Ultrasonic agitation reduces the time of calcium hydroxide antimicrobial effect and enhances its penetrability.

OBJECTIVES: The objective of the present work was to evaluate the ultrasonic agitation, time and vehicle (propylene glycol or distilled water) on the antimicrobial potential and penetrability of calcium hydroxide pastes on infected dentin by means of Confocal Laser Scanning Microscopy (CLSM) and microbiological culture (MC). MATERIALS AND METHODS: Dentin specimens were infected with Enterococcus faecalis using a new contamination protocol of 5 days. The specimens were divided into eight groups and dressed with the pastes for 7 or 15 days: G1) calcium hydroxide (CH) + propylene glycol (prop)/7 days (d), G2) CH + prop/7d + ultrasonic agitation (U), G3) CH + distilled water (dw)/7d, G4) CH + dw/7d + U, G5) CH + prop/15d, G6) CH + prop/15d + U, G7) CH + dw/15d, G8) CH + dw/15d + U. The ultrasonic activation was made for 1 min in both directions with a plain point insert. After medications removal, the images obtained by CLSM showed the viable (green) and dead (red) bacteria with Live and Dead dye. By the MC, the dentinal wall debris obtained by burs were collected for colony counts. For the penetration test, the Rodamine B dye was added to the CH pastes and analyzed by CLSM. RESULTS: The 7 and 15-days CH + prop+U pastes performed better antimicrobial efficacy, followed by the CH + dw+U/15d paste. CONCLUSIONS: All pastes demonstrated better penetration and antimicrobial activity against E. faecalis when agitated with ultrasound, even in periods of up to seven days. The propylene glycol vehicle showed better results. CLINICAL RELEVANCE: Agitation of the dressing that remains for less time inside the root canal can optimize the decontamination of endodontic treatment.

Impact of transparent tray-based application of bioactive glasses desensitizer on the permeability of enamel and dentin to hydrogen peroxide: an in vitro study.

BACKGROUND: To investigate the effect of transparent tray-based application of bioactive glasses (BGs) desensitizer on the permeability of enamel and dentin to hydrogen peroxide (H2O2). METHODS: Freshly extracted human first premolars were divided into 6 groups (n = 8). Group A and B: without pretreatments; Group C and E: treated with BGs desensitizer only; Group D and F: treated with BGs desensitizer dispensed with a transparent tray. After roots and pulp tissues of the treated tooth specimens were thoroughly removed, acetate buffer was added into pulp chambers and the treated specimens were immersed in distilled water (Groups A, E, and F) or 30% H2O2 (Groups B, C, and D) for 30 min at 37 °C. The amount of H2O2 in the pulp chamber of each group was measured using ultraviolet-visible spectrophotometry. RESULTS: In control groups (Group A, E, and F), H2O2 was not detected. The amount of pulpal H2O2 in Group B, C, and D were 21.149 ± 0.489 µg, 9.813 ± 0.426 µg, and 4.065 ± 0.268 µg respectively. One-way ANOVA analysis indicated that significant differences existed in these groups (F = 459.748, p < 0.05). CONCLUSIONS: The effect of BGs desensitizer in reducing the permeability of enamel and dentin to H2O2 could be enhanced when dispensed with a transparent tray.

Evaluation of Microleakage by Gas Permeability and Marginal Adaptation of MTA and BiodentineTM Apical Plugs: In Vitro Study / Evaluación de la microfiltración por permeabilidad de gas y adaptación marginal de tapones apicales de MTA y BiodentineTM: Estudio in vitro

