Influence of Modulated Photo-Activation on Shrinkage Stress and Degree of Conversion of Bulk-Fill Composites.

This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey's HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

Influence of modulated photo-activation on shrinkage stress and degree of conversion of bulk-fill composites

Abstract This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey's HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

Resumo O presente estudo teve como objetivo avaliar as propriedades de polimerização de materiais bulk-fill (baixa e alta viscosidade) utilizando luz contínua de alta intensidade e fotoativação intermitente em relação ao estresse de contração de polimerização e grau de conversão (DC). As seguintes resinas compostas Bulk-fill e nanohíbridas convencionais foram avaliadas: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) e Filtek Bulk Fill Posterior (3M/ESPE). Um dispositivo de LED (DB 685, Dabi Atlante) foi utilizado nos dois protocolos: fotoativação contínua e intermitente contínua (ciclos de liga e desliga) com exposição idêntica (14 J/cm2). A tensão de contração de polimerização (n=6) foi avaliada através da inserção de um incremento único de 12 mm3 entre duas placas de aço inoxidável (6×2 mm) adaptadas a uma Máquina de Ensaio Universal (UTM), em tempos diferentes. As medições foram registradas após a fotoativação. O grau de conversão foi avaliado por FTIR-ATR (n=5). Os dados foram analisados ​​pelos testes ANOVA a três fatores e teste de Tukey (α=0,05). A resina Bulk Fill Posterior apresentou maiores valores de tensão de contração quando fotoativadas com a técnica intermitente (p<0,05). A fotoativação intermitente aumentou o grau de conversão nas resinas bulk-fill de baixa viscosidade (p<0,05). Portanto, o uso de fotoativação modulada (intermitente) deve ser indicado com cautela, uma vez que seu uso pode influenciar a tensão de contração e o grau de conversão dos compósitos, o que varia de acordo com as formulações da resina.

Clinical perceptions of zirconia-reinforced lithium silicate ceramic: a case report and 6-month follow-up.

Zirconia-reinforced lithium silicate (ZLS) has recently been introduced in an effort to improve the mechanical properties of glass-ceramic materials. In vitro evaluations suggest that this class of material has high flexural strength and exhibits satisfactory adhesion to resin cement and wear resistance. Since few clinical reports of this novel material are currently available, the aim of this case report is to describe clinical perceptions regarding the handling and performance of ZLS ceramics when used for laminate veneers on the maxillary incisors.

Interdental papilla formation after diastema closure.

Due to improvements in esthetic dentistry, the number of patients seeking to obtain a more harmonious smile has increased. A 40-year-old woman was referred for treatment because she was dissatisfied with the effect that diastemas and a conoid tooth had on her smile. Her maxillary anterior teeth were relatively short, resulting in a compromised esthetic relationship between height and width. Orthodontic treatment for better distribution of her teeth was recommended to the patient, but she refused, wanting faster and less expensive treatment. After diagnostic and waxed-up study casts were obtained, composite resin esthetic mock-ups were made to confirm that sufficient space was left for formation of the interdental papilla. After the patient approved the mock-ups, her anterior teeth were submitted to bleaching, definitive restoration, and additional occlusal adjustments. At the 1-year follow-up, the patient exhibited a harmonious, esthetic smile without black spaces or periodontal inflammation.

Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

OBJECTIVE: This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. MATERIAL AND METHODS: Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups - no laser irradiation) and SB-L and SU-L [SB and SU laser (L) - irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). RESULTS: Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (µg/mm3), only the dentin bonding system (DBS) was a significant factor (p<0.05): SB>SU. CONCLUSION: Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

Abstract Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups - no laser irradiation) and SB-L and SU-L [SB and SU laser (L) - irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). Results Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3), only the dentin bonding system (DBS) was a significant factor (p<0.05): SB>SU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

Orthodontic treatment finishing with minimally invasive resin composite veneers / Finalização de tratamento ortodôntico facetas de resina composta minimamente invasivas

Anatomic alterations caused by incisal guide wear, even when small, can cause the aspect of an aged smile. The objective of this clinical case is to reporta highly conservative esthetic treatment performed through the association of in-office bleaching andresin composite veneers. In-office bleaching was performed with 35% hydrogen peroxide, and in the following week, minimal invasive resin composite veneers were installed on the upper incisors and canines. In the next appointment, finishing and polishing were performed with abrasive discs and silicon carbide brushes. The results were considered highly satisfactory, establishing a younger aspectof the patient’s smile. Resin composite veneers are still an excellent alternative for esthetic reanatomizationof anterior teeth, capable of generating optimal results with low costs and time...

