Rose Bengal incorporated to α-cyclodextrin microparticles for photodynamic therapy against the cariogenic microorganism Streptococcus mutans.

Rose Bengal@α-cyclodextrin (RB@α-CD) microparticles (µPs) were prepared and the RB inclusion in α-CD was experimentally demonstrated through infrared, UV-VIS absorption spectroscopy and cyclic voltammetry. The RB inclusion in α-CD was theoretically investigated using classical molecular mechanics calculations, the simulation results showing that RB can be included in both the narrow and wide apertures of the α-cyclodextrin ring with configurations exhibiting average binding energies of about 27 kcal mol-1. The prepared RB@α-CD microparticles were characterized through Scanning Electron Microscopy (SEM) and it was demonstrated that they are highly efficient in the photodynamic therapy against a Streptococcus mutans (the main bacteria of cariogenic dental plaque) suspension, as a concentration of RB@α-CD µPs 10 times smaller than the usual concentration of pure RB is still capable to produce significant antibacterial activity.

Novel hydroxyapatite nanorods improve anti-caries efficacy of enamel infiltrants.

OBJECTIVES: Enamel resin infiltrants are biomaterials able to treat enamel caries at early stages. Nevertheless, they cannot prevent further demineralization of mineral-depleted enamel. Therefore, the aim of this work was to synthesize and incorporate specific hydroxyapatite nanoparticles (HAps) into the resin infiltrant to overcome this issue. METHODS: HAps were prepared using a hydrothermal method (0h, 2h and 5h). The crystallinity, crystallite size and morphology of the nanoparticles were characterized through XRD, FT-IR and TEM. HAps were then incorporated (10wt%) into a light-curing co-monomer resin blend (control) to create different resin-based enamel infiltrants (HAp-0h, HAp-2h and HAp-5h), whose degree of conversion (DC) was assessed by FT-IR. Enamel caries lesions were first artificially created in extracted human molars and infiltrated using the tested resin infiltrants. Specimens were submitted to pH-cycling to simulate recurrent caries. Knoop microhardness of resin-infiltrated underlying and surrounding enamel was analyzed before and after pH challenge. RESULTS: Whilst HAp-0h resulted amorphous, HAp-2h and HAp-5h presented nanorod morphology and higher crystallinity. Resin infiltration doped with HAp-2h and HAp-5h caused higher enamel resistance against demineralization compared to control HAp-free and HAp-0h infiltration. The inclusion of more crystalline HAp nanorods (HAp-2h and HAp-5h) increased significantly (p<0.05) the DC. SIGNIFICANCE: Incorporation of more crystalline HAp nanorods into enamel resin infiltrants may be a feasible method to improve the overall performance in the prevention of recurrent demineralization (e.g. caries lesion) in resin-infiltrated enamel.

Can insoluble polysaccharide concentration in dental plaque, sugar exposure and cariogenic microorganisms predict early childhood caries? A follow-up study.

BACKGROUND: Insoluble polysaccharide (IP) has been associated with caries prevalence in young children. However, the power of IP to predict ECC needs to be demonstrated. AIMS: To assess the relationships between early childhood caries (ECC) and extracellular insoluble polysaccharides (IP) in dental plaque, sugar exposure and cariogenic microorganisms. DESIGN: Visible plaque on maxillary incisors was recorded, followed by caries diagnosis in 65 preschoolers (3-4 years) at baseline and after 1 year. Plaque was collected for mutans streptococci (MS), total microorganism (TM) and lactobacilli (LB) enumerations in selective media, as well as for IP analysis, which was later assessed by colorimetry. Sugar/sucrose exposure was assessed by a diet chart. RESULTS: Positive correlations were found among the prevalence of caries and MS, TM, LB, solid sucrose and visible dental plaque. Additionally, children with IP concentrations in dental plaque higher than 2.36 µg/mg (odds ratio-OR=6.8), with visible plaque on maxillary incisors (OR=4.3), harbouring LB (OR=13) and exposed to solid sugar more than twice/day (OR=5) showed higher risk of developing caries (p<0.05). CONCLUSION: Extracellular insoluble polysaccharides, solid sugar/sucrose, visible dental plaque and cariogenic microorganisms could predict caries development, partially explaining the ECC pattern.

In vitro evaluation of enamel demineralization after several overlapping CO2 laser applications.

