Effect of iontophoresis on fluoride uptake in enamel with artificial caries lesion

Abstract: Iontophoresis is a noninvasive technique, based on the application of a constant low-intensity electric current to facilitate the release of a variety of drugs, whether ionized or not, through biological membranes. The objective of this research was to evaluate the effect of iontophoresis using different electric current intensities on the uptake of fluoride in dental enamel with artificial caries lesions. In this in vitro operator-blind experiment, bovine enamel blocks (n = 10/group) with caries-like lesions and predetermined surface hardness were randomized into 6 groups: placebo gel without fluoride applied with a current of 0.8 mA (negative control), 2% NaF gel without application of any current, and 2% NaF gel applied with currents of 0.1, 0.2, 0.4 and 0.8 mA. Cathodic iontophoresis was applied for 4 min. The concentration of loosely bound fluoride (calcium fluoride) and firmly bound fluoride (fluorapatite) was determined. The results were analyzed by the nonparametric Kruskal-Wallis and Dunn tests. Iontophoresis at 0.8 mA, combined with the application of fluoridated gel (2% NaF), increased fluoride uptake in enamel with caries-like lesions, as either calcium fluoride or fluorapatite.

Multiple-peak and single-peak dental curing lights comparison on the wear resistance of bulk-fill composites

Abstract: The effects of tooth brushing could affect the long-term esthetic outcome of composite restorations. This study evaluated the effect of two different emission spectrum light-curing units on the surface roughness, roughness profile, topography and microhardness of bulk-fill composites after in vitro toothbrushing. Valo (multiple-peak) and Demi Ultra (single-peak) curing lights were each used for 10s to polymerize three bulk-fill resin composites: Filtek Bulk Fill Posterior Restorative (FBF), Tetric EvoCeram Bulk Fill (TET) and Surefil SDR Flow (SDR). After 30,000 reciprocal strokes in a toothbrushing machine, the roughness profile, surface roughness, surface morphology, and microhardness were examined. Representative SEM images were also obtained. When light-cured with the Demi Ultra, SDR showed the most loss in volume compared to the other composites and higher volume loss compared to when was light-cured with Valo. The highest surface roughness and roughness profile values were found in SDR after toothbrushing, for both light-curing units tested. FBF always had the greatest microhardness values. Light-curing TET with Valo resulted in higher microhardness compared to when using the Demi Ultra. Confocal and SEM images show that toothbrushing resulted in smoother surfaces for FBF and TET. All composites exhibited surface volume loss after toothbrushing. The loss in volume of SDR depended on the light-curing unit used. Toothbrushing can alter the surface roughness and superficial aspect of some bulk-fill composites. The choice of light-curing unit did not affect the roughness profile, but, depending on the composite, it affected the microhardness.

Micro hardness of dental tissues influenced by administration of aspirin during pregnancy / Microdureza de los tejidos dentales influenciada por la administración de aspirina durante el embarazo

The study is associated with the effect of aspirin (Acetyl Salicylic Acid) on the microhardness of mineralized tissues of the offspring's teeth, in response to the ingestion of the drug during pregnancy. Aspirin is a widely used analgesic and antipyretic medicine, for symptomatic treatment. Misuse of this drug during pregnancy may instigate developmental defects in offspring. An experimental control study was designed, in which female rabbits were taken as representative mammalian models and treated with aspirin during pregnancy. Their offspring's teeth were used to assess the microhardness of dental tissues. The rabbits were alienated into two groups, treated and control, consisting of seven rabbits in each set (n= 7). Microhardness was evaluated in three types of the sample teeth. The total number of teeth examined were, 2x7x12= 168 samples. Vicker's Hardness degree values were measured and recorded vis-à-vis (50 g for 15 s with 3 indentations per specimen on enamel and dentine separately). The range of hardness obtained was statistically analyzed and the Student's t-tests was applied, with the aid of SPSS version 20. The P-values for both enamel and dentine from maxillary incisors and molars were less than 0.05. The same trend was observed in the mandibular teeth. However, a teratogenicity of Acetyl Salicylic Acid was pragmatic in the recent in vivo studies. Based on the analysis, it was evident that the aspirin administration could produce negative effects leading to reduction in the microhardness of dental tissues of the offsprings.