Alterações anatômicas causadas pelo desgaste da guia incisal, mesmo quando pequeno, podem causar um aspecto de um sorriso envelhecido. O objetivo deste caso clínico é reportar uma tratamento estético altamente conservativo realizado por meio da associação de clareamento em consultório e facetas de resina composta. O clareamento em consultório foi realizado com peróxido de hidrogênio a 35%,e na semana seguinte, facetas de resina composta minimamente invasivas foram instaladas nos incisivos e caninos superiores. Na próxima consulta, acabamento e polimento foram realizados com discos abrasivos e escova de carbeto de silício. Os resultados foram considerados altamente satisfatórios, estabelecendo um aspecto jovial ao sorriso da paciente. Facetas de resinas compostas são ainda uma excelente alternativa para reanatomização estética dos dentes anteriores, capazes de gerar resultados ótimos com baixo custo e tempo...

Intra pulp chamber temperature variation caused by Nd: YAG and Diode LASER irradiation / Variação da temperatura intracâmara pulpar provocada pela irradiação com laser de Diodo e Nd: YAG

A irradiação com LASER de Neodímio (Nd:YAG) e de Diodo sobre sistemas adesivos pode aumentar a resistência de união em dentina, no entanto a existe a preocupação com a variação de temperatura intracâmara pulpar. O objetivo deste trabalho foi avaliar a variação da temperatura intracâmara pulpar após a aplicação dos sistemas adesivos e subsequente a irradiação com LASER de diodo e Nd:YAG. Material e Métodos: Este estudo apresentou um desenho experimental fatorial com dois fatores: LASER em dois níveis (Diodo [D] e Nd:YAG [N]) e sistema adesivo em quatro níveis (Adper™ Scotchbond™ Multi-Purpose [MP], Adper™ SingleBond 2 [SB], Clearfil™ SE Bond [CSE] e Adper™ Easy One [EO]). A variável de resposta quantitativa foi a variação da temperatura (∆t) em ºC .Utilizou-se 40 dentes bovinos, separados em 8 grupos (n=5), a superfície vestibular foi desgastada até 1 mm de espessura. Depois da aplicação de cada sistema adesivo, mas previamente a fotopolimerização, os espécimes eram irradiados com LASER de diodo e Nd:YAG com parâmetro padronizados. A ∆t foi obtida com um termopar inserido intracâmara pulpar. Os valores obtidos foram submetidos ao teste ANOVA a 2 critérios seguido de Tukey para comparações individuais(p<0,05). Resultados: A média e o desvio padrão da ∆t obtidos foram: N-MP: 12.60 (± 2.51), N-SB: 10.40 (± 5.03), N-CSE: 11.80 (± 5.12) e N-EO: 10.20 (± 2.39), D-MP: 4.4 (± 1.82), D-SB: 5.20 (± 1.54), D-CSE: 4.60 (± 1.14), D-EO: 3.60 (± 1.52). Conclusão: O tipo de sistema adesivo não foi significante no aquecimento gerado pela irradiação com LASER, mas o LASER de Nd:YAG pode fornecer um potencial maior para causar danos a pulpar...