Abstract The endodontic treatment of teeth with incomplete development is always a complex task. Nowadays, biomaterials such as bioceramics offers promising clinical evidence that supports its use. However, the standardization of its use for apexification purpose still needs a deeper understanding of the materials' behavior. The aim of this investigation was to evaluate the marginal adaptability and microleakage by gas permeability of MTA and Biodentine™ apical plugs in an in vitro model. Materials and methods: Twenty- four single rooted human teeth were selected according to previously stablished inclusion criteria. All samples were prepared obtaining standard cylindrical internal canals with a diameter of 1.3 mm. Root canals were gently rinsed using 5.25% sodium hypochlorite and EDTA 17%. The apical 3mm and remaining coronal dental structure were sectioned to obtain 10mm roots. Roots were randomly assigned to 3 different groups as follows: GROUP A: MTA (n=10), GROUP B: Biodentine™ (n=10) and Group C: Control (positive n=1, negative n=3). MTA and Biodentine™ were prepared according to manufacturer's indications, and apical plugs of 4mm were passively placed in the correspondent teeth. All samples were stored in saline solution for 7 days at 37°C before evaluation. Samples were mounted in cylindrical sample-holders using epoxy resin. Microleakage was evaluated with an automatic permeability detector that calculates nitrogen diffusion between the material-root interphase. After microleakage evaluation, the samples were recovered and analyzed by scanning electron microscopy (SEM). Microleakage results were analyzed using Chi-square and adaptation was evaluated with a descriptive analysis. Results: None of the evaluated materials completely avoided the nitrogen microleakage (positive leakage of 10% and 20% of samples for MTA and Biodentine™ respectively); with no statistical significant difference between groups (p=0.527). All apical plugs showed good adaptation under SEM, at 30x, 200x, 1000x and 2500x; with microscopical structures similar to previous reports. Conclusions: Both bioceramics behave similar when used as apical barriers to avoid permeability, with acceptable marginal adaptation. Further in vivo studies are needed to validate these results.

Resumen El tratamiento endodóntico de dientes con desarrollo incompleto es siempre una tarea compleja. Hoy en día, biomateriales como las biocerámicas ofrecen una evidencia clínica prometedora que apoya su uso. Sin embargo, la estandarización de su uso para fines de apexificación todavía necesita una comprensión más profunda del comportamiento de los materiales. El objetivo de esta investigación fue evaluar la adaptabilidad marginal y microfiltración por permeabilidad de gas de los tapones apicales de MTA y Biodentine™ en un modelo in vitro. Materiales y métodos: Veiticuatro dientes humanos uniradiculares fueron seleccionados meticulosamente según criterios de inclusión previamente establecidos. Todas las muestras fueron preparadas con canales cilíndricos internos estandarizados de 1,3 mm de diámetro. Los conductos radiculares fueron gentilmente lavados con hipoclorito de sodio al 5,25% y EDTA al 17%. La estructura dental apical de 3 mm y la coronal restante se seccionó para obtener raíces de 10 mm de longitud. Las raíces se asignaron aleatoriamente a 3 grupos diferentes de la siguiente manera: GRUPO A: MTA (n = 10), GRUPO B: Biodentine™ (n = 10) y Grupo C: Control (n = 1 positivo, n = 3 negativos). El MTA y Biodentine™ se prepararon de acuerdo con las indicaciones de los fabricantes, y se colocaron pasivamente los tapones apicales de 4 mm en los dientes correspondientes. Todas las muestras se almacenaron en solución salina durante 7 días a 37ºC antes de la evaluación. Las muestras se montaron en porta-muestras cilíndricos utilizando resina epóxica. La microfiltración se evaluó con un detector de permeabilidad automática que calcula la difusión de nitrógeno entre la interfase material-raíz. Después de la evaluación de microfiltración, las muestras fueron recuperadas y analizadas por microscopía electrónica de barrido (SEM). Los resultados de microfiltración se analizaron utilizando una prueba estadística de Chi-cuadrado y la adaptación se evaluó con un análisis descriptivo. Resultados: Ninguno de los materiales evaluados evitó completamente la microfiltración de nitrógeno (fuga positiva de 10% y 20% de muestras para MTA y Biodentine™, respectivamente); sin diferencias estadísticamente significativas entre los grupos (p = 0,527). Todos los tapones apicales mostraron una buena adaptación bajo SEM, a 30x, 200x, 1000x y 2500x; con morfologías similares a las previamente reportadas. Conclusiones: ambas biocerámicas se comportan de forma similar cuando se usan como barreras apicales para evitar la permeabilidad de gas, con adaptación marginal aceptable. Se necesitan más estudios in vivo para validar estos resultados.

