Molecular detection of in-vivo microbial contamination of metallic orthodontic brackets by checkerboard DNA-DNA hybridization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mechanical and biological characterization of resin-modified glass-ionomer cement containing doxycycline hyclate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dentine microhardness after different methods for detection and removal of carious dentine tissue

There are several methods for identifying carious dentinal tissue aiming to avoid removal of healthy dentinal tissue. Objectives: The purpose of this study was to test different methods for the detection of carious dentinal tissue regarding the amount of carious tissue removed and the remaining dentin microhardness after caries removal. Material and methods: The dentin surfaces of 20 bovine teeth were exposed and half of the surface was protected with nail polish. Cariogenic challenge was performed by immersion in a demineralizing solution for 14 days. After transverse cross-section of the crown, the specimens were divided into four groups (n=10), according to the method used to identify and remove the carious tissue: "Papacarie", Caries-detector dye, DIAGNOdent and Tactile method. After caries removal, the cross-sectional surface was included in acrylic resin and polished. In a microhardness tester, the removed dentin thickness and the Vickers microhardness of the following regions were evaluated: remaining dentin after caries removal and superficial and deep healthy dentin. Results: ANOVA and Tukey's test (alpha=0.05) were performed, except for DIAGNOdent, which did not detect the presence of caries. Results for removed dentin thickness were: "Papacarie" (424.7 +/- 105.0; a), Caries-detector dye (370.5 +/- 78.3; ab), Tactile method (322.8 +/- 51.5; bc). Results for the remaining dentin microhardness were: "Papacarie" (42.2 +/- 10.5; bc), Caries-detector dye (44.6 +/- 11.8; bc), Tactile method (24.3 +/- 9.0; d). Conclusions: DIAGNOdent did not detect the presence of carious tissue; Tactile method and "Papacarie" resulted in the least and the most dentinal thickness removal, respectively; Tactile method differed significantly from "Papacarie" and Caries-detector dye in terms of the remaining dentin microhardness, and Tactile method was the one which presented the lowest microhardness values.

Ability of different restorative materials to prevent in situ secondary caries: analysis by polarized light-microscopy and energy-dispersive X-ray

Secondary caries is the main cause of direct restoration replacement. The purpose of this study was to analyze enamel adjacent to different restorative materials after in situ cariogenic challenge using polarized-light microscopy (PLM), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDS). Twelve volunteers, with a low level of dental plaque, a low level of mutans streptococci, and normal salivary flow, wore removable palatal acrylic appliances containing enamel specimens restored with Z250 composite, Freedom composite, Fuji IX glass-ionomer cement, or Vitremer resin-modified glass-ionomer for 14 days. Volunteers dripped one drop of 20% sucrose solution (n = 10) or distilled water (control group) onto each specimen 8 times per day. Specimens were removed from the appliances and submitted to PLM for examination of the lesion area (in mm(2)), followed by dehydration, gold-sputtering, and submission to SEM and EDS. The calcium (Ca) and phosphorus (P) contents were evaluated in weight per cent (%wt). Differences were found between Z250 and Vitremer, and between Z250 and FujiIX, when analyzed using PLM. Energy-dispersive X-ray analysis results showed differences between the studied materials regarding Ca %wt. In conclusion, enamel adjacent to glass-ionomer cement presented a higher Ca %wt, but this material did not completely prevent enamel secondary caries under in situ cariogenic challenge.

Fluoride dose response in pH-cycling models using bovine enamel

The aim of this study was to establish methodologies for verification of the fluoride solution dose-response relationship using bovine enamel and pH-cycling models. Six models of the cariogenic challenge were performed, varying the time of demineralization and pH, time of remineralization, composition of de- and remineralization solutions, frequency and time of application of treatment solutions and pH-cycling duration. For the evaluation of the fluoride effect on caries dynamics, two proposed models provided for improvement in standardization of methods leading to a higher level of precision, demonstrating a dose response between treatments with regard to surface microhardness and Delta Z. For the evaluation of the fluoride effect on enamel remineralization, the addition of fluoride to the de- and remineralization solutions and the reduction of frequency and time of application of fluoride solutions led to a more suitable pH-cycling model. Copyright (C) 2005 S. Karger AG, Basel.

