence of saliva contamination over the structural strength and integrity of conventional glass-ionomer cements used for cementing orthodontic bands in the absence and presence of a surface-protecting varnish. METHOD: 48 samples were prepared by inserting 3 types of glass-ionomer cements into standardized metallic matrixes of 10 mm of diameter and 2 mm of depth. The cements used were: Meron (VOCO), Ketac-Cem (3M ESPE) and Vidrion C (DFL), all of which comprised groups A, B and C, respectively. Subgroups A1, B1 and C1 comprised samples with no surface protection, whereas subgroups A2, B2 and C2 comprised samples of which surface was coated with Cavitine varnish (SS White), after cement manipulation and application, in order to protect the cement applied. All samples were stored in artificial saliva for 24 hours at 37ºC. A Vickers diamond micro-durometer was used to produce indentations on the non-treated group (non-varnished) and the treated group (varnished). RESULTS: Varnished materials had significantly higher microhardness values in comparison to non-varnished materials. Ketac-Cem had the highest microhardness value among the varnished materials. CONCLUSION: Varnish application is necessary to preserve the cement and avoid enamel decalcification. Glass-ionomer cements should be protected in order to fully keep their properties, thus, contributing to dental health during orthodontic treatment.

OBJETIVO: avaliar a influência da contaminação salivar na resistência estrutural e integridade de cimentos de ionômero de vidro convencionais utilizados para cimentação de bandas ortodônticas na ausência e na presença de um verniz protetor de superfície. MÉTODOS: quarenta e oito corpos de prova foram confeccionados a partir de três cimentos ortodônticos, com auxílio de matrizes metálicas padronizadas com 10mm de diâmetro e 2mm de altura. Os cimentos utilizados foram: Meron (Voco), Ketac-Cem (3M ESPE) e Vidrion C (DFL), compondo os grupos A, B e C, respectivamente. Metade dessas amostras não recebeu nenhum tipo de proteção superficial, constituindo os subgrupos A1, B1 e C1, enquanto, os subgrupos A2, B2 e C2 tiveram suas superfícies isoladas com verniz Cavitine (SS White) após manipulação e aplicação do cimento, com intuito de proteger a superfície do cimento. As amostras foram armazenadas em saliva artificial por 24 horas a 37ºC. Foi realizado um ensaio de microdureza (Vickers) para avaliação da dureza de superfície do grupo não-tratado (sem isolamento) e do grupo tratado (agente protetor). RESULTADOS: os materiais previamente isolados com o verniz obtiveram valores de microdureza significativamente maiores que os não-isolados. O cimento Ketac-Cem apresentou, estatisticamente, a maior microdureza entre os materiais protegidos. CONCLUSÃO: o isolamento com verniz mostrou-se necessário para preservação do cimento e, consequentemente, de sua capacidade de evitar possíveis desmineralizações dentárias. Os cimentos de ionômero de vidro devem ser protegidos para manutenção de sua integridade, contribuindo para saúde dental durante o tratamento ortodôntico.

Resistencia compresiva vidrio ionómero Ionofil Molar® y Vitremer® según tiempo de exposición en saliva artificial / Compressive strength of glass ionomer Ionofil Molar® and Vitremer® according to exposure time in artificial saliva