Neodymium (Nd:YAG) and Diode LASER irradiation on adhesive systems canincrease bond strength to dentin, however, concerns about the temperature variation inside pulp chamber still remain. The aim of this study was to evaluate the intra pulp chamber temperature variation caused by irradiation with Nd:YAG or Diode LASER on different adhesive systems. Material and Methods: This study presented experimental design with two factors: LASER on two levels (Diode [D] and Nd:YAG [N]) and adhesive system on four levels (Adper™ Scotchbond™ Multi-Purpose [MP], Adper™ SingleBond 2 [SB], Clearfil™ SE Bond [CSE] and Adper™ Easy One [EO]). The quantitative response variable was the temperature variation (∆t) in ºC. Forty bovine teeth, distributed into 8 groups (n = 5), had the buccal surface flattened up to1 mm thickness of dentin. After the application of each adhesive system, but previously to the light curing, specimens were irradiated with Nd:YAG or Diode LASER with standardized parameters. The ∆t was obtained through a thermocouple inserted into pulp chamber. The values of ∆t were submitted to two-way ANOVA, followed by Tukey (p < 0.05) for individual comparisons. Results: The means (± standard deviation) of ∆t were: N-MP: 12.60 (± 2.51), N-SB: 10.40 (± 5.03), N-CSE: 11.80 (± 5.12) and N-EO: 10.20 (± 2.39), D-MP: 4.4 (± 1.82), D-SB: 5.20 (± 1.54), D-CSE: 4.60 (± 1.14), D-EO: 3.60 (± 1.52). Conclusion: The type of adhesive system was not significant in temperature changes generated by LASER irradiation, but Nd:YAG LASER may provide a higher potential to cause pulp damage...

Influence of temporary cement in the tensile strenght of fullcrowns cemented with resin cement / Influência do cimento temporário na resistência à tração de coroas totais cimentadas com cimento resinoso

Objetivo: Este estudo avaliou a influência do eugenol residual a resistência à tração na cimentação decoroas cerômero, usando cimento resinoso. Material e Métodos: Trinta e nove terceiros molares foram preparados para coroa total. Para cada dente preparado uma restauração provisória e uma coroa de cerômero foram feitas. Os dentes foram divididos em três grupos de acordo com o cimento provisório (n = 13): [GTB]Temp de Bond; [GTBNE] Temp NE Bond e [GDY] Dycal. Após a cimentação temporária, os dentes foram mantidos em água destilada por uma semana e, em seguida, submetidos ao teste de tração em uma máquina universal de ensaios (EMIC DL 500), usando uma célula de carga 200 kgf em 0,5 mm/min. Após o teste, os dentes foram limpos e receberam a cimentação adesiva final das coroas de cerômero. Em seguida, as amostras foram mantidas em água destilada (37 ºC) durante uma semana e, em seguida, foi realizado o teste de resistência à tração, também a 0,5 mm/ min. A comparação entre grupos foi realizada por análise de variância (ANOVA)seguida pelo teste de Tukey (p < 0,05). Resultados: Os resultados (kgf) de cimentação provisória para grupos GTB, GTBNE e GDY foram respectivamente: 2,75 ± (1.35b), 3,43 ± (1.66ab), e 4,48 ± (1.11a).Os resultados da cimentação adesiva (Kgf) eram respectivamente: 42,71 ± (15.33b), 57,59 ± (15.66a),e 54,75 ± (15.28ab). Conclusão: Concluiu-se que o cimento temporário, contendo eugenol apresentou influência negativa sobre a resistência à remoção de coroas cimentados com cimento de resinoso. Além disso, o dycal apresentou melhor resistência à remoção.

Objectives: This study evaluated the influenceof residual eugenol on the tensile strength in the ceromer crowns cementation, using resin cement. Material and Methods: Thirty-nine third molarswere prepared for a full crown. For each prepared tooth one provisional and one ceromer crown were made. The teeth were divided into three groups according the temporary cement (n = 13): [GT]Temp Bond; [GTBNE] Temp Bond NE and [GDY]Dycal. After temporary cementation, the teeth were kept in distilled water for one week and then submitted to traction test in a universal testing machine (EMIC DL 500), using a 200 Kgf loadcell at 0.5 mm/min. After the test, the teeth werecleaned and received the final adhesive cementationof ceromer crowns. Next, the specimens were keptin distilled water (37 0C) for a week and then the tensile strength test was performed, also at 0.5 mm/min. The comparison among groups was carriedout by variance analysis (ANOVA) followed by theTukey test (p ≤ 0.05). Results: The results (Kgf)of provisional cementation for groups GTB, GTBNEand GDY were respectively: 2.75 ± (1.35b), 3.43± (1.66ab), and 4.48 ± (1.11a). The results of the adhesive cementation (Kgf) were respectively:42.71 ± (15.33b), 57.59 ± (15.66a), and 54.75 ±(15.28ab). Conclusion: It was concluded that the temporary cement containing eugenol presented negative influence on the removal resistance of crowns cemented with resin cement. Furthermore,dycal presented best result for removal resistance.