El estudio asocia el efecto de la aspirina (ácido acetil salicílico) sobre la microdureza de los tejidos mineralizados de los dientes de crías, en respuesta a la ingesta del fármaco durante la preñez. La aspirina es un analgésico y antipirético ampliamente utilizado para el tratamiento sintomático. El mal uso de esta droga durante la preñez puede inducir defectos en el desarrollo de las crías. Se diseñó un estudio experimental de control, en el que se tomaron conejas como modelos de mamíferos representativos y fueron tratados con aspirina durante la preñez. Los dientes de sus crías fueron utilizados para evaluar la microdureza de los tejidos dentales. Los animales fueron distribuidos en dos grupos, tratados y control, con siete animales en cada grupo (n= 7). La microdureza se evaluó en tres tipos de dientes de la muestra. El número total de dientes examinados fueron 168 (2x7x12). Se midieron y registraron valores del grado de dureza Vickers vis-à-vis (50 g por 15 s con 3 indentaciones por especimen sobre el esmalte y la dentina por separado). Se analizó estadísticamente la gama de dureza obtenida y se aplicaron pruebas t de Student con la ayuda del programa SPSS versión 20. Los valores de p para el esmalte y la dentina de los incisivos maxilares y molares fueron menores a 0,05. Se observó la misma tendencia en los dientes mandibulares. Sin embargo, teratogenicidad producto del ácido acetil salicílico se encontró en recientes estudios in vivo. De acuerdo al análisis de los resultados, se evidenció que la administración de aspirina provocó efectos negativos que determinaron la reducción de la microdureza de los tejidos dentales de las crías.

Effect of low fluoride acidic dentifrices on dental remineralization

This study evaluated the capacity of fluoride acidic dentifrices (pH 4.5) to promote enamel remineralization using a pH cycling model, comparing them with a standard dentifrice (1,100 µgF/g). Enamel blocks had their surface polished and surface hardness determined (SH). Next, they were submitted to subsurface enamel demineralization and to post-demineralization surface hardness analysis. The blocks were divided into 6 experimental groups (n=10): placebo (without F, pH 4.5, negative control), 275, 412, 550, 1,100 µgF/g and a standard dentifrice (positive control). The blocks were submitted to pH cycling for 6 days and treatment with dentifrice slurries twice a day. After pH cycling, surface and cross-sectional hardness were assessed to obtain the percentage of surface hardness recovery (%SHR) and the integrated loss of subsurface hardness (ΔKHN). The results showed that %SHR was similar among acidic dentifrices with 412, 550, 1,100 µgF/g and to the positive control (Tukey's test; p>0.05). For ΔKHN, the acidic dentifrice with 550 µg F/g showed a better performance when compared with the positive control. It can be concluded that acidic dentifrice 550 µgF/g had similar remineralization capacity to that of positive control.

O presente estudo objetivou avaliar a capacidade de dentifrícios fluoretados acidulados (pH 4,5) em promover a remineralização do esmalte utilizando um modelo de ciclagem de pH e compará-lo a um dentifrício padrão (1.100 µgF/g). Blocos de esmalte tiveram suas superfícies polidas e a dureza de superfície determinada (SH). Em seguida, foram submetidos à desmineralização subsuperficial e a dureza de superfície pós-desmineralização foi determinada. Os blocos foram divididos em seis grupos experimentais (n=10): placebo (controle negativo), 275, 412, 550, 1.100 µgF/g e um dentifrício padrão (controle positivo). Os blocos foram submetidos à ciclagem de pH durante seis dias e tratamentos com dentifrício diluído duas vezes por dia. Após a ciclagem de pH, a dureza de superfície e em secção transversal foram avaliadas para obtenção da porcentagem de recuperação de dureza de superfície (%SHR) e área integrada da perda de dureza de subsuperfície (ΔKHN). Os resultados mostraram que %SHR foi semelhante entre os dentifrícios ácidos 412, 550, 1.100 µgF/g e controle positivo (teste de Tukey; p>0,05). Para ΔKHN, o dentifrício acidulado com 550 µgF/g mostrou uma performance melhor quando comparado ao controle positivo. Conclui-se que os dentifrícios acidulados 550 µgF/g apresentaram capacidade de remineralização semelhante ao controle positivo.