Objetivo: El conocimiento sobre las propiedades mecánicas de los materiales dentales es fundamental para una correcta indicación y funcionamiento en la cavidad oral, permitiéndole al profesional optar por el que presente mejor comportamiento durante la masticación. El objetivo de este estudio fue evaluar la resistencia a la compresión de Ionofil Molar® y Vitremer®, según tiempo de exposición en saliva artificial. Materiales y Métodos: Se prepararon 5 muestras para cada material evaluadas a los tiempos 0, 168 y 504 horas en saliva artificial a 37° C, según las especificaciones propuestas por la norma ANSI/ADA n°66. La resistencia a la compresión se determinó sometiendo las muestras a cargas en un equipo de ensayo de fuerzas Instron® a una velocidad de carga de 1 mm/min. Se realizó una prueba de homogeneidad de varianzas, la normalidad se determinó mediante Kolmogorov-Smirnov, y posteriormente un ANOVA. Se realizó el test de Tukey para determinar si existió diferencia significativa entre variables. Resultados: La resistencia compresiva de Vitremer no presentó diferencias estadísticamente significativas en el tiempo (p=0.282), a diferencia de Ionofil Molar, que sí presentó diferencias entre los distintos tiempos (p=0.011). Además en las muestras sin sumergir, no hubo diferencia estadísticamente significativa entre materiales (p=0.091), en cambio sí existió diferencia al cabo de una y tres semanas de exposición (p=0). Conclusión: El vidrio ionómero Vitremer presenta mayor resistencia compresiva a lo largo del tiempo, sin presentar alteraciones significativas en el tiempo al ser inmerso en saliva, a diferencia del Ionofil Molar que disminuyó significativamente su resistencia en las mismas condiciones.

Objective: Understanding the mechanical properties of dental materials is essential for proper indication and a correct functioning in the oral cavity, as it allows the dentist to choose the material that presents better performance during mastication. The aim of this study was to evaluate the compressive strength of Ionofil Molar and Vitremer, according to the exposure time in artificial saliva. Materials: 5 samples were prepared for each material evaluated at 0, 168 and 504 hours in artificial saliva at 37º Celsius, according to the specifications suggested by ANSI/ADA specification No 66. The compressive strength was determined by subjecting the samples to an Instron strength-testing machine at a load speed of 1 mm/min. A test of homogeneity of variance was conducted; normality was determined by Kolmogorov-Smirnov, and ANOVA. Tukey’s test was performed to determine if significant differences existed between variables. Results: Vitremer compressive strength did not show statistically significant differences over time (p=0.282), unlike Ionofil Molar, which did present differences between times (p=0.011). Besides, there were no statistically significant differences in the samples without submerging (p=0.091), unlike after one to three weeks of exposure, were a difference did exist (p=0). Conclusion: Vitremer has greater compressive strength over time, without showing significant changes in time after being immersed in saliva, unlike Ionofil Molar, whose resistance decreased significantly under the same conditions.

Avaliação da microestrutura, microdureza e resistência à corrosão de juntas soldadas de uma liga de Ni-Cr obtidas através de diferentes processos de soldagem / Evaluation of the microstructure, hardness and corrosion resistance of welded joints of a Ni-Cr alloy obtained by different welding processes

Este trabalho avaliou o comportamento eletroquímico do metal de base (MB) de uma liga a base de níquel-cromo em relação a juntas soldadas desta liga obtidas pelos processos de brasagem (BRA) e Tungsten Inert Gas (TIG), imersos em saliva artificial com pH 2,5 e 5,5. Foram também realizados ensaios de microdureza e caracterização microestrutural, por meio de microscopia óptica e eletrônica de varredura e análise química semi-quantitativa por EDS, nos grupos MB, TIG, BRA e no cordão de solda a laser (LAS). O MB apresentou uma matriz rica em níquel e cromo, distribuída em um arranjo dendrítico típico, apresentando inclusões metálicas de silício e titânio, além de porosidades. As soldas TIG e LAS revelaram uma microestrutura mais refinada que o MB, mostrando, entretanto, uma mesma composição química e distribuição de seus elementos. A solda BRA apresentou diferenças marcantes em sua microestrutura, composição química e distribuição de seus elementos em relação ao MB. Os dados de microdureza Vickers (HV), potencial de corrosão (Ecorr) e densidade de corrente de corrosão (jcorr) foram analisados com ANOVA e teste de Tukey (p<0,05). Para determinação da influência do pH quanto a resistência à corrosão dos grupos MB, TIG e BRA, empregou-se o teste t de Student (p<0,05). O MB apresentou menor média de microdureza (256,13 ± 9,39 HV), seguido pelos grupos TIG (271,53 ± 8,07 HV), LAS (303,73 ± 13,93 HV) e BRA (551,99 ± 37,73 HV). Em pH 2,5 as médias do Ecorr (mV) para o MB, TIG e BRA foram, respectivamente, -67,9 ± 8,43, -52,78 ± 16,74, e -284,33 ± 19,04; e em pH 5,5, médias de -54,03 ± 21,15, -62,08 ± 20,16 e -278,8 ± 28,96. Os valores médios de jcorr (µA.cm-2) para o MB, TIG e BRA em pH 2,5 foram, respectivamente, 2,49 ± 0,95, 5,584 ± 1,64 e 27,45 ± 4,9; e em pH 5,5, médias de 1,929 ± 0,83, 4,267 ± 1,51 e 54,2 ± 11,96. Os grupos MB e TIG apresentaram boa resistência à corrosão, com maior módulo de impedância em relação ao grupo BRA. As diferenças no pH da ...

