Effect of a resin-modified glass-ionomer with calcium on enamel demineralization inhibition: an in vitro study

Abstract We assessed the effect of a new coating material based on resin-modified glass-ionomer with calcium (Ca) in inhibiting the demineralization of underlying and adjacent areas surrounding caries-like lesions in enamel. The measures used were surface hardness (SH) and cross-sectional hardness (CSH). Thirty-six bovine enamel specimens (3 × 6 × 2 mm) were randomly allocated into three groups (n = 12): No treatment (NT); resin-modified glass-ionomer with Ca (Clinpro XT Varnish, 3M ESPE) (CL), and fluoride varnish (Duraphat, Colgate) (DU). The specimens were subjected to alternated immersions in demineralizing (6 h) and remineralizing solutions (18 h) for 7 days. SH measurements were conducted at standard distances of 150, 300, and 450 µm from the treatment area. CSH evaluated the mean hardness profile over the depth of the enamel surface and at standard distances from the materials. The energy-dispersive X-ray spectroscopy analysis was conducted to evaluate the demineralization bands created on the sublayer by % of calcium (Ca), phosphorus (P), and fluoride (F). Ca/P weight ratio was also calculated. Based on SH and CSH measurements, there was no difference between groups at the distances 150 µm (p = 0.882), 300 µm (p = 0.995), and 450 µm (p = 0.998). Up to 50 µm depth (at 150 µm from the treatment area), CL showed better performance than DU ( p< 0.05). NT presented higher loss of Ca and P than CL and DU (p < 0.05). There was no significant difference in the % of F ion among the three groups. The new coating material was similar to F varnish in attenuating enamel demineralization.

Fluoride release and uptake in enhanced bioactivity glass ionomer cement ("glass carbomer™") compared with conventional and resin-modified glass ionomer cements

Abstract Objectives To study the fluoride uptake and release properties of glass carbomer dental cements and compare them with those of conventional and resin-modified glass ionomers. Materials and Methods Three materials were used, as follows: glass carbomer (Glass Fill), conventional glass ionomer (Chemfil Rock) and resin-modified glass ionomer (Fuji II LC). For all materials, specimens (sets of six) were matured at room temperature for time intervals of 10 minutes, 1 hour and 6 weeks, then exposed to either deionized water or sodium fluoride solution (1000 ppm in fluoride) for 24 hours. Following this, all specimens were placed in deionized water for additional 24 hours and fluoride release was measured. Results Storage in water led to increase in mass in all cases due to water uptake, with uptake varying with maturing time and material type. Storage in aqueous NaF led to variable results. Glass carbomer showed mass losses at all maturing times, whereas the conventional glass ionomer gained mass for some maturing times, and the resin-modified glass ionomer gained mass for all maturing times. All materials released fluoride into deionized water, with glass carbomer showing the highest release. For both types of glass ionomer, uptake of fluoride led to enhanced fluoride release into deionized water. In contrast, uptake by glass carbomer did not lead to increased fluoride release, although it was substantially higher than the uptake by both types of glass ionomer. Conclusions Glass carbomer resembles glass ionomer cements in its fluoride uptake behavior but differs when considering that its fluoride uptake does not lead to increased fluoride release.

TiF4 varnish protects the retention of brackets to enamel after in vitro mild erosive challenge

Abstract The effect of fluoride agents on the retention of orthodontic brackets to enamel under erosive challenge is little investigated. Objective: The aim of this study was to evaluate the effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) agents on the shear bond strength of brackets to enamel and on the enamel microhardness around brackets under erosive challenge. Methods: Brackets were bonded to bovine incisors. Five groups were formed according to fluoride application (n=10): TiF4 varnish, TiF4 solution, NaF varnish, NaF solution and control (without application). The specimens were submitted to erosive challenge (90 s cola drink/2h artificial saliva, 4x per day for 7 days). Solutions were applied before each erosive cycle and varnishes were applied once. Vickers Microhardness (VHN) was obtained before and after all cycles of erosion and the percentage of microhardness loss was calculated. Shear bond strength, adhesive remnant index and polarized light microscopy were conducted after erosion. The data were analyzed by ANOVA, Tukey, Kruskal-Wallis and Mann-Whitney U tests (α=0.05). Results: The %VHN had no statistically significant differences among the experimental groups. However, considering the comparisons of all groups with the control group, TiF4 varnish showed the highest protection from enamel demineralization (effect size of 2.94, while the effect size for the other groups was >2.4). The TiF4 varnish group had significantly higher shear bond strength compared to other groups. There was no difference among groups for adhesive remnant index. Polarized light microscopy showed higher demineralization depth for the control group. Conclusions: Application of NaF and TiF4 agents during mild erosive challenge minimized the enamel mineral loss around brackets, however only the experimental TiF4 varnish was able to prevent the reduction of shear bond strength of brackets to enamel.

The use of sodium trimetaphosphate for matrix metalloproteinase inhibition, remineralization and bonding to dentin / O uso de trimetafosfato de sódio sobre a inibição de metaloproteinases e na remineralização e adesão à dentina

The adhesive process to dentin substrate depends on the condition determined by the combined action of the mineral loss and the endogenous enzymes activity. Thus, considering a more complete therapeutic approach, sodium trimetaphosphate (STMP) may be a novel strategy that conciliates the remineralization potential to the promotion of dentin strengthening and its stability, possibly directing mineral nucleation and controlling the rate of biodegradation. In this study, the effect of STMP was evaluated in 2 studies. In study 1, different concentrations of STMP (0.5, 1.5, 3.5 and 5%) were investigated to assess their anti-proteolytic capacity on human purified MMPs-2 and -9 by zymography. Afterwards, only the concentrations (1.5, 3.5 and 5%) that showed total inhibition of both MMPs were used to evaluate their remineralizing capacity in dentin substrate submitted to artificial cariogenic challenge, through surface hardness (SH) and cross-sectional hardness (CSH). In study 2, based on the previous results, the capacity of the 1.5% STMP associated or not with NaF or Ca(OH)2 solutions in improving the dentin bond strength of a universal adhesive system was evaluated by the microtensile test . Thus, these studies suggest that 1.5% STMP is an effective inhibitor of collagen degradation mediated by purified human MMPs-2 and -9. In addition, demineralized and treated dentin with 1.5% STMP supplemented with Ca(OH)2 may induce remineralization. Thus, the use of STMP can be introduced as a new strategy that combines enzymatic inhibition and remineralization potential, reestablishing favorable conditions to affected dentin. These evidences support perspectives of therapies to restructure dentin and propose feasible and promising clinical strategies.(AU)