Avaliação do grau de sorção, solubilidade e taxa de conversão de sistemas adesivos irradiados com laser de diodo / Evaluation of water sorption/solubility and conversion degree of the adhesive systems irradiated with diode laser

O LASER tem sido utilizado previamente a polimerização de sistemas adesivos em dentina como uma estratégia para melhorar as suas propriedades. O objetivo deste estudo foi investigar o efeito do LASER de diodo na sorção (SB), solubilidade e grau de conversão das principais categorias de sistemas adesivos. Quatro sistemas adesivos foram testados: convencional de 3 passos (Adper™ Scotchbond™ Multi-Purpose-MP), convencional de 2 passos (Adper™ Single Bond 2-SB), autocondicionante de 2 passos (Clearfil™ SE Bond-SE) e o sistema universal (Adper™ Single Bond Universal-SU). O adesivo fluido foi dispensado numa matriz de teflon (6.0 x 6.0 x 1 m),irradiado com laser de diodo com 970 nm e polimerizado com luz LED. Para o teste de sorção e solubilidade foram preparados espécimes em uma matriz de teflon quadrada (n=10): MP, SB, SE e SU (sem irradiação) e MP-L, SB-L, SE-L e SU-L (grupos com irradiação). Essa mensuração foi monitorando a mudança de massa depois dos ciclos de armazenamento de desidratação/ água. Para o grau de conversão, espécimes similares eram preparados e divididos 8 grupos iguais (n=5), utilizando a espectroscopia infravermelho transformada de Fourrrier (FTIR) com reflectância total atenuada (ATR). Cada espécime era comprimido contra o cristal do ATR (diamante/ZnSe) com um pressão micrométrica. As amostras não polimerizadas (≈3.0μL, n=5) de cada adesivo era escaneada para calcular o grau de conversão. Para sorção (μg/mm3) houve diferença estatisticamente significante para ambos os fatores (p<0.05) sem interação entre eles SB> SU> MP> SE. Para a solubilidade (μg/mm3), somente o fator adesivo foi significante (p<0.05): SB>SU>MP=SE. A irradiação do LASER antes da polimerização aumentou o grau de conversão dos sistemas adesivos SBL> MP-L> SE-L> MP> SB> SE> SU-L> SU. A irradiação aumentou a sorção, mas não afetou a solubilidade dos sistemas adesivos. Além disso, a irradiação com LASER de diodo melhorou o grau de conversão de três sistemas adesivos testados.

