Hydroxyapatite decreases cytotoxicity of a glass ionomer cement by calcium fluoride uptake in vitro.

BACKGROUND: Glass ionomer cements (GICs) are widely used in dentistry because of their remineralizing and cariostatic potential induced by fluoride. In vitro studies have reported cell toxicity triggered by GICs; however, the influence of hydroxyapatite (HAp) must be considered. The aim of this study was to evaluate the effect of HAp in decreasing the cytotoxicity of the GIC 3M Vitrebond in vitro. METHODS: Samples of 3M Vitrebond (powder, liquid and light-cured) were incubated in Dulbecco's modified Eagle's medium-Ham's F12 (DMEM-F12) for 24 hours at 37°C. Subsequently, the light-cured medium was treated with 100 mg/mL of HAp overnight. Toxicity of conditioned media diluted 1:2, 1:4, 1:8 and 1:20 was analyzed on human gingival fibroblasts (HGFs) using light microscopy and the fluorometric microculture cytotoxicity assay. The amounts of calcium fluoride (CaF2) were determined by the alizarin red S method. RESULTS: The exposure of HGFs to light-cured induced cell death and morphological changes such as chromatin condensation, pyknotic nuclei and cytoplasmic modifications. Exposure to light-cured treated with HAp, significantly increased cell viability leading to mostly spindle-shaped cells (p<0.001). The concentration of CaF2 released by the light-cured was 200 ppm, although, in the light-cured/HAp conditioned medium, this quantity decreased to 88 ppm (p<0.01). CONCLUSIONS: These data suggest that HAp plays a protective role, decreasing the cytotoxic effect of 3M Vitrebond induced by CaF2.

Antimicrobial Activity of Glass lonomer Cement Incorporated with Chlorhexidine-Loaded Zeolite Nanoparticles.

A functional dental restorative system with antimicrobial properties was developed using zeolite (ZE) nanoparticles (NPs) as a drug delivery carrier. ZE NPs loaded with chlorhexidine (CHX) were prepared using the ionic immobilization method. The resulting CHX-loaded ZE NPs were then incorporated into commercial dental glass ionomer cement (GIC). The average size of the CHX-loaded ZE NPs was about 100 to 200 nm, and the NPs were dispersed homogeneously in the GIC. The in vitro release profile of encapsulated GIC containing CHX showed an early release burst of approximately 30% of the total CHX by day 7, whereas GIC containing CHX-loaded ZE NPs showed a sustained release of CHX without the early release burst in a 4-week immersion study. The agar diffusion test results showed that the GIC incorporated with CHX-loaded ZE NPs showed a larger growth inhibition zone of Streptococcus mutans than GIC alone, indicating that this innovative delivery platform potently imparted antimicrobial activity to the GIC. Moreover, these findings suggest that a range of antimicrobial drugs that inhibit the growth of oral bacteria can be incorporated efficiently into dental GIC using CHX-loaded ZE NPs.

Microleakage comparison of glass-ionomer and white mineral trioxideaggregate used as a coronal barrier in nonvital bleaching

Objectives: There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrierbe used over the canal filling to prevent leak age of bleaching agents. Glass-ionomer (GI) is commonly used asa coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinityafter mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluates ealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching.Study design: Root canals of one hundred thirty human maxillary incisors were instrumented and filled withgutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). Theteeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups,glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following threebleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agentswere 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixedwith distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no (..) (AU)

Shear bond strengths of three glass ionomer cements to enamel and dentine

Objectives: The shear bond strength of three glass ionomer cements (GIC) to enamel and dentine was evaluated.Study Design: Sound permanent human molars (n=12) were grinded perpendicular to their axial axes, exposingsmooth, flat enamel and dentine surfaces. The teeth were embedded in resin and conditioned with polyacrylic acid(25%; 10s). Twenty four specimens of each GIC: Fuji IX (FJ - GC), Ketac Molar Easymix (KM – 3M ESPE) andMaxxion (MX - FGM) were prepared according to the Atraumatic Restorative Treatment (ART) (12 enamel and12 dentine), in a bonding area of 4.91 mm2 and immersed in water (37oC, 24h). The shear bond strength was testedin a universal testing machine. Non-parametric statistical tests (Friedman and post-hoc Wilcoxon Signed Ranks)were carried out (p=0.05).Results: The mean (±sd) of shear bond strength (MPa), on enamel and dentine, were: KM (6.4±1.4 and 7.6±1.5),FJ (5.9±1.5 and 6.0±1.9) and MX (4.2±1.5 and 4.9±1.5), respectively. There was a statistically significant differencebetween the GICs in both groups: enamel (p=0.004) and dentine (p=0.002). The lowest shear bond value forenamel was with MX and the highest for dentine was KM (p<0.05).Conclusion: It is concluded that KM has the best adhesion to both enamel and dentine, followed by FJ and MX (AU)

No disponible

A spectroscopic investigation into the setting and mechanical properties of titanium containing glass polyalkenoate cements.