This study evaluated and compared the electrochemical behavior of the base metal (BM) of a nickel-chromium dental alloy with welded joints obtained by brazing processes (BRA) and Tungsten Inert Gas (TIG), when immersed in artificial saliva at pH 2.5 and 5.5. Microhardness, microstructural characterization by means of optical microscopy, scanning electron microscopy (SEM) and semi-quantitative chemical analysis by Energy Dispersive Spectroscopy (EDS), were performed in the groups BM, TIG, BRA and in joints weld by laser (LAS). The BM showed a matrix rich in nickel and chromium, distributed in a typical dendritic arrangement, with inclusions of silicon and titanium, and porosities. LAS and TIG welds reveled a microstructure more refined than the BM, however, the same chemical composition and distribution of its elements. BRA showed marked differences in their microstructure, chemical composition and distribution of the elements in relation to BM. Vickers microhardness (HV), corrosion potential (Ecorr) and corrosion current density (jcorr) were statistically analyzed with ANOVA and Tukey test (p <0.05). In order to determine the influence of pH and corrosion resistance in groups BM, TIG and BRA, Student t test, with significance level of 95% was used. BM had the lowest average microhardness (HV 256.13 ± 9.39), followed by groups TIG (271.53 ± 8.07 HV), LAS (303.73 ± 13.93 HV) and BRA (551, HV 99 ± 37.73). At pH 2.5 the average Ecorr (mV) for the MB and TIG were respectively -67.9 ± 8.43 and -52.78 ± 16.74, and at pH 5.5, averaging -54, 03 ± 21.15 and -62.08 ± 20.16. LAS group showed averages of Ecorr (mV) at pH 2.5 and 5.5, respectively, -284.33 ± 19.04 and 28.96 ± -278.8. The average values of jcorr (ìA.cm-2) to BM and TIG at pH 2.5 were respectively 2.49 ± 0.95 and 5.584 ± 1.64, and at pH 5.5, 1.929 ± 0.83 and 4.267 ± 1.51. Average jcorr for LAS group (ìA.cm-2) at pH 2.5 and 5.5 were respectively 27.45 ± 4.9 and 11.96 ± 54.2. BM and TIG ...

May the flexural strength of ceramics be influenced by salivary pH? / A resistência à flexão de cerâmicas pode ser influenciada pelo pH salivar?

Objective: This study purpose was to compare the three-point flexural strength of feldspathic ceramic after storage in artificial saliva for 30 days with different pH regimens, as acidic pH (3.5), neutral pH (7.0), basic pH (10) and alternating between acid/ basic pH, for 15 days each. Material and Methods: The bars were luted with resin cement and subjected to storage in artificial saliva of different pH values. Results: The values of flexural strength were significantly higher for bars stored in distilled water, at neutral and basic pH, when compared with the results for bars stored in acidic pH and in acid/basic pH. Conclusions: Storage for 30 days in artificial saliva at acidic pH, or alternating between acidic and basic pH, can reduce the mechanical properties of ceramics.

