A novel application of nano eggshell/titanium dioxide composite on occluding dentine tubules: an in vitro study

Abstract To synthesize Nano eggshell-titanium-dioxide (EB@TiO2) biocomposite and to evaluate its effectiveness in occluding opened dentine tubules. EB@TiO2 was synthesized and characterized using X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). Sixteen simulated bovine dentine discs were prepared and randomly assigned into four groups according to the following treatment (n = 4): Group 1: No treatment; Group 2: eggshell powder; Group 3: EB@TiO2; Group 4: Sensodyne. These were then agitated in a solution of 1g powder and 40mL water for 3hours. Thereafter, each dentine discs from the respective groups were post-treated for 5 min with 2wt% citric acid to test their acid resistant characteristics. Scanning Electron Microscope (SEM) was used to observe the effectiveness of occluded dentine pre-and post-treatment. The cytotoxicity of the synthesized EB@TiO2 was tested using NIH 3T3 assay. ANOVA was used to evaluate the mean values of the occluded area ratio and the data of MTS assay. This was followed by a multi-comparison test with Bonferroni correction (α = .05). The XRD confirmed that EB@TiO2 was successfully modified through ball-milling. The TEM revealed the presence of both spherical and irregular particle shape powders. The SEM result showed that EB@TiO2 could effectively occlude open dentine tubules. Equally, the result demonstrated that EB@TiO2 exhibited the highest acid resistant stability post-treatment. NIH 3T3 assay identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100µg/ml. This study suggests that the application of EB@TiO2 effectively occluded dentine tubules and the occlusion showed a high acid resistant stability.

Effect of two desensitizing agents on dentin permeability in vitro

Abstract Objective The aim of this in vitro study was to investigate the effect of two desensitizing agents and water on hydraulic conductance in human dentin. Material and Methods GLUMA Desensitizer PowerGel (GLU) contains glutaraldehyde (GA) and 2-hydroxyethyl methacrylate (HEMA), and Teethmate Desensitizer (TD) is a powder comprising tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) that is mixed with water. Deionized water was used as a negative control (CTR). Thirty discs with a thickness of 1.2 mm were cut from the coronal dentin of the third molars and cleaned with 0.5 M EDTA (pH 7.4). After being mounted in a split-chamber device, the discs were pressurized with water at 1 kPa and 3 kPa in order to measure flow rates with a highly sensitive micro-flow sensor and to calculate hydraulic conductance as a baseline value (BL). Following the application of GLU, TD, and CTR (n=10), hydraulic conductance was remeasured with intermittent storage in water after 15 min, 1 d, 1 w, and 1 m. Reduction in permeability (PR%) was calculated from hydraulic conductance. Data were statistically analyzed using nonparametric methods (α<0.05). Representative discs were inspected by SEM. Results PR% for GLU and TD were 30-50% 15 min and 1 m after their application. Post hoc tests indicated that PR% of CTR was significantly greater than those of GLU and TD at all time points tested. The PR% of GLU and TD were not significantly different. SEM examinations showed noncollapsed collagen meshes at the tubular entrances after GLU, and crystalline precipitates occluding the tubular orifices after TD, whereas CTR specimens showed typical patterns of etched dentin. Conclusions The present study on hydraulic conductance in dentin discs treated with two chemically different desensitizing agents and water as a control demonstrated that both products may be characterized as effective.

Avaliação in vitro de novos produtos na diminuição da permeabilidade dentinária antes e após desafios ácidos / In vitro evaluation of new products in regarding dentin permeability reduction before and after acid challenge model

Objetivo: avaliar in vitro a efetividade de aplicações sucessivas de diferentes produtos utilizados para o tratamento da hipersensibilidade dentinária cervical na redução da permeabilidade dentinária, assim como avaliar a resistência destes produtos a desafios ácidos. Material e métodos: foram utilizados 72 terceiros molares humanos íntegros para a preparação de 72 amostras, que foram ligadas a um sistema de pressão hidráulica para mensurar a permeabilidade dentinária após os seguintes passos: 1) preparação da amostra; 2) tratamento com ácido fosfórico a 37% durante 30 segundos; 3) cinco aplicações dos produtos testados; 4) primeiro desafio ácido; 5) segundo desafio ácido; e 6) terceiro desafio ácido. As amostras foram divididas aleatoriamente em seis grupos (n=12), de acordo com os tratamentos propostos: Desensibilize Nano P, Clinpro XT, dentifrício Colgate Sensitive Pró-Alívio, dentifrício Duraphat, dentifrício Sensodyne Repair e após restauração com resina composta (grupo-controle). Conclusão: que todos os produtos testados foram capazes de promover a redução da permeabilidade dentinária significativamente, sendo que os grupos Clinpro XT, Desensibilize Nano P e controle mantiveram esses níveis reduzidos estatisticamente até o terceiro desafio ácido, enquanto que os dentifrícios Duraphat, Sensodyne Repair e Colgate Sensitive Pró-Alívio mantiveram essas reduções estatisticamente significativas até o segundo desafio ácido.