Titanium (Ti) implants are extensively used in a number of biomedical and dental applications. This work introduces Ti into the glass phase of a zinc based glass polyalkenoate cement (GPC) and investigates changes in handling and mechanical properties considering two molecular weight polyacrylic acids (PAA), E9 and E11. Considering the handling properties, the working time (T (w)) increased from 50 s(E9), 32 s(E11) (BT 101, Ti-free) to 169 s(E9), 74 s(E11) with TW-Z (highest Ti content), respectively. The setting time (T (s)) increased from 76 s(E9), 47 s(E11) (BT 101) to 303 s(E9), 232 s(E11) with TW-Z, respectively. Ti was also found to have a significant increase on both compressive (sigma (c)) and biaxial flexural strength (sigma (f)), where sigma (c) increased from 36 MPa(E9), 56 MPa(E11) (BT 101) to 56 MPa(E9) and 70 MPa(E11) with TW-Z respectfully. sigma (f) also increased from 11 MPa(E9), 22 MPa(E11) (BT 101) to 22 MPa(E9) and 77 MPa(E11) with TW-Z, respectively. No increase in mechanical properties was evident with respect to maturation. Raman Spectroscopy was employed to investigate changes in glass structure and the setting of the cements with. This revealed increased glass network disruption with increasing TiO(2) content and matured cement setting with TW-Z as compared to the control BT 101. FT-IR was then employed to investigate any additional setting mechanism and changes with time. Spectroscopy determined that Ca(2+)/Sr(2+)PAA complexes are primarily responsible for the setting and mechanical strength with no changes occurring over time.

Zinc polycarboxylate dental cement for the controlled release of an active organic substance: proof of concept.

The potential of employing zinc polycarboxylate dental cement as a controlled release material has been studied. Benzalkonium chloride was used as the active ingredient, and incorporated at concentrations of 1, 2 and 3% by mass within the cement. At these levels, there was no observable effect on the speed of setting. Release was followed using an ion-selective electrode to determine changes in chloride ion concentration with time. This technique showed that the additive was released when the cured cement was placed in water, with release occurring by a diffusion mechanism for the first 3 h, but continuing beyond that for up to 1 week. Diffusion coefficients were in the range 5.62 x 10(-6) cm(2) s(-1) (for 1% concentration) to 10.90 x 10(-6) cm(2) s(-1) (for 3% concentration). Up to 3% of the total loading of benzalkonium chloride was released from the zinc polycarboxylate after a week, which is similar to that found in previous studies with glass-ionomer cement. It is concluded that zinc polycarboxylate cement is capable of acting as a useful material for the controlled release of active organic compounds.

Effect of fluoride-releasing filling materials on underlying dentinal lesions in vitro.

Fluoride-releasing materials placed over carious tissue are assumed to enhance remineralisation of the underlying lesion. This remineralisation, however, also depends on the availability of calcium and phosphate, which may be supplied by the pulpal fluid. The aim of this study was to measure the fluoride release of glass ionomer cements (GICs) into underlying dentin and to measure the effect of the released fluoride on the remineralisation of the underlying dentinal lesions using transversal microradiography. Discs of fluoride-releasing GIC were placed on top of dentinal lesions in an in vitro model. The discs and the dentin slabs were covered completely by a protective layer of nail varnish, leaving only the pulpal side of the dentin slab open, and hence the dentinal tubules as the pathway for the incubation fluid to the GIC disc. Specimens were incubated in a remineralisation buffer. The materials tested were a conventional GIC, an experimental GIC that was designed to have a high fluoride release, and an inert material. Fluoride was found to penetrate through the dentin slab into the surrounding fluid. Fluoride uptake from the experimental GIC was higher than from the conventional GIC. Mineral content-depth profiles after 10 weeks' remineralisation revealed that in the outer 30 microm of the lesion a higher mineral deposition occurred for the experimental GIC than in both other groups. No differences in the overall change of integrated mineral loss were found for the tested materials. We conclude that high fluoride release from filling materials only results in superficially increased remineralisation of underlying demineralised dentin.

Antibacterial properties of 4 orthodontic cements.