Objetivo: O objetivo do estudo foi comparar a resistência à flexão três pontos de uma cerâmica feldspática após armazenagem em saliva artificial, durante 30 dias com diferentes regimes de pH: pH ácido (3,5), pH neutro (7,0), pH básico (10) e alternando entre pH ácido/básico durante 15 dias cada. Material e Métodos: As barras foram cimentados com cimento resinoso e submetidas a armazenagem em saliva artificial com os diferentes valores de pH. Resultados: Os valores de resistência à flexão foram significativamente maiores para as barras armazenadas em água destilada, em pH neutro e em básico, quando comparadas com os resultados para as barras armazenadas em pH ácido e em meio ácido/básico. Conclusões: A armazenamento durante 30 dias em saliva artificial, com pH ácido, ou alternando entre pH ácido e basico, pode reduzir as propriedades mecânicas das cerâmicas

Caracterização de resinas para base de prótese e reembasamento: propriedades físico-químicas e mecânicas / Characterization of denture base and reline resins: physical, chemical and mechanical properties

Este estudo avaliou propriedades físico-químicas e mecânicas de resinas para base de prótese, uma fotoativada (Eclipse - E) à base de UDMA e outra termicamente ativada por micro-ondas (Nature Cryl MC - NC) à base de PMMA, e um reembasador quimicamente ativado (Tokuyama Rebase Fast II - TR II) à base de PEMA. Propriedades viscoelásticas (E', tan δ e Tg), contração linear de polimerização (CLP), sorção (Sor) e solubilidade (Sol) em água e em saliva artificial, grau de conversão (GC) e coeficiente de inchamento (CI) foram avaliados para a caracterização dos polímeros. A resistência à flexão dos materiais intactos (E, NC, TR II) e reembasados (E-E, E-TRII, NC-NC- NC-TR II) também foi avaliada. As propriedades viscoelásticas foram avaliadas em corpos-de-prova retangulares (64 x 10 x 3,3 mm), submetidos (n=2) à análise térmica dinâmico-mecânica (DMTA) em dois ciclos de varredura após confecção (controle) e armazenagem em saliva. O módulo de armazenamento (E') e o amortecimento mecânico (tan δ) a 37 ºC e a temperatura de transição vítrea (Tg) foram registrados durante o 1º ciclo da DMTA. A CLP (%) foi avaliada (n=10), em projetor de perfil (Nikon 6C), em corpos-de-prova circulares (50 x 0,5 mm). A Sor e a Sol (µg/mm3) foram mensuradas (n=5) seguindo as recomendações da ISO 1567. O GC (%) foi avaliado (n=5) por espectroscopia de infravermelho por transformadas de Fourier (32 leituras; resolução 4,0 cm-1 ). O coeficiente de inchamento foi realizado (n=5) de acordo com a teoria de Flory-Rhener. Os ensaios mecânicos de flexão (0,5 mm/min) foram realizados (n=10) em corpos-de-prova (64 x 10 x 3,3 mm) intactos ou reembasados e a resistência (MPa) calculada na tensão máxima (RFM) e no limite de proporcionalidade (RFLP). Os dados foram avaliados por ANOVA, seguida por Tukey HSD (α=0,05) ou Dunnett (α=0,05). As resinas E e NC apresentaram similar E', superior a TR II. O tan δ foi ordenado como TR II > NC > E. A Tg não foi alterada após armazenagem em saliva artificial. Os maiores valores de Tg nos grupos controle e armazenados foram apresentados, respectivamente, pelos materiais E e NC. Houve deslocamento dos picos de tan δ após o segundo ciclo de DMTA. Independente do meio de imersão, a Sor (µg/mm3 ) foi ordenada em NC > E > TR II. A armazenagem em saliva reduziu a Sol (µg/mm3 ) dos materiais. A resina E exibiu os menores valores de CLP, CI e o maior GC. NC exibiu a maior CLP e CI. TR II exibiu valores intermediários de CLP, CI e o menor GC. Os maiores valores de RFM e RFLP foram produzidos por E. A RFM e RFLP dos materiais reembasados foi ordenada em E-E > NC-NC > E-TRII> NC-TR II. A armazenagem em saliva não influenciou a resistência à flexão dos materiais intactos ou reembasados. No geral, a resina para base de prótese E apresentou propriedades físico-químicas e mecânicas superiores à NC e TR II