O processo adesivo ao substrato dentinário depende da condição determinada pela ação combinada da perda mineral e atividade de enzimas endógenas. Deste modo, considerando uma abordagem terapêutica mais completa, o trimetafosfato de sódio (STMP) pode ser uma estratégia inovadora que concilia o potencial remineralizador à promoção do fortalecimento da dentina e sua estabilidade, possivelmente direcionando a nucleação mineral e controlando a taxa de biodegradação. Neste trabalho, o efeito do STMP foi avaliado em 2 estudos. No estudo 1, diferentes concentrações de STMP (0,5; 1,5; 3,5 e 5%) foram investigadas para avaliar sua capacidade anti-proteolítica sobre as MMPs-2 e -9 purificadas humanas, por zimografia. Posteriormente, somente as concentrações (1,5; 3,5 e 5%) que apresentaram capacidade de inibição total de ambas MMPs foram utilizadas para avaliar sua capacidade remineralizadora em substrato dentinário submetido ao desafio cariogênico artificial, através da dureza de superfície (DS) e longitudinal (DL). No estudo 2, baseado nos resultados anteriores, foi avaliada a capacidade do STMP à 1,5% associado ou não a soluções de NaF ou Ca(OH)2 em melhorar a resistência de união à dentina de um sistema adesivo universal pelo teste de microtração. Desta forma, estes estudos sugerem que o STMP à 1,5% apresenta-se como um inibidor eficaz da degradação do colágeno mediada por MMPs-2 e -9 humanas purificadas. Além disso, a dentina humana desmineralizada e tratada com STMP à 1,5% suplementada com Ca(OH)2 pode induzir à remineralização. Assim, o uso de STMP pode ser introduzido como uma nova estratégia que combina inibição enzimática e potencial de remineralização, reestabelecendo condições favoráveis a partir de uma dentina afetada. Estas evidências sustentam perspectivas de terapias para reestruturar a dentina e propor estratégias clínicas factíveis e promissoras.(AU)

Papel das proteases na erosão dentinária / The role of proteases on dental erosion

Na dentina, a matriz orgânica desmineralizada tem um papel protetor contra desafios erosivos subsequentes. Porém, essa camada pode ser degradada por proteases, como as metaloproteinases da matriz (MMPs) e cisteína catepsinas (CCs). Recentemente, o uso de inibidores de proteases da matriz surgiu como uma importante ferramenta preventiva contra a erosão dentinária. Entretanto, o(s) mecanismo(s) exato(s) pelo(s) qual(is) os inibidores de proteases podem prevenir a erosão dentinária, bem como os tipos de proteases mais envolvidas neste processo ainda não são completamente conhecidos. O projeto foi desenvolvido em 2 subprojetos, com os seguintes objetivos: A)Subprojeto 1:Avaliar o papel das proteases na progressão da erosão dentária; B)subprojeto 2: Testar o potencial inibitório do NaF em CCs dentinárias. Para cumprir esses objetivos, foram utilizadas dentina de terceiros molares humanos para a preparação dos espécimes. A)Subprojeto1:Blocos de dentina (4 X 4 x 2 mm) (n=119) foram obtidos de raízes. Os espécimes foram divididos em 7 grupos de acordo com o seu tratamento (E-64, inibidor especifico II de catepsinas B, clorexidina, galardina NaF, placebo) ou sem tratamento, géis foram aplicados uma única vez sobre a superfície e feito o desafio erosivo (90s, 4x por dia por 5 dias) e feita analise perfilométrica. Os espécimes foram incubadas em solução contendo colagenase de Clostridium histolyticum tipo VII por 96hrs e então feita uma segunda analise perfilometrica para se determinar a espessura da MOD. Dois espécimes foram separados para análise de microscopia eletrônica de varredura. B)Subprojeto 2: Palitos de dentina (6 mm X 2 mm X 1 mm) (n=60) foram cortados da porção médio coronária dos dentes e completamente desmineralizados por imersão em EDTA 0,5 M (pH7,4) por 30 dias e lavados em água deionizada sob constante agitação a 4ºC por 72 h. Os espécimes foram divididos em 6 grupos (E-64, NaF e controle negativo, pH 5,5 ou 7,2) e incubados em saliva artificial contendo seus respectivos inibidores por 24 h 7 dias e 21 dias; ao termino de cada período, os espécimes eram pesados para avaliar a perda de massa e analisada a presença de CTX. A)Subprojeto 1: a perda de tecido desmineralizado (m, média± SD) foi: CHX 8,4±1,7b, Gala 8,6±1,9b, IECB 9,6±1,4a, E64 9,9±1,3a, NaF 9,9±1,7a, P 10,9±2,2a, ST 11,0±1,5a. A perda de tecido mineralizado foi: CHX 15,4±2,2b, Gala 16,0±1,8b, IECB 17,6±2,4a, E64 17,6±2,0a, NaF 17,3±2,8a, P 19,1±2,1a, ST 18,9±2,4a. Os inibidores de MMP reduziu significativamente a perda de matriz orgânica e tecido mineralizado em comparação com os outros grupos (p<0,05). Não foi achada diferença significante entre a espessura da matriz orgânica desmineralizada remanescente (p=0,845). B)Subprojeto 2: Na perda de massa houve diferença significante em relação ao inibidor (F=20,047, p<0,0001) e tempo de incubação (F=222,462, p<0,0001) com significante interação entre esses critérios, nos período de menor tempo de incubação, a perda foi similar para todos os grupos testados, no período de maior tempo de incubação, o grupo contendo NaF demostrou os melhores resultados. Na analise de CTX, houve diferença significante em relação aos inibidores (F46,543, p<0,0001), pH (F=14,836, p<0,0004) e tempo de incubação (F=161,438, p<0,0001) com significante interação entre esses critérios, como ocorrido na perda de massa, não houve diferença estatística nos períodos de menor incubação. No período de maior tempo de incubação, mais uma vez o grupo NaF mostrou os melhores resultados. No valor acumulado de CTX, os grupos E64 e controle negativo tiveram os maiores valores de CTX acumulado, o grupo NaF, independente do pH mostrou redução significante em relação aos demais grupos. Após analise dos resultados dos dois subprojetos, podemos indicar que as MMPs são as proteases de maior importância na progressão da erosão dentinária, assim, sua inibição é de maior importância para a redução desta patologia. Mesmo as CCs não exercendo papel direto para a progressão da erosão, elas são efetivas na cascata da ativação de outras proteases, como as próprias MMPs. Com isso, sua inibição também pode ser importante para a redução indireta da progressão da erosão. Neste presente estudo, pudemos comprovar que o NaF tem potencial inibitório sobre as CCs dentinárias, assim, sugerindo um novo inbidor de CCs. Com os resultados deste estudo, podemos afirmar que as MMPs são as principais proteases na progressão da erosão dentinária e que o NaF tem potencial inibitório nas CCs dentinárias.(AU)

