Influência do tratamento do substrato com plasma não térmico na resistência de união em cimentação adesiva / Influence of the substrate treatment with non-thermal plasma on bond strength of adhesive cementation

Objetivo: avaliar a influência do tratamento de superfície com plasma não térmico de argônio (PLA) na resistência de união de cimentos resinosos ao esmalte, à dentina e à cerâmica de dissilicato de lítio. Observar, no esmalte e na dentina, através de espectroscopia de infravermelho por transformada de Fourier (FTIR) os compostos inorgânicos e da cromatografia gasosa a alteração dos compostos orgânicos voláteis nas condições experimentais propostas. Material e Método: Foram avaliados 3 cimentos resinosos: Variolink Esthetic LC e N (Ivoclar Vivadent), e Panavia V5 (Kuraray). Foram utilizados 240 dentes bovinos, dos quais 150 tiveram a superfície do esmalte exposta e 90 a de dentina. Foram obtidas 150 lâminas de cerâmica de dissilicato de lítio (12 x 14 x 0,5 mm). Os grupos foram divididos de acordo com o tratamento de superfície e o substrato. Os tratamentos para as superfícies de esmalte e dentina foram: EA (esmalte/ácido fosfórico); DA (dentina/ácido fosfórico); EPS (esmalte/PLA 30 s); EPM (esmalte/PLA 1 min); DPS (dentina/PLA 30 s); EAPS (esmalte/ácido fosfórico/PLA 30 s) e EAPM (esmalte/ácido fosfórico/PLA 1 min); e, DAPS (dentina/ácido fosfórico/PLA 30 s). Os tratamentos para as superfícies da cerâmica foram: CA (cerâmica/ácido fluorídrico), CPS (cerâmica/PLA 30 s); CPM (cerâmica/PLA 1 min); CAPS (cerâmica/ácido fluorídrico/PLA 30 s) e CAPM (cerâmica/ácido fluorídrico/PLA 1 min). Posterior aos tratamentos, cilindros dos cimentos resinosos (0,8 mm/1,5 mm) foram confeccionados sobre as superfícies dos substratos. Após 48 h, os espécimes foram submetidos ao ensaio mecânico de microcisalhamento (10 Kgf/1 mm/min) até a fratura. A área fraturada foi analisada em estereomicroscópio. As superfícies tratadas e a interface adesiva foram analisadas por Microscopia Eletrônica de Varredura (MEV). Através do FTIR foram observados os espectros de amostras tratadas de esmalte e dentina. Os dados da resistência de união foram submetidos à análise estatística ANOVA e teste de Tukey (5%). Resultados: Para o esmalte os tratamentos de superfície não apresentaram diferença estatisticamente significante entre si; para a dentina o grupo DPS apresentou os maiores valores de resistência de união; e, para a cerâmica o tratamento CA apresentou os maiores valores de resistência de união. Para esmalte e dentina, o FTIR, mostrou alterações do conteúdo da água, carbonato e fosfato e a cromatografia gasosa das substâncias orgânicas voláteis. Conclusão: O tratamento de superfície com PLA não influencia a resistência de união de cimentos resinosos ao esmalte, aumenta à dentina e diminui ao dissilicato de lítio. As análises observacionais no FTIR sugerem que o plasma não altera compostos do esmalte e da dentina(AU)

Objective: to evaluate the influence of surface treatment with non - thermal argon plasma (PLA) on bond strength of resin cements to enamel, dentin and lithium disilicate glass ceramic; and, to observe, through Fourier Transform Modified Infrared Spectroscopy (FTIR), the inorganic compounds and through gas chromatography, the alteration of the volatile organic compounds, on the enamel and dentin, under the experimental conditions. Material and Method: Three resin cements: Variolink Esthetic LC and N (Ivoclar Vivadent) and Panavia V5 (Kuraray) were evaluated. Twenty hundred and forty bovine teeth were used, among which 150 specimens with enamel surface exposure and 90 with dentine exposure. One hundred and fifty lithium disilicate glass ceramic slices (12 x 14 x 0.5 mm) were obtained. The groups were divided according to the substrate and surface treatment. The treatments for enamel and dentin surfaces were: EA (enamel / phosphoric acid); DA (dentin / phosphoric acid); EPS (enamel / PLA 30 s); EPM (enamel / PLA 1 min); DPS (dentin / PLA 30 s); EAPS (enamel / phosphoric acid / PLA 30 s) and EAPM (enamel / phosphoric acid / PLA 1 min); and, DAPS (dentin / phosphoric acid / PLA 30 s). The treatments for the ceramic surfaces were: CA (ceramic / hydrofluoric acid), CPS (ceramic / PLA 30 s); CPM (ceramic / PLA 1 min); CAPS (ceramic / hydrofluoric acid / PLA 30s) and CAPM (ceramic / hydrofluoric acid / PLA 1 min). After the treatments, resin cement cylinders (0.8 mm / 1.5 mm) were built on the substrate's surfaces. After 48 h storage bond strength tests (µSBS) were performed in a universal testing machine (10 Kgf / 1 mm / min) until failure to fracture, and failure mode was analyzed under a stereomicroscope. The treated surfaces and the adhesive interface were analyzed by Scanning Electron Microscopy (SEM). The FTIR was used to observe the spectra of enamel and dentin treated samples. Bond strength data were submitted to ANOVA and Tukey test (5%). Results: for the enamel there was not a statistically significant difference among surface treatments; for the dentin, the DPS group presented the highest bond strength; and for the ceramic the AC treatment presented the highest values of bond strength. For the enamel and the dentin samples, the FTIR observations showed changes in water, carbonate and phosphate contents and the gas chromatography in the volatile organic substances. Conclusion: Surface treatment with PLA does not influence the bond strength of resin cements to the enamel, increases the bonding to dentin and decreases to the lithium disilicate. Observational analysis on FTIR suggest that non-thermal plasma does not alter enamel and dentin compounds(AU)