Enamel caries resistance accidentally irradiated by the Nd : YAG laser

When the carious tissue is eliminated either by conventional methods (with burs) or with lasers, the risk of accidentally damage the surface of adjacent teeth may occur, which hypothetically could lead to a more susceptible surface for canes formation. This in vitro study aims to evaluate the caries resistance of the dental enamel surface irradiated by the Nd:YAG laser applied in conditions simulating accidental exposition. Thirteen third molars were used in this study. The experimental groups were: G1: sound control and control + carious; G2: contact Nd:YAG laser at 0.75, 1, 2, or 3 W; 10 Hz; 3 sec (27, 35, 71, and 106 J/cm(2)); G3: same parameters from G2 + caries artificial induction through the demineralization and demineralization (DES/RE) dynamic model. The caries resistance analysis was evaluated by the superficial morphological aspect through SEM images and also by Ca/P proportion through energy dispersive X-ray spectroscopy (EDX). The micrograph images showed that the Nd:YAG laser changed the normalmorphology of the enamel prisms resulting in a melted and re-solidified surface intensified with the power increase. Significant statistical differences were observed applying the Kruskal-Wallis statistical test (p <= 0.01) among the Nd:YAG laser irradiated groups and the control with caries regarding the Ca/P proportion. As an exception, this was not observed when 3 W; 10 Hz; 3 sec; 106 J/cm(2) was applied and posteriously submitted to a cariogenic challenge. The results indicate that the Nd:YAG laser accidental irradiation at low power settings did not represent risks to the enamel caries resistance.

Effect of Hydrogen Peroxide at 35% on the Morphology of Enamel and Interference in the De-remineralization Process: An In Situ Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of the diet of 0- to 6-year-old children in municipal schools in a Brazilian city

Diet control is one of the important factors in the prevention of dental caries because food functions as substratum for fermentation and, consequently, for the formation of the organic acids that demineralize the tooth surface. This study aims to descriptively assess school diet and the associated caries-preventive methods applied to children in all municipal nursery schools of a Brazilian city (Aragatuba/SP). For this, a questionnaire with open and closed questions was used. The results showed that all schools serve school meal, which is composed mainly of sugar, carbohydrates, and proteins. The students enjoy the meal very much because for most of them, the meal served at school is the only source of food. It was observed that 90% of the schools offer other kinds of food besides the main school meal. The snacks served such as cakes, white hominy, and milk fudge are composed of sweet and highly cariogenic foods. It was also verified that in 13.30% of the schools, the daily supervised dental hygiene, an important procedure that should not be neglected, is not carried out. This procedure introduces the children to healthy habits that are added to those acquired in the family environment. It was concluded that the school diet is potentially cariogenic and, in association with the lack of daily dental hygiene, this potential may become even higher.

Análise da dieta e condição de saúde bucal em pacientes gestantes

Objectve: To perform a critical analysis of the diet record model adopted, to evaluate the cariogenicity of the maternal diet, and the incidence of dental caries in pregnant women treated at a prevent on clinic in an undergraduate dental course. Method: A cross-sectional study was performed with consultations to the database of the clinic and review of patients' charts and diet records. The sample was calculated and 205 patents were randomly selected. Bivariate statistical analysis was done at a significance level of 5% (α=0.05), using the statistical soft wares Epi Info versão 3.2, GraphPad Instat 3.6 and BioEstat. Results: The analysis of the diet records showed that 68.8% of the pregnant women presented a cariogenic diet, with high frequency of ingest on of fermentable carbon hydrates, mainly sucrose, with liquid consistency, and preferably consumed between the main meals. There was higher trend of the pregnant women mentioning a low frequency of carbon hydrate ingestion during the interview, while registering a diet rich of these components in their diet records (p<0.0001). The mean DMFT of the patients was 13.9 ± 5.4. There was no statistically significant association between diet and oral health variables (p>0.05). Conclusion: The diet record was proven an effective and valid method, if correctly employed. The prevalence of dental caries in the group of pregnant women was high and, although more than half of the sample presented a cariogenic diet, a significant association between diet and co-factors was not found.

In vitro and in vivo investigation of the biological and mechanical behaviour of resin-modified glass-ionomer cement containing chlorhexidine

Objectives: To evaluate: (1) the in vitro antibacterial, cytotoxic and mechanical properties of a resin-modified glass ionomer cement (RMGIC) containing different concentrations of chlorhexidine (CHX) and (2) the in vivo microbiologic action of the best concentration of CHX associated with the RMGIC applied on remaining dentine after indirect pulp treatment (IPT). Methods: For the in vitro studies, RMGIC was associated with 0.2, 0.5, 1.25 and 2.5% CHX. Microbiologic evaluation consisted of an agar diffusion test on cariogenic bacteria for 24 h. Odontoblast-like cell metabolism and morphology analyses measured the cytotoxic effects of the RMGIC groups after 24 h. The same groups were submitted to compressive and diametral tensile strength. The in vivo treatment consisted of IPT using an RMGIC associated with the best CHX concentration. Clinical and microbiologic evaluations were performed before and after 3 months. Results: The use of 1.25% CHX significantly improved the antibacterial effects of the evaluated RMGIC, without causing any detrimental effects to the odontoblast-like cells and on the mechanical properties. This RMGIC and CHX combination completely eliminated mutans streptococci after 3 months of IPT. Conclusion: The RMGIC and 1.25% CHX mixture showed great biological and mechanical behaviour and could be a good treatment against caries progression. Clinical significance: The association of CHX with a liner RMGIC opens a new perspective for arresting residual caries after IPT. © 2012 Elsevier Ltd. All rights reserved.