In the dentine, the demineralized organic matrix has a protector part against the following erosive challenges. Nevertheless, this layer can be degraded by proteases, like the matrix metalloproteinases (MMPS) and cystein cathepsins (CCs). Recently, the use of proteases of the matrix´s inhibitors, emerged as an important preventive tool against the dentinária erosion. However, the exact mechanisms from which the inhibitors of the proteases may prevent the dentin erosion, as much as the kinds of proteases more involved in this process are not completely known yet. Therefore, the general objective of this project was to investigate the part of the two main proteases of the matrix (MMPs and CCs) in the dental erosion. The project was developed in 2 subprojects, with the following objectives: A)Subproject 1: Evaluate the part of the proteases in the progression of the dental erosion; B)subproject 2: To test the NaF inhibitory potencial in the dentin CCs. To accomplish these objectives, human third molar dentin were used for the preparation of the specimens, obtained in the surgery and urgency clinics of FOB-USP (subproject 1) or granted by the University of Oulu (subproject 2). A) Subproject 1: Dentine blocks 4 X 4 X 2 mm) (n=119) were obtained from the roots of the obtained teeth. The specimens were divided in 7 groups according with their treatment. Gels containing inhibitors (E-64, specific cathepsin B inhibitor II, chlorhexidine, galardin NaF, placebo), or without treatment, were produced, applied only one time over the surface and made the erosive challenge (90s, 4x a day for 5 days) and made profilometric analysis. The specimens were incubated in a solution containing collagenase of Clostridium histolyticum type VII for 96 hours and then a second profilometric analysis was made to determine the thickness of the MOD. Two specimens were separated for the electronic microscopy scan analysis. B) Subproject 2: Dentine sticks (6 mm X 2 mm X 1 mm) (n=60) were cut from the medium coronary portion of the teeth and completely demineralized by immersion in EDTA 0,5 M (pH7,4) ifor 30 days and washed in deionized water under constant agitation in 4º C for 72 hours. The specimens were divided in 6 groups (divided by inhibitors: E-64, NaF and negative control, pH 5,5 or 7,2) and incubated in artificial saliva containing their respective inhibitors for 24 hours, 7 days and 21 days; by the end of each period, the specimens were weighted to evaluate the loss of mass and analised the presence of CTX. A)Subproject 1: the loss of demineralized tissue (m, média± SD) was : CHX 8,4±1,7b, Gala 8,6±1,9b, IECB 9,6±1,4a, E64 9,9±1,3a, NaF 9,9±1,7a, P 10,9±2,2a, ST 11,0±1,5a. The loss of demineralized tissue was: CHX 15,4±2,2b, Gala 16,0±1,8b, IECB 17,6±2,4a, E64 17,6±2,0a, NaF 17,3±2,8a, P 19,1±2,1a, ST 18,9±2,4a. The MMP inhibitors reduced significantly the loss of organic matrix and demineralized tissue in comparison with other groups (p<0,05). There was no significant difference found between the thickness of the remaining demineralized organic matrix.(p=0,845). B)Subproject: In the loss of mass, there was a significant difference in relation to the inhibitor (F=20,047, p<0,0001) and incubation time (F=222,462, p<0,0001) with significant interaction between these criteria, in the periods of lesser time of incubation, the loss was similar for all the tested groups, in the period of higher time of incubation, the group containing NaF demonstrated the best results. In the analysis of CTX, there was significant difference in relation the inhibitors (F46,543, p<0,0001), pH (F=14,836, p<0,0004) and time of incubation (F=161,438, p<0,0001)with significant interaction between these criteria, as occurred in the mass loss, there was no statistic difference in the period of lesser incubation. In the period of higher time of incubation, once again, the NaF group demonstrated the best results. The CTX accumulated value, the E64 groups and negative control had the greater accumulated values of CTX, the NaF group, regardlessof the pH, demonstrated significant reduction in relation to the other groups. After the analysisof the results of both subprojects, we can indicate that the MMPs are the proteases of greater importance in the progression of the dentin erosion, thus, its inhibition is of graeter importance for the reduction of this pathology. Even the CCs don´t playing the part directly for the progression of erosion, they are effective in the cascade of the activation of other proteases, like the MMPs themselves. In this manner, its inhibition can also be important for the indirect reduction of the progression of the erosion. In this present study, we can prove that the NaF has inhibiting potential over the dentin CCs, thus, suggesting a new inhibitor of CCs. With the results of this study, we can affirm that the MMPs are the main proteases in the progression of the dentin erosion and that the NaF has inhibiting potential in the dentin CCs.(AU)

Evaluación de fluoruro residual en saliva después de la aplicación de barnices fluorados al 2.26 por ciento: estudio comparativo / An evaluation of the residual fluoride in saliva after applying 2.26 per cent fluoride varnishes: a comparative study