This study aimed to evaluate the effects of repeated CO2 laser applications on the inhibition of enamel demineralization. Sixty-five human dental enamel slabs were randomly assigned to the following groups (n = 13): control (C), one application of the CO2 laser (L1), two applications of the CO2 laser (L2), three applications of the CO2 laser (L3), and four applications of the CO2 laser (L4). Enamel slabs were irradiated by a 10.6-µm CO2 laser operating at 5 J/cm(2). The slabs were subjected to a pH-cycling regimen and then analyzed by FT-Raman spectroscopy, energy-dispersive X-ray fluorescence spectrometry (EDXRF), cross-sectional micro-hardness, and scanning electron microscopy (SEM). Statistical analysis was performed using ANOVA and Tukey tests (p < 0.05). FT-Raman spectroscopy showed a reduced carbonate content for L1, L3, and L4 groups when compared to C (p < 0.05). The EDXRF data showed no statistical differences between the control and irradiated groups for calcium and phosphorus components (p > 0.05). Cross-sectional micro-hardness data showed a statistically significant difference between the control and all irradiated groups (p < 0.05), but no difference was found among the irradiated groups (p > 0.05) up to 30-µm depth. A tendency of lower demineralization occurred in deeper depths for L3 and L4 groups. The SEM results showed that with repeated applications of the CO2 laser, a progressive melting and recrystallization of the enamel surface occurred. Repeated irradiations of dental enamel may enhance the inhibition of enamel demineralization.

Effect of photodynamic antimicrobial chemotherapy on in vitro and in situ biofilms.

AIM: The effect of photodynamic antimicrobial chemotherapy (PACT) on oral biofilms was evaluated. METHODS: Biofilms formed in vitro were treated with sensitizer (S) and/or light (L) in the test (S+L+) and control (S-L-, S+L-, S-L+) groups. Additionally, 21 volunteers wore intraoral devices and the biofilms formed on each side of the device were referred to as S+L+ or S-L- groups. RESULTS: Significant decreases in the viability of in vitro biofilms were observed after PACT. PACT was ineffective in inhibiting multi-species biofilms formed in situ. CONCLUSION: PACT was effective on in vitro biofilms and was ineffective on in situ biofilms.

Análisis de microdureza de dos diferentes resinas relacionadas a la intensidad de fotopolimerización dependiendo de la distancia utilizada / Microhardness of two different composite resind related to light curing intensity depending on distance

Objetivo: El presente estudio evaluó la microdureza de dos distintas resinas que fueron fotopolimerizadas a cuatro distancias diferentes. Materiales y Métodos: Se obtuvieron cuarenta muestras utilizando una matriz metálica de acero y dos resinas fotopolimerizables (Filtek-A110, Filtek-Z250). Las muestras se prepararon de forma aleatoria constituyendo 8 grupos, 4 por cada resina fotopolimerizable (n igual que 5), las cuales fueron polimerizadas a 0, 2, 4 y 8 mm de distancia de la fuente de luz, usando la misma intensidad de energía. Posteriormente, las medidas de microdureza Vickers fueron obtenidas en la superficie superior e inferior de las muestras. Los datos resultantes fueron sometidos al t test o ANOVA y al test Tukey (alfa igual que 0.05). Resultados: La microdureza de la resina microhíbrida (Filtek-Z250), fue superior en todas las distancias analizadas en relación con la resina de microrelleno (Filtek-A110). Para la resina Filtek-Z250, la distancia de polimerización no influyó en la dureza de la parte superior o inferior, excepto a 8mm de la distancia inferior, donde se encontró el menor valor de microdureza. En la resina Filtek-A110, se observó una disminución progresiva de la microdureza con el incremento de la distancia, en la parte superior e inferior. En general, la microdureza en la parte superior fue significativamente mayor que en la parte inferior de ambas resinas. Conclusiones: El incremento en la distancia de fotopolimerización no modificó el grado de polimerización de la resina microhíbrida. Sin embargo, esta distancia es un factor importante a ser considerado durante la polimerización de las resinas de microrelleno.

Objetive: This study investigated the surface microhardness of two different composite resins light cured at four different distance. Material and methods: Forty specimens were obtained sin composites (Filtek-A110 and Filtek-Z250). The samples were randomly prepared, constituting 8 groups, 4 for each resin composite (n=5), which were light cured at 0,2,4 or 8 mm distances, using the same output power. Afterwards, Vickers microhardness measurements were obtained on top and botton surfaces of the samples. Data were submitted to t test or ANOVA followed by Turkey test (a=0.05). Results: The microhardness of the microhybrid resin, Filtek-Z250, was superior in all distances analyzed in relation to the microfilled resin, Filtek-A110. Filtek-Z250, the distance of polymerization did not influence the hardness at top or bottom, except for 8 mm distance at bottom, where the lowest microharness was found. For Filtek-A110, a progressive decrease in microhardness with the increase of distance was observed at both top and bottom. At general, hardness at top was significantly higher than at bottom for both resins. Conclusions: In the conditions of this study, the increase in the distance of polymerization did no change microhybrid composite resin polymerization. However, this distance is an important factor to be observed in polymerization of microfilled composite resins.