Antimicrobial activity of the synthetic peptide Lys-a1 against oral streptococci

The peptide LYS-[TRP6]-Hy-A1 (Lys-a1) is a synthetic derivative of the peptide Hy-A1, initially isolated from the frog species Hypsiboas albopunctatus. According to previous research, it is a molecule with broad antimicrobial activity. The objective of this study was to evaluate the antimicrobial activity of the synthetic peptide Lys-a1 (KIFGAIWPLALGALKNLIK- NH2) on the planktonic and biofilm growth of oral bacteria. The methods used to evaluate antimicrobial activity include the following: determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in microtiter plates for growth in suspension and quantification of biomass by crystal violet staining and counting of colony forming units for biofilm growth. The microorganisms Streptococcus oralis, Streptococcus sanguinis, Streptococcus parasanguinis, Streptococcus salivarius, Streptococcus mutans and Streptococcus sobrinus were grown in Brain Heart Infusion broth at 37 °C under atmospheric pressure with 10% CO2. The peptide was solubilized in 0.1% acetic acid (v/v) at various concentrations (500-1.9 μg mL-1). Chlorhexidine gluconate 0.12% was used as the positive control, and BHI culture medium was used as the negative control. The tested peptide demonstrated a remarkable antimicrobial effect, inhibiting the planktonic and biofilm growth of all strains tested, even at low concentrations. Thus, the peptide Lys-a1 is an important source for potential antimicrobial agents, especially for the control and prevention of microbial biofilms, which is one of the most important factors in cariogenic processes. © 2012 Elsevier Inc.

Differences in loosely bound fluoride formation and anticaries effect of resin-based fluoride varnishes

International Journal of Paediatric Dentistry 2013; 23: 166-172 Objective. Our in vitro study evaluated calcium fluoride formation in enamel and the anticaries effect of seven resin-based varnishes under cariogenic challenge. Methods. Enamel blocks were subjected to pH cycling. The experimental groups received fluoride varnish application, the positive control received topical fluoride gel treatment, and the negative control did not receive any treatment. The pH cycling surface hardness (SH1) and integrated loss of subsurface hardness (ΔKHN) were then determined. We measured the amount of fluoride released into the demineralizing and remineralizing (DE-RE) solutions used in pH cycling. The fluoride concentration in the enamel was determined 24h after application of the products as loosely bound fluoride and firmly bound fluoride. Results. Higher deposits of loosely bound fluoride were observed for Duofluorid, followed by Biophat. For Duraphat, Bifluorid, Duraflur, and Duofluorid, no difference was observed in the SH1 and ΔKHN values, with the lowest mineral loss compared to the other groups. The Bifluorid and Duofluorid groups released high fluoride amounts into the DE-RE, and statistically significant difference was noted between them. Conclusions. The anticaries effect showed no correlation with higher deposited fluoride amounts, resin type, or fluoride source. © 2012 John Wiley & Sons Ltd, BSPD and IAPD.

Photodynamic antimicrobial therapy of curcumin in biofilms and carious dentine

Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizers by light in the presence of oxygen, resulting in the production of reactive radicals that are capable of inducing cell death. The present study evaluated the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to PDT grown as multi-species in the biofilm phase versus in dentine carious lesions. A brain-heart infusion culture medium supplemented with 1 % glucose, 2 % sucrose, and 1 % young primary culture of L. acidophilus 108 CFU/mL and S. mutans 108 CFU/mL was used to develop multi-species biofilms and to induce caries on human dentine slabs. Five different concentrations of curcumin (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were used associated with 5.7 J/cm2 light emission diode. Four different groups were analyzed L-D- (control group), L-D+ (drug group), L+D- (light group), and L+D+ (PDT group). ANOVA/Tukey's tests were conducted to compare groups. A significant reduction (p <0.05) in cell viability was observed in the biofilm phase following photosensitization with all curcumin concentrations tested. To achieve significant bacterial reduction (p <0.05) in carious dentine, it was necessary to utilize 5.0 g/L of curcumin in association with blue light. No significant reduction was found for L-D+, supporting the absence of the drug's dark toxicity. S. mutans and L. acidophilus were susceptible to curcumin in the presence of blue light. However, due to light penetration and drug diffusion difficulties, these microorganisms within dentine carious lesions were less affected than they were in the biofilm phase. © 2013 Springer-Verlag London.

Effect of low-fluoride dentifrices supplemented with calcium glycerophosphate on enamel demineralization in situ

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação do risco de cárie e microbiota fúngica em pacientes pediátricos com anemia falciforme

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)