Objective: to evaluate in vitro the effectiveness of successive applications of different products used for the treatment of cervical dentinal hypersensitivity, reducing dentin permeability, as well as to evaluate the resistance of these products, acids challenges. Material and methods: 72 intact human third molars were used for the preparation of 72 samples were bound to a hydraulic pressure system to measure the dentin after the following steps: 1) sample preparation; 2) treatment with 37% phosphoric acid for 30 seconds; 3) 5 applications of the products tested; 4) first challenge acid; 5) second challenge acid; 6) third challenge acid. The samples were randomly divided into 6 groups (n=12) according to the proposed treatments: Desensibilize Nano P, Clinpro XT, toothpaste Colgate Sensitive Pro-Relief, Duraphat toothpaste, toothpaste Sensodyne Repair and after restoration with composite resin (control group). Conclusion: all products tested were able to significantly promote the reduction of dentin, and the Clinpro XT groups Desensibilize Nano P and control these reduced levels remained statistically to the third challenge acid, while toothpaste Duraphat, Sensodyne Repair and Colgate Sensitive Pro-Relief kept these statistically significant reductions to the second challenge acid.

Effects of different desensitizing treatments on root dentin permeability

Abstract The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm) and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13): G1, control (no treatment); G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s); G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba); and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM). The leakage data were subjected to ANOVA test, followed by Tukey's t-test (α = 5%). Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05), but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.

Demineralization and Hydrogen Peroxide Penetration in Teeth with Incipient Lesions

The aim of this study was to evaluate the demineralization and hydrogen peroxide (HP) penetration in teeth with incipient lesions submitted to bleaching treatment. For analysis of HP penetration, sound and demineralized enamel/dentin discs were placed in artificial pulp chambers containing acetate buffer solution. After bleaching treatment, this solution was subjected for analysis of optical density by spectrophotometry and the disc surfaces were analyzed with scanning electron microscopy (SEM) and polarized light microscopy (PLM). The remaining discs were subjected for cross-sectional hardness analysis at different depths. Data were analyzed by repeated measures ANOVA and PLSD Fisher test (a=0.05). It was observed that previously demineralized teeth showed greater HP penetration (p<0.05). The bleaching treatment caused changes to a depth of 20 µm in sound enamel and up to 90 µm in demineralized enamel. SEM and PLM images revealed that the bleaching treatment caused superficial changes that were considerably more accentuated in previously demineralized teeth. It may be concluded that the enamel mineralization level influences HP penetration and the bleaching agent contributed to increase the demineralization depth.

O objetivo deste estudo foi avaliar a desmineralização e a penetração do peróxido de hidrogênio (HP) em dentes com lesões incipientes submetidos ao tratamento clareador. Para analisar a penetração do peróxido de hidrogênio, discos de esmalte/dentina hígidos e desmineralizados foram posicionados em câmaras pulpares artificiais contendo solução tampão de acetato. Após o tratamento clareador, esta solução foi submetida à análise da densidade óptica no espectrofotômetro e as superfícies dos discos foram analisadas por meio de microscopia eletrônica de varredura (MEV) e microscopia de luz polarizada (MLP). Os discos restantes foram submetidos à análise de microdureza transversal em diferentes profundidades. Os dados foram submetidos aos testes ANOVA e teste PLSD Fisher (= 5%). Observou-se que os dentes previamente desmineralizados mostraram maior penetração de HP (p<0,05). O tratamento clareador causou alterações em uma profundidade de 20 μm em esmalte hígido e até 90 μm em esmalte desmineralizado. As imagens obtidas em PLM e MEV mostraram que o tratamento clareador promove alterações superficiais no esmalte, sendo mais pronunciadas em dentes previamente desmineralizados. Foi concluído que o nível de mineralização do esmalte influencia a penetração do PH e que o agente clareador contribuiu para o aumento da profundidade de desmineralização.

Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

Objective: This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS). Material and Methods: An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angle measurement (WCA). The effectiveness of the modification of hydrophobicity was verified by the fluid permeability test (FPT). Results and Conclusions: Statistically significant differences were found in the values of WCA and FPT between the two groups. After silanization, the hydrophobic intraradicular dentin surface exhibited in vitro properties that limit fluid penetration into the sealed root canal. This chemical treatment is a new approach for improving the sealing of the root canal system.

