Thiourethane-functionalized fillers: biological properties and degradation resistance

Abstract This study determined the effect of thiourethane-functionalized fillers (TU) on the antimicrobial properties, cytotoxicity, degree of conversion (DC), water sorption (Wsp) and solubility (Wsl) of experimental composites. TU-modified fillers were added at different ratios in experimental composites: 0 (Control-TU0), 25% (TU25), 50% (TU50), 75% (TU75) and 100wt% (TU100). The antimicrobial properties were detected through the exhaustion test and counting of Streptococus mutans colonies for biofilm formation. Cytotoxicity to human gingival fibroblasts was evaluated in three different parameters: XTT (2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide), NRU (Neutral Red Uptake assay) and CVDE (Crystal Violet Dye Exclusion test)) at the same cells. ELISA was used to measure the IL-6 and b-FGF biomarkers. DC was determined by Fourier-transformed infrared spectroscopy, while Wsp and Wsl by mass variations. Inhibitory capacity of biofilm formation was not observed for any material. All groups presented at least 70% of cell survival within the observed periods (24h and 7 days). Positive control (toxic) had high IL-6 values and low b-FGF values. No significant variations in DC, Wsp, and Wsl were observed among the experimental groups. The use of thiourethane did not present antimicrobial and cytotoxic activity and the tested materials presented equivalent properties to those conventionally used in dentistry.

Micro-shear bond strength of composite resin to glass ionomer cement using an alternative method to build up test specimens

Despite the relevance of the sandwich technique, there are still doubts about the best adhesive strategy and surface treatment for glass ionomer cements (GICs). Aim: The aim of this study is to evaluate the best surface treatment for GIC to ensure an effective and durable adhesion to resin, through micro-shear test, using an alternative method to build up test specimens. Subjects and Methods: Eighty GIC samples were divided into eight groups (n = 10) according to five surface treatments (none, etching, air drying, grinding, and grinding plus etching) and according to the adhesive system (conventional or self-etch). Five starch tubes were positioned on each sample, and a flowable composite was inserted generating 50 resin test bodies per group and a total of 400 tested areas. All specimens were submitted to the micro-shear test: half immediately and half after thermal cycling (10,000 cycles of 20 s each/5° and 55°C). All samples were analyzed to evaluate fracture. Representative samples were also analyzed by scanning electron microscopy and energy dispersive spectroscopy. Data were analyzed with two-way ANOVA and Tukey's honest significant difference post hoc test (P <.05). Results: The bond strengths in the thermal cycled specimens were lower and showed a statistically significant difference (P = 0). The “grinding” groups showed the highest bond strength. Conclusions: The alternative method to build up test specimens was effective and easy to execute. Grinding of the GIC surface, which is not normally performed before the use of the adhesive system, represented the best option of surface treatment.

Adesão de resina composta a cimento de ionômero de vidro submetido a diferentes tratamentos de superfície / Adhesion of composite resin to glass ionomer cement subjected to different surface treatments

O uso combinado de cimento de ionômero de vidro (CIV) e resina composta é largamente indicado nos procedimentos clínicos odontológicos. Ao associar os dois materiais objetiva-se que as características desejáveis de cada um sejam somadas, melhorando as propriedades e a taxa de sucesso da restauração final. Com base nisso, o objetivo do trabalho foi avaliar, através de ensaio de microcisalhamento, nos estágios imediato e após envelhecimento simulado, o melhor tratamento de superfície sobre o cimento de ionômero de vidro convencional a fim de garantir uma adesão eficaz e duradoura com resinas compostas. Para confecção dos corpos de prova, foram feitas cavidades padrão (0,2x1x1cm) em uma matriz circular de resina acrílica no qual o CIV (Ionofil Plus ­ VOCO, Alemanha) foi inserido. Foram ao todo 80 amostras de CIV divididas em 8 grupos (n=10). Em cada amostra foram confeccionados 5 corpos de prova de resina composta, gerando 50 por grupo e um total de 400. Os grupos foram divididos de acordo com o tratamento de superfície (somente aplicação de adesivo, dessecamento com ar comprimido, condicionamento ácido e asperização com broca) e de acordo com o tipo de sistema adesivo utilizado (convencional de dois passos e autocondicionante de passo único). Após os tratamentos, as amostras foram armazenadas em meio úmido por 48h e, em seguida, metade dos corpos de prova de cada grupo foi submetido ao ensaio de microcisalhamento e a outra metade ao envelhecimento em uma termocicladora com 10.000 ciclos de 20s cada a temperaturas de 5 e 55ºC para posteriormente ser submetida ao mesmo ensaio. Os resultados de resistência ao microcisalhamento foram analisados por ANOVA (two-way) e pelo teste de Tukey HSD post hoc com nível de significância de 5% (p<0,05). Os valores de resistência adesiva no grupo envelhecido foram inferiores e apresentaram diferença estatisticamente significativa (p=0). A asperização da superfície seguida de condicionamento ácido apresentou os maiores valores de resistência adesiva nos dois estágios avaliados. Todos os corpos de prova foram analisados no microscópio óptico para avaliar o tipo de fratura ocorrida. Em seguida, amostras representativas foram preparadas para análise em microscopia eletrônica de varredura (MEV) e espectroscopia de raios-x por dispersão em energia (EDX/ EDS). Nas condições do estudo, foi possível concluir que a asperização da superfície do ionômero de vidro, seguida de condicionamento ácido e sistema adesivo convencional representou a melhor opção de estratégia adesiva.