Management of dentinal hypersensitivity.

Dentinal hypersensitivity is a complex condition that can cause considerable concern in the dental office. Despite the large number of available treatment modalities, no current desensitizing agent is considered ideal for managing this uncomfortable condition. Selecting the right therapy requires a complete understanding of how applying a stimulus to the exposed dentin surface can influence the nerve fibers and produce hyperesthesia. This article reviews the etiology and critically analyzes management of dentinal hypersensitivity by reviewing laboratory and clinical investigations.

Bases neurofisiológicas para el manejo clínico del complejo dentinopulpar / Neurophysiological basis for the clinical management of the dentino pulpal complex

El complejo dentinopulpar cuenta con una inervación muy abundante. Por el foramen apical de cada diente humano pasan de1000 a 2000 fibras nerviosas. De ellas el 75 por ciento son amielínicas –fibras C- y el 25 por ciento mielínicas -la mayoría Aδ y pocas Aβ -. Lasramificaciones de las fibras Aδ penetran de 100 a 200 micrómetros en aproximadamente la mitad de los túbulos dentinarios,inervando la porción más interna de la dentina. Las terminaciones de las fibras nerviosas funcionan como receptores. Existiríantres grupos de receptores intradentarios: nociceptores específicos, receptores polimodales y posiblemente mecanorreceptores.Los dos primeros proveen información de alerta frente al daño tisular y su estimulación produce sensaciones dolorosas. Lasfibras Aδ intradentales median el dolor agudo intenso, pasajero, típico de la sensibilidad dentinaria. Diversos estímulos (térmicos,mecánicos, osmóticos, etc.) provocan flujo de líquido dentro de los túbulos dentinarios y es este flujo el que estimula a lasfibras nerviosas dentinopulpares. La permeabilidad de la dentina expuesta es una de las variables más importantes en la sensibilidaddentinaria. Las fibras intradentales C median el dolor sordo, difuso, mal localizado y prolongado. Hay pocas evidencias deque los estímulos mecánicos puedan causar una sensación diferente a la dolorosa cuando se aplican al complejo dentinopulpar.Existen también algunas fibras nerviosas autonómicas que tendrían función en la regulación del flujo vascular pulpar...

The dental pulp and dentin are very innervated. Between one and two thousand nerve fibers pass through the apical foramen of ahuman tooth. 75 percent of them are amielinic C-fibers and the rest are mielinic fibers, most of them from the Aδ and some from the Aβtypes. The Aδ endings penetrate 100 –200 micrometers in near half the dentin tubules, innervating the inner portion of the dentin.The endings of the nerve fibers act like receptors. There are three types of intradental receptors: specific nociceptors, polimodalreceptors and probably mechanoreceptors. The first two types provide information about threat of tissue damage and theirstimulation leads to painful sensations. Intradental Aδ fibers mediate sharp temporary pain characteristic of dentin sensibility.Many stimuli (thermal, mechanic, osmotic, etc.) produce fluid flow inside the dentinal tubules, and this flow stimulates dentinopulpalnerve fibers. The permeability of the exposed dentin is one of the main variables in dentin sensibility. Intradental C-fibers mediatedull, bad localized, diffuse pain. There is little evidence that the mechanical stimuli produce a sensation different than pain whenapplied to the dentinopulpal complex. There are some intradental autonomic fibers that may play a role in pulpal blood flowregulation...