Effect of desensitizing toothpastes on dentin

The objective of this study was to analyze the effects of toothbrushing with desensitizing toothpastes on dentin permeability and dentinal tubule occlusion. Fifty rats provided two hundred incisor teeth divided into five groups: DW, brushed with distilled water (control); FT, brushed with fluoride toothpaste; SCT, brushed with strontium chloride toothpaste; PCT, brushed with potassium citrate toothpaste; and PNT, brushed with potassium nitrate toothpaste. Cavities were prepared to expose the dentinal tubules, and the incisor teeth were brushed using the experimental agents. After each treatment, Evans blue dye solution was applied to the teeth. Dentin permeability was analyzed using scanning electron microscopy and energy-dispersive X-rays (EDX). There were significant differences (p < 0.0001, ANOVA) among the groups regarding dentin permeability, number of dentinal tubules, diameter of dentinal tubules, and opened tubular area. In the SCT, PCT and PNT groups, opened and partially occluded tubules, deposits, and a few smear layers were observed. In the DW and FT groups, most of the dentinal tubules were open, with no deposits or smear layers on the dentin. EDX revealed peaks of calcium and phosphorus in all of the groups, as well as traces of strontium in the SCT group and of potassium in the PCT and PNT groups. Desensitizing toothpaste decreased dentin permeability, although it produced only partial dentin tubule occlusion.

Effect of adhesive system and application strategy on reduction of dentin permeability

This study evaluated the effect of adhesive systems and application strategies on dentin hydraulic conductance (HC). The buccal enamel was removed from bovine incisors to simulate laminate cavity preparations. After removing the roots and the coronal pulp, the buccal dentin was treated with EDTA solution (0.5 M) for 5 minutes, rinsed, ultrasonicated for 12 minutes and connected to a permeability device. HC of the specimens was measured at 10 psi (n = 5). Permeability was measured before and after bonding procedures using G-Bond (GB), Clearfil Tri-S Bond (CTS), Hybrid Coat (HY), Bond Force (BF), Adper Easy Bond (AEB) Silorane (SI), Clearfil SE Bond (CSE) and Adper Scotchbond Multi-Purpose (SMP) adhesives systems, which were applied following three strategies: 1) according to the manufacturers' instructions; 2) two coats of all-in-one self-etching adhesives (GB, CTS, HY, BF, AEB) or priming step plus two coats of bonding resin for the other systems (SI, CSE and SMP); and 3) a thin layer of a flowable composite applied over one coat of all-in-one self-etching adhesives or primed surface for SI, CSE and SMP adhesives. No significant difference was observed among the application modes concerning their ability to reduce HC. None of the adhesives showed complete sealing (100%) of the bovine tooth dentin. SI exhibited lower HC than SMP, however, they were not significantly different from the other systems. The results suggest that all systems tested result in an HC reduction of more than 90%. The wet bonding technique seemed to be more sensitive for dentin sealing.

Influence of thicknesses of smear layer on the transdentinal cytotoxicity and bond strength of a resin-modified glass-ionomer cement

This study evaluated the transdentinal cytotoxicity (TC) and the bond strength (BS) of a resin-modified glass-ionomer cement (RMGIC) applied to dentin covered with smear layer (SL) of different thicknesses. Forty dentin discs had thick (TSL) or thin (THSL) smear layer created on their occlusal side. In artificial pulp chambers, MDPC-23 cells were seeded on the pulpal side of the dentin discs and divided into five groups: G1TC: no treatment (control); G2TC: TSL + RMGIC; G3TC: THSL + RMGIC; G4TC: TSL removal + RMGIC; G5TC: THSL removal + RMGIC. After 24 h, cell metabolism and morphology were evaluated by the methyltetrazolium (MTT) assay and by scanning electron microscopy (SEM), respectively. For BS, the following groups were determined: G1BS: TSL removal + RMGIC; G2BS: THSL removal + RMGIC; G3BS: TSL + RMGIC; G4BS: THSL + RMGIC. Shear bond strength was tested to failure in a mechanical testing machine MTS (0.5 mm/min). Statistically significant difference was observed only between the control and experimental groups (Kruskal-Wallis, p<0.05). The metabolic activity of the viable MDPC-23 cells in G2TC, G3TC, G4TC and G5TC decreased by 54.85%, 60.79%, 64.12% and 62.51%, respectively. Mean shear bond strength values for G1BS, G2BS, G3BS and G4BS were 7.5, 7.4, 6.4 and 6.7 MPa, respectively, without significant difference among them (ANOVA, p>0.05). RMGIC presented moderate transdentinal cytotoxic effects. Maintenance or removal of smear layer did not affect the bond strength of RMGIC to dentin substrate.