BACKGROUND: White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. Long-lasting antibacterial properties of orthodontic cements can reduce this phenomenon. METHODS: The antibacterial properties of 4 orthodontic cements were evaluated by direct contact test (DCT) and agar diffusion test (ADT). With the DCT technique, octet specimens of glass ionomer (CX-Plus; Shofu, Kyoto, Japan), reinforced glass ionomer (GC Fuji ORTHO LC; GC Corporation, Tokyo, Japan), and 2 composite (Transbond XT and Transbond Plus; 3M Unitek, Monrovia, Calif) orthodontic cements were placed on the sidewalls of wells of a 96-microtiter plate. Streptococcus mutans cells (ca. 1 x 10(6) ) were placed on the surface of each specimen for 1 hour at 37 degrees C. Then, fresh media was added to each well, and bacterial growth was monitored for 16 hours with a temperature-controlled spectrophotometer. This was repeated on specimens aged in phosphate-buffered saline for 1 day, 1 week, and 1 month. The ADT was performed by placing specimens in wells punched in agar plates. RESULTS: Measurement of the halo in bacterial lawn after 48 hours showed that only the glass ionomer cement (CX-Plus) produced an inhibition zone (1.2 mm around the sample). Results at the DCT showed that only the reinforced glass ionomer cement (GC Fuji ORTHO LC) exhibited potent antibacterial activity, which lasted 1 week and diminished over the next 3 weeks. CONCLUSIONS: The reinforced glass ionomer cement possessed the most potent and long-lasting antibacterial activity.

[Release of fluoride ions into saliva from some dental materials]. / Uwalnianie jonów fluorkowych do sliny z wybranych materialów stomatologicznych.

The aim of the study was to evaluate fluoride release from dental materials: resin composites--Tetric Ceram and Degufill Mineral, fissure sealants--Conseal F and Admira seal, compomer--Freedom and glass-ionomer cement--Vitremer. Release to the patient's unstimulated mixed saliva was studied after treatment with the material. The study group comprised 72 patients and fluoride concentrations were measured with an ion-selective electrode (Orion). The following release of fluoride in decreasing order was found: Vitremer (6.03 microM), Degufill Mineral (2.79 microM), Teric Ceram (2.54 microM), Freedom (2.52 microM), Admira seal (1.85 microM) and Conseal F (1.80 microM).

Avaliação do desempenho clínico de restaurações com cimento de ionômetro de vidro modificado por resina em dentes posteriores permanentes / Evaluation of clinical performace of resin-modified glass ionomer restorations in permanent posterior teeth

A proposta deste estudo foi avaliar o desempenho clínico a longo prazo de 159 restaurações feitas em dentes posteriores permanentes restaurados, após eliminação de cáries incipientes, com um cimento de ionômetro de vidro modificado por resina (Vitrimer-3M) em 81 pacientes jovens regularmente matriculados e atendidos no setor de odontologia geral do HRAC-USP. As restaurações foram divididas em grupos, de acordo com o tempo decorrido da inserção do material na cavidade bucal (6 a 12 meses, 12 a 18 meses e de 18 a 36 meses), sendo avaliadas segundo os itens: restaurações presentes, restaurações ausentes (perdidas ou substituidas por outro material), recorrência de cárie, desgaste do material, fratura da estrutura dentária, alteração de cor, integridade marginal e presença de contatos oclusais sobre a restauração. Os resultados mostraram um índice de restaurações presente e aceitável clinicamente superior a 91 por cento, considerado como sucesso, pois nos vários itens abordados, somente poucos casos de fratura do material e recidiva de cárie implicaram na troca da restauração. Cocluimos que o cimento de ionômetro de vidro Vitremer-3M apresenta bom desempenho clínico nos casos de lesões incipientes, de pré-molares e molares, em áreas de poucos esforços oclusais, principalmente em pacientes de alto risco...

Hipermineralizaçäo da dentina a partir dos cimentos ionoméricos: aspectos de relevância clínica / Dentin hypermineralization due to ionomeric cements: aspects of clinical relevance

O presente trabalho embasado em uma análise sistemática da Literatura teve por objetivo avaliar aspectos histológicos e biológicos de relevância clínica com relaçäo à suposta bioatividade dos cimentos ionoméricos aplicados ao substrato dentinário. Fatores como hipermineralizaçäo dentinária, efeito inibidor ou mesmo paralisador de lesöes de cárie na dentina säo discutidos comparando os cimentos ionoméricos a outros materiais

Utilizaçäo clínica de cimentos ionoméricos híbridos como dentina artificial / clinical use of hybrid ionomers cements as dentin substitutes