This study evaluated the physical-chemical and mechanical properties of denture base resins, one UDMA light-activated (Eclipse-E) and one PMMA heat-polymerized (Nature Cryl MC - NC). The PEMA autopolymerizing reliner (Tokuyama Rebase Fast II - TR II) was also evaluated. Viscoelastic properties (E', tan δ e Tg), linear shrinkage polymerization (LPS), sorption (Sor) and solubility (Sol) in water and in artificial saliva, degree of conversion (DC) and coefficient of swelling (CS) were employed for polymer characterization. The flexural strength of intact (E, NC, TR II) and relined samples (E-E, E-TRII, NC-NC- NC-TR II) was also made. The viscoelastic properties were evaluated by two cycles of dynamic mechanical thermal analysis (DMTA) on each rectangular (64 x 10 x 3.3 mm) samples (n=2). The storage modulus (E') and loss tangent (tan δ) at 37 ºC and the glass transition temperature (Tg) were recorded from the 1st DMTA cycle. LPS (%) was evaluated (n=10) by a Nikon 6C optical comparator, on circular samples (50 x 0.5 mm). Sor and Sol (µg/mm3 ) were measured (n=6) according to ISO 1567. DC (%) was evaluated (n=5) by FTIR spectroscopy (32 scans; resolution 4.0 cm-1). CS was evaluated (n=5) by Flory-Rhener theory. A three-point flexural tests (0.5 mm/min) was applied (n=10) on rectangular intact and relined samples. The ultimate flexural strength (FSU) and the flexural strength at the proportional limit (FSPl) were recorded in MPa. Data were analyzed with ANOVA, followed by Tukey HSD (α=0.05) ou Dunnett (α=0.05). E and NC had similar E', higher than TR II. Tan δ was arranged as TR II > NC > E. The Tg was not affected after saliva storage. The higher Tg values were obtained for E and NC. Tan δ peaks were shifted after 2 DMTA cycles. Regardless the medium immersion, Sor (µg/mm3 was arranged as NC > E > TR II. Saliva storage reduced Sol (µg/mm3) of the materials. E showed the lowest values of LPS, CS and the highest value of DC. NC showed the highest LPS and CS.TR II showed intermediated values of LPS, CS and the lowest DC. The highest FSU and FSPl values were exhibited by E. The FSU and FSPl of relined samples were arranged as E-E > NC-NC > E-TRII > NC-TR II. Saliva storage did not affect the flexural strength of intact and relined samples. Overall, the denture base resin E showed higher physicochemical and mechanical properties than NC and TR II

Dynamic study on fluoride release from glass ionomer cement in distilled water and artificial saliva / 中国基层医药

Objective In this study,the fluorine release behavior of six glass ionomer cements (GIC) samples was investigated in distilled water and artificial saliva.Methods The fluorine release behavior in GIC was measured by gas chromatography.Results Various GIC materials had the maxium fluorine release rate in the beginning,and the rate decreased rapidly.After 56 days,although the fluorine release quantity was in a trend of decreasing,the release process can be retained during a long period.For No3,No5,and No6 sampler,the fluorine release quantity in artificial saliva was lower than distilled water,whereas no significant difference was observed for Nol and No2 materials.The No4 sample produced a larger fluorine release quantity in artificial saliva.It can also be conducted that the immersible time of GIC and the fluorine release quantity met the equation of log ( Y ) =a + b x log ( t ).Conclusion The fluorine release behavior of six GIC matched the logarithmic regulation.

