RESUMO
OBJECTIVES: The relative effect of pH and titratable acidity on tooth erosion remains unclear. We determined the effect of both properties on in vivo salivary pH recovery and on enamel and dentine early erosion in situ. METHODS: Solutions simulating acidic beverages with different pHs (2.5 or 3.5) and titratable acidities (0, 25, or 100 mM citric acid) were tested. In an in vivo study (n = 20 participants), the salivary pH was determined before, during, and up to 2 min after exposure to the tested solutions. In situ, 12 participants exposed enamel and root dentine slabs to the tested solutions simulating a beverage consumption; early erosion was assessed by percentage of surface hardness loss (%SHL). Groups were compared by ANOVA (p < 0.05). RESULTS: Saliva pH was lower after exposure to solutions at pH 2.5, irrespective of titratable acidity; pH recovery took longer for solutions with higher titratable acidities, irrespective of their pHs. In situ, the highest %SHL was observed for the solution with lower pH and higher titratable acidities. The addition of citric acid increased the %SHL by 2.5-3 times in enamel, and at least 5 times in dentine. CONCLUSIONS: Both pH and titratable acidity may play a role on the erosive potential of acidic beverages. CLINICAL RELEVANCE: Acidic beverages with lower pHs promote erosion by an initial acid etching of the surface; those with a higher titratable acidity slow down the salivary pH recovery. Both properties contribute to the overall erosive potential.
Assuntos
Erosão Dentária , Ácidos , Bebidas , Ácido Cítrico , Esmalte Dentário , Dentina , Humanos , Concentração de Íons de Hidrogênio , Erosão Dentária/induzido quimicamenteRESUMO
Biofilm fluoride reservoirs may be a source of fluoride to the fluid phase during a sugar challenge reducing tooth mineral loss. However, the evidence for that is conflicting and has not been studied in biofilms containing different fluoride levels. In order to test fluoride release from biofilms with distinct fluoride concentrations, biofilms were grown in situ exposed to a combination of placebo, calcium and fluoride rinses forming biofilms with no (fluoride-free rinses), low (fluoride-only rinses) or high (calcium followed by fluoride rinses) fluoride concentrations, and collected before and 5 min after a sucrose challenge. Rinsing with fluoride increased fluoride concentration in the biofilm (p < 0.05), mainly when a calcium pre-rinse was used before the fluoride (p < 0.05). However, after a sugar challenge, no significant increase in the biofilm fluid fluoride concentration was observed, even in the fluoride-rich biofilms (p > 0.05). Fluoride-rich biofilms do not release fluoride to the fluid phase during a sugar challenge.
Assuntos
Biofilmes , Cariostáticos , Fluoretos , Cálcio , Fluoretos/farmacocinética , Concentração de Íons de Hidrogênio , Minerais , SacaroseRESUMO
Knowledge about fluoride delivery to oral fluids from foods cooked with fluoridated water and salt is scarce, and no study has evaluated fluoride concentrations in saliva or biofilm during meal consumption. In this randomized double-blind crossover study, 12 volunteers ingested meals (rice, beans, meat, and legumes) prepared with nonfluoridated water and salt (control group), fluoridated water (0.70 mg F/L; water group), and fluoridated salt (183.7 mg F/kg; salt group). Whole saliva was collected before meal ingestion, during mastication, and up to 2 h after meal ingestion. Dental biofilm was collected before and immediately after meal ingestion. Fluoride concentrations in saliva and dental biofilm were determined by an ion-specific electrode. The mean (±standard deviation; n = 4) fluoride concentrations in meals prepared for the control, water, and salt groups were 0.039 ± 0.01, 0.43 ± 0.04, and 1.71 ± 0.32 µg F/g, respectively. The three groups had significantly different fluoride concentrations in saliva collected during mastication (p < 0.0001) and after meal ingestion (p < 0.04; salt > water > control). The fluoride concentration in saliva returned to baseline 30 min after meal ingestion in the water group but remained high for up to 2 h in the salt group (p = 0.002). The fluoride concentration in biofilm fluid differed only between the salt and control groups (p = 0.008). The mastication of foods cooked with fluoridated water and salt increases fluoride concentrations in oral fluids and may contribute to the local effect of these community-based fluoride interventions on caries control.
