Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses.

OBJECTIVES: To evaluate obliterating capability and biological performance of desensitizing agents. METHODS: 50 dentin blocks were distributed according to the desensitizing agent used (n = 10): Control (Artificial saliva); Ultra EZ (Ultradent); Desensibilize Nano P (FGM); T5-OH Bioactive Glass (Experimental solution); F18 Bioactive Glass (Experimental solution). Desensitizing treatments were performed for 15 days. In addition, specimens were subjected to acid challenge to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after desensitizing procedures and acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid assay at 15 min, 24-h and 48-h time points. Scanning electron microscopy and energy dispersion X-ray spectroscopy were performed for qualitative analysis. Data of dentin permeability was analyzed by two-way repeated measures ANOVA and Tukey's test. For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests. RESULTS: for dentin permeability there was no significant difference among desensitizing agents after treatment, but control group presented highest values (0.131 ± 0.076 Lp). After acid challenge, control group maintained highest values (0.044 ± 0.014 Lp) with significant difference to other groups, except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among groups. CONCLUSION: Bioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties. CLINICAL SIGNIFICANCE: There is no gold standard protocol for dentin sensitivity. The study of novel desensitizing agents that can obliterate dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.

Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses / Análise da permeabilidade e propriedades biológicas da dentina tratada com vidros bioativos experimentais

O objetivo deste estudo foi avaliar a capacidade obliteradora de diferentes agentes dessensibilizantes em dentina humana através da mensuração da permeabilidade dentinária, e suas performances biológicas através da análise de citotoxicidade em fibroblastos gengivais humanos. Cinquenta molares humanos foram utilizados, dos quais foram obtidos blocos de dentina (4x4x1mm) posteriormente distribuídos em grupos de acordo com o dessensibilizante a ser utilizado (n=10): Grupo 1 - Controle (Saliva artificial. Sem aplicação de agente dessensibilizante); Grupo 2 - Ultra EZ (Ultradent); Grupo 3 - Desensibilize Nano P (FGM); Grupo 4 - Vidro Bioativo T5-OH (solução experimental); Grupo 5 - Vidro Bioativo F18 (solução experimental). Os tratamentos dessensibilizantes foram realizados durante 15 dias. Além disso, os espécimes foram submetidos ao desafio com ácido cítrico para simular condições desmineralizantes do ambiente oral. As amostras foram submetidas à análise de permeabilidade antes e após os procedimentos dessensibilizantes e o desafio ácido. Análise de citotoxicidade foi realizada pelo ensaio Alamar Blue complementado pela quantificação de proteína pelo Método BCA (ácido bicinconínico) (N=3; n=3) nos tempos de avaliação de 15 minutos, 24 horas e 48 horas. Microscopia eletrônica de varredura (MEV) e Espectroscopia de Raio-X por Energia Dispersiva (EDS) foram realizadas para análise qualitativa da dentina tratada. Dados de permeabilidade dentinária foram analisados por ANOVA dois fatores medidas repetidas e Teste de Tukey (α=0,05). Para a citotoxicidade, foram utilizados os testes Kruskal-Wallis e Newman-Keuls (α=0,05). Os resultados mostraram que para a permeabilidade dentinária não houve diferença significante entre os agentes dessensibilizantes após os tratamentos (p> 0,05), porém o grupo controle apresentou os maiores valores (0,131 ± 0,076 Lp, p< 0,05). Após o desafio ácido, o grupo controle manteve os maiores valores (0,044 ± 0,014 Lp) com diferença significante para os demais grupos (p< 0,05), exceto para o Desensibilize Nano P (0,037 ± 0,019 Lp). Quanto à citotoxicidade, não houve diferença entre os grupos experimentais (p> 0,05). Assim, foi possível concluir que o uso de dessensibilizantes à base de biovidros causou efeito similar ao uso de produtos disponíveis comercialmente, em relação à permeabilidade e propriedades biológicas da dentina(AU)

