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).

Factors Affecting Sorption and Solubility of Denture Base Acrylic Materials: A Review

@#Heat-cured PMMA is one of the most frequently used materials in the manufacture of removable dentures. Heat-cured material used to fabricate dentures contain soluble elements, allowing the material to absorb and release substances. These factors all directly affect the longevity and performance of protheses fabricated from polymethyl methacrylate denture base material. Various procedures associated with fabrication of removable dentures from heat-cure denture base material are reported to significantly influence the sorption and solubility experienced by the prosthesis. A comprehensive search of peer-reviewed journals located within academic databases was conducted to identify relevant literature pertaining to sorption and solubility of denture base materials. Key aspects of each paper were captured in Microsoft® Excel® to record author/s, location, study design, sample size, methodology, results and conclusions. Mixing ratios and polymerisation cycles have been identified as variables that can negatively influence the rate of sorption and solubility of denture base materials during the fabrication process. Certain surface treatment procedures, as well as storing the denture in artificial saliva solution may reduce the levels of sorption and solubility experienced and optimise its lifespan. In this review we identify these factors and consider the detrimental effects of sorption and solubility on denture base acrylic materials.

In Vitro Evaluation of Fluoride in Saliva After Topical Application of Professional Use Products

Objective: To evaluate in vitro the presence of fluoride in saliva after applying professional use products on the surface of dental enamel. Material and Methods: Experimental groups were composed by: Cariostatic 12% (CA), Fluoridated Varnish 5% (FV), Fluorine Acidulate Gel 1.23% (AG) and Fluorine Neutral Gel 2% (NG). Fluoridated dentifrice (FD) and Artificial Saliva (AS) were used as controls. Products (10 µL) were applied to the surface of bovine enamel blocks (4×4×1 mm, n = 18) and immersed in 10 mL of artificial saliva at room temperature. Aliquots of artificial saliva (750 µL) of each sample were collected 1, 2, 4, 8, 24 and 48 hours after application of the products. Analyses were performed in triplicate, using a fluoride ion-specific electrode coupled to a potentiometer. The equipment was calibrated using a standard curve for fluoride analysis from 0.125 to 64 µgF-/mL. Results: Greater fluoride concentration (µgF-/mL) was observed after 1h application, as follows: 197.40 (NG), 172.21 (AG), 20.25 (CA), 14.49 (FV) e 11.81 (FD). Fluoride concentration increased overtime for all groups. After 48h, the following fluoride concentrations were assessed: 428.12 (AG), 267.25 (NG), 65.36 (FV), and 62.52 (CA). Conclusion: Greater fluoride release was observed for AG and NG groups, mostly after 1h application.

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.

Effect of two aging methods on the bonding interface between glass ceramics and dentin / 口腔疾病防治

Objective@#To study the effects of bacterial invasion and artificial saliva immersion on the bond strength and nanoleakage between healthy dentin and glass ceramics-bonded specimens using three types of resin cements and provide a reference for the selection of clinical bonding materials.@*Methods @#One hundred eight dentin blocks were selected to prepare bonded specimens with Variolink N, Multilink N, RelyX Unicem and glass ceramics blocks. The adhesive specimens of each type of resin cements were divided into three groups according to the aging method: bacterial invasiveness group (the specimens were cultured under anaerobic conditions for 14 days after inoculation with Streptococcus mutans), artificial saliva immersion group (the specimens were immersed in artificial saliva for 6 months), and control group (the immediate test group). Each group comprised 12 specimens: 6 were selected to test the bonding strength, and 6 were observed by scanning field emission scanning electron microscopy (FESEM). @*Results @#The bond strength of Variolink N in the immediate test group was significantly higher than that of Multilink N and RelyX Unicem, and the difference was statistically significant (P < 0.05). However, no significant difference was found in the bacterial invasiveness group and artificial saliva immersion group (P > 0.05). In the bacterial invasion group, the difference in the nanoleakage of the three adhesives was statistically significant (P < 0.05), with a trend of Variolink N > Multilink N > RelyX Unicem, and pairwise comparison was statistically significant (P < 0.05). The nanoleakage of the three resin adhesives showed an increasing trend in the bacterial invasion group and artificial saliva group compared with that of the immediate test group. @* Conclusion@#Both artificial saliva soaking and bacterial invasion can reduce the sealing property of the adhesive interface of 3 types of resin cements to different degrees. The presence of Streptococcus mutans in the oral cavity may reduce the sealing performance of the resin dentine adhesive interface.