Assuntos
Biofilmes , Cariostáticos/administração & dosagem , Culinária/métodos , Ingestão de Alimentos , Fluoretação , Fluoretos/administração & dosagem , Saliva/química , Adolescente , Adulto , Análise de Variância , Desjejum , Estudos Cross-Over , Método Duplo-Cego , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Concentração Osmolar , Adulto JovemRESUMO
Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8×/day to 10% sucrose and treated 2×/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2×/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (%SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and %SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Fluoreto de Sódio/farmacologia , Dente/efeitos dos fármacos , Animais , Biofilmes/efeitos dos fármacos , Bovinos , Cárie Dentária/complicações , Cárie Dentária/microbiologia , Esmalte Dentário/microbiologia , Dentina/microbiologia , Modelos Biológicos , Streptococcus mutans/efeitos dos fármacos , Dente/microbiologia , Desmineralização do Dente/etiologia , Desmineralização do Dente/microbiologiaRESUMO
Despite promising results using probiotics, evidence of the preventive effect on enamel demineralization is insufficient and the cariogenic potential of probiotics is still controversial. Probiotics could affect biofilm formation and interfere with adherence, growth or coaggregation with Streptococcus mutans in biofilms. However, most of the studies have been conducted using planktonic bacteria. Hence, the aim of the study was to assess the effect of probiotic bacteria on the cariogenicity of S. mutans using an in vitro biofilm caries model on enamel. Single-species biofilms (S. mutans UA159, SM or Lactobacillus rhamnosus LB21, LB) or dual-species biofilms simultaneously inoculated (SM + LB) or LB inoculated 8 h after SM (SM x2192; LB) were grown for 96 h. Biofilms were formed on bovine enamel saliva-coated slabs of known surface hardness (SH) and immersed in culture media. Biofilms were exposed 8 times per day to 10% sucrose. Medium pH was monitored twice daily as a biofilm acidogenicity indicator. After 96 h, biofilms were collected to determine biomass and bacteria viability. Slab demineralization was calculated as percentage of SH loss (%SHL). Additionally, the model was tested with different concentrations of the initial inoculum (103, 106, 108 cells/ml) and different adhesion times (2 or 8 h). The dual-species biofilm revealed no LB effects on SM cariogenicity, without changes in acidogenicity or %SHL among groups (p > 0.05, n = 12). Lack of activity of LB on SM cariogenicity persisted even when 105 times higher concentration of the probiotic was tested. Coaggregation was not observed. In conclusion, findings suggest that LB does not reduce cariogenicity of SM in a validated experimental caries model.
Assuntos
Biofilmes , Lacticaseibacillus rhamnosus/fisiologia , Streptococcus mutans/fisiologia , Animais , Cariogênicos , Bovinos , Probióticos , Desmineralização do DenteRESUMO
OBJETIVO La mayoría de los estudios cruzados con dentífrico fluoretado (DF) de concentración estándar (1.000-1.500 ppm F) han empíricamente utilizado un periodo de wash-out de 7 días para eliminar el efecto residual del tratamiento. Para DF de alta concentración (5.000 ppm F) este periodo es desconocido y sería necesario un tiempo mayor para la remoción de fluoruro (F) de la saliva. Este estudio verificó si menos de 7 días sería suficiente para eliminar el F residual de la saliva después de uso DF de 5.000 ppm F. METODOLOGÍA Estudio in vivo, análisis ciego, donde voluntarios (n = 6) cepillaron sus dientes 3 veces por día en la secuencia: a) periodo inicial o lead-in de 3 días con uso de dentífrico placebo de fluoruro (DP) (0 ppm F); b) uso de DF de alta concentración (5.000 ppm F) por 4 días; y c) wash-out con uso de DP por 3 días. Durante los 3 periodos, saliva estimulada y no estimulada fue colectada en ayuno (después del periodo overnight del último cepillado). La concentración de F en la saliva fue evaluada utilizando electrodo específico. RESULTADOS El F en la saliva después de suspendido el uso de DF (periodo de wash-out) fue similar a los valores basales. Concentraciones de F no presentaron diferencias entre saliva estimulada y no estimulada. CONCLUSIÓN Dos días de wash-out con dentífrico no fluorado fueron suficientes para eliminar F residual en la saliva después de haber utilizado dentífrico de alta concentración. Estos resultados son válidos también para dentífrico de concentración estándar.