In situ effects of restorative materials on dental biofilm and enamel demineralisation.

OBJECTIVES: Since secondary caries is one of the main reasons for replacing restorations, this study assessed the effects of different restorative materials on the microbiological composition of dental biofilm and on enamel demineralisation around the restoration. METHODS: A randomized, double-blind, split-mouth in situ design was conducted in one phase of 14 days, during which, 20 volunteers wore palatal devices containing five human dental enamel slabs. Each slab was randomly restored with one of the following materials: Filtek-Z-250/Single Bond, control group (composite resin), Permite (amalgam), Fuji II (encapsulated resin-modified glass ionomer), Vitremer (resin-modified glass ionomer) and Ketac Molar (conventional glass ionomer). The volunteers used fluoride dentifrice, 3x/day and a 20% sucrose solution was dripped onto the slabs 8x/day. The biofilm formed on the slabs was analyzed to determine the counts of total streptococci, mutans streptococci and lactobacilli. Enamel demineralisation was determined by cross-sectional microhardness (CSMH) at 20 and 70 microm from the margin of the restoration. Kruskal-Wallis and analysis of variance, followed by least mean squares (LMS) test, were used to evaluate microbiota and CSMH among the groups. The significance level used was 5%. RESULTS: No statistically significant differences were found in the cariogenic microbiota grown on the slabs. At a 20-mum distance, only Fuji II statistically differed from the other groups, showing the lowest demineralisation. At 70 microm, Fuji II significantly inhibited demineralisation when compared to Permite, Filtek-Z-250 and Ketac Molar. CONCLUSIONS: In the context of fluoride dentifrice and under the cariogenic exposure conditions of this study, only the encapsulated resin-modified glass ionomer material provided additional protection against secondary caries.

Effect of the CO2 laser combined with fluoridated products on the inhibition of enamel demineralization.

AIM: This in vitro study evaluated the combined effects of a 10.6 microm CO2 laser, fluoridated dentifrice, and mouthrinse on the reduction of lesion progression in carious human enamel. METHODS AND MATERIALS: Slabs of previously demineralized dental enamel were assigned to nine groups, either treated with/without a CO2 laser, with/without fluoridated dentifrice, and with/without fluoridated mouthrinse. After a pH-cycling regime, fluoride concentrations were determined in the demin- and remineralizing solutions. A qualitative polarized light analysis was performed on enamel, and enamel mineral loss was determined by cross-sectional microhardness testing. RESULTS: All treatments were able to decrease mineral loss, and the inhibition of demineralization progression ranged from 48% to 60%. CONCLUSION: The 10.6 microm CO2 laser irradiation alone or combined with fluoridated products reduced demineralization progression in enamel. However, there was no significant additional demineralization inhibitory effect with the use of the combined laser-fluoride treatments. CLINICAL SIGNIFICANCE: CO2 lasers have proven to be efficient in reducing subsurface enamel demineralization. Its association with a high frequent fluoride therapy may enhance this protective effect.

Combined effects of carbon dioxide laser and fluoride on demineralized primary enamel: an in vitro study.

This in vitro study aimed at evaluating the efficacy of a CO(2) laser (10.6 microm) alone or combined with acidulated phosphate fluoride (APF) on the inhibition of lesion progression in primary enamel. The specimens were treated with/without CO(2) laser and/or APF and submitted to pH cycling. Microhardness analysis was performed and the enamel mineral loss values were obtained. The groups treated with laser and/or APF presented lower mineral loss when compared to the control group (p < 0.05). Laser irradiation alone or combined with APF decreased lesion progression in primary enamel. However, the combined treatment did not show any significant additional effect.

In situ mineral loss inhibition by CO2 laser and fluoride.

Laser and fluoride treatments have been shown to inhibit enamel demineralization in the laboratory. However, the intra-oral effects of this association have not been tested. This study assessed in situ the effect of a Transversely Excited Atmospheric CO2 laser (lambda = 9.6 mum) and the use of pressure fluoridated dentifrice on enamel demineralization. During two 14-day phases, 17 volunteers wore palatal appliances containing human enamel slabs assigned to treatment groups, as follows: (1) non-fluoride dentifrice, (2) CO2 laser irradiation plus non-fluoride dentifrice, (3) fluoride dentifrice, and (4) CO2 laser irradiation plus fluoride dentifrice. A 20% sucrose solution was dripped onto the slabs 8 times per day. The specimens treated with laser and/or fluoridated dentifrice presented a significantly lower mineral loss when compared with those from the non-fluoride dentifrice group. The results suggested that CO2 laser treatment of enamel inhibits demineralization in the human mouth, being more effective when associated with fluoride.