The effect of iron on Streptococcus mutans biofilm and on enamel demineralization

Iron (Fe) may have an anticaries effect by specific inhibition of glycosyltransferase (GTF) enzymes of Streptococcus mutans, but this hypothesis has not yet been clarified. In this study, S. mutans biofilms were formed on blocks of bovine dental enamel of a predetermined surface hardness (SH). These biofilms were exposed eight times/day to 10% sucrose, and two times/day they were subjected to one of the following treatments: G1, 0.9% NaCl as a negative control; G2, 0.12% chlorhexidine digluconate (CHX) as a positive antibacterial control; G3, 0.05% NaF (225 ppm F) as a positive anticaries control; G4, G5, and G6, ferrous sulfate (Fe2+) at concentrations of 1.0, 10.0, and 100.0 µg Fe/mL, respectively. The experiment was performed in triplicate and was repeated three times (n = 9). The pH of the culture medium was determined every 24 h as an indicator of the biofilm's acidogenicity. The biofilm formed on each block was collected for determination of the viable bacteria and concentration of extracellular polysaccharides (EPS). Enamel SH was again determined and the percentage of SH loss (%SHL) was calculated as an indicator of demineralization. Iron treatment reduced the number of viable bacteria formed in the S. mutans biofilm (p = 0.04), in a dose-dependent manner, and also reduced the enamel's %SHL (p = 0.005). At 100 µg/mL, Fe reduced enamel demineralization as effectively as CHX and NaF (p < 0.05), but it did not inhibit EPS production. In conclusion, the data suggest that the anticaries mechanism of action of Fe may not involve the oxidative inhibition of GTFs.

Effect of antibacterial agents on the surface hardness of a conventional glass-ionomer cement

In atraumatic restorative treatment (ART), caries removal with hand excavation instruments is not as efficient as that with rotary burs in eliminating bacteria under the glass ionomer cements (GICs). Thus, different antibacterial agents have been used in recent studies to enhance the antibacterial properties of the GICs, without jeopardizing their basic physical properties. OBJECTIVE: The objective of this study was to evaluate the effect of antibacterial agents on the surface hardness of a conventional GIC (Fuji IX) using Vickers microhardness [Vickers hardness number (VHN)] test. MATERIAL AND METHODS: Cetrimide (CT), cetylpyridinium chloride (CPC) and chlorhexidine (CHX) were added to the powder and benzalkonium chloride (BC) was added to the liquid of Fuji IX in concentrations of 1 percent and 2 percent, and served as the experimental groups. A control group containing no additive was also prepared. After the completion of setting reaction, VHN measurements were recorded at 1, 7, 15, 30, 60, and 90 days after storage in 37°C distilled water. A one-way ANOVA was performed followed by a Dunnett t test and Tamhane T2 tests and also repeated measurements ANOVA was used for multiple comparisons in 95 percent confidence interval. RESULTS: VHN results showed significant differences between the control and the experimental groups at all time periods (p<0.05 for all). Significant differences were observed between all study periods for individual groups (p<0.05). After 7 days, VHNs were decreased in all experimental groups while they continued to increase in the control group. BC and CHX groups demonstrated the least whereas CT and CPC groups exhibited most adverse effect on the hardness of set cements. CONCLUSIONS: Despite the decreased microhardness values in all experimental groups compared to the controls after 7 up to 90 days, incorporating certain antibacterial agents into Fuji IX GIC showed tolerable microhardness alterations within the limitations of this in vitro study.