Comparative remineralization effects of human and artificial saliva compositions on incipient dental caries / 대한구강보건학회지

OBJECTIVES: The purpose of this study was to compare enamel remineralization effects of human whole saliva and currently available artificial saliva compositions, using teeth exposed to chemical pH cycling conditions, and to obtain data that can inform future design and manufacturing of additional artificial saliva compositions. METHODS: Seventy-two specimens of bovine tooth enamel were embedded in resin, then polished and exposed to a lactate/carbopol buffer system for 48-52 hours. Specimens were allocated into six experimental groups (n=12 specimens per group) by randomized blocks, such that each group contained an equivalent proportion of specimens at each Vickers hardness number (VHN) stratum: deionized water as a negative control, human whole saliva and artificial saliva compositions A, B, C and D. Surface hardness was measured before and after 15 days of chemical pH cycling. Surface microhardness was measured (Fm-7, Future-tech Corp, Japan) before and after treatment with test saliva compositions. One-way ANOVA, with post hoc Tukey test, was used to evaluate statistical differences with a significance threshold of P<0.05. RESULTS: The intragroup changes in microhardness (ΔVHN) for treatment with each saliva composition were (in ascending order of ΔVHN): ―0.39±16.08 (deionized water control), 7.32±11.52 (artificial saliva B), 39.18±11.94 (artificial saliva C), 3.83±13.81 (artificial saliva D), 62.44±29.23 (artificial saliva A) and 102.90±25.89 (human whole saliva). Enamel treated with human saliva, or with artificial saliva compositions A, C, or D, demonstrated comparatively greater microhardness than enamel treated with deionized water or artificial saliva B. There was no difference in surface hardness between enamel treated with artificial saliva B and enamel treated with deionized water. CONCLUSIONS: Our study suggests that human saliva and artificial saliva compositions A, C, and D are effective remineralization solutions for use in pH cycling.

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.

The effect of two artificial salivas on the adhesion of Candida albicans to heat-polymerized acrylic resin

PURPOSE: Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens. MATERIALS AND METHODS: Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at 37degrees C. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using x40 magnification under a light microscope and data were analysed. RESULTS: Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05). CONCLUSION: In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia.

Investigation of the Characteristics of Orally Disintegrating Film Formulation / 医薬品情報学

<b>Objective: </b>In Japan, to prevent an increase in medical expenditure associated with development of super-aging society, the use of generic drugs is being promoted.  To help patients financially and meet their various other needs, generic drugs (e.g., orally disintegrating film formulations) whose dosage forms do not exist for original drugs are manufactured and distributed.  In this study, to evaluate the characteristics of an orally disintegrating film formulation, we performed dissolution, disintegration, and simulated intraoral tests of Amlodin® tablets 2.5 mg, Amlodin® OD tablets 2.5 mg, and Amlodipine OD film 2.5 mg that were manufactured by TEVA-KOWA PHARMA Co., Ltd.<br><b>Methods: </b>Dissolution and disintegration tests were performed in line with the Japanese Pharmacopoeia, Sixteenth Edition, and the dose of amlodipine was determined by high-performance liquid chromatography.  During the simulated intraoral test, the tested drugs’ disintegration in purified water and artificial saliva was observed macroscopically, and recorded using a digital camera.<br><b>Results: </b>Since the each formulation showed an over 85.0% rate of dissolution 15 min after the initiation of the dissolution test, no difference was found in elution behavior.  Also, in the simulated intraoral test, the film formulation began to disintegrate the earliest (2 and 10 min when using purified water and artificial saliva, respectively) among the tested drugs.<br><b>Conclusion: </b>Our findings suggest that orally disintegrating film formulations show superior disintegration to uncoated or orally disintegrating tablets, and benefits on taking medicine was observed.

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.

In vitro cytotoxicity of indirect composite resins: Effect of storing in artificial saliva.

Aim: The aim of this study was to compare the cytotoxic effects of two indirect composite resins (Artglass and Solidex) on the viability of L-929 fibroblast cells at different incubation periods by storing them in artificial saliva (AS). Materials and Methods: Disk-shaped test samples were prepared according to manufacturers' instructions. Test materials were cured with light source (Dentacolor XS, Heraus Kulzer, Germany). The samples were divided into two groups. The first group's samples were transferred into a culture medium for 1 hour, 24 hours, 72 hours, 1 week and 2 weeks. The other group's samples were transferred into a culture medium for 1 hours, 24 hours, 72 hours, 1 week, and 2 weeks after being stored in AS for 48 hours. The eluates were obtained and pipetted for evaluation onto L-929 mouse fibroblast cultures incubated for 24 hours. Measurements were performed by MTT (3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The degree of cytotoxicity for each sample was determined according to the reference values represented by the cells with a control group. Results: Statistical significance was determined by ANOVA. Both groups presented lower cell viability in comparison to the control group at all periods. Storing in artificial saliva reduced cytotoxicity significantly (P < 0.05). Stored Artglass and Solidex showed similar effects on cytotoxicity. Nonstored Solidex samples were found more cytotoxic than Artglass samples. The cell survival rate results of 24-hour incubation period were significantly lower than those of the other experimental periods (P < 0.05). Conclusion: Storing indirect composite resins in AS may reduce cytotoxic effects on the fibroblast cells. However, resin-based dental materials continue to release sufficient components to cause cytotoxic effects in vitro after 48 hours of storing in AS.

The influence of storage time and pH variation on water sorption by different composite resins.