Este estudo avaliou a citotoxicidade transdentinária (CT) e a resistência de união (RU) de um cimento de ionômero de vidro modificado por resina (CIVMR) aplicado sobre dentina coberta com smear layer (SL) de diferentes espessuras. Quarenta discos de dentina tiveram smear layer espessa (TSL) ou delgada (THSL) criadas sobre a superfície oclusal. Após terem sido posicionados em câmaras pulpares artificiais, os discos de dentina receberam células MDPC-23, as quais foram semeadas sobre a supefície pulpar. Assim, os seguintes grupos foram estabelecidos: G1TC: sem tratamento (controle); G2TC: TSL + CIVMR; G3TC: THSL + CIVMR; G4TC: remoção TSL + CIVRM; G5TC: remoção THSL + CIVMR. Após 24 h, o metabolismo e morfologia celular foram avaliados pelo ensaio de metiltetrazolium (MTT) e por microscopia eletrônica de varredura (MEV), respectivamente. Para BS, os seguintes grupos foram determinados: G1BS: remoção TSL + CIVRM; G2BS: remoção THSL + CIVRM; G3BS: TSL + CIVRM; G4BS: THSL + CIVMR. A resistência de união ao cisalhamento foi avaliada em uma máquina de ensaios mecânicos MTS (0,5 mm/min). Diferença estatisticamente significativa foi observada apenas entre os grupos controle e experimentais (Kruskal-Wallis, p<0,05). A redução da atividade metabólica das células MDPC-23 viáveis nos grupos G2TC, G3TC, G4TC e G5TC foi de 54,85%; 60,79%; 64,12%; e 62,51%, respectivamente. Os valores médios de resistência de união para G1BS, G2BS, G3BS e G4BS foram de 7,5; 7,4; 6,4; e 6,7 MPa, respectivamente, sem diferença significativa entre eles (ANOVA, p>0,05). O CIVMR avaliado neste estudo apresentou moderado efeito citotóxico transdentinário. A manutenção ou remoção da smear layer não afetou a resistência de união deste material resinoso ionomérico sobre a dentina.

Effect of acid fruit juices combined with electric or sonic toothbrushing on root dentin permeability: an in vitro study

The purpose of this in vitro study was to quantify the alterations on human root dentin permeability after exposure to different acid fruit juices and to evaluate the effect of toothbrushing with electric or sonic toothbrush after acid exposure. The root dentin of 50 extracted third molars was exposed with a high speed bur. Crowns were sectioned above the cementoenamel junction and root fragments were used to prepare dentin specimens. Specimens were randomly assigned to 5 groups according to the fruit juice (kiwifruit, starfruit, green apple, pineapple and acerolla). Each specimen was connected to a hydraulic pressure apparatus to measure root dentin permeability using fluid filtration method after the following sequential steps: I) conditioning with 37% phosphoric acid for 30 s, II) root scaling, III) exposure to acid fruit juices for 5 min and IV) electric or sonic toothbrushing without dentifrice for 3 min. Data were analyzed statistically by the Wilcoxon and Mann-Whitney tests at 5% significance level. All fruit juices promoted a significant increase of dentin permeability while toothbrushing decreased it significantly (p<0.05). It may be concluded that all acid fruit juices increased root dentin permeability, while toothbrushing without dentifrice after acid exposure decreased the permeability. The toothbrush mechanism (electric or sonic) had no influence on the decrease of root dentin permeability.

O objetivo deste trabalho in vitro foi quantificar as alterações na permebilidade da dentina radicular humana após exposição a diferentes sucos de frutas ácidas e avaliar o efeito da escovação, com escova elétrica ou sônica, após a exposição ácida. A dentina radicular de 50 terceiros molares foi exposta com a utilização de fresas em alta rotação. As coroas foram seccionadas acima da junção cemento-esmalte e apenas os fragmentos radiculares foram utilizados no preparo dos espécimes. Os espécimes foram aleatoriamente divididos em 5 grupos de acordo com o suco de fruta aplicado (kiwi, carambola, maça verde, abacaxi e acerola). Cada espécime foi conectado a um aparelho de pressão para medir a permeabilidade dentinária por meio do método de filtração de líquidos após as seguintes etapas sequências: I) condicionamento com ácido fosfórico 37% durante 30 s, II) raspagem da raiz, III) exposição aos sucos de frutas por 5 min, IV) escovação com escova elétrica ou sônica durante 3 min. Os dados foram analisados estatisticamente pelos testes Wilcoxon e Mann-Whitney com nível de significância de 5%. Os resultados mostraram que todos os sucos de frutas testados promoveram aumento significativo da permeabilidade dentinária e os procedimentos de escovação causaram diminuição. Pode-se concluir que os sucos de frutas ácidas aumentaram a permeabilidade da dentina radicular, enquanto que a escovação sem dentifrício imediatamente após a exposição ácida promoveu redução da permeabilidade. Além disso, o mecanismo da escova (elétrica ou sônica) não teve influência na redução da permeabilidade dentinária.