The association of glass ionomer cement (GIC) and composite resin is widely indicated in dental clinical procedures. The association of the two materials aims to combine the desirable characteristics of each one increasing the properties and the success rate of the final restoration. Based on this, the aim of this study was to evaluate, through a microshear test, the better surface treatment of glass ionomer cements, in the initial stages and after thermocycling, in order to ensure an effective and durable adhesion to composite resins. Standard cavities were made (0,2x1x1cm) in a circular acrylic resin matrix in which the GIC (Ionofil Plus - VOCO, Germany) was inserted. Eighty samples were divided into 8 groups (n = 10). Five resin composite test bodies were made in each sample, generating 50 per group and a total of 400. Groups were divided according to the surface treatment (adhesive application, desiccation with compressed air, etching, roughening with a bur), and according to the type of adhesive system used (two-step etch-rinse and single-step self-etching). After treatment, the samples were stored in humid conditions for 48 hours and then half of the specimens in each group was submitted to microshear test and the other half to thermal cycling with 10.000 cycles of 20s each one at temperatures of 5 and 55°C and then microshear test. The results of microshear resistance were analyzed with Two-way ANOVA and Tukey's HSD post hoc test with a significance level of 0,05 (p <0.05). The bond strength in aged group were lower and showed statistically significant difference (p = 0) when compared to the groups that had the same surface treatment, but were not aged. The roughening of the surface followed by etching showed the highest bond strength values in both stages. All samples were analyzed in optical microscopy to evaluate the type of fracture that occurred in the adhesive interface. Then, representative samples were prepared for analysis by scanning electron microscopy (SEM) and x-ray spectroscopy for energy dispersion (EDS / EDX). Under the conditions of the study, it was concluded that the roughening of the glass ionomer surface, followed by etching and conventional adhesive system represented the best option of adhesive strategy.

Avaliação da eficácia das fitas para clareamento dental / Evaluation of the Effectiveness of Dental Whitening Strips

O objetivo deste estudo foi discutir, através de uma revista da literatura, a eficácia, limitações e efeitos colaterais relacionados com as fitas para clareamento dental. Dentre os vários artigos apresentados neste estudo, todos relatam um efeito branqueador em esmalte e dentina com o uso de fitas clareadoras impregnadas com peróxido de hidrogênio entre 5% a 10%. Porém, pouco se sabe se o grau de clareamento atingido se equipara ao das demais técnicas clareadoras. Além disso, somente um estudo acompanhou a duração do resultado por três meses. Portanto, mais pesquisas são necessárias para avaliar o tempo total de duração do clareamento através do uso de fitas, assim como comprovar se o grau de clareamento alcançado pode ser comparável às outras técnicas.

The aim of this study was to discuss, through a literature review, the effectiveness, limitations and side effects related to tooth whitening strips. Among the various articles shown in this study, all of them describe a whitening effect on enamel and dentin using whitening strips impregnated with hydrogen peroxide between 5% and 10%. However, little is known whether the degree of whitening achieved is comparable to the effect produced by other bleaching techniques. Furthermore, only one study followed the length of the result for three months. Therefore, more research is needed to assess the full duration of whitening through the use of whitening strips, as well as demonstrate the degree of whitening that can be achieved compared to other techniques.

Oral squamous cell carcinoma: clinicopathological features from 346 cases from a single Oral Pathology service during an 8-year period

Epidemiological data from oral squamous cell carcinoma (OSCC) is mostly derived from North American, European and East Asian populations. OBJECTIVE: The aim of this study was to report the demographic and clinicopathological features from OSCC diagnosed in an Oral Pathology service in southeastern Brazil in an 8-year period. MATERIAL AND METHODS: All OSCC diagnosed from 2005 to 2012 were reviewed, including histological analysis of all hematoxylin and eosin stained slides and review of all demographic and clinical information from the laboratory records. RESULTS: A total of 346 OSCC was retrieved and males represented 67% of the sample. Mean age of the patients was 62.3 years-old and females were affected a decade older than males (p<0.001). Mean time of complaint with the tumors was 10 months and site distribution showed that the border of the tongue (37%), alveolar mucosa/gingiva (20%) and floor of mouth/ventral tongue (19%) were the most common affected sites. Mean size of the tumors was 3.4 cm, with no differences for males and females (p=0.091) and males reported both tobacco and alcohol consumption more frequently than females. Histological grade of the tumors revealed that 27%, 40% and 21% of the tumors were, respectively, classified as well-, moderately- and poorly-differentiated OSCC, 26 cases (7.5%) were microinvasive OSCC and 17 cases were OSCC variants. OSCC in males mostly affected the border of tongue, floor of mouth/ventral tongue and alveolar mucosa/gingival, while they were more frequent on the border of tongue, alveolar mucosa/gingival and buccal mucosa/buccal sulcus in females (p=0.004). CONCLUSIONS: The present data reflect the epidemiological characteristics of OSCC diagnosed in a public Oral Pathology laboratory in southeastern Brazil and have highlighted several differences in clinicopathological features when comparing male and female OSCC-affected patients. .