El objetivo de este estudio fue comparar la cantidad de fluoruro (F) residual en saliva después de la aplicación de barniz de fluoruro desodio al 5 por ciento y de barniz fluorado con fosfato tricálcico al 5 por ciento en niños de 2 a 5 años de edad. Se recolectó la saliva no estimulada de 24 niños que tenían acceso a sal fluorada diariamente y utilizaban dentífricos infantiles conteniendo 550 ppm F. La primera toma de muestrasalival fue colectada como basal y las siguientes fueron tomadas en diferentes intervalos de tiempo luego de realizar la aplicación del barnizfluorado (15; 30; 60 minutos y 24; 48; 72; 96; 168 horas). Un total de 216 muestras fueron obtenidas, siendo 96 muestras de barniz de Duraphat®, 96 muestras de barniz de ClinproTM WV y 24 muestras muestras basales. Los análisis de laboratorio fueron realizadosen el departamento de Bioquímica de la Facultad de Odontología de Baurú (FOB), Universidad de Sao Paulo. Un electrodo Orión 9409 y un microelectrodo acoplados a un potenciómetro Orion EA 940 se utilizaron para analizar las muestras previa difusión de las muestrascon el método de Taves. La concentración de iones de flúor mostró diferencias estadísticamente significativas entre ambos productos desde las 24 horas (p<0.001), esta característica se repite a las 48 (p=0.003); 96 (p<0.001) y 168 horas (p<0.001). Se utilizó el análisisestadístico de Shapiro Wilks y T de Student. Ambos barnices mostraron un incremento de fluoruro residual en saliva durante los 15; 30 y 60 minutos, sin embargo, posteriormente a estos tiempos, ambos muestran niveles no significativamente diferentes al basal.

The aim of this study was compared the amount of residual fluoride after application of sodium fluoride varnish 5% and application offluoride varnish with phosphate tricalcium 5% in children from 2 to 5 years old. Unstimulated saliva was collected of 24 children who hadaccess to fluoridate salt daily and used children´s tooth pastes containing 550ppm F. The first salivary sample was collected as a base lineand the following were taken at different intervals after making the application of fluoride varnish (15; 30; 60 minutes; 24; 48; 72; 96;168 hours).Children were grouped in two groups according of type of varnish containing fluoride going to be applied. A total of 216samples were obtained, 96 samples from Duraphat® and 96 samples from ClinproTM WV 3M ESPE. The lab analyzes wereconducted in the Department of Biochemistry at the Faculty of Dentistry, Bauru (FOB), University of Sao Paulo. An Orion 9409electrode and a microelectrode coupled to a potentiometer Orion EA 940 analyzed the samples prior dissemination of samples with themethod of work. The fluoride concentration was statistically significant after 24 (p<0.001); 48 (p=0.003); 96 (p<0.001) y 168 hours(p<0.001) for both products. We used Shapiro Wilks and T student test for statistical analysis. Both products showed an increased inresidual fluoride in saliva during the 15; 30 and 60 minutes, however, both showed not differences that baseline levels.

Fluoride and sodium trimetaphosphate (TMP) release from fluoride varnishes supplemented with TMP

Abstract This study assessed fluoride (F) and sodium trimetaphosphate (TMP) release into artificial saliva from varnishes containing 0%, 2.5%, and 5% NaF, supplemented or not with 5% TMP. The varnishes were applied on polyester sheets (n = 8/group), and F and TMP released into artificial saliva were measured for up to 24 hours. The amount of F and TMP released were directly related to NaF and TMP concentrations in the varnishes. The highest F release was seen for 5% NaF and 5% NaF + 5% TMP, whereas 5% TMP released the highest amount of TMP. However, the simultaneous addition of NaF and TMP to varnishes significantly reduced the amount of F and TMP released from the products.

Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion

Abstract The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey's test and Student's t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.

F-18 Sodium Fluoride Positron Emission Tomography/Computed Tomography for Detection of Thyroid Cancer Bone Metastasis Compared with Bone Scintigraphy

OBJECTIVE: The aim of the study was to compare the diagnostic performances of F-18 sodium fluoride positron emission tomography/computed tomography (bone PET/CT) and bone scintigraphy (BS) for the detection of thyroid cancer bone metastasis. MATERIALS AND METHODS: We retrospectively enrolled 6 thyroid cancer patients (age = 44.7 ± 9.8 years, M:F = 1:5, papillary:follicular = 2:4) with suspected bone metastatic lesions in the whole body iodine scintigraphy or BS, who subsequently underwent bone PET/CT. Pathologic diagnosis was conducted for 4 lesions of 4 patients. RESULTS: Of the 17 suspected bone lesions, 10 were metastatic and 7 benign. Compared to BS, bone PET/CT exhibited superior sensitivity (10/10 = 100% vs. 2/10 = 20%, p = 0.008), and accuracy (14/17 = 82.4% vs. 7/17 = 41.2%, p 0.05). CONCLUSION: Bone PET/CT may be more sensitive and accurate than BS for the detection of thyroid cancer bone metastasis.

Protective effect of experimental mouthrinses containing NaF and TiF4 on dentin erosive loss in vitro

Objective This in vitro study assessed the anti-erosive effect of experimental mouthrinses containing TiF4 and NaF on dentin erosive loss.Material and Methods Bovine dentin specimens were randomly allocated into the groups (n=15): 1) SnCl2/NaF/AmF (Erosion Protection®/GABA, pH 4.5, positive control); 2) experimental solution with 0.0815% TiF4(pH 2.5); 3) 0.105% NaF (pH 4.5); 4) 0.042% NaF+0.049% TiF4 (pH 4.4); 5) 0.063% NaF+0.036% TiF4 (pH 4.5); 6) no treatment (negative control). Each specimen was cyclically demineralized (Sprite Zero, pH 2.6, 4x90 s/day) and exposed to artificial saliva between the erosive challenges for 7 days. The treatment with the fluoride solutions was done 2x60 s/day, immediately after the first and the last erosive challenges of the day. Dentin erosive loss was measured by profilometry (μm). The data were analyzed using Kruskal Wallis/Dunn tests (p<0.05).Results Mouthrinses containing TiF4or Sn/F were able to show some protective effect against dentin erosive loss compared to negative control. The best anti-erosive effect was found for experimental solution containing 0.0815% TiF4 (100% reduction in dentin loss), followed by 0.042% NaF+0.049% TiF4 (58.3%), SnCl2/NaF/AmF (52%) and 0.063% NaF+0.036% TiF4 (40%). NaF solution (13.3%) did not significantly differ from control.Conclusion The daily application of experimental mouthrinse containing TiF4and NaF has the ability to reduce dentin erosion, as well as Erosion Protection® and TiF4 alone.