Laser irradiation has been used over the dentin bonding systems (DBS) prior to polymerization as a strategy to improve their properties. The aim of this study was to investigate the effect of diode laser on water sorption (WS), solubility (WSB) and conversion degree (DC) of main categories of DBS. Four bonding agents were tested: 3-step total-etch (Adper™ Scotchbond™ Multi-Purpose-MP), 2-step total-etch (Adper™ Single Bond 2-SB), 2-step self-etch Clearfil™ SE Bond-SE) and universal system (Adper™ Single Bond Universal-SU). The fluid DBSs were dispensed into Teflon molds (6.0 x 6.0 x 1mm), irradiated with a 970 nm diode laser and then polymerized with a LED curing unit. For WS/WSB tests, square-shaped DBS were prepared (n=10): MP, SB, SE and SU (control groups/ no laser irradiation) and MP-L, SB-L, SE-L and SU-L (laser irradiated groups). WS/WSB were measured by monitoring the mass changes after dehydration/water storage cycles. For DC tests, similar square-shaped specimens were prepared and assigned into eight similar groups (n=5), using Fourier transform infrared spectroscopy (FT-IR) with attenuated total reflectance (ATR). Each cured specimen was compressed against the ATR crystal (diamond/ZnSe) with a micrometric, low-pressure clamp. Uncured resin samples (≈3.0μL, n=5) of each adhesive were also scanned for DC calculation. For WS (μg/mm3), both factors were statistically significant (p<0.05), without interaction between them SB>SU>MP>SE. For WSB (μg/mm3), only DBS was a significant factor (p<0.05): SB>SU>MP=SE. Laser irradiation immediately before photopolymerization has increased the DC (%) of the tested adhesives: SB-L> MPL> SE-L> MP> SB> SE> SU-L> SU. Irradiation with diode laser improved the conversion degree of all tested dentin bonding systems. Furthermore the diode laser increased the sorption, but did not affect their water solubility.

Impacto da obesidade na saúde bucal: revisão de literatura / Impact of obesity on oral health: a literature review

As taxas de prevalência e de incidência referentes à obesidade têm se tornado alarmantes, tanto em adultos como em crianças. O acúmulo excessivo de gordura no organismo pode acarretar prejuízos à saúde dos indivíduos. Objetivo: o presente estudo tem como objetivo apresentar uma revisão de literatura sobre a interação da obesidade com a saúde bucal por meio de um estudo ordenado em periódicos de circulação nacional e internacional. Materiais e método: foram encontrados 514 estudos, dentre os quais, foram selecionados 18 artigos, com base nos seguintes critérios: época de publicação, tema adequado ao proposto neste trabalho, ideias claras, objetivas e condizentes com o título do estudo. Resultados: os estudos selecionados mostraram associações entre doença periodontal e obesidade. Já em relação aos trabalhos que associavam cárie dental e obesidade, houve algumas divergências, estando estas em minoria. Conclusão: conclui-se que os pacientes obesos necessitam de atenção em saúde bucal, especialmente em relação à prevenção da doença periodontal e cárie dentária.

Prevalence and incidence rates regarding obesity have become alarming in both adults and children. The excessive fat buildup in the body may lead to health problems of individuals. Objective: this study aims to present a literature review on the interaction between obesity and oral health from a study ordered in journals of national and international circulation. Materials and method: five hundred and fourteen (514) studies were found, among which 18 were selected based on the following criteria: time of publication, proper subject to the proposal of this work, clear, objective and consistent ideas for the title of the study. Results: the selected studies have shown associations between periodontal disease and obesity. There were differences regarding the work that linked obesity to dental caries, but those were the minority. Conclusion: it is concluded that obese patients require oral health care, especially concerning prevention of periodontal disease and dental caries.

Evaluation of an Experimental Gel Containing Euclea natalensis: An In Vitro Study.

Objective. To evaluate the effect of an experimental gel containing Euclea natalensis extract on dentin permeability. Methods. Thirty-six dentin discs, 1-mm-thick. The discs were prepared from the coronal dentin of extracted human third molars that were divided into 3 groups (n = 10). The dentin discs in each group were treated with the groups following experimental materials: (FG): 1.23% fluoride gel, pH 4.1; (EG): Euclea natalensis extract gel, pH 4.1; (CG): control gel, pH 4.1. The gels were applied to the occlusal slide of the dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. The hydraulic conductance (HC) of each condition was determined four times using a fluid flow apparatus (Flodec). The data were analyzed using Two-way ANOVA and Tukey's test (P < 0.05). Results. The greatest mean reduction in HC was produced in group EG dentin discs (61.2%; P < 0.05). Even after acid challenge with 6% citric acid the great reduction occurred in group EG (66.0%; P < 0.05) than other groups (CG-77.1%, FG-90.8%). Conclusion. E. natalensis gel not only reduced dentin permeability, but also resisted posttreatment citric acid challenge without changing its permeability. Further research has to confirm this promising result in the clinical situation.