Avaliação da dureza de resina composta à base de silorano fotoativada com diferentes fotopolimerizadores e após o uso de colutórios bucais / Evaluation of hardness of the silorane-based composite resin cured with different photoactivators and after use of mouthwashes

Este estudo avaliou a microdureza da resina composta à base de silorano (RCS) fotoativada com luz halógena (LH) e LED, seguido da exposição aos colutórios bucais Periogard, Listerine e Colgate Plax Sem Álcool. Foram confeccionados 40 espécimes da RCS Filtek P90 e divididos em 2 grupos (n = 20): Grupo LED - fotoativação com LED por 40 s (1200 mW/cm2); Grupo LH - fotoativação com LH por 40 s (600 mW/cm2). Os espécimes foram distribuídos em 4 subgrupos (n-5) de acordo com o bochecho: Subgrupo C - imersos em saliva artificial por 7 dias; Subgrupo LI - agitados no colutório Listerine 1 vez ao dia por 1 minuto durante 7 dias, em seguida, armazenados em saliva artificial; Subgrupo CP - agitados no colutório Colgate Plax Sem Álcool, seguindo o mesmo protocolo acima; Subgrupo PE - agitados no colutório Periogard, seguindo o mesmo protocolo acima. Os espécimes foram submetidos ao ensaio de microdureza no Microdurômetro digital Vickers com três endentações e carga de 50 g/ 15 s e os dados, submetidos aos testes ANOVA dois fatores (Fonte de luz e Colutório bucal) e Tukey (5%). Houve diferença significante para os fatores Fonte de luz e Colutório bucal (p = 0,00). Os valores da microdureza para o fator Fonte de luz: Grupo LED - 72,61 a; Grupo LH - 67,21 b; para o fator Colutório bucal: Subgrupo C - 79,29 a; Subgrupo PL - 75,5 a; Subgrupo PE - 66,12 b; Subgrupo LI - 58,75c. Para o fator Fonte de luz, LED apresentou dureza superior a LH. Para o fator Colutório bucal, o armazenamento em saliva artificial apresentou dureza superior em relação ao uso dos colutórios Periogard e Listerine.

This study evaluated the microhardness of silorane-based composite resin cured with halogen light and LED, followed by the use of mouthwashes: Periogard, Listerine, and Colgate Plax Without Alcohol. Forty specimens were fabricated with silorane-based composite resin Filtek P90 and divided into two groups (n = 20): Group LED - LED light curing for 40 s (1200 mW/cm2), Group HL - Halogen light curing for 40 s (600 mW/cm2). The specimens were divided into four subgroups (n-5) in accordance with the use of the mouthwash: Subgroup C - immersed in artificial saliva for 7 days; Subgroup LI - Listerine mouthwash once daily for 1 minute during 7 days, then stored in artificial saliva; Subgroup CP - Colgate Plax Without Alcohol mouthwash, following the same protocol above; Subgroup PE - Periogard mouthwash, following the same protocol above. The specimens were subjected to microhardness test on digital Microhardness Vickers with three indentations and load of 50 g/ 15 s. The data were submitted to ANOVA two factors (Light and Mouthwash) and Tukey (5%). There were significant differences for the factors Light and Mouthwash (p = 0.00). The values of microhardness for Light Factor: LED Group - to 72.61 a and Group HL - 67.21 b; for Mouthwash Factor: Subgroup C - 79.29 a; subgroup PL - to 75.5 a; subgroup EP - 66.12 b; Subgroup LI - 58.75 c. For Light Factor, LED showed hardness higher than halogen light. For Mouthwash Factor, storage in artificial saliva showed higher hardness compared to the use of Listerine and Periogard mouthwashes.