Objective: The objective of this work was to assess the influence of storage time and pH cycling on water sorption by different composite resins. Materials and Methods: Nine resin brands were selected and divided into groups: G1-ROK (SDI), G2-ICE (SDI), G3-GLACIER (SDI), G4-Z350 (3M/ESPE), G5-Z250 (3M/ESPE), G6-TPH 3 (DENTSPLY), G7-ESTHET X (DENTSPLY), G8-SUPRAFILL (SSWHITE), and G9-MASTERFILL (BIODINΒMICS). Ninety specimens, ten per group, were obtained using an aluminum matrix. Specimens measured 10 mm diameter × 2 mm width. The groups were divided into subgroups according to the immersion solution: A - control (n = 05) stored in artificial saliva pH = 7.0 and B-test (n = 05) submitted to seven consecutive days of pH cycling (cariogenic challenger) that consisted of immersion in a pH° = 4.3 solution for 6 h followed by immersion in a pH¹ =7.0 solution for 18 h and stored in artificial saliva pH = 7.0 until the end of the experiment. The specimens were weighed on six occasions: T 0 (after fabrication), T 1 (24 h), T 2 (7 days), T 3 (15 days), T 4 (30 days), T 5 (60 days), and then analyzed. The water sorption was determined by the weight difference between the specimens at the time intervals. Results: The mean weight gain was exactly the same for both the subgroups within group G4. The highest means for the control subgroup were found in groups: G1, G5, G7, G8, and G9. For the pH cycling subgroup, the highest means were found in G2, G3, and G6; however, significant differences between the subgroups compared to the mean-weight gain were found for G1, G5, and G7. Conclusion: The water sorption of composite resins is dependent upon their storage time. The pH cycling created a significant impact on resins G1, G5, and G7. The sorption and solubility of composite resins vary according to their chemical composition.

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

Xylitol concentrations in artificial saliva after application of different xylitol dental varnishes

OBJECTIVE: The present study analyzed xylitol concentrations in artificial saliva over time after application of varnishes containing 10% and 20% xylitol. MATERIAL AND METHODS: Fifteen bovine enamel specimens (8x4 mm) were randomly allocated to 3 groups (n=5/group), according to the type of varnish used: 10% xylitol, 20% xylitol and no xylitol (control). After varnish application (4 mg), specimens were immersed in vials containing 500 µL of artificial saliva. Saliva samples were collected in different times (1, 8, 12, 16, 24, 48 and 72 h) and xylitol concentrations were analyzed. Data were assessed by two-way repeated-measures ANOVA (p<0.05). RESULTS: Colorimetric analysis was not able to detect xylitol in saliva samples of the control group. Salivary xylitol concentrations were significantly higher up to 8 h after application of the 20% xylitol varnish. Thereafter, the 10% xylitol varnish released larger amounts of that polyol in artificial saliva. CONCLUSIONS: Despite the results in short-term, sustained xylitol releases could be obtained when the 10% xylitol varnish was used. These varnishes seem to be viable alternatives to increase salivary xylitol levels, and therefore, should be clinically tested to confirm their effectiveness.

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.

An Invitro Comparative Evaluation of Fluoride Release From Different Fluoride Containng Restorative Materials In Various Study Solutions.

The aim of this study was to determine the level of fluoride released from four different tooth colored restorative materials; Vitremer, Fuji II LC, Dyract and Tetric ceram in three different storage solutions; artificial saliva, De-ionized water and pH cycling system and also to compare the amount of fluoride released. Fifteen discs of each material were prepared in a Teflon mould, varnish applied, polished, then stored at 370C and 100% relative humidity for a day. Each storage solution of 2 ml was pipetted into five polypropylene tubes and five samples of each material were suspended individually and the fluoride released was measured using an Orion fluoride Specific Electrode and Digital Ion Analyzer. All the results were statistically analyzed and was concluded that vitremer showed the highest fluoride release followed by Fuji II LC, Dyract and Tetric Ceram in the pH cycling system followed by De-ionized water and least in Artificial saliva.

Analysis of Chemical Components of Mainstream Smoke Trapped by Artificial Saliva Using Stir Bar Sorptive Extraction and Thermal Desorption Coupled with Gas Chromatography-Mass Spectrometry / 分析化学

The chemical components of mainstream smoke were trapped by the artifical salvia. A novel method) for the analysis of the trapped chemical components was established using stir bar sorptive extraction(SBSE)) followed by a thermal desorption-gas chromatography-mass spectrometry(TD-GC-MS). The major) factors including desorption temperature, desorption time, cryofocusing temperature, extraction time and the addition of sodium chloride were studied. Under the optimized conditions, the average relative standard deviation(RSD) of peak areas of 44 components which were identified from the artifical saliva for 6 determinations was less than 10%, which showed the good repeatability of this method. The experiment result indicated that the SBSE-TD-GC-MS technique provided a powerful tool for the analysis of smoke components of some cigarette) trapped and dissolved in the saliva.