Avaliação da interação do TiF4 com a hidroxiapatita e esmalte bem como o efeito sobre a des-remineralização do esmalte dentário com lesão de cárie artificial in situ / Interaction of TiF4 varnish with enamel and hydroxyapatite and its effect on the de-remineralization of pre-demineralized enamel in situ

Este estudo teve como o objetivo avaliar in vitro o efeito do tratamento com vernizes de tetrafluoreto de titânio (TiF4) e fluoreto de sódio (NaF) (ambos com 0,95%, 1,95% e 2,45% F) sobre 1) a quantidade de F- liberada em água deionizada e saliva artificial, por período de 12h; 2) os tipos de compostos formados pela interação com a hidroxiapatita (neste caso, com soluções ao invés dos vernizes); 3) a porcentagem de elementos presentes na superfície do esmalte bovino e humano, hígidos (H) e desmineralizados (DES); 4) a quantidade de CaF2 sobre a superfície do esmalte bovino e humano, H e DES. Adicionalmente, 5) o efeito dos vernizes de TiF4 e NaF sobre a remineralização do esmalte bovino, em diferentes condições in situ, foi avaliado. Para etapa 1, a liberação de F- foi quantificada por eletrodo de íon específico. Na etapa 2, pó de HAP produzido por precipitação foi tratado com soluções fluoretadas. Os compostos formados foram avaliados por espectroscopia de infravermelho e difração de raios-X. Nas etapas 3 e 4, as superfícies tratadas com os vernizes foram analisadas por MEV- EDAX e por biópsias básicas, respectivamente. Vinte voluntários (n final=17) participaram do ensaio in situ com 3 fases cruzadas, os quais utilizaram aparelhos palatinos contendo amostras de esmalte bovino desmineralizadas tratadas com vernizes de TiF4, NaF ou placebo. As amostras foram submetidas a diferentes condições de des-remineralização (presença ou não de tela plástica; variação da frequência de aplicação de sacarose 20%) e à exposição ao dentifrício fluoretado. O volume mineral e profundidade da lesão foram avaliados por microradiografia transversal (TMR). 1) Os vernizes de TiF4 (1,95 e 2,45% F) liberaram mais fluoreto comparados aos vernizes de NaF tanto em água como em saliva artificial, sendo a diferença significativa nas primeiras 6h de contato (p<0,0001). 2) O TiF4 causou alteração na estrutura da HAP e induziu à formação de novos compostos como TiO2 e Ti (HPO4)2. 3)...

This study aimed to evaluate the in vitro effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) varnishes (both with 0.95%, 1.95%, 2.45% F) treatment on the 1) F- release in deionized water and artificial saliva for 12h period; 2) types of compounds formed by the interaction with hydroxyapatite (in this case, solutions were tested instead of varnishes); 3) percentage of the elements on bovine and human, sound (S) and demineralized (DE), enamel surface; 4) F- uptake (CaF2 deposition) on human and bovine, S and DE, enamel surface. Additionally, 5) the effect of TiF4 and NaF varnishes on bovine enamel remineralization, in different in situ conditions, was assessed. In study 1, the F- release was measured by ion specific electrode. In study 2, HAP powder, produced by precipitation, was treated with fluoride solutions. The compounds formed were evaluated by infrared spectroscopy and X-ray diffraction. In studies 3 and 4, the surfaces treated with the varnishes were analyzed by SEM-EDAX and basic biopsies, respectively. Twenty volunteers (final n=17) participated of the in situ study with 3 crossover phases, in which they wore palatal appliances containing bovine demineralized enamel samples treated with TiF4, NaF or placebo varnishes. The samples were subjected to different de-remineralization conditions (presence or absence of plastic mesh and variation in frequency of application of 20% sucrose) and exposure to fluoride dentifrice. Themineral content and lesion depth were evaluated by transverse microradiography (TMR). 1) The TiF4 varnishes (1.95 and 2.45% F) released more F- compared to NaF varnishes in both water and artificial saliva, and significant difference was found in the first 6h (p<0.0001). 2) The TiF4 caused change in the HAP structure and induced the formation of new compounds such as TiO2 and Ti (HPO4)2. 3) The TiF4 varnishes induced the formation of a coating layer rich in Ti and F, with microcracks in its extension, on the enamel...

Avaliação da interação do TiF4 com a hidroxiapatita e esmalte bem como o efeito sobre a des-remineralização do esmalte dentário com lesão de cárie artificial in situ / Interaction of TiF4 varnish with enamel and hydroxyapatite and its effect on the de-remineralization of pre-demineralized enamel in situ