OBJECTIVE Most crossover studies using fluoride dentifrice (FD) of standard concentration (1000-1500 ppm F) have empirically used a wash-out period of 7 days to remove the residual effect of the treatment. For higher concentrations of FD (5000 ppm F) the period is unknown, and a longer time may be required to remove fluoride (F) from saliva. Therefore, the aim of the study was to determine if less than 7 days of wash-out would be sufficient to remove residual F in saliva after using 5000 ppm F FD. METHODOLOGY An in vivo study, blind analysis, was conducted on volunteers (n = 6) who brushed their teeth 3 times per day in the following sequence: a) initial or lead-in period of 3 days using placebo fluoride dentifrice (PD) (0 ppm F); b) using a high concentration FD (5000 ppm F) for 4 days; and c) wash-out using PD for 3 days. During the 3 periods, samples of non-stimulated and stimulated saliva were collected after fasting (one overnight period from the last brushing). Fluoride concentration was assessed in saliva using a fluoride specific electrode. RESULTS F concentrations in saliva after discontinued use of FD (wash-out period of 2 and 3 days) were similar to baseline values. F concentrations did not differ between unstimulated and stimulated saliva. CONCLUSION A two day wash-out period using non-fluoridated dentifrice was sufficient to eliminate residual F in saliva after use of a high concentration F dentifrice. These results are also valid for standard concentrations of dentifrice.
Assuntos
Humanos , Adulto , Saliva , Dentifrícios , Fluoretos/análise , Fluoretos/farmacocinética , Fatores de TempoRESUMO
The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride-TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children's toothpaste (n = 78)). The estimated dose (mg F/day/Kg of body weight) of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested dose of TF from the family toothpastes was higher than that from the children's toothpastes (0.074 ± 0.007 and 0.039 ± 0.003 mg F/day/Kg, respectively; p < 0.05), no difference between types of toothpaste was found regarding the ingested dose based on TSF (0.039 ± 0.005 and 0.039 ± 0.005 mg F/day/Kg, respectively; p > 0.05). The fluoride dose ingested by children from toothpastes may be overestimated if based on the TF of the product. This finding suggests that the ingested dose should be calculated based on TSF. Dose of TSF ingested by children is similar whether family or children's toothpaste is used.
Assuntos
Cariostáticos/química , Fluoretos/química , Cremes Dentais/química , Brasil , Cariostáticos/análise , Pré-Escolar , Fluoretos/análise , Humanos , Eletrodos Seletivos de Íons , Solubilidade , Escovação Dentária , Cremes Dentais/análiseRESUMO
Much more than mechanical biofilm removal, toothbrushing with fluoride toothpastes is an effective way of increasing the availability of fluoride in the oral cavity to reduce demineralization and enhance remineralization of enamel and dentine. These effects of fluoride toothpastes have been estimated by a wide range of laboratory and human studies, which have helped to develop anticaries effective formulations and understand their mechanism of action. These studies have focused on the availability of fluoride in the toothpaste formulations, its bioavailability in saliva and remnants of disturbed biofilm, its reaction with the dental substrate to form loosely bound reservoirs as well as the ultimate reduction of mineral loss and increase in mineral and fluoride content of caries lesions. The specifics of these modes of action and their application in in vitro, in situ and in vivo preclinical tests is presented and discussed.