Avaliação in vitro da penetração de corante em dentes submetidos ao clareamento dental com peróxido de hidrogênio 35% / Evaluation of in vitro tooth stain after dental bleaching using 35% hydrogen peroxide

Dentes brancos são requisitos importantes para um belo sorriso e uma das formas para conseguir isso é através do clareamento dental. No entanto, a técnica de clareamento pode aumentar a permeabilidade do esmalte. Este estudo teve como objetivo verificar a penetração do corante nos dentes através de um processo de branqueamento com peróxido de hidrogênio a 35%, Total Blank Office® (DFL). foram utilizados 41 dentes humanos e divididos em 03 grupos experimentais. O G1 foi o grupo controle, no qual foi submetido apenas ao corante azul de metileno a 0,5%. O grupo G2 foi clareado com peróxido de hidrogênio 35% e, em seguida, foi imerso em solução de azul de metileno a 0,5%. O grupo G3 foi clareado com peróxido de hidrogênio 35% e foi imerso em saliva artificial antes de ser mergulhado na solução de azul de metileno a 0,5%. Todos os dentes foram cortados longitudinalmente e avaliados com lupa estereoscópica. A penetração do corante em cada dente foi verificada usando uma escala numérica que representava a profundidade de penetração do corante no dente. Os resultados mostraram que a saliva desempenha um papel positivo para reduzir a permeabilidade do esmalte durante o branqueamento e os dentes que não foram expostos à saliva artificial mostrou uma penetração maior do corante. foi concluído que o clareamento dental com peróxido de hidrogênio 35% aumentou a penetração do corante no esmalte dentário e a saliva mostrou um efeito positivo para minimizar essa penetração.

White teeth is a requisite for beautiful smile and dental bleaching is one best manners to achieve it. But, this technique may increase enamel permeability. To verify stain penetration in bleached teeth it was used 35% hydrogen peroxide, Total Blank Office® (DFL). human teeth were divided into 03 experimental groups. Group G1 was the control group, subjected only to 0.5% methylene blue solution. Group G2 was bleached with 35% hydrogen peroxide, following immersion in a 0.5% methylene blue solution. Group G3 was also bleached with 35% hydrogen peroxide, but was immersed in artificial saliva before been immersed in a 0.5% methylene blue solution. All the teeth were cut along their longitudinal length and taken to a 45x stereoscopic magnifying glass. Stain penetration in each tooth was verified using a score system, which represented the depth of stain penetration within the tooth. The results showed that saliva has a positive role to reduce enamel permeability during dental bleaching, and the teeth not exposed to saliva showed a greater stain penetration. It was concluded that dental bleaching with 35% hydrogen peroxide increases stain penetration, and saliva had a positive effect to minimize stain penetration.

Graded changes in enamel component volumes resulted from a short tooth bleaching procedure.

AIM: To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure. MATERIALS AND METHODS: Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching. RESULTS: Tooth shade changes were significant (p<0.001; 95% CI=-1/-8; power=99%), and most of the enamel layer was unaffected after bleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p<0.0001; power>99%). CONCLUSIONS: Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward.

Effect of dentin desensitizing procedures on methyl methacrylate diffusion through dentin.