Este estudo teve como o objetivo avaliar in vitro o efeito do tratamento com vernizes de tetrafluoreto de titânio (TiF4) e fluoreto de sódio (NaF) (ambos com 0,95%, 1,95% e 2,45% F) sobre 1) a quantidade de F- liberada em água deionizada e saliva artificial, por período de 12h; 2) os tipos de compostos formados pela interação com a hidroxiapatita (neste caso, com soluções ao invés dos vernizes); 3) a porcentagem de elementos presentes na superfície do esmalte bovino e humano, hígidos (H) e desmineralizados (DES); 4) a quantidade de CaF2 sobre a superfície do esmalte bovino e humano, H e DES. Adicionalmente, 5) o efeito dos vernizes de TiF4 e NaF sobre a remineralização do esmalte bovino, em diferentes condições in situ, foi avaliado. Para etapa 1, a liberação de F- foi quantificada por eletrodo de íon específico. Na etapa 2, pó de HAP produzido por precipitação foi tratado com soluções fluoretadas. Os compostos formados foram avaliados por espectroscopia de infravermelho e difração de raios-X. Nas etapas 3 e 4, as superfícies tratadas com os vernizes foram analisadas por MEV- EDAX e por biópsias básicas, respectivamente. Vinte voluntários (n final=17) participaram do ensaio in situ com 3 fases cruzadas, os quais utilizaram aparelhos palatinos contendo amostras de esmalte bovino desmineralizadas tratadas com vernizes de TiF4, NaF ou placebo. As amostras foram submetidas a diferentes condições de des-remineralização (presença ou não de tela plástica; variação da frequência de aplicação de sacarose 20%) e à exposição ao dentifrício fluoretado. O volume mineral e profundidade da lesão foram avaliados por microradiografia transversal (TMR). 1) Os vernizes de TiF4 (1,95 e 2,45% F) liberaram mais fluoreto comparados aos vernizes de NaF tanto em água como em saliva artificial, sendo a diferença significativa nas primeiras 6h de contato (p<0,0001). 2) O TiF4 causou alteração na estrutura da HAP e induziu à formação de novos compostos como TiO2 e Ti (HPO4)2. 3)...

This study aimed to evaluate the in vitro effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) varnishes (both with 0.95%, 1.95%, 2.45% F) treatment on the 1) F- release in deionized water and artificial saliva for 12h period; 2) types of compounds formed by the interaction with hydroxyapatite (in this case, solutions were tested instead of varnishes); 3) percentage of the elements on bovine and human, sound (S) and demineralized (DE), enamel surface; 4) F- uptake (CaF2 deposition) on human and bovine, S and DE, enamel surface. Additionally, 5) the effect of TiF4 and NaF varnishes on bovine enamel remineralization, in different in situ conditions, was assessed. In study 1, the F- release was measured by ion specific electrode. In study 2, HAP powder, produced by precipitation, was treated with fluoride solutions. The compounds formed were evaluated by infrared spectroscopy and X-ray diffraction. In studies 3 and 4, the surfaces treated with the varnishes were analyzed by SEM-EDAX and basic biopsies, respectively. Twenty volunteers (final n=17) participated of the in situ study with 3 crossover phases, in which they wore palatal appliances containing bovine demineralized enamel samples treated with TiF4, NaF or placebo varnishes. The samples were subjected to different de-remineralization conditions (presence or absence of plastic mesh and variation in frequency of application of 20% sucrose) and exposure to fluoride dentifrice. Themineral content and lesion depth were evaluated by transverse microradiography (TMR). 1) The TiF4 varnishes (1.95 and 2.45% F) released more F- compared to NaF varnishes in both water and artificial saliva, and significant difference was found in the first 6h (p<0.0001). 2) The TiF4 caused change in the HAP structure and induced the formation of new compounds such as TiO2 and Ti (HPO4)2. 3) The TiF4 varnishes induced the formation of a coating layer rich in Ti and F, with microcracks in its extension, on the enamel...

Fluoride varnishes with calcium glycerophosphate: fluoride release and effect on in vitro enamel demineralization

The aims of this study were (1) to assess the amount of fluoride (F) released from varnishes containing calcium glycerophosphate (CaGP) and (2) to assess the effect of the experimental varnishes on in vitrodemineralization. Six test groups using 5 varnishes: base varnish (no active ingredients); Duraphat® (2.26% NaF); Duofluorid® (5.63% NaF/CaF2); experimental varnish 1 (1% CaGP/5.63% NaF/CaF2); experimental varnish 2 (5% CaGP/5.63% NaF/CaF2); and no varnish were set up. In stage 1, 60 acrylic blocks were randomly distributed into 6 groups (n = 10). Then 300 µg of each varnish was applied to each block. The blocks were immersed in deionized water, which was changed after 1, 8, 12, 24, 48 and 72 hours. Fluoride concentration in the water was analyzed using a fluoride electrode. In stage 2, 60 bovine enamel samples were distributed into 6 groups (n = 10), and treated with 300 µg of the respective varnish. After 6 h the varnish was removed and the samples were subjected to a 7-day in vitro pH cycle (6 h demineralization/18 h remineralization per day). The demineralization was measured using surface hardness. The results showed that both experimental varnishes released more fluoride than Duofluorid® and Duraphat® (p < 0.05), but Duraphat® showed the best preventive effect by decreasing enamel hardness loss (p < 0.05). Therefore, we conclude that even though (1) the experimental varnishes containing CaGP released greater amounts of F, (2) they did not increase in the preventive effect against enamel demineralization.

Una década de monitoreo de plomo en sangre en niños escolares del área metropolitana de Monterrey, NL / A decade of lead monitoring in schoolchildren in the metropolitan area of Monterrey NL, Mexico

Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 2008, así como su asociación con factores de riesgo. Material y métodos. Se llevó a cabo un monitoreo de Pb en sangre de niños de entre 6 y 12 años que cursan educación primaria en 17 escuelas diferentes, ubicadas en distintas zonas del área metropolitana de Monterrey, de 1998 a 2008. Resultados. Se obtuvieron niveles séricos de 9.6 ± 3.0 (µg/dL rango de 3.18 a 20.88) en 1998 y de 4.5±4.8 µg/dL (rango de 3.3 a 53.7) en 2008, lo que mostró una disminución de 2.1 veces en nivel de Pb (p<0.01). Conclusiones. La reducción de los niveles séricos de Pb demuestran los mejores controles ambientales e industriales y probablemente el éxito de retirar el Pb de la gasolina durante los años noventa.

Objective. To establish the blood lead concentration and associated risk factors in schoolchildren during 1998 and 2008. Materials and methods. A blood lead screening was conducted in schoolchildren of 6-12 years of age, enrolled in 17 elementary schools of the metropolitan area of Monterrey, México, during 1998 and 2008. Results. The mean blood lead level were 9.6 ± 3.0 (µg/dL range of 3.18 to 20.88) in 1998 and 4.5±4.8 µg/dL (range of 3.3 to 53.7) showing a 2.1-times reduction in blood lead levels (p<0.01). Conclusions. This reduction in blood lead levels demonstrate environmental and industrial control improvements and the benefits of fading out the leaded gasoline during the 1990's.