Avaliação das tensões liberadas por elásticos ortodônticos em cadeia: estudo in vitro / Assessment of force decay in orthodontic elastomeric chains: an in vitro study

INTRODUÇÃO: os materiais elastoméricos são considerados importantes fontes de força para a movimentação ortodôntica. OBJETIVO: avaliar a liberação de tensões de quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek), em função do tempo, quando mantidas tensionadas por uma força inicial de 150g e imersas em saliva artificial a 37ºC. MÉTODOS: os elásticos em cadeia foram tensionados entre pinos de aço, fixados em uma placa de resina acrílica à distância de 15mm (Morelli e TP) e de 16mm (Unitek e Ormco), ambas medidas correspondendo a uma força de 150g. A leitura da quantidade de tensão liberada pelos elásticos foi realizada com um dinamômetro nos intervalos 30 minutos, 7, 14 e 21 dias. Os dados obtidos foram submetidos à análise de variância (ANOVA) (p<0,05) e ao teste de Comparações Múltiplas de Tukey. RESULTADOS: após 30 minutos de teste, verificou-se redução entre 19 por cento e 26,67 por cento na quantidade de tensão liberada pelos elásticos; e entre 36,67 por cento e 57 por cento após 21 dias de estiramento constante. CONCLUSÕES: os elásticos em cadeia que apresentaram comportamento mais estável foram os da marca TP, pois relataram menor perda de potencial elástico nos intervalos de tempo testados. Os da marca Unitek demonstraram maior redução de tensão liberada. As marcas Ormco e Morelli obtiveram resultados semelhantes entre si.

INTRODUCTION: Elastomeric materials are considered important sources of orthodontic forces. OBJECTIVE: To assess force degradation over time of four commercially available orthodontic elastomeric chains (Morelli, Ormco, TP and Unitek). METHODS: The synthetic elastics were submerged in 37 ºC synthetic saliva and stretched by a force of 150 g (15 mm - Morelli and TP; 16mm - Unitek and Ormco). With a dynamometer, the delivered force was evaluated at different intervals: 30 minutes, 7 days, 14 days and 21 days. The results were subjected to ANOVA and Tukey's test. RESULTS: There was a force decay between 19 percent to 26.67 percent after 30 minutes, and 36.67 percent to 57 percent after 21 days of activation. CONCLUSIONS: TP elastomeric chains exhibited the smallest percentage of force decay, with greater stability at all time intervals tested. Meanwhile, the Unitek chains displayed the highest percentage of force degradation, and no statically significant difference was found in force decay between Ormco and Morelli elastomeric chains during the study period.

An in vitro comparison of nickel and chromium release from brackets

This study aimed at comparing amounts of nickel (Ni) and chromium (Cr) released from brackets from different manufacturers in simulated oral environments. 280 brackets were equally divided into 7 groups according to manufacturer. 6 groups of brackets were stainless steel, and 1 group of brackets was made of a cobalt-chromium alloy with low Ni content (0.5 percent). International standard ISO 10271/2001 was applied to provide test methods. Each bracket was immersed in 0.5 ml of synthetic saliva (SS) or artificial plaque fluid (PF) over a period of 28 days at 37ºC. Solutions were replaced every 7 days, and were analyzed by spectrometry. The Kruskal-Wallis test was applied. Amounts of Ni release in SS (µg L-1 per week) varied between groups from "bellow detection limits" to 694, and from 49 to 5,948.5 in PF. The group of brackets made of cobalt-chromium alloy, with the least nickel content, did not release the least amounts of Ni. Amounts of Cr detected in SS and in PF (µg L-1 per week) were from 1 to 10.4 and from 50.5 to 8,225, respectively. It was therefore concluded that brackets from different manufacturers present different corrosion behavior. Further studies are necessary to determine clinical implications of the findings.