Effect of propolis gel on the in vitro reduction of dentin permeability

OBJECTIVE: The aim of this study was to evaluate the capacity of potassium oxalate, fluoride gel and two kinds of propolis gel to reduce the hydraulic conductance of dentin, in vitro. MATERIAL AND METHODS: The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on a model proposed in literature. Thirty-six 1-mm-thick dentin discs, obtained from extracted human third molars were divided into 4 groups (n=9). The groups corresponded to the following experimental materials: GI-10 percent propolis gel, pH 4.1; GII-30 percent propolis gel; GIII-3 percent potassium oxalate gel, pH 4,1; and GIV-1.23 percent fluoride gel, pH 4.1, applied to the dentin under the following surface conditions: after 37 percent phosphoric acid and before 6 percent citric acid application. The occluding capacity of the dentin tubules was evaluated using scanning electron microscopy (SEM) at ×500, ×1,000 and ×2,000 magnifications. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5 percent significance level. RESULTS: Groups I, II, III, IV did not differ significantly from the others in any conditions by reducing in hydraulic conductance. The active agents reduced dentin permeability; however they produced the smallest reduction in hydraulic conductance when compared to the presence of smear layer (P<0.05). The effectiveness in reducing dentin permeability did not differ significantly from 10 percent or 30 percent propolis gels. SEM micrographs revealed that dentin tubules were partially occluded after treatment with propolis. CONCLUSIONS: Under the conditions of this study, the application of 10 percent and 30 percent propolis gels did not seem to reduce the hydraulic conductance of dentin in vitro, but it showed capacity of partially obliterating the dentin tubules. Propolis is used in the treatment of different oral problems without causing significant great collateral effects, and can be a good option in the treatment of patients with dentin sensitivity.

In vitro dentin permeability after application of Gluma® desensitizer as aqueous solution or aqueous fumed silica dispersion

OBJECTIVES: To assess and to compare the effects of Gluma® Desensitizer (GDL) with an experimental glutaraldehyde and HEMA containing fumed silica dispersion (GDG) on dentin permeability using a chemiluminous tracer penetration test. MATERIAL AND METHODS: Twenty disc-shaped dentin specimens were dissected from extracted human third molars. The dentin specimens were mounted in a split chamber device for determination of permeability under liquid pressure using a photochemical method. Ten specimens were randomly selected and allocated to the evaluation groups Gluma® Desensitizer as aqueous solution and glutaraldehyde/HEMA as fumed silica dispersion, respectively. Dentin disc permeability was determined at two pressure levels after removal of smear with EDTA, after albumin soaking, and after application of the desensitizing agents. Two desensitizer-treated and rinsed specimens of each group were examined by scanning electron microscopy (SEM) for surface remnants. RESULTS: Comparatively large standard deviations of the mean EDTA reference and albumin soaked samples permeability values refected the differences of the dentin substrates. The mean chemiluminescence values of specimen treated with GDL and GDG, respectively, were signifcantly reduced after topical application of the desensitizing agents on albumin-soaked dentin. The effects of GDL and GDG on permeability were not signifcantly different. Treated specimens showed no surface remnants after rinsing. CONCLUSIONS: The experimental desensitizer gel formulation reduced dentin permeability as effectively as the original Gluma® Desensitizer solution.

Effect of iron gel on dentin permeability

This study evaluated in vitro the effect of an experimental gel containing iron on the reduction of hydraulic conductance of dentin. Thirty-six 1-mm-thick dentin discs obtained from extracted human third molars were divided into 3 groups of 10 specimens each. The groups corresponded to the following experimental materials: 1.23 percent acidulated phosphate fluoride gel, pH 4.1; 3 percent potassium oxalate gel, pH 4.1 (Oxa-Gel®); and iron sulfate gel (10 mmol/L FeSO4), pH 4.1. The gels were applied to dentin under the following conditions: after 37 percent phosphoric acid and before 6 percent citric acid. Data were analyzed statistically by ANOVA and Tukey's test at 5 percent significance level. There was no significant differences (p<0.05) among the groups in any of the conditions for hydraulic conductance reduction, except for smear layer presence. The active agents reduced dentin permeability, but they produced significantly lower (p<0.05) reduction in hydraulic conductance when compared to presence of smear layer. The effectiveness in reducing dentin permeability was not significantly different (p>0.05) among the gels. This study suggests that the iron gel promoted reduction in dentin permeability comparable to that of the other agents and thus may be considered a good clinical alternative for the treatment of dentin hypersensitivity.

Este estudo objetivou avaliar in vitro o efeito do gel experimental contendo ferro na redução da condutividade hidráulica na dentina. Trinta e seis discos de dentina humana de 1 mm de espessura, foram obtidos de terceiros molares extraídos divididos em 3 grupos de 10 espécimes cada. Os grupos foram divididos nos seguintes grupos experimentais: F- flúor gel a 1,23 por cento, pH 4,1; O- gel de oxalato de potássio a 3 por cento, pH 4,1; I- gel de sulfato ferroso FeSO4 a 10 mmol/L, pH 4,1. Os géis foram aplicados na dentina sob as diferentes condições: após o ácido fosfórico a 37 por cento a antes do ácido cítrico a 6 por cento. Os resultados foram analisados por ANOVA e teste de Tukey, com nível de significância de 5 por cento. Todos os grupos (gel de flúor, oxalato de potássio e gel de ferro) não apresentaram diferenças significativas entre si para todas as condições testadas, exceto na presença da smear layer (p<0,05). Os produtos utilizados reduziram a permeabilidade dentinária, entretanto apresentaram baixa redução quando comparados à smear layer (p<0,05). Não houve diferença significativa na efetividade dos géis testados para reduzir a permeabilidade dentinária (p<0,05). Este estudo sugere que o gel de ferro promoveu redução na permeabilidade dentinária comparável à dos outros agentes e, portanto, pode ser considerada uma boa alternativa clínica para o tratamento da hipersensibilidade dentinária.