In vitro evaluation of the microhardness of bovine enamel exposed to acid solutions after bleaching

Acid erosion is a superficial loss of enamel caused by chemical processes that do not involve bacteria. Intrinsic and extrinsic factors, such as the presence of acid substances in the oral cavity, may cause a pH reduction, thus potentially increasing acid erosion. The aim of this study was to evaluate the microhardness of bleached and unbleached bovine enamel after immersion in a soda beverage, artificial powder juice and hydrochloric acid. The results obtained for the variables of exposure time, acid solution and substrate condition (bleached or unbleached enamel) were statistically analyzed by the ANOVA and Tukey tests. It was concluded that a decrease in microhardness renders dental structures more susceptible to erosion and mineral loss, and that teeth left unbleached show higher values of microhardness compared to bleached teeth.

The effect of carbamide peroxide bleaching agents on the microhardness of dental ceramics

This study examined the effect of 10% and 16% carbamide peroxide bleaching agents on the surface microhardness of micro-particulate feldspathic ceramics (VM7 and VM13, Vita Zahnfabrik). Forty specimens (8-mm diameter, 2-mm thickness) were divided into four groups (n=10): G1- VM7 + 10% Whiteness, G2- VM7 + 16% Whiteness, G3- VM13 + 10% and G4- VM13 + 16% Whiteness. The home-use bleaching agents were applied for 8 hours on 15 days, and the specimens were stored in distilled water at 37°C. The Vickers hardness number (HV) was determined for each specimen. Data were analyzed by the Wilcoxon and Mann- Whitney tests (p<0.05). The microhardness values before exposure were: g1- 433 (57); g2- 486 (22); g3- 509 (28); g4- 518 (24), and after exposure: G1- 349 (32); G2- 496 (95); G3- 519 (38); G4- 502 (81). G2 exhibited a higher and significant difference than G1 in VM7 groups, and the effect of bleaching concentration was shown to be significant by the Mann-Whitney test. And for VM13, both the Wilcoxon and Mann-Whitney tests showed no significant differences. When using 10% carbamide peroxide, the microhardness of VM7 ceramic was affected, and there were no effect on the microhardness between VM7 and VM13 ceramics when 16% carbamide peroxide was used.

Este estudo examinou o efeito do agente clareador peroxido de carbamida a 10% e a 16% na microdureza superficial de ceramicas feldspaticas micro-particuladas (VM7 e VM13, Vita Zahnfabrik). Quarenta corpos-de-prova (8 mm de diametro, 2 mm de espessura) foram divididos em quatro grupos (n=10): G1- VM7 + 10% Whiteness, G2- VM7 + 16% Whiteness, G3- VM13 + 10% e G4- VM13 + 16% Whiteness. Os agentes clareadores foram aplicados por 8 horas durante 15 dias e os cp foram armazenados em agua destilada a 37°C. A dureza Vickers (HV) de cada cp foi determinada. Os dados foram analisados pelos testes de Wilcoxon e Mann-Whitney (p<0.05). Os valores da dureza antes da exposicao ao agente clareador foram: g1- 433 (57); g2- 486 (22); g3- 509 (28); g4- 518 (24), e depois da exposicao: G1- 349 (32); G2- 496 (95); G3- 519 (38); G4- 502 (81). G2 exibiu diferenca significante e microdureza maior comparado ao G1 nos grupos da VM7 e o efeito da concentracao do clareador foi significante, apresentados atraves dos testes Mann-Whitney. Para VM13, ambos testes, Wilcoxon e Mann-Whitney, nao apresentaram diferenca significante. Quando o peroxido de carbamida a 10% foi avaliado, a microdureza da ceramica VM7 foi afetada, e nao houve diferenca na microdureza entre as ceramicas VM7 e VM13 quando o peroxido de carbamida a 16% foi utilizado.