Insoluble NaF in Duraphat® May Prolong Fluoride Reactivity of Varnish Retained on Dental Surfaces

There is no consensus about the clinical recommendation of the time that Duraphat® varnish should be maintained on enamel surfaces without suffering mechanical disturbance by the patient. Considering the importance of calcium fluoride (CaF2)-like reservoirs on the anticaries effect of professional fluoride application, an in vitro study was designed to test the reactivity of Duraphat® varnish with enamel forming these reservoirs as a function of time. Since most fluoride in Duraphat® varnish is insoluble to react and form products on enamel, the relative contribution of the varnish soluble and insoluble fluoride fractions to the reactivity was also evaluated. For this, whole-varnish, containing soluble and insoluble fluoride (total fluoride concentration of 23699±384 µg F/g), or centrifuged varnish, containing only soluble fluoride (fluoride concentration of 258±97 µg F/g), were applied in a standardized manner on enamel slabs (n=8/varnish group/time), which were immersed in continuously renewed artificial saliva for up to 36 h. CaF2-like reservoirs formed on enamel by varnish application were extracted using 1 M KOH and fluoride concentration was measured with ion specific electrode. The results were expressed as µg F/cm2 of enamel area. Whole varnish formed significantly higher fluoride concentration on enamel than centrifuged varnish, reaching maximum concentration at 24 h (22.0±4.5 µg F/cm2). Centrifuged varnish reached maximum concentration at 6 h (3.20±0.81 µg F/cm2). In conclusion, a longer varnish retention time than the usually recommended could improve the anticaries effect of Duraphat® varnish, allowing that NaF particles, initially insoluble in the varnish matrix, prolong the reactivity with enamel.

Não há consenso sobre a recomendação clínica do tempo que o verniz Duraphat® deve ser mantido nas superfícies de esmalte sem ter perturbação mecânica pelo paciente. Considerando a importância dos reservatórios tipo fluoreto de cálcio (“CaF2”) no efeito anticárie da aplicação profissional de fluoreto, um estudo in vitro foi delineado para testar a reatividade do verniz Duraphat® com o esmalte na formação desses reservatórios em função do tempo. Como a maioria do fluoreto no verniz Duraphat® é insolúvel para reagir e formar produtos no esmalte, também se avaliou a contribuição relativa das frações solúvel e insolúvel do verniz na reatividade. Assim, verniz total, contendo fluoreto solúvel e insolúvel (concentração total de 23699±384 µg F/g), ou verniz centrifugado, contendo somente o fluoreto solúvel (concentração de 258±97 µg F/g), foram aplicados de maneira padronizada sobre blocos de esmalte (n =8/grupo de verniz/tempo), os quais foram imersos em saliva artificial com renovação continua por até 36 h. Os reservatórios tipo “CaF2” formados no esmalte pela aplicação do verniz foram extraídos com KOH 1 M e a concentração de F foi medida utilizando um eletrodo específico. Os resultados foram expressos como µg F/cm2. O verniz total formou significativamente maior concentração de fluoreto no esmalte que o verniz centrifugado, atingindo concentrações máximas após 24 h (22,0±4,5 µg F/cm2 de área de esmalte). O verniz centrifugado apresentou a máxima formação após 6 h (3,20 ± 0,81 µg F/cm2). Em conclusão, um tempo maior de retenção do que habitualmente recomendado poderia melhorar o efeito anticárie do verniz Duraphat®, pois partículas de NaF, inicialmente insolúveis na matriz do mesmo, possibilitam uma reatividade prolongada do verniz com o esmalte em função do tempo.

Evaluation of fluoride release from experimental TiF4 and NaF varnishes in vitro

Fluoride varnishes play an important role in the prevention of dental caries, promoting the inhibition of demineralization and the increase of remineralization. Objective: This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF4 and NaF varnishes, with different concentrations, for 12 h. Material and Methods: Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF4 varnish (0.95% F, pH 1.0); 3.10% TiF4 varnish (1.90% F, pH 1.0); 3.10% and 4% TiF4 varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni's test were applied for the statistical analysis (p<0.05). Results: TiF4 varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF4 varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva. Conclusions: The 3.10% and 4% TiF4 -based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF4 varnish on tooth surface. .

Effect of fluoride sodium mouthwash solutions on cpTI: evaluation of physicochemical properties

The effects of fluoride, which is present in different oral hygiene products, deserve more investigation because little is known about their impact on the surface of titanium, which is largely used in Implantology. This study evaluated the surface of commercially pure titanium (cpTi) after exposure to different concentrations of sodium fluoride (NaF). The hypothesis tested in this study was that different concentrations of NaF applied at different time intervals can affect the titanium surface in different ways. The treatments resulted in the following groups: GA (control): immersion in distilled water; GB: immersion in 0.05% NaF for 3 min daily; GC: immersion in 0.2% NaF for 3 min daily; GD: immersion in 0.05% NaF for 3 min every 2 weeks; and GE: immersion in 0.2% NaF for 3 min every 2 weeks. The experiment lasted 60 days. Roughness was measured initially and every 15 days subsequently up to 60 days. After 60 days, corrosion analysis and anodic polarization were done. The samples were examined by scanning electron microscopy (SEM). The roughness data were analyzed by ANOVA and there was no significant difference among groups and among time intervals. The corrosion data (i corr) were analyzed by the Mann-Whitney test, and significant differences were found between GA and GC, GB and GC, GC and GD, GC and GE. SEM micrographs showed that the titanium surface exposed to NaF presented corrosion that varied with the different concentrations. This study suggests that the use of 0.05% NaF solution on cpTi is safe, whereas the 0.2% NaF solution should be carefully evaluated with regard to its daily use.