Effect of an acid diet allied to sonic toothbrushing on root dentin permeability / an in vitro study

This study quantified alterations in root dentin permeability after exposure to different acid beverages. Twenty-five third molars were sectioned below the cementoenamel junction, the root segment was collected, and the pulp tissue was removed. The root segments were connected to a hydraulic pressure apparatus to measure the permeability of root dentin after the following sequential steps, with 5 specimens in each: 1) phosphoric acid etching for 30 s (maximum permeability), 2) root planning to create new smear layer, 3) exposure to different acid substances for 5 min (orange, cola drink, vinegar, white wine, lemon juice), 4) toothbrushing with sonic toothbrush for 3 min, 5) toothbrushing with sonic toothbrush plus dentifrice for 3 min. Considering step I as 100 percent, the data were converted into percentage and each specimen was its own control. Data were analyzed statistically by Kruskal-Wallis and Dunn's post test at 5 percent significance level. All acidic substances increased dentin permeability significantly after scraping (p< 0.05). Toothbrushing after exposure to acid substances decreased dentin permeability and the association with dentifrice accentuated the decrease (p< 0.05), except for the specimens treated with cola drink. Thus, it may be concluded that all tested acid fruit juices increased dentin permeability, and toothbrushing with or without dentifrice can decrease root dentin permeability after dentin exposure to acid diet.

Este estudo quantificou a alteração na permeabilidade da dentina radicular submetida a diferentes dietas ácidas. Vinte e cinco terceiros molares foram seccionados abaixo da junção cemento-esmalte, a raiz seccionada foi selecionada, e a polpa removida. A seguir, as amostras foram conectadas a um aparato de pressão hidráulica para medir a permeabilidade da dentina radicular de acordo com os seguintes passos: I) tratamento com ácido fosfórico por 30 s (permeabilidade máxima), II) aplainamento radicular para criar nova smear layer, III) exposição a diferentes substâncias ácidas por 5 min (suco de laranja, coca-cola, vinagre, vinho branco e suco de limão), IV) escovação com escova sônica por 3 min, V) escovação com escova sonica mais dentifrício, por 3 min. Os dados foram convertidos em porcentagem em relação ao passo I (100 por cento) e cada amostra foi seu próprio controle. Os resultados mostraram que todas as substâncias ácidas aumentaram significantemente a permeabilidade dentinária após raspagem. Escovação após a exposição a substâncias ácidas diminuiu a permeabilidade e a associação com dentifrício aumentou a redução na permeabilidade dentinária; essa redução adicional não foi observada somente nas amostras tratadas com coca-cola. Com isso, pode-se concluir que todas as substâncias ácidas testadas aumentaram a permeabilidade dentinária, e a escovação com ou sem dentifrício pode diminuir a permeabilidade dentinária radicular após a exposição da dentina a dieta ácida.

[ effect of smear layer removal on permeability of dentinal tubules in human by dye penetration method]

The effect of smear layer on dentinal tubules is remarkable in endodontic treatments. The aim of this study was measuring the range of dye penetration in dentinal tubules with and without smear layer. Thirty extracted human teeth used in this study. At first, segments e prepared with 5 mm length from each tooth's root and then their canals widened by a 1/4 mm diameter bur, so that the smear layer appeared. The external, superior and inferior surfaces of the segments covered by 2 layers of nail varnish. The segments divided to 2 groups of 15 samples. The first group samples immersed in 17% EDTA for 2 minutes and then in 5.25% NaOCl for 20 minutes to remove the smear layer. After that the samples immersed in 2% basic fushin for 24 hours, the second group samples immersed in 2% basic fushin without removing the smear layer. After water rinse, all samples sectioned horizontally from middle of the root and photographs was taken of each samples surfaces. After transmitting the photographs to a computer, the percentage of the dye penetration into dentinal tubules of each sample calculated by Photoshop software. Due to results, the range of dye penetration in dentine tubules of the teeth with and without smear layer had no statistically significant difference [P-Value=0.120]. According to the result, smear layer removal have no effect on dentin permeability to dye penetration and dentin sclerosis is an important factor in this subject. Performing studies on the teeth with certain age and using other methods such as microbial permeability evaluation are needed

Indirect cytotoxicity of a 35 percent hydrogen peroxide bleaching gel on cultured odontoblast-like cells