Effect of 4 percent titanium tetrafluoride solution on the erosion of permanent and deciduous human enamel: an in situ/ex vivo study

This in situ/ex vivo study assessed the effect of titanium tetrafluoride (TiF4) solution on erosion of permanent (P) and deciduous (d) human enamel. Ten volunteers wore acrylic palatal appliances containing 4 enamel samples, divided into two rows: TiF4 and no - TiF4 (control). Each row contained one deciduous and one permanent enamel sample. During the 1st day, formation of a salivary pellicle was allowed. At the 2nd day, the 4 percent TiF4 solution was applied on one row (TiF4), while the other row remained untreated (control). From the 3rd until the 7th day, the samples were subjected to erosion by immersion in a cola drink for 5 min, 4 times/day. Enamel alterations were determined by microhardness testing ( percentSMHC). Data were analyzed using 2 two-way ANOVA and Tukey's post hoc test (α=0.05). The mean percentSMHC (±SD) amounted to: P (TiF4 - 73.32 ± 5.16 and control - 83.49 ± 4.59) and d (TiF4 - 83.01 ± 7.41 and control - 75.75 ± 2.57). In conclusion, the application of 4 percent TiF4 solution reduced the softening of permanent enamel but not of deciduous enamel significantly. However, no significant differences were detected between the permanent and deciduous enamel when the factor substrate was considered.

Effect of 10 percent carbamide peroxide bleaching on sound and artificial enamel carious lesions

This study evaluated the effect of 10 percent carbamide peroxide (CP) bleaching on Knoop surface microhardness (KHN) and morphology of sound enamel and enamel with early artificial caries lesions (CL) after pH-cycling model (pHcm). Human dental enamel blocks were randomly divided into 6 groups (n=10): 1 - sound enamel bleached (S) with CP (Rembrandt/Den-Mat); 2 - S and submitted to pHcm; 3 - CL bleached with CP; 4 - CL stored in artificial saliva and submitted to pHcm; 5 - CL treated with placebo gel and submitted to pHcm; 6 - CL bleached with CP and submitted to pHcm. Enamel blocks with known initial KHN values were demineralized (groups 3 to 6) and submitted to 12 day pHcm (groups 2, 4, 5 and 6). After demineralization and treatments, KHN was determined and the specimens were examined using scanning electron microscopy (SEM). Data were analyzed statistically by ANOVA and Tukey's test at 5 percent significance level. The results showed that among CL groups (3 to 6) only the group 3 presented remineralization after treatments. S groups (1 and 2) showed higher KHN and presented less formation of porosities on enamel surface than CL groups after treatments. In conclusion, bleaching procedures on enamel with CL did not exacerbate the demineralization, but should be indicated with caution.

Este estudo analisou o efeito do peróxido de carbamida a 10 por cento (PC) na microdureza Knoop de superfície (KHN) e morfologia do esmalte hígido e com lesões iniciais de cárie artificial (EC), após modelo de ciclagem de pH (cpH). Blocos de esmalte dental humano foram divididos aleatoriamente em 6 grupos (n=10): 1- esmalte hígido clareado (EHC) com PC (Rembrandt/Den-Mat); 2- EHC e submetido a cpH; 3- EC clareado com PC; 4- EC armazenado em saliva artificial e submetido a cpH; 5- EC tratado com gel placebo e submetido a cpH; 6- EC clareado com PC e submetido a cpH. Blocos de esmalte com a KHN conhecida eram desmineralizados (grupos 3 a 6) e submetidos a cpH (grupos 2, 4, 5 e 6). KHN foi determinada após a desmineralização e os tratamentos. Os espécimes foram examinados através de Microscopia Eletrônica de Varredura (MEV). Os dados foram analisados através de ANOVA e teste de Tukey (p<0,05). Os resultados indicaram que entre os grupos com EC (3 a 6) somente o grupo 3 apresentou remineralização após os tratamentos. Os grupos EHC (1 e 2) mostraram maior KHN e menor formação porosidades quando comparados aos grupos EC após os tratamentos. Os procedimentos clareadores no esmalte com lesão de cárie não exacerbaram a desmineralização, entretanto precisam ser indicados com cautela.