BACKGROUND: Acrylic and bisacryl resins are widely used both during the temporization phase as well as for provisional restorations and the effect of external agents on dentin sensitivity can be reduced by the obliteration of the tubules. OBJECTIVE: The purpose of this study was to evaluate diffusion of methyl methacrylate monomer through dentin by high performance liquid chromatography (HPLC) after three different desensitizing procedures during the fabrication of two different provisional crown materials. MATERIALS AND METHODS: Forty extracted restoration and caries free human premolar teeth were used in this study. Thermoplastic vacuum formed material was used as a matrix to fabricate provisional restorations for each tooth before crown preparation. Teeth were prepared for a metal supported ceramic crown with 1 mm shoulder margins and then crown parts were separated from cementoenamel junction with a carborundum disk perpendicular to the long axis of the teeth. To the cementoenamel junction of each tooth a polypropylene chamber was attached that contains 1.5 cm 3 of deionized distilled water. Prepared teeth were divided into four groups ( n = 10) including control, desensitizing agent (DA) application, neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation (LI), and LI after DA application groups. After application of DA (except control) each group were divided into two subgroups for fabrication of provisional restorations ( n = 5). Two autopolymerizing provisional materials (Imident (Imicryl) and Systemp C and B (Ivoclar, vivadent)) were used to fabricate provisional restorations using the strips. Water elutes were analyzed by HPLC at 10 min and 24 h. RESULTS: The monomer diffusion values varied statistically according to desensitizing procedures, provisional resin systems, and the time periods. Monomer diffusion through dentin surfaces desensitized with Nd: YAG LI after DA application was the lowest. CONCLUSIONS: Nd: YAG LI in association with DA application is an effective combination to eliminate monomer diffusion through dentin to pulpal chamber.

Hydrogen peroxide penetration into the pulp chamber and dental permeability after bleaching.

This study sought to quantify the concentration of hydrogen peroxide (HP) in the pulp chamber and evaluate changes on dental permeability after bleaching with 3 HP concentrations (10%, 35%, and 50%). This study was divided into 2 experiments and the bleaching treatments consisted of 3 applications of HP for 30 minutes during a single session. The first experiment tested HP penetration into the pulp chamber of 4 experimental groups (n = 10) of bovine crowns, which were divided by HP concentration: an unbleached control group (0% HP), 10% HP, 35% HP, and 50% HP. Acetate buffer solution was placed into the pulp chamber and after each application of HP. This solution was collected to determine spectrophotometrically the concentration of HP that reached the pulp chamber. The second experiment evaluated dental permeability. Bovine crowns were divided into 3 groups (n = 10). The crowns were connected to a permeability device and the initial permeability was measured at 10 psi. Three different concentrations of HP gels (10%, 35% and 50%) were applied to the buccal enamel surfaces and the dental permeability was measured after the first, second, and third applications of HP. The data were analyzed by 2-way ANOVA and Tukey test (P ≤ 0.05). All concentrations of HP reached the pulp chamber, although no significant differences were noted between the 3 concentrations tested (P > 0.05). However, the increase of dental permeability in the group that received 50% HP was significantly higher than the 10% HP group (P < 0.05). The results indicate that the HP bleaching treatments increased dental permeability.

In situ effect of dentifrices associated to CO2 laser in the permeability of eroded root dentin.

OBJECTIVE: The aim of this study was to evaluate, through a crossover 2×2 in situ trial, the effect of a desensitizing dentifrice associated with CO2 laser irradiation to control the permeability of eroded root dentin. BACKGROUND DATA: Facing the increased prevalence of erosive lesion and the need for preventive means to control painful symptoms related to them. METHODS: Eighty slabs of bovine root dentin were subjected to initial erosive challenge (citric acid 0.3%, 2 h), followed by a remineralizing period in artificial saliva (24 h). Specimens were then divided according to dentin treatment: desensitizing dentifrice, desensitizing dentifrice+CO2 laser, fluoride anticavity dentifrice. and fluoride anticavity dentifrice+CO2 laser. After a 2-day lead-in period, 10 volunteers wore an intraoral palatal appliance containing four root dentin slabs, in two phases of 5 days each. During the intraoral phase, one side of the appliance was immersed in 0.3% citric acid, and the opposite side was immersed in deionized water, four times a day. One hour after the immersions, all specimens were brushed with dentifrice slurry provided by the researcher. After a 7-day washout period, volunteers were crossed over on the different dentifrice group. Each phase having been completed, the specimens were evaluated for permeability through an optical microscope. RESULTS: Data were analyzed using ANOVA and no significant difference (p=0.272) was found between the surface treatments performed on bovine root dentin. CONCLUSIONS: It can be concluded that fluoride anticavity or desensitizing dentifrice, regardless of the association with the CO2 laser irradiation, was able to control the permeability of eroded root dentin.