The aim of this study was to evaluate the trans-enamel and trans-dentinal effects of a 35 percent hydrogen peroxide (H2O2) bleaching gel on odontoblast-like cells. Enamel/dentin discs obtained from bovine incisors were mounted in artificial pulp chambers (APCs). Three groups were formed: G1- 35 percent H2O2; G2- 35 percent H2O2 + halogen light application; G3- control. The treatments were repeated 5 times and the APCs were incubated for 12 h. Then, the extract was collected and applied for 24 h on the cells. Cell metabolism, total protein dosage and cell morphology were evaluated. Cell metabolism decreased by 62.09 percent and 61.83 percent in G1 and G2, respectively. The depression of cell metabolism was statistically significant when G1 and G2 were compared to G3. Total protein dosage decreased by 93.13 percent and 91.80 percent in G1 and G2, respectively. The cells in G1 and G2 exhibited significant morphological alterations after contact with the extracts. Regardless of halogen light application, the extracts caused significantly more intense cytopathic effects compared to the control group. After 5 consecutive applications of a 35 percent H2O2 bleaching agent, either catalyzed or not by halogen light, products of gel degradation were capable to diffuse through enamel and dentin causing toxic effects to the cells.

O objetivo deste estudo foi avaliar os efeitos citotóxicos de um agente clareador com 35 por cento de peróxido de hidrogênio (H2O2) sobre células da linhagem odontoblástica. Foram confeccionados discos de esmalte/dentina obtidos de incisivos bovinos, os quais foram posicionados em câmaras pulpares artificiais (CPAs). Três grupos foram formados: G1: gel clareador; G2: gel clareador + luz halógena e G3: controle. Após 5 aplicações consecutivas do gel clareador sobre o esmalte, os extratos foram obtidos e aplicados por 24 h sobre as células. Foram realizadas avaliações do metabolismo celular, morfologia das células e expressão total de proteína. O metabolismo celular para G1 e G2 reduziu em 62,09 por cento e 61,83 por cento, respectivamente. A redução do metabolismo celular foi estatisticamente significante quando se comparou G1 e G2 com G3. A expressão de proteína total reduziu em 93,13 por cento e 91,80 por cento para G1 e G2, respectivamente. As células em G1 e G2 apresentaram importantes alterações morfológicas após contato com os extratos. Foi possível concluir que independente da catalização ou não do gel clareador por luz halógena, os componentes que se difundiram através dos tecidos duros do dente após sua quinta aplicação sobre o esmalte, causaram intensos efeitos citotóxicos para as células.

Permeability of different groups of maxillary teeth after 38 percent hydrogen peroxide internal bleaching

This study evaluated the influence of internal tooth bleaching with 38 percent hydrogen peroxide (H2O2) on the permeability of the coronal dentin in maxillary anterior teeth and premolars. Seventy teeth (14 per group) were used: central incisors (CI), lateral incisor (LI), canines (C), first premolars (1PM) and second premolars (2PM). Pulp chamber access and transversal sectioning at 2 mm from the cementoenamel junction were performed and the specimens were divided into 2 groups (n= 7): a) no treatment and b) bleaching with 38 percent H2O2. The bleaching agent was applied to the buccal surface and to the pulp chamber for 10 min. This procedure was repeated 3 times. The specimens were processed histochemically with copper sulfate and rubeanic acid, sectioned longitudinally, and digitalized in a scanner. The area of stained dentin was measured using Image Tool software. Data were analyzed statistically by ANOVA and Tukey's HSD test (?=0.05). There was statistically significant difference (p<0.001) among the untreated groups, CI (0.23 ± 0.26) having the lowest permeability and LI (10.14 ± 1.89) the highest permeability. Among the bleached groups, dentin permeability was increased in all groups of teeth except for 2PM. It may be concluded that bleaching with 38 percent H2O2 affected dentin permeability near the pulp chamber in maxillary anterior teeth and in first and second premolars.

Este estudo avaliou a influência do clareamento interno com peróxido de hidrogênio (H2O2) a 38 por cento na permeabilidade da dentina coronária de dentes anteriores superiores e pré-molares superiores. Quatorze incisivos centrais (IC), incisivos laterais (IL), caninos (C), primeiros (1PM) e segundos (2PM) pré-molares foram seccionados transversalmente e distribuídos em 2 grupos (n=7) sendo: G1: não receberam tratamento e, G2: clareados com aplicação de gel na face vestibular e câmara pulpar por 10 min, repetido 3 vezes. Os espécimes foram processados histoquimicamente por meio de imersão em sulfato de cobre e ácido rubeânico e digitalizados em escaner. A área corada foi aferida (Programa Image Tool). Os dentes que não receberam tratamento, apresentaram diferença estatisticamente significante (p<0,001), sendo o ICS (0,23 ± 0,26) e o ILS (10,14 ± 1,89) os grupo com os menores e os maiores valores de permeabilidade, respectivamente. Quando clareados, a permeabilidade coronária dos grupos dentais foi aumentada, exceto no grupo do 2PM. Concluiu-se que a permeabilidade da dentina coronária nos dentes anteriores superiores e primeiros pré-molares foi alterada pelo clareamento dental interno.

