Potencial erosivo de jugos de frutas amazónicas / Erosive potential of juices of amazonian fruits

RESUMEN La erosión dental es la pérdida irreversible de la superficie del esmalte o dentina, debido a exposición frecuente de ácidos de origen no bacteriano. A pesar de que ciertos jugos de frutas presentan potencial erosivo in vitro, no existe una evidencia conclusiva al respecto. Objetivos: Evaluar in situ el potencial erosivo de jugos de frutas amazónicas sobre el esmalte dental. Material y métodos: Se evaluó in situ la microdureza superficial Vickers (MSV) del esmalte dental luego de la exposición a las bebidas Physalis Peruviana (aguaymanto), Averrhoa Carambola (carambola), Myrciaria Dubia (camu camu), Coca cola (control positivo) y agua destilada (control negativo). Participaron quince voluntarios (18 a 30 años) quienes utilizaron placas palatinas para reproducir el medio de almacenamiento. Se colocaron 6 fragmentos por placa. Las placas fueron expuestas a las diferentes bebidas 4 v/d (9:00 am, 11:00 am, 13:00 pm y 15:00 pm) durante 5 minutos por 5 días. Por cada ciclo erosivo se expuso a dos bebidas, inmediatamente los dispositivos palatinos fueron recolocados en la boca de los participantes. Hubo un periodo de washout de 8 días entre cada ciclo. Se calculó la diferencia de MSV antes y después de la exposición. El análisis de ANOVA/Tukey se utilizó para determinar las diferencias entre las bebidas en el programa SPSS 19, con un nivel de significancia de 0,5%. Resultados: Las cuatro bebidas evaluadas disminuyeron la MSV del esmalte (p<0,05) sin diferencia significativa entre ellas. Conclusiones: Los jugos a base de camu camu, aguaymanto y carambola son potencialmente erosivos.

SUMMARY Dental erosion is the irreversible loss of the surface of the enamel or dentin, due to frequent exposure of non- bacterial acids. Although certain fruit juices have erosive potential in vitro, there is no conclusive evidence in this regard. Objective: To evaluate in situ the erosive potential of Amazonian fruit juices on dental enamel. Material and methods: The Vickers surface microhardness (VMH) of dental enamel was evaluated in situ after exposure to drinks Physalis Peruviana (aguaymanto), Averrhoa Carambola (carambola), Myrciaria Dubia (camu camu), Coca cola (positive control) and distilled water (negative control). Fifteen volunteers (18 to 30 years) participated who wore palatal appliances to reproduce the storage medium. Each one containing 6 enamel blocks. The appliances were exposed to the different drinks 4 times a day (9:00 am, 11: 00 am, 13:00 pm and 15:00 pm) for 5 minutes during 5 days. For each erosive cycle, they were exposed to two drinks, immediately the palatal devices were repositioned in the participants' mouth. There was an 8-day washout period between each cycle. The difference in VMH before and after exposure was calculated. The ANOVA/Tukey analysis was used to determine the differences between beverages in the SPSS 19 program, with a significance level of 0.5%. Results: The four experimental groups decreased enamel VMH (p<0.05) without significant difference between them. Conclusions: The juices based on camu camu, aguaymanto and carambola are potentially erosive.

Cómo desarrollar ciencia odontológica en el Perú / How to develop dental science in Peru

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

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

Photoelastic evaluation of the effect of composite formulation on polymerization shrinkage stress

We compared polymerization stress in two commercial composites and three experimental composites made using camphorquinone (CQ) and/or phenylpropanedione (PPD) as photoinitiators. The internal surfaces of photoelastic resin discs with cylindrical cavities were roughened and treated with adhesive. Composites were divided into five groups: two commercial composites (Filtek Silorane and Filtek Z250) and three experimental composites with CQ/amine, CQ/PPD/amine, and PPD/amine. Composites were photopolymerized inside cavities, and subjected to photoelastic analysis immediately and at 24 hours and 7 days later using a plane polariscope. Stress created by Silorane (3.08 ± 0.09 MPa) was similar to that of Z250 (3.19 ± 0.13 MPa) immediately after photopolymerization (p > 0.05). After 24 hours and 7 days, Z250 (3.53 ± 0.15 and 3.69 ± 0.10 MPa, respectively) showed higher stress than Silorane (3.19 ± 0.10 and 3.16 ± 0.10 MPa, respectively). Qualitative analysis immediately after photopolymerization showed composite/CQ promoted higher stress than PPD, but stress levels at other evaluated times were statistically similar, varying between 3.45 ± 0.11 MPa and 3.92 ± 0.13 MPa. At 24 hours and 7 days, Silorane created the lowest stress. All photoinitiators created comparable tensions during polymerization.