Evaluation of hardness and surface roughness of two maxillofacial silicones following disinfection

The purpose of this study was to evaluate the Shore A hardness and surface roughness of two silicones for maxillofacial prosthetic treatment, under the influence of chemical disinfection and storage. Twenty-eight specimens were obtained, half of which were made of Silastic MDX 4-4210 silicone and, the other half were made of Silastic 732 RTV silicone. The specimens were divided into four groups: Silastic 732 RTV and MDX 4-4210 with disinfection 3 times a week with Efferdent tablets and the same materials without disinfection. The hardness of the materials was analyzed with a Shore A Durometer. The surface roughness was established by a digital portable roughness tester, initially and 2 months after the confection of the specimens. A variance test was applied (2-way ANOVA), followed by Tukey test (the level of significance was set at 1%). The storage time factor statistically influenced (p < 0.01) the materials' properties of hardness and roughness. MDX 4-4210 (28.59 Shore A, 0.789 Ra) presented higher values than Silastic 732 RTV (18.08 Shore A, 0.656 Ra) for both properties. Regarding the disinfection period, there was no significant difference in any of the materials tested.

Effect of thickener agents on dental enamel microhardness submitted to at-home bleaching

Dental bleaching occurs due to an oxidation reaction between the bleaching agents and the macromolecules of pigments in the teeth. This reaction is unspecific and the peroxides can also affect the dental matrix causing mineral loss. On the other hand, recent studies have suggested that the thickener agent carbopol can also cause mineral loss. Thus, the objective of this study was to evaluate in vitro the effect of at-home dental bleaching on dental enamel microhardness after the use of bleaching agents with and without carbopol as a thickener agent. Bovine dental slabs with 3 x 3 x 3 mm were obtained, sequentially polished, and randomly divided into 4 groups according to the experimental treatment: G1: 2 percent carbopol; G2: 10 percent carbamide peroxide with carbopol; G3: carbowax; G4: 10 percent carbamide peroxide with poloxamer. Bleaching was performed daily for 4 weeks, immersed in artificial saliva. Enamel microhardness values were obtained before the treatment (T0) and 7 (T1), 14 (T2), 21 (T3), 28 (T4), and 42 (T5) days after the beginning of the treatment. ANOVA and Tukey's test revealed statistically significant differences only for the factor Time (F = 5.48; p < 0.01). All bleaching and thickener agents caused no alterations on the enamel microhardness.

O clareamento dental ocorre devido a uma reação de oxidação entre o agente clareador e as macromoléculas de pigmentos presentes nos dentes. Esta reação é inespecífica e o peróxido pode agir na matriz dental causando perdas de mineral. Por outro lado, estudos recentes sugerem que o agente espessante carbopol também pode causar perda mineral. Assim, o objetivo deste trabalho foi avaliar in vitro o efeito do clareamento caseiro sobre a microdureza do esmalte após o uso de agentes clareadores com e sem carbopol como espessante. Fragmentos de esmalte bovino de 3 x 3 x 3 mm foram obtidos, polidos seqüencialmente e aleatoriamente divididos em 4 grupos de acordo com o tratamento experimental: G1: carbopol a 2 por cento; G2: peróxido de carbamida a 10 por cento com carbopol; G3: carbowax; G4: peróxido de carbamida a 10 por cento com poloxamer. O clareamento foi realizado diariamente por 4 semanas em saliva artificial. A microdureza do esmalte foi avaliada antes (T0) e após 7 (T1), 14 (T2), 21 (T3), 28 (T4), e 42 (T5) dias do início do tratamento. A ANOVA e o teste de Tukey revelaram diferenças estatísticas significantes somente para o fator Tempo (F = 5,48; p < 0,01). Os agentes clareadores e espessantes não causaram alterações na microdureza do esmalte.

Effectiveness and efficiency of chemomechanical carious dentin removal

O objetivo deste estudo in vitro foi determinar o tempo gasto para a remoção de dentina cariada (eficiência) e a microdureza Knoop (KHN) da dentina remanescente (eficiência), usando o método químico-mecânico (Carisolv) ou escavação manual. Trinta molares humanos foram seccionados através da lesão de cárie oclusal, produzindo duas metades iguais. Cada metade foi escavada, aleatoriamente, utilizando um escavador manual ou o kit Carisolv gel, seguindo as instruções do fabricante. O tempo gasto para a remoção da dentina cariada foi registrado. As hemi-secções foram incluídas em resina, planificadas e polidas. KHN da dentina remanescente foi determinada nas distâncias de 100, 200, 300, 400 e 500 mm, a partir do assoalho cavitário. Os dados foram analisados pelos testes de Wilcoxon (a=0,01), ANOVA e t de Student (a=0,05). O tempo gasto na escavação químico-mecânica foi significativamente maior que na escavação manual. As médias e os desvios-padrão de KHN a 100, 200, 300, 400, 500 mm foram, respectivamente, para o método químico-mecânico: 15,6 (±4,96), 18,0 (±6,22), 21,3 (±9,30), 24,3 (±9,25), 28,5 (±11,80); e para a escavação manual: 21,2 (±10,26); 23,4 (±9,49); 28,2 (±11,62); 31,0 (±12,17); 34,3 (±11,95). Concluiu-se que a escavação manual apresentou maior efetividade e eficiência que a escavação assistida pelo Carisolv.