Sealing ability of a new carrier-based obturating material.

AIM: The aim of the present study was to investigate the in vitro sealing ability of a new obturating material (Real Seal 1, SybronEndo, Orange, CA, USA) and compare it with the Thermafil (Dentsply Maillefer, Baillargues, Switzerland) and One-Step systems (CMS Dental, Copenhagen, Denmark). METHODS: Forty-four freshly extracted lower premolars teeth were selected and a root canal treatment was performed using a crown-down Nickel-Titanium rotary preparation technique. Teeth were randomized into three groups (N.=14): 1) Thermafil group; 2) One/step group; 3) Real Seal 1 (RS1) group. The remaining two teeth served as controls. A fluid filtration system device was utilized to assess quantitatively the microleakage. Statistical analyses were performed by ANOVA and significance was set at 95%. RESULTS: Data clearly showed that the RS1 provided the best results, showing a minimal leakage after 24 hours. Statystical analysis showed a significant difference about the RS1 group, the Thermafil and One/Step group, while no significant differences were noted between these last two groups. Results show that the number of teeth that had no (=0) leakage was higher in the RS1 group (8 specimens) than in the remaining ones (1 and 1 specimen, respectively). CONCLUSIONS: Under the conditions of the present experimental test, the new RS1 material (carrier-based Resilon) provided excellent preliminary results showing sealing ability at 24 hours significantly better that traditional carrier-based gutta-percha systems.

Evaluacion de la permeabilidad radicular en el tercio cervical de los dientes anterosuperiores / Evaluation of the permeability at the cervical area of the upper anterior teeth

En la presente experiencia se evaluo el indice de permeabilidad presente a nivel del margen cervical en 100 piezas dentarias extraidas correspondientes al sector anterosuperior, de canino a canino. De las piezas dentarias analizadas, 95 correspondieron al grupo experimental y 5 al control. Los especimenes del grupo control fueron recubiertos totalmente con esmalte sintetico de uñas, en tanto que en los del grupo experimental, solo se recubrieron las zonas media y apical de la raiz dejando expuesto el margen cervical. Todos los dientes fueron sumergidos en azul de metileno al 2 por ciento durante 72 hs. Luego de lavados y cepillados, se seccionaron longitudinalmente con discos de carborundum. Las hemisecciones obtenidas fueron observadas con una lupa estereoscopica a x4 a fin de consignar el indice de permeabilidad cervical. Los resultados mostraron una media de 54,74 por ciento de dientes con permeabilidad, con un intervalo de confianza con limites de 44,2 por ciento y 65 por ciento.

Evaluacion de la permeabilidad radicular en el tercio cervical de los dientes anterosuperiores / Evaluation of the permeability at the cervical area of the upper anterior teeth

En la presente experiencia se evaluo el indice de permeabilidad presente a nivel del margen cervical en 100 piezas dentarias extraidas correspondientes al sector anterosuperior, de canino a canino. De las piezas dentarias analizadas, 95 correspondieron al grupo experimental y 5 al control. Los especimenes del grupo control fueron recubiertos totalmente con esmalte sintetico de uñas, en tanto que en los del grupo experimental, solo se recubrieron las zonas media y apical de la raiz dejando expuesto el margen cervical. Todos los dientes fueron sumergidos en azul de metileno al 2 por ciento durante 72 hs. Luego de lavados y cepillados, se seccionaron longitudinalmente con discos de carborundum. Las hemisecciones obtenidas fueron observadas con una lupa estereoscopica a x4 a fin de consignar el indice de permeabilidad cervical. Los resultados mostraron una media de 54,74 por ciento de dientes con permeabilidad, con un intervalo de confianza con limites de 44,2 por ciento y 65 por ciento. (AU)

Interfacial characteristics of resin-modified glass-ionomer materials: a study on fluid permeability using confocal fluorescence microscopy.