O objetivo desse trabalho é relatar um caso clínico, no qual foi utilizado um cimento de ionômero de vidro modificado por resina como suporte para o esmalte socavado, tendo a funçäo de dentina artificial, para posteriormente ser restaurado com amálgama de prata. Devido a esse procedimento, o preparo cavitário realizado foi mais conservador, ao mesmo tempo que se promoveu um esforço das estruturas dentais, as quais se encontravam friáveis

Avaliação in vitro da liberação de flúor de cimentos de ionômero de vidro utilizados na técnica da restauração atraumática, antes e após aplicação tópica de NaF 2 por cento / In vitro fluoride release evaluation from glass ionomer cements used in the atraumatic restorative treatment, before and after 2 percent Naf topical application

O objetivo deste estudo in vitro foi avaliar a capacidade de liberação e "recarregamento" de flúor de dois cimentos de ionômero de vidro utilizados na técnica de restauração atraumática (Fuji IX e Ketac Molar) e compará-los com um cimento de ionômero de vidro convencional (Chelon Fil). Para cada material, foram preparados 3 corpos de prova com área de 1,64 cm². Os espécimes foram imersos em 3 ml de água deionizada a 37ºC. A análise foi realizada utilizando-se um eletrodo específico para íons flúor após, 1, 2, 3, 4, 5, 6, 7, 14, 21 e 28 dias. No 30º dia, os espécimes receberam a aplicação de um gel de NaF a 2 por cento por 4 minutos, sendo realizada nova análise após 1, 2 e 3 dias, a fim de se avaliar a capacidade de "recarregamento" de flúor dos materiais. Os resultados obtido foram analisados estatisticamente aplicando-se o teste ANOVA. Observou-se que todos os materiais liberaram quantidades significantes de flúor, com uma liberação inicial acentuada nos primeiros dias que tendeu a uma estabilização nos dias seguintes. O Chelon Fil liberou significativamente mais flúor que o Fuji IX e o Ketac Molar nos dias 1 e 2, sendo que estes dois não foram estatisticamente diferentes entre si. Apenas no 1º dia após o "recarregamento" houve aumento da liberação de flúor pelos materiais testados, sendo significante somente a diferença entre o Chelon Fil e o Fuji IX, maior para o Chelon Fil somente no 1º dia

Avaliaçäo in vitro da liberaçäo de flúor de cimentos de ionômero de vidro e outros materiais que contêm flúor / In vitro release from glass-ionomer cement and other materials

Este estudo avaliou in vitro, durante 28 dias, a propriedade de liberaçäo de flúor de cimentos de ionômero de vidro (CIV) restauradores e outros materiais que contêm flúor. Os resultados mostraram que o padräo de liberaçäo de flúor foi semelhante para todos os CIV testados, sendo que houve uma liberaçäo inicial acentuada, seguida por um rápido declínio, tendendo a uma estabilizaçäo após 7 dias. Os CIV liberaram mais flúor do uma resina composta e um selante de cicatrículas e fissuras. Dentre todos os materiais, o Vitrion R foi o que mais liberou flúor

Liberaçäo de fluoretos pelo cimento de ionômero de vidro: consideraçöes de interesse clínico / The fluoride released by glass-ionomer cements: clinical considerations

O cimento de ionômero de vidro tem sido um material cada vez mais empregado em Odontologia, principalmente em funçäo de seu potencial de liberaçäo de fluoretos. Porém, muitas dúvidas existem quanto às características que envolvem esse processo. A fim de esclarecer esses questionamentos, o presente trabalho discorre sobre fatores tais como: liberaçäo de flúor do cimento de ionômero de vidro para esmalte, dentina, placa e saliva, propriedades que interferem com a liberaçäo de flúor, recarregamento do material com flúor e sua atuaçäo no processo de des-remineralizaçäo do esmalte

The comparative evaluation of release profiles of aluminium, fluoride, sodium and strontium by resin modified and conventional glass polyalkenoate cements in neutral and acidic medium--an in vitro study.

The present study was carried out to evaluate the Al, F, Na and Sr release profiles of conventional and resin modified glass polyalkenoate cements in neutral (deionized water) and acidic medium (lactic acid). Twelve pellets of each material were prepared under standardised conditions and were immersed in their respective solutions for a study period of 90 days. Fluoride analysis was carried out by Orion Electrode and the other elemental analysis were done by Atomic Absorption Spectrophotometer. Statistical analysis revealed no significant difference in the Al, F and Na release profiles between the two materials in both neutral and acidic media.

Inhibitive effect of a resin-modified glass ionomer cement on remote enamel artificial caries.