The aim of this study was to evaluate the obliterating capability of different desensitizing agents on human dentin by measuring dentin permeability, and their biological performance by the analysis of cytotoxicity in human gingival fibroblasts. Fifty human molars were used, from which dentin blocks were obtained (4x4x1mm) and distributed in groups according to the desensitizing agent used (n=10): Group 1 - Control (Artificial saliva. No desensitizing agent applied); Group 2 ­ Ultra EZ (Ultradent); Group 3 ­ Desensibilize Nano P (FGM); Group 4 - T5-OH Bioactive Glass (Experimental solution); Group 5 - F18 Bioactive Glass (Experimental solution). The desensitizing treatments were performed for 15 days. In addition, the specimens were subjected to challenge with citric acid to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after the desensitizing procedures and the acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid (BCA) assay (N=3; n=3) at 15 minutes, 24-hour and 48-hour time points. Scanning electron microscopy (SEM) and energy dispersion X-ray spectroscopy (EDS) were performed for qualitative analysis of treated dentin. Data of dentin permeability was analyzed by twoway repeated measures ANOVA and Tukey's post-hoc test (α=0.05). For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests were used (α=0.05). The results showed that for dentin permeability there was no significant difference among the desensitizing agents after treatment (p> 0.05), but the control group presented the highest values (0.131 ± 0.076 Lp, p< 0.05). And after acid challenge, the control group maintained the highest values (0.044 ± 0.014 Lp) with significant difference to the other groups (p< 0.05), except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among the experimental groups (p> 0.05). It was concluded that the use of bioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties(AU)

Influence of different types of light curing units and photoinitiators in microhardness and color of composite resins after immersion in wine / Influencia dos diferentes tipos de unidade fotoativadoras e fotoiniciadores na microdureza e cor de resinas compostas após imersão em vinho

Objective: the aim of this study is to evaluate the microhardness and color change (∆E) of composite resins, that were light-cured with different LEDs, after being immersed in a staining drink. Material and Methods: Two composite resins with Lucerin-TPO (Tetric N-Ceram/ Vit-l-escence) and camphorquinone (Filtek Z350) were selected. The specimens (n=120) were prepared and lightcured with LED of monowave or polywave lightemitting diode (LED) devices. Microhardness and color evaluations were measured before and after immersion in staining drink. Microhardness data were evaluated by Kruskal-Wallis test, MannWhitney and Wilcoxon tests. Color changes were evaluated by two-way analysis of variance (ANOVA) and Tukey test (p ≤ 0.05). Results: No statistically significant difference between the two generations of LEDs was found for microhardness data. Regarding the ∆E, a statistical difference between the two LEDs was observed for Tetric NCeram and Filtek Z350. Conclusion: The compostion of composites appears to have more influence on analyses than the type of LEDs used. A decreased microhardness occurred to Vit-lescence for monowave and to Filtek Z350 for both LED devices. A clinically perceptible color change was observed for Tetric-N Ceram and Filtek Z350 when polywave LED were used. (AU)

Objetivo: o objetivo deste estudo foi aviliar a microdureza e alteração de cor (∆E) de resinas compostas, fotoativadas com diferentes LEDs, imergidas em bebidas pigmetadas. Material e métodos: Duas resinas compostas com Lucerina-TPO (Tetric N-Ceram/ VIt-l-essence) e canforoquinona (Filtek Z350) foram selecionadas. Os espécimes (n=120) foram preparados. Os mesmos foram fotopolimerizados com LED monowave ou polywave. Microdureza e cor foram avaliadas antes e após a imersão em bebidas pigmentadas. Os dados de microdureza foram avaliados pelos testes de Kruskal-Wallis, Mann-Whitney e Wilcoxon. As alterações de cor foram avaliadas por análise de variância a dois critérios (ANOVA) e Tukey (p ≤ 0,05). Resultados: Não foi encontrada diferença estatística entre as duas gerações de LEDs, para os dados da microdureza. Quanto ao ∆E, foi encontrada diferença estatisticamente significante entre os dois LEDs, sendo observadas na Tetric N-Ceram na FIltek Z350. Conclusão: A composição das resinas compostas parece ter mais influencia nas análises do que o tipo de LEDs. Uma redução na microdureza ocorreu para Vit-lescence para monowave e para Filtek Z350 para ambos os dispositivos LED. Uma mudança de cor clinicamente perceptível foi observada em Tetric-N Ceram para polywave e Filtek Z350 para ambos os dispositivos LED. (AU)

Microshear bond strength of conventional and self-adhesive resin cements to feldsphatic ceramic

Aim: The aim of this study was to verify the microshear bond strength of conventional and self-adhesive resin cements to feldsphatic ceramic. Methods: Twenty discs of Starlight ceramic (Degudent) were made (15mm x 2mm). The bonding procedure was accomplished by insertion of resin cements into tubes of 0.7mm internal diameter in contact with the ceramic. The resin cements used were: RelyX ARC (3M Espe), Panavia F (Kuraray), RelyX Unicem (3M Espe) and seT (SDI). Total of six tubes of each material on each ceramic disc. The specimens were tested for microshear in a universal testing machine, 24hours and 6months after bonding procedure. Values of microshear bonding strength (MPa) were subjected to ANOVA and Fisher PLSD test (p<0.05). Results: For 24hours analysis, RelyX ARC showed the highest microshear bonding strength without statistical difference to RelyX Unicem and seT. Panavia F showed the lowest values of microshear bonding strength in both periods. In the analysis after 6months there was a significant increase in the microshear bonding strength values for all cements compared to 24hours. Only for RelyX ARC, the increase was not statistically significant. Conclusion: In conclusion, the bond strength depends mainly on the type of resin cement used, and the self-adhesive cements behave similarly to conventional resin cement