The tooth interface with resin-modified glass-ionomer cements (RM GICs) is poorly understood. This study examined the interface, especially with dentin. Cervical cavities in extracted teeth were restored with Fuji II LC, Vitremer, Photac-Fil, or a conventional GIC, Fuji Cap II. Fluorescent dye was placed in the pulp chambers for 3 hrs before the specimens were sectioned. Examination of the tooth/material interface with a confocal microscope showed that dye uptake by the restoration varied among materials. A "structureless", non-particulate, highly-stained layer of GIC was observed next to dentin in Fuji II LC. This layer varied in width, was prominent where the dentin tubules were cut "end-on" and in areas closer to the pulp, and was not seen adjacent to enamel. Vitremer showed minimal dye uptake, and the "structureless" layer was barely discernible. Photac-Fil showed more uniform uptake and absence of this layer. Cracking of enamel was also noted with these materials. The conventional GIC did not show any dye uptake, presence of a "structureless" layer, or enamel cracking. We elucidated the potential mechanisms involved in the formation of a "structureless" interfacial layer in Fuji II LC by studying the variables of cavity design, surface pre-treatment, water content of the tooth, time for it to develop, early finishing, and coating of the restoration. This layer, the "absorption layer", is probably related to water flux within the maturing cement, depending on environmental moisture changes and communication with the pulp in a wet tooth. The "micropermeability model" was useful in this study of the interfacial characteristics of RM GICs.

Prevention of tooth hypersensitivity caused by the hydrodynamic action of zinc phosphate and composite resin luting cements (SEM) study.

This study was done to determine the role of cement liner as a reducing factor to the fluid movement in order to prevent tooth hypersensitivity according to the hydrodynamic theory during cementation of crowns. A total of fourty freshly extracted intact lower molar were selected for this study. After conventional tooth preparation the teeth were sub-divided into four equal groups to identify the role of cement liner in preventing the penetration of used cement into the dentinal tubules. Scanning electron microscopic study proved the efficiency of glass ionomer liner on preventing cement penetration into the dentinal tubules.

Effect of cervical coating of ethyl cellulose polymer and metacrylic acid copolymer on the radicular penetration of hydrogen peroxide during bleaching.

Extraradicular leakage of oxidizing agents during bleaching is an undesirable event and thus need to be prevented. The effect of external cervical coating of ethyl cellulose (EC) and metacrylic acid copolymer (MAC) on the radicular penetration of hydrogen peroxide during intracoronal bleaching was examined. Single rooted human premolars extracted for orthodontic reasons were used. The cementum covering the cemento-enamel junction was mechanically removed and the teeth treated endodontically and bleached with 30% hydrogen peroxide. Radicular hydrogen peroxide penetration was measured before coating the teeth and after applications of 1-3 layers of EC or 3 layers of MAC external cervical coatings. It was found that the radicular penetration of 30% hydrogen peroxide was related to the number of layers of cervical EC coatings. Application of one layer of EC did not reduce the hydrogen peroxide penetration. Two and three layers of EC reduced the hydrogen peroxide penetration by 38% and 85% respectively. Three layers of MAC reduced the radicular hydrogen peroxide penetration in 83%. Statistically, a highly significant difference was found between the teeth coated with three layers of either EC or MAC and the noncoated teeth (p < 0.001). It was concluded that application of ethyl cellulose or metacrylic acid copolymer to exposed cervical root surfaces may effectively prevent extraradicular leakage of bleaching agents.

Some notes on the diffusion of acidic and alkaline agents into natural human caries lesions in vitro.