Glass ionomer cements (GICs) demonstrate the inhibition of caries lesions formed immediately adjacent to the restoration. This in vitro study was conducted to evaluate the distance at which a resin-modified GIC is able to exert its cariostatic effect on artificial enamel lesions ('remote effect'). Resin-modified GIC or bis-GMA resin was applied on the cervical third of the labial surface of 10 paired halves of bovine incisors. Specimens were separately immersed for 3 weeks in lactic acid gel which was changed every other day to reduce fluoride accumulation. Artificial lesions were examined by the cross-sectional microhardness (MHN) method. Volume percent mineral, mineral loss (delta Z value) and change in mineral content (delta M) were computed for each MHN profile, performed at distances of 0.2, 0.5, 1.0, 2.0, 4.0 and 7.0 mm from the edge of the materials. delta Z values of the resin-modified GIC group were significantly lower than those of the bis-GMA control group at all remote sites (t test, p < 0.05). The delta M caused by resin-modified GIC was more pronounced within 1.0 mm from the material which suggested that the demineralization inhibition can be divided into the near effect (< 1.0 mm). In this in vitro study, resin-modified GIC provided caries resistance in bovine enamel located at a considerable distance from the margin of the material.

Efeito da aplicaçäo tópica de flúor sobre o cimento de ionômero de vidro restaurador quando protegido com diferentes materiais: estudo in situ / Effect of topical fluoride application on glass ionomer restotative material with or without protect by surface treatment: in situ study

Foi avaliado o efeito de uma ou quatro aplicaçöes de flúor sobre superfícies de cimento de ionômero de vidro restaurador, que receberam ou näo proteçäo superficial com verniz especial ou selante. Observou-se que maior alteraçäo foi causada pelo flúor fosfato acidulado após quatro semanas e que o melhor material utilizado para proteçäo foi o selante de fossas e fissuras

Resistência ao cisalhamento da uniäo de cimentos de ionômero de vidro à dentina, em relaçäo à profundidade do substrato e ao tipo de ativaçäo do material / Shear strength of bonding between glass ionomer cements and dentin regarding substrate depth and type of material

Um dos grandes objetivos da odontologia restauradora e preocupaçäo constante dos pesquisadores da área tem sido encontrar um material que apresente adesäo às estruturas dentárias, impedindo desta forma a infiltraçäo de fluidos bucais e microorganismos que possam comprometer as estruturas remanescentes. Graças ao advento de novas técnicas e novos materiais restauradores, pode-se afirmar que chegou-se hoje a um estágio bastante promissor. Entre os novos materiais, os cimentos de ionômero de vidro, comercializados a partir da década de 70, tinham como principal objetivo aderir às estruturas dentárias, devido a sua composiçäo, sua capacidade de molhamento e troca iônica com o substrato. Mais recentemente, o lançamento dos cimentos de ionômero de vidro fotoativados tornou disponível um material que, paralelamente às qualidades inerentes aos cimentos de ionômero convencionais, demonstra superioridade nas propriedades físicas e mecânicas. Com base nos materiais existentes, avaliou-se entäo a capacidade de adesäo de dois cimentos de ionômero de vidro químicos (Vidrion R e Chelon Fil) e um cimento fotoativado (Vitremer), através da resistência ao cisalhamento, em relaçäo à profundidade do substrato-dentina superficial e dentina profunda. De acordo com a metodologia empregada, observou-se que o cimento de ionômero de vidro fotoativado apresentou valores mais altos, tendo portanto maior resistência ao cisalhamento do que os cimentos de ionômero de vidro convencionais. Em relaçäo ao substrato, observou-se que, tanto os cimentos de ionômero de vidro convencionais quanto o cimento de ionômero de vidro fotoativado tiveram uma resistência ao cisalhamento mais alta em dentina profunda do que em dentina superficial

Efeito da aplicaçäo de flúor sobre cimento de ionômero de vidro restaurador quando protegido com diferentes materiais: estudo in vitro / Topic application of fluoride gel on glass ionomer restorative material protected by surface treatments. In vitro study

Este estudo avaliou in vitro o efeito da aplicaçäo tópica de flúor sobre superfícies de ionômero de vidro que receberam diferentes tipos de proteçäo superficial. Os resultados mostraram que quando a superfície do material estava protegida por selante (Fluoroshied), o flúor fosfato acidulado näo provocou alteraçöes. Pouca degradaçäo foi observada quando o cimento de ionômero de vidro estava revestido por verniz especial e grande perda de material ocorreu quando o mesmo näo recebeu nenhum tipo de proteçäo