Dentin permeability: the basis for understanding pulp reactions and adhesive technology

Permeability involves the passage of fluids, ions, molecules, particulate matter and bacteria into and through a substance or tissue under different and varying conditions. The permeability of the dentin is essential to support the physiology and reaction patterns of the pulp-dentin organ. Nutrients and impulses are transported from the pulp via the odontoblast process and the contents of its tubules maintain the dentin as a vital tissue. However, the main interest of this paper focuses on penetration from the outside towards the pulp rather than from the pulp towards the outside. The present overview centers on the dentinal tubules; how they are formed and how they change as a result of normal and abnormal function, age, and pathological processes and the effect of these processes on the permeability of dentin. Particular attention is focused on the patency of the dentinal tubules.This overview is largely based on the author’s own research, clinical insights and active participation in continuing dental education over the last 50 years. It is not a review of the literature related to the permeability of dentin. Rather it presents interpretation of results related to the permeability of dentin based on experience and opinions acquired over a lifetime in dental research.

A permeabilidade envolve a passagem de fluidos, íons, moléculas, material particulado e bactérias para o interior e através de uma substância ou tecido sob diferentes e variáveis condições. A permeabilidade da dentina é essencial para a fisiologia e para os padrões de reação do órgão dentino-pulpar. Nutrientes e impulsos são transportados a partir da polpa por meio dos processos odontoblásticos e o conteúdo dos seus túbulos mantém a vitalidade da dentina. Entretanto, o principal interesse deste artigo concentra-se na penetração do exterior para a polpa e não da polpa para o exterior. O presente artigo centra-se essencialmente nos túbulos dentinários; como eles são formados e como eles mudam em razão da função normal e anormal, idade e processos patológicos, e o efeito destes processos na permeabilidade da dentina. Especial atenção é dada à patência dos túbulos dentinários. Este artigo apresenta uma visão geral do assunto e baseia-se amplamente nas pesquisas e percepções clinicas do próprio autor e em sua ativa participação na educação odontológica continuada ao longo dos últimos 50 anos. Não se trata de uma revisão da literatura relacionada à permeabilidade dentinária, mas sim da interpretação de resultados relacionados à permeabilidade dentinária com base na experiência e opiniões formadas ao longo de toda uma vida dedicada à pesquisa odontológica.

Effect of commercially available and experimental potassium oxalate-based dentin desensitizing agents in dentin permeability: influence of time and filtration system

This study evaluated the influence of time after application of oxalate solutions in reducing dentin hydraulic conductance. Fifty dentin discs were obtained from extracted human third molars and assigned to 5 groups (n=10), according to the desensitizing agent used: Group I: OxaGel; Group II: experimental agent DD-1: Group III: experimental agent DD-2. In Groups IV and V, a placebo gel and deionized water were used as control, respectively. The agents were applied for 3 min, washed out and the hydraulic conductance was measured immediately and at 5-, 15- and 30-min intervals, and after acid etching. Data were analyzed statistically by two-way ANOVA and Duncan's test at 5 percent significance level. Groups I, II and III did not differ significantly from each other in any of the time intervals (p>0.05). Likewise, Groups IV and V were statistically similar to each other (p>0.05). The active agents reduced significantly dentin permeability in comparison to control groups (p<0.05). Dentin permeability measured in vitro decreased significantly with time regardless of the agent applied (either active or control agents). The results of Group V, in which no dentin desensitizing agent was employed, indicates that the assessment of dentin permeability by this method must be interpreted with caution.

O objetivo deste estudo in vitro foi avaliar a influência do tempo pós-aplicação de agentes anti-hiperestésicos comercial e experimentais na permeabilidade dentinária por meio da medição da condutibilidade hidráulica da dentina, utilizando-se o método de discos de dentina. Cinqüenta discos de dentina obtidos a partir de terceiros molares humanos recém extraídos foram divididos em 5 grupos (n=10), de acordo com o agente utilizado: Grupo I: OxaGel; Grupo II: agente experimental DD-1: Grupo III: agente experimental DD-2: Grupo IV: gel placebo; e Grupo V: água deionizada. Os agentes foram aplicados por 3 min e em seguida mediu-se a condutibilidade hidráulica da dentina nos tempos imediato, 5, 15, 30 min e após a aplicação de ácido. Os dados foram submetidos a análise estatística pelos testes de ANOVA a dois critérios e teste de Duncan com nível de significância de 5 por cento. Os Grupos I, II e III não diferiram significantemente uns dos outros em nenhum dos intervalos (p>0,05). Do mesmo modo, os Grupos IV e V foram similares estatisticamente (p>0,05). Os agentes ativos reduziram significantemente a permeabilidade dentinária em comparação aos controles (p<0,05). A redução dos valores de permeabilidade em função do tempo apresentada pelo Grupo V, o qual não foi empregado agente anti-hiperestésico, faz com que a interpretação dos resultados dos demais grupos leve em consideração um arrefecimento natural da permeabilidade com o passar do tempo, proporcionado pelo dispositivo utilizado para a medição da condutibilidade hidráulica da dentina.