Influência de inibidores de proteases no potencial de degradação do colágeno proveniente da dentina sadia, esclerótica e afetada por cárie / Influence of protease inhibitors on the degradation potential of collagen from sound, sclerotic and caries-affected dentin

Objetivo: Avaliar a influência de inibidores de proteases no potencial de degradação do colágeno das dentina sadia, esclerótica e afetada por cárie. Materiais e métodos: Trinta e nove molares humanos foram utilizados, treze para cada condição dentinária. Três fatias foram obtidas de cada dente, cada uma imersa em diferentes soluções: 1) saliva artificial; 2) clorexidina 2%; 3) EGCG 0,5%. Após incubação nas soluções por 1h, amostras foram sujeitas à degradação enzimática pela colagenase derivada da Clostridium histolyticum. Propriedades mecânicas de nanodureza (HIT) e módulo de elasticidade (Er) dos três diferentes tipos de dentina foram mensuradas antes e após a degradação, bem como a resistência à tração do colágeno. Resultados do teste de resistência à tração e nanoindentação foram submetidos à ANOVA dois e três fatores para medidas repetidas, e pós-teste de Tukey (α=0,05). Resultados: Maiores valores de resistência à tração foram encontrados para dentina sadia, nos grupos controle (40,30 ± 21,38 MPa) e EGCG 0,5% (30,05 ± 19,67 MPa). Antes da degradação, maiores valores de HIT (0,237 ± 0,062 GPa) e Er (5,58 ± 1,75 GPa) foram encontrados para o grupo EGCG 0,5%, na dentina afetada por cárie. Após a degradação, grupo clorexidina 2% apresentou maiores valores de HIT e Er para dentinas sadia (0,134 ± 0,020 GPa e 3,57 ± 0,40 GPa) e esclerótica (0,201 ± 0,048 GPa e 4,30 ± 0,56 GPa). Conclusões: O uso da clorexidina 2%, principalmente em dentina esclerótica, mostrou-se mais efetivo em promover aumento na resistência à tração e nas propriedades mecânicas, antes e após a degradação. A EGCG 0,5% apresentou melhor efeito sobre as propriedades mecânicas na dentina afetada por cárie, especialmente antes da degradação enzimática. Relevância Clínica: O efetivo conhecimento do mecanismo de ação de inibidores de proteases em diferentes tipos de dentina poderia contribuir para melhoria da resistência do substrato e para maior longevidade dos processos de união sobre este tecido(AU)

Objetive: To evaluate the influence of proteases inhibitors on the collagen degradation from sound, sclerotic and caries-affected dentin. Materials and Methods: Thirty-nine human molars were used, thirteen for each dentin condition. Three slices were obtained from each tooth, each one immersed in different solutions: 1) artificial saliva; 2) 2% chlorhexidine; 3) 0.5% EGCG. After incubation in the solutions for 1h, samples were subjected to enzymatic degradation by collagenase derived from Clostridium histolyticum. Mechanical properties of nanohardness (HIT) and elastic modulus (Er) of the three types of dentin were measured before and after degradation, as well as the microtensile strength. Results of the microtensile strength and nanoindentation tests were submitted to ANOVA two and three factors for repeated measurements, and Tukey post-test (α = 0.05). Results: Higher values of tensile strength were found for sound dentin in control (40.30 ± 21.38 MPa) and 0.5% EGCG (30.05 ± 19.67 MPa) groups. Before degradation, higher values of HIT (0.237 ± 0.062 GPa) and Er (5.58 ± 1.75 GPa) were found for the 0.5% EGCG group in caries-affected dentin. After degradation, 2% chlorhexidine group had higher values of HIT and Er for sound (0.134 ± 0.020 GPa and 3.57 ± 0.40 GPa) and sclerotic (0.201 ± 0.048 GPa and 4.30 ± 0.56 GPa) dentin. Conclusions: The use of 2% chlorhexidine, mainly in sclerotic dentin, was shown to be more effective in promoting increase in the microtensile strength and mechanical properties, before and after the degradation. The 0.5% EGCG showed a better effect on mechanical properties in caries-affected dentin, before the enzymatic degradation. Clinical Relevance: The effective knowledge of the mechanism of action of protease inhibitors in different types of dentin could contribute to the improvement of the resistance of the substrate and to the longer longevity of the bonding processes on this tissue(AU)