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology

O objetivo deste estudo foi avaliar a rugosidade, microdureza e morfologia superficial do esmalte dental humano tratado com seis agentes clareadores (antes e depois do tratamento). Amostras de esmalte dental humano foram obtidas de terceiros molares e aleatoriamente distribuídas em sete grupos (n = 11): controle, Whiteness Perfect - peróxido de carbamida a 10% (PC 10%), Colgate Platinum - PC 10%, Day White 2Z - peróxido de hidrogênio a 7,5% (PH 7,5%), Whiteness Super - PC 37%, Opalescence Quick - PC 35% e Whiteness HP - PH 35%. Os agentes clareadores foram aplicados de acordo com as instruções dos fabricantes. O grupo controle permaneceu sem tratamento e armazenado em saliva artificial. O teste de microdureza foi realizado com o indentador Knoop, e a rugosidade superficial foi verificada através do rugosímetro. Observações morfológicas foram realizadas através de microscopia eletrônica de varredura (MEV). Os resultados foram estatisticamente analisados com ANOVA (dois fatores) e teste Tukey (5%) e revelaram uma redução significante nos valores de microdureza e um aumento significante da rugosidade de superfície após o clareamento. Alterações na morfologia do esmalte após o clareamento foram observadas através de MEV. Concluiu-se que os agentes clareadores podem alterar a microdureza, rugosidade e morfologia superficial do esmalte dental.

Dureza knoop de resinas compostas em funçäo de três anos de armazenagem e da profundidade / Knoop hardness of composites due to three years of storage and depth

A finalidade da pesquisa foi determinar a dureza knoop de três resinas compostas (Z100 A2, silux plus XL e Heliomolar RO 20) nos tempos de uma semana, um mês, um ano e três anos, nos lados da irradiaçäo (frente) e do oposto (fundo). Discos de poliacetal foram perfurados (2,5mm de diâmetro por 2,0mm de profundidade, correspondente à espessura dos discos), constituindo a"cavidades", que foram preenchidas com as resinas para a obtençäo dos corpos-de-prova; para a polimerizaçäo, foi usada a intensidade de 300mW/cm² por 40 segundo. Os resultados permitiram concluir que: o lado do fundi apresentou manor dureza, tanto significante, quanto numericamente; a comparaçäo das durezas correspondentes aos tempos de uma semana e três anos mostrou um aumento significante apenas na resina Heliomolar RO, mas todos os materiais toleraram bem o meio de armazenagem soro fisiológico; foi observado que as durezas dos lados do fundo näo convergem para as da face de irradiaçäo

Avaliaçäo da microdureza superficial de resinas compostas condensáveis submetidas à diferentes tratamentos superficiais / In vitro superficial microhardness of condensable composite resins submitted to different superficial treatments