S. mutans biofilm model to evaluate antimicrobial substances and enamel demineralization

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37°C, 10 percent CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12 percent (concentration with recognized anti-plaque effect) and 0.05 percent NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05 percent NaF did not show antimicrobial effect but had similar effect to that of 0.12 percent CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.

Polarization of dental caries among individuals aged 15 to 18 years

OBJECTIVE: To evaluate the role of socioeconomic variables and self-perceived oral health in the polarization of caries among adolescents in Santa Bárbara D'Oeste, Brazil. MATERIAL AND METHODS: Cross-sectional study. Sampling was randomized and sample size was defined according to WHO criteria. Two hundred and seventy seven adolescents (15 to 18 year-old) were examined by five trained examiners that assessed DMFT index according to WHO criteria. Self-perceived oral health, access to dental services and socio-demographic variables were self-reported. Student's t tests, chi-square tests, and multivariate logistic regression (with significant caries index (SiC) as the outcome), were performed. RESULTS: Mean DMFT was 5.48 (±4.22) and the proportion of "caries free" subjects was 15.5 percent. Mean DMFT (9.71±2.85) and mean D (1.67±2.18) of SiC positive subjects were significantly higher than mean DMFT (2.88±2.17) and mean D (0.45±0.87) of SiC negative subjects (p<0.0001). Mean D of white (0.76±1.51) was significantly smaller than mean D of non-white subjects (1.32±2.01). The only variable independently associated with the "SiC positive" outcome was "report of toothache within six months prior to the study" [OR=1.83 (95 percentCI 1.08 to 3.12)], p<0.001. CONCLUSION: SiC was associated with "report of toothache" but not with socio-demographic variables in the studied population.

Antimicrobial activity of Uncaria tomentosa against oral human pathogens

Uncaria tomentosa is considered a medicinal plant used over centuries by the peruvian population as an alternative treatment for several diseases. Many microorganisms usually inhabit the human oral cavity and under certain conditions can become etiologic agents of diseases. The aim of the present study was to evaluate the antimicrobial activity of different concentrations of Uncaria tomentosa on different strains of microorganisms isolated from the human oral cavity. Micropulverized Uncaria tomentosa was tested in vitro to determine the minimum inhibitory concentration (MIC) on selected microbial strains. The tested strains were oral clinical isolates of Streptococcus mutans, Staphylococcus spp., Candida albicans, Enterobacteriaceae and Pseudomonas aeruginosa. The tested concentrations of Uncaria tomentosa ranged from 0.25-5 percent in Müeller-Hinton agar. Three percent Uncaria tomentosa inhibited 8 percent of Enterobacteriaceae isolates, 52 percent of S. mutans and 96 percent of Staphylococcus spp. The tested concentrations did not present inhibitory effect on P. aeruginosa and C. albicans. It could be concluded that micropulverized Uncaria tomentosa presented antimicrobial activity on Enterobacteriaceae, S. mutans and Staphylococcus spp. isolates.

Uncaria tomentosa é uma planta medicinal usada por vários séculos pela população peruana como alternativa de tratamento para diversas doenças. Muitos microrganismos que usualmente não habitam a cavidade bucal humana podem se tornar agentes etiológicos de doenças sob certas condições. O objetivo deste estudo foi avaliar a atividade antimicrobiana de diferentes concentrações de Uncaria tomentosa sobre diferentes cepas de microrganismos isolados de cavidades bucais humanas. Uncaria tomentosa micropulverizada foi testada in vitro para determinar a concentração inibitória mínima (CIM) em isolados microbianos selecionados. Cepas de Streptococcus mutans, Staphylococcus spp., Candida albicans, Enterobacteriaceae e Pseudomonas aeruginosa avaliadas foram isoladas de cavidades bucais humanas. Foram preparadas as concentrações de Uncaria tomentosa entre 0.25 e 5 por cento em ágar Müeller-Hinton. Uncaria tomentosa a 3 por cento inibiu 8 por cento de Enterobacteriaceae, 52 por cento de S. mutans e 96 por cento de Staphylococcus spp. As concentrações testadas não apresentaram efeito inibitório sobre P. aeruginosa e C. albicans. Concluiu-se que Uncaria tomentosa micropulverizada apresenta atividade antimicrobiana sobre cepas de Enterobacteriaceae, S. mutans e Staphylococcus spp.