Os efeitos do fluoreto, o qual está presente em diferentes produtos de higiene oral, necessita de maiores investigações, pois pouco se sabe sobre seus efeitos na superfície do titânio, o qual possui amplo uso na implantodontia. Este estudo objetivou avaliar a superfície do titânio comercialmente puro (cpTi) após exposição a diferentes concentrações de fluoreto de sódio (NaF). A hipótese testada neste estudo foi que diferentes concentrações de NaF aplicadas em diferentes intervalos de tempo seriam capazes de afetar diferentemente a superfície do titânio. Os tratamentos realizados foram: GA (controle): imersão em água destilada; GB: imersão diária por 3 min em NaF a 0,05%; GC: imersão diária por 3 min em NaF a 0,2%; GD: imersão quinzenal por 3 min em NaF a 0,05%; e GE: imersão quinzenal por 3 min em NaF a 0,2%. O tempo do experimento foi de 60 dias. A análise da rugosidade foi efetuada inicialmente e a cada 15 dias. Após 60 dias foi realizada análise de corrosão e polarização anódica. As amostras foram analisadas em MEV. Os dados de rugosidade foram analisados por ANOVA e não houve diferença estatisticamente significante entre grupos e entre tempos. Os dados de corrosão (i corr) foram analisados pelo teste de Mann-Whitney e foram encontradas diferenças significantes entre GA e GC, GC e GB, GC e GD, GC e GE. A MEV evidenciou que a superfície do titânio exposto ao NaF apresentou corrosão variando de acordo com a concentração. Com base nos dados encontrados conclui-se que o uso de solução NaF a 0,05% em cpTi é seguro, enquanto a solução NaF 0,2% para uso diário deve ser cuidadosamente avaliada.

Effect of fluoride solutions on the shear bond strength of orthodontic brackets

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values.

O objetivo deste estudo foi o de avaliar in vitro a resistência adesiva de bráquetes após o pré-tratamento do esmalte com diferentes soluções fluoretadas. Foram utilizados 48 incisivos bovinos hígidos recém-extraídos que foram aleatoriamente divididos em 4 grupos experimentais (n=12). CG (controle): sem tratamento; FN: aplicação de flúor neutro por 4 min; FFA: aplicação de flúor fosfato acidulado (FFA) a 1,23% por 4 min; e VFS: aplicação de verniz de fluoreto de sódio a 5% por 6 h. Após o tratamento dos grupos, foi realizada a profilaxia do esmalte e os bráquetes foram fixados utilizando o compósito Transbond XT (3M), seguindo as especificações do fabricante. A resistência adesiva foi verificada através do teste de cisalhamento, realizado na Máquina de Ensaio Universal DL-2000 24 h após a fixação dos bráquetes. As superfícies dos dentes foram analisadas para verificação do índice de adesivo remanescente (IAR). Por meio dos testes estatísticos ANOVA e Tukey (α=5%), observou-se diferença estatisticamente significante entre os grupos estudados (p<0,0001), sendo que GC e FN, apresentaram valores superiores de resistência adesiva quando comparados aos grupos FFA e VFS, porém GC-NF e FFA-VFS não apresentaram diferenças estatisticas entre si (p>0,05). A análise dos escores do IAR revelou que grande parte das falhas ocorreram na interface esmalte-resina. Conclui-se que o tratamento do esmalte com FFA 1,23% e VFS a 5%, previamente à fixação de bráquetes ortodônticos, reduziu os valores de resistência adesiva ao cisalhamento.

Ionómeros de vidrio remineralizantes: una alternativa de tratamiento preventivo o terapéutico / Remineralizing glass ionomers: an alternative of preventive or therapeutic treatment

La Odontología de Mínima Intervención es una de las áreas de mayor auge y crecimiento en la última década. Dentro de esta filosofía de aplicar la prevención, se encuentra el resurgimiento de los selladores de fosas y fisuras debido a la llegada de los materiales bioactivos. Estos selladores han demostrado ser eficaces no sóloen prevenir las desmineralizaciones antes de su inicio, sino también, deteniendo el progreso de las lesiones en sus fases más tempranas y también remineralizando la estructura dentaldañada. Debido a las propiedades de estos materiales, no solo están indicados en niños y adolescentes, sino también en adultos. Una de las ventajas de los selladores es la posibilidad de que ellos podrían ser colocados inadvertidamente sobre desmineralizaciones incipientes,previniendo la progresión de la lesión cariosa y el daño a la integridad del diente. Con los ionómeros de vidrio remineralizantes, al ser colocados no sólo remineralizan la lesión, sino también la estructura circundante.Además se recargan con enjuagues y pastas, a base de fluoruros de sodio y de fosfato de calcio y lo que es mejor, ayudan a neutralizar el pH de la saliva y disminuir el número de bacterias.Cuando los selladores son utilizados como alternativa terapéutica, se realizan procedimientos restauradores microconservadores, los cuales fomentan la preservación de la estructura dental y no su remoción innecesaria. Estas restauraciones con instrumentación mínima, poseen simultáneamente una finalidad terapéutica y una preventiva. La odontología de mínima intervención.

Effect of fluoride-containing desensitizing agents on the bond strength of resin-based cements to dentin

OBJECTIVE: The objective of this study was to evaluate the effect of desensitizing agents containing different amounts of fluoride on the shear bond strength of a dual polymerized resin cement and a resin-modified glass ionomer cement (RMGIC) to dentin. MATERIAL AND METHODS: One hundred human molars were mounted in acrylic resin blocks and prepared until the dentin surface was exposed. The specimens were treated with one of four desensitizing agents: Bifluorid 12, Fluoridin, Thermoline and PrepEze. The remaining 20 specimens served as untreated controls. All groups were further divided into 2 subgroups in which a dual polymerized resin cement (Bifix QM) or a resin-modified glass ionomer cement (AVANTO) was used. The shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. The data were analyzed statistically with a 2-way ANOVA, Tukey HSD test and regression analysis (α=0.05). The effect of the desensitizing agents on the dentin surface was examined by scanning electron microscopy. RESULTS: The fluoride-containing desensitizing agents affected the bond strength of the resin-based cements to dentin (p<0.001). PrepEze showed the highest bond strength values in all groups (p<0.001). CONCLUSION: Regression analysis showed a reverse relation between bond strength values of resin cements to dentin and the amount of fluoride in the desensitizing agent (p<0.05).