As resinas compostas tem sido alvo de inúmeras pesquisas, por se tratarem de um material estético de grande utilizaçäo na odontologia. Atualmente novas resinas compostas condensáveis estäo disponíveis no mercado com a finalidade de restaurar funcional e esteticamente os dentes posteriores. Neste trabalho realizou-se um estudo comparativo da microdureza superficial de diferentes resinas compostas condensáveis (Filtek P60/3M, Alert/Jeneric Pentron Incorporated e SureFill/DENTSPLY-Caulk), submetidas a três diferentes tratamentos superficiais (Polimento com discos de óxido de alumínio Sof Lex/3M, polimento com pontas siliconizadas Enhance/DENTSPLY-CaulK e selante superficial Fortify/Bisco). Pelos resultados obtidos pode-se concluir que a resina SureFill apresentou maiores valores de microdureza superficial do que as resinas Filtek P60 e Alert. O tratamento superficial com as pontas Enhance revelou maiores valores de microdureza superficial das resinas do que os discos de Sol Lex e o selante Fortify. A microdureza superficial da resina apresentou maiores valores com a combinaçäo SureFill e Enhance e menores valores com o Fortity para todas as resinas testadas. Apresentou ainda valores estatisticamente iguais com o tratamento superficial dos discos Sof Lex para as resinas SureFill e Alert, porém os resultados da resina Filtek P60 foram menores que os da resina SureFill. Ainda, apresentou valores maiores para o tratamento superficial com pontas Enhance na resina Alert do que na resina Filtek P60

Effect of peroxide bleaching gel preparations on light-cured glass-ionomer restorative materials: hardness and tensile strength 1

The purpose of this study was to evaluate the effect of peroxide bleaching gel preparation on the hardness and tensile strength of restorative glass ionomer materials. The results showed that there were significant reductions in hardness and tensile strength of the tested materials

Dureza Knnop de resinas compostas em funçäo de tempos de imersäo em meios ácidos e profundidade / Knoop hardness of composites as function of storing time acids solution and depth

O objetivo da pesquisa foi avaliar a dureza Knoop de 4 resinas compostas (Definite, Z100, Degufill Mineral e Charisma F) em funçäo de 4 meios de armazenagem (soro fisiológico, ácidos, lático, cítrico e acético), com determinaçöes feitas em 1 semana, 1, 2 e 4 meses, nas profundidades, a partir da superfície de irradiaçäo, 0,2; 2,0 e 3,8mm. Os corpos-de-prova foram obtidos em cavidade de teflon de 3x2x4mm. Os resultados permitiram concluir que: a compatibilidade entre materiais e ácidos depende de ambos e no soro fisiológico näo houve alteraçöes; o ácido lático foi pouco agressivo para o Definite e Z100, mas acentuadamente para o Degufill Mineral e Charisma F; o ácido cítrico em alguns casos até aumentou a dureza do Denitite, diminuiu-a nos demais materiais; o ácido acético apresentou boa compatibilidade com o definite e Degufill Mineral, pouca com o Z100 nas profundidades e razoável com o Charisma F

Effect of low fluoride dentifrices on microhardness of sound enamel. In vitro study.

The present study was undertaken to evaluate the effect of dentifrices containing low fluoride concentrations on microhardness of sound enamel in 50 healthy young premolar teeth. They were divided into five different groups according to the concentrations of fluoride in dentifrice used. The Vickers hardness of enamel was measured using a Zwick microhardness tester under 1000 g load and a Vickers indenter before and after the application of fluoride dentifrices. The results of the present study suggest that low fluoride concentration dentifrices are as effective as the higher concentrations in increasing the hardness of enamel.

Efeito da brunidura e do polimento sobre o conteúdo de mercúrio, topografia e dureza superficial de um amálgama convencional / Effect of brunishing and the polishing on the content of the mercury, topography and surface hardness from a conventional amalgam

O presente trabalho foi conduzido com a finalidade de estudar os efeitos dos procedimentos de acabamento superficial do amálgama preparado a partir de uma liga convencional (Velvalloy), sobre o conteúdo de mercúrio, topografia e dureza superficial. Foram estabelecidas as seguintes condiçöes: A) brunidura 15 minutos após trituraçäo; B) brunidura após 7 dias; C) brunidura após 15 minutos e polimento após 7 dias; D) polimento após 7 dias; E) brunidura após 7 dias em seguida polimento; F) polimento após 7 dias e em seguida brunidura e G) somente escultura. Os corpos de prova foram preparados da seguinte maneira: (1) para verificaçäo do conteúdo de mercúrio superficial: cavidades circulares foram confeccionadas nas superfícies vestibulares de dentes extraídos...