The aim was to obtain information on the penetration of ions, in particular H+ and OH-, into a wide variety of natural caries lesions in human teeth. Thirty-seven permanent teeth were slit in half and soaked in a 1% neutral (blue) litmus solution for at least a week. The cut face of the tooth was painted with a transparent, colourless nail varnish before the tooth was immersed in either of 0.1 M hydrochloric acid or 0.1 M phosphoric acid. In a reverse experiment the samples were soaked in acid (red) litmus solution and then immersed in 0.1 M sodium hydroxide after varnishing the cut face. All solutions were saturated with enamel apatite to avoid the possibility that the solutions might etch their way into the enamel. The colour change was recorded photographically. Several days of external acid/alkali exposure were required to change the litmus colour in the body of most of the lesions, suggesting that diffusion of acidic and alkaline species through the natural surface into the body was slow. The presence of a well-mineralized surface layer covering the lesion postponed the colour change. In contrast, the colour change of two root surface lesions was rapid, occurring within an hour. Thus, because the lesion body is relatively isolated and because lesion fluid is in intimate contact with the enamel apatite, we conclude that lesion fluid is close to saturation with respect to this mineral. Further, a pH change of lesion fluid in vivo paralleling that in plaque after a sucrose intake is unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of 25% tannic acid on prepared dentin: a scanning electron microscope-methylene blue dye study.

The effect on the permeability of prepared dentin treated with 25% tannic acid and 6% citric acid was compared with the untreated dentinal surface. Methylene blue was applied to the dentin surface after treatment to evaluate penetration into dentinal tubules. The tannic acid solution reduced or prevented dye penetration of the dentinal tubules. Citric acid treatment permitted severe penetration. The 25% tannic acid solution removed the smear layer while inhibiting penetration of the dye.

Dentinal permeability in assessing therapeutic agents.

The measurement of dentinal permeability has been useful in confirming the mechanism of the hydrodynamic hypothesis for pain transmission in hypersensitive patients, has advanced our understanding of how neural agents can reach the pulpal nerves, and has provided useful data to compare and evaluate therapeutic agents. Methods to assess permeability have varied from direct dye penetration techniques to measurement of fluid flow through dentin sections to SEM photography of impression replicas in vivo. A number of clinical therapeutic strategies have emerged from this work as well as ways to mitigate the progressive nature of the condition.

Protective effects of cavity liners on dentin.

Smear layers are very soluble in acidic solutions. Removal of smear layers increases dentin permeability and the potential for pulpal irritation. In this study, smear layers were treated with either saline, Barrier, Copalite, LC-Scotchbond, Hydroxyline, or DDS 1 & 2 to determine how well they protected the dentin from subsequent acid attack with 37% phosphoric acid for two minutes. Using both SEM and permeability measurements, the materials were ranked from least to most effective as: Saline less than Barrier = Copalite less than Hydroxyline = Scotchbond = DDS 1 & 2.

[The effect of calcium glycerophosphate and Remodent on the dental enamel permeability in dogs with fluorosis]. / Vliianie glitserofosfata kal'tsiia i remodenta na pronitsaemost' émali zubov sobak pri fliuoroze.

In 14 dogs aged 6 months with severe fluorosis, the authors studied the effects of intake of calcium glycerophosphate and local remodent application on 45Ca enamel incorporation and the depth of its penetration into the dental hard tissues. The treatment led to a substantial decrease in both enamel 45Ca accumulation and the depth of its penetration under severe fluorosis. Combined use of the drugs was more beneficial in terms of enamel 45Ca permeability.

The penetration of smear material into dentinal tubules during instrumentation with surface-active reagents: a scanning electron microscopic study.

Thirty freshly extracted, single-rooted anterior teeth were used. They were divided into three groups and instrumented conventionally with #10 to 50 K files. During instrumentation, the K files in the first group were moistened with saline solution, in the second group with 50% sodium dodecylbenzenesulfonate solution, and in the third group with Sulfapon (sodium salt of sulfonated condensation product of ethylen oxide with a fatty acid) solution. After the experimental procedure the specimens were examined in a scanning electron microscope to observe packing of smear material into dentinal tubules. Results showed the surface-active reagents cause the deeper penetration of the smear material into the dentinal tubules. These findings support the hypothesis that the phenomenon of the packing of smear material into the dentinal tubules is by capillary action and fluid dynamics.