Solubilidad y dureza superficial de cerámicas odontológicas después de ser expuestas a fluido gástrico artificial: estudio in vitro / Solubility and surface hardness of dental ceramics after exposure to artificial gastric fluids: an in vitro study

Enfermedades como reflujo gastroesofágico y bulimia, provocan alteraciones ácidas en la cavidad bucal que pueden causar erosión dental. El efecto de este medio ácido sobre materiales restauradores y posibles cambios en sus propiedades son poco relatado en la literatura. De esta forma, el objetivo de este trabajo fue evaluar la solubilidad y la microdureza de cerámicas feldespáticas expuestas in vitro a fluido gástrico simulado sin enzimas (pH 1,2). Fueron confeccionados 100 discos, de 8mm de diámetro y 2mm de altura, con las siguientes cerâmicas: Vitadur Alfa (I), Vita Omega 900 (II) Finesse All-Ceramic (III), IPS dSign (IV) y Carmen (V). Estos fueron divididos en tres grandes grupos según la exposición al fluido gástrico: (A) sin exposición, (B) 24 horas de exposición y (C) 7 días de exposición. La solubilidad fue evaluada por medio del pesaje en balanza digital (Metler Toledo), calculándose la cantidad de pérdida de masa (MP). El análisis de microdureza Vickers (MD) fué realizado utilizando un microdurómetro FM-700 (Future Tech). Los resultados obtenidos mostraron valores de pérdida de masa (por ciento) de B, comparado con A, de: 0,1280(I), 0,2143(II), 0,0485(III), 0,1377(IV), 0,0824(V); y para C de: 0,1182(I), 0,2305(II), 0,0773(III), 0,1653(IV), 0,3256(V). Se observaron valores de dureza superficial para A de: 527,53(I), 531,67(II), 519,85(III), 544,72(IV), 523,72(V); para B de: 505,38(I), 529,63(II), 478,60(III), 514,91(IV); 504,97; y C de: 484,96(I), 495,61(II), 493,5(III), 482,76(IV), 488,22(V). El análisis estadístico con el test de ANOVA (p<0,05), mostró influencia del fluido gástrico tanto en la pérdida de masa como en la solubilidad de las cerámicas evaluadas.

Influência do tipo de ponteira condutora de luz de aparelhos LED na microdureza das resinas compostas / Influence of the differents light-curing tips of LED photo-curing units in the microhardness of the composite resins

Avaliou-se a influência do tipo de ponteira condutora de luz de aparelhos LED na microdureza das resinas compostas. Os espécimes foram confeccionados utilizando-se matriz de aço com perfurações padronizadas. As resinas Fill Magic-Vigodent (FM), Z100-3M, TPH Spectrum-Dentsply (TPH) e Glacier-SDI (GL) foram inseridas em incremento único e polimerizadas (40 s)com os aparelhos Optilight LD-Gnatus (OL) e Light 3000-Clean Line (LI), alternando-se o tipo de ponteira condutora de luz (Fibra Óptica–FO ou Polímero–PO) e vieram a compor os seguintes grupos (n = 10): G1A - FM + OL + FO; G1B - FM + OL + PO; G2A - FM + LI + FO; G2B-FM +LI + PO; G3A - Z100 + OL + FO; G3B - Z100 + OL + PO; G4A - Z100 + LI + FO; G4B - Z100+ LI + PO; G5A - TPH + OL + FO; G5B - TPH + OL + PO; G6A - TPH + LI + FO; G6B - TPH + LI + PO; G7A - GL + OL + FO; G7B - GL + OL + PO; G8A - GL + LI + FO; G8B - GL + LI + PO. A dureza Vickers da superfície foi avaliada por meio de um microdurômetro (FM-700, Future-Tech, 50 g/10 s). Para a análise estatística, foram empregados os testes t não pareado, ANOVA e Tukey. As médias (± DP) obtidas foram: G1A:45,9(± 1,8)/G1B:47,9(± 2,8) com p = 0,08;G2A:44,3(± 2,6)/G2B:41.5(± 3,2) com p = 0,04; G3A:90,0(± 2,3)/G3B:90,4(± 3,7) com p = 0,77; G4A:81,55(± 5,0)/G4B:79, 4(± 4,6) com p = 0,34; G5A:46,55(± 1,4)/G5B:52,60(± 2,0) com p = 0,00; G6A:42,3(± ,5)/G6B:42,9(± 3,7) com p = 0,70; G7A:36,1(± 4,1)/G7B:39,1(± 3,3) com p = 0,09; G8A:23,8(± 1,9)/G8B:22,0(± 1,8) com p = 0,04. Concluiu-se que, para o aparelho Optilight LD, a ponteira polimérica proporciona melhores resultados, enquanto, para Light 3000, a ponteira de fibra óptica é mais favorável.