Assuntos
Cariostáticos/uso terapêutico , Fluoretos/uso terapêutico , Cremes Dentais/uso terapêutico , Disponibilidade Biológica , Cariostáticos/química , Cariostáticos/farmacocinética , Química Farmacêutica , Avaliação Pré-Clínica de Medicamentos , Fluoretos/química , Fluoretos/farmacocinética , Humanos , Desmineralização do Dente/metabolismo , Desmineralização do Dente/prevenção & controle , Remineralização Dentária/métodos , Escovação Dentária , Cremes Dentais/química , Cremes Dentais/farmacocinéticaRESUMO
Characteristics of enamel may influence or modulate individual susceptibility to caries and erosion. These characteristics are defined during development, which is under strict genetic control, but can easily be modified in many ways by environmental factors. In the symposium, translational aspects of embryology, biochemistry, and genetics of amelogenesis were presented. The symposium provided unique insight into how basic sciences integrate with clinically relevant problems. The need for improved understanding of risks at the individual level, taking into consideration both environmental exposures and genetic background, was presented. The symposium was divided into four stepwise and interconnected topics as follows: 1) The Many Faces of Enamel Development; 2) Enamel Pathogenesis: Biochemistry Lessons; 3) Environmental Factors on Enamel Formation; and, 4) Genetic Variation in Enamel Formation Genes.
RESUMO
Because low-fluoride toothpaste (500 p.p.m. F) has not clearly been shown to be effective for controlling caries in caries-active children, this experimental in situ study was conducted to evaluate whether its effect, when compared with a conventional toothpaste (1,000-1,500 p.p.m. F), would depend on the cariogenic challenge. During four phases of 14 d each, 14 volunteers used 500 or 1,100 p.p.m. F toothpaste and wore palatal appliances containing deciduous enamel slabs, on which biofilm was accumulated and exposed to 20% sucrose solution at frequencies increasing from two to eight times per day. The F concentration was determined in the biofilm formed, and enamel demineralization was assessed by surface hardness loss (% SHL) and integrated area of hardness x lesion depth (DeltaS). The F uptake by enamel was also determined. Fluoride in biofilm fluid and solids was statistically higher when conventional F toothpaste was used. The toothpastes did not differ statistically in terms of % SHL, DeltaS, and F in enamel, but only the conventional F toothpaste significantly reduced caries-lesion progression according to the frequency of sucrose exposure. The findings suggest that the high-F availability in biofilm, resulting from the use of conventional toothpaste compared with low-F toothpaste, may be important for reducing caries-lesion progression in conjunction with a high frequency of sucrose exposure.
Assuntos
Biofilmes , Cariogênicos/administração & dosagem , Cariostáticos/uso terapêutico , Esmalte Dentário/patologia , Sacarose Alimentar/administração & dosagem , Fluoretos/uso terapêutico , Desmineralização do Dente/etiologia , Dente Decíduo/patologia , Cremes Dentais/uso terapêutico , Adolescente , Adulto , Disponibilidade Biológica , Cariogênicos/efeitos adversos , Cariostáticos/análise , Cariostáticos/farmacocinética , Estudos Cross-Over , Cárie Dentária/etiologia , Cárie Dentária/microbiologia , Cárie Dentária/prevenção & controle , Esmalte Dentário/metabolismo , Placa Dentária/metabolismo , Placa Dentária/microbiologia , Sacarose Alimentar/efeitos adversos , Progressão da Doença , Método Duplo-Cego , Fluoretos/análise , Fluoretos/farmacocinética , Dureza , Humanos , Fatores de Tempo , Desmineralização do Dente/microbiologia , Desmineralização do Dente/prevenção & controle , Escovação Dentária , Cremes Dentais/análise , Adulto JovemRESUMO
Since in vitro and animal studies suggest that the combination of starch with sucrose may be more cariogenic than sucrose alone, the study assessed in situ the effects of this association applied in vitro on the acidogenicity, biochemical and microbiological composition of dental biofilm, as well as on enamel demineralization. During two phases of 14 d each, fifteen volunteers wore palatal appliances containing blocks of human deciduous enamel, which were extra-orally submitted to four groups of treatments: water (negative control, T1); 2 % starch (T2); 10 % sucrose (T3); and 2 % starch+10 % sucrose (T4). The solutions were dripped onto the blocks eight times per day. The biofilm formed on the blocks was analysed with regard to amylase activity, acidogenicity, and biochemical and microbiological composition. Demineralization was determined on enamel by cross-sectional microhardness. The greatest mineral loss was observed for the association starch+sucrose (P<0.05). Also, this association resulted in the highest lactobacillus count in the biofilm formed (P<0.05). In conclusion, the findings suggest that a small amount of added starch increases the cariogenic potential of sucrose.