Abstract Regular use of toothpaste with fluoride (F) concentrations of ≥ 1000 ppm has been shown to contribute to reducing caries increment. However, when used by children during the period of dental development, it can lead to dental fluorosis. Objective: In this study, we aimed to evaluate the in vitro effect of a toothpaste formulation with reduced fluoride (F) concentration (200 ppm) supplemented with sodium trimetaphosphate (TMP: 0.2%), Xylitol (X:16%), and Erythritol (E: 4%) on dental enamel demineralization. Methodology: Bovine enamel blocks were selected according to initial surface hardness (SHi) and then divided into seven experimental toothpaste groups (n=12). These groups included 1) no F-TMP-X-E (Placebo); 2) 16% Xylitol and 4% Erythritol (X-E); 3) 16% Xylitol, 4% Erythritol and 0.2%TMP (X-E-TMP); 4) 200 ppm F (no X-E-TMP: (200F)); 5) 200 ppm F and 0.2% TMP (200F-TMP); 200 ppm F, 16% Xylitol, 4% Erythritol, and 0.2% TMP (200F-X-E-TMP); and 7) 1,100 ppm F (1100F). Blocks were individually treated 2×/day with slurries of toothpastes and subjected to a pH cycling regimen for five days (DES: 6 hours and RE: 18 hours). Then, the percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), fluoride (F), calcium (Ca), and phosphorus (P) in enamel were determined. The data were analyzed by ANOVA (1-criterion) and the Student-Newman-Keuls test (p<0.001). Results: We found that the 200F-X-E-TMP treatment reduced %SH by 43% compared to the 1100F treatments (p<0.001). The ΔKHN was ~ 65% higher with 200F-X-E-TMP compared to 1100F (p<0.001). The highest concentration of F in enamel was observed on the 1100F treatment (p<0.001). The 200F-X-E-TMP treatment promote higher increase of Ca and P concentration in the enamel (p<0.001). Conclusion: The association of 200F-X-E-TMP led to a significant increase of the protective effect on enamel demineralization compared to the 1100F toothpaste.

Abstract Objective To evaluate the effects of fluoride (F) gels supplemented with micrometric or nano-sized sodium trimetaphosphate (TMPmicro and TMPnano, respectively) on the in vitro remineralization of caries-like lesions. Methodology Bovine enamel subsurface lesions (n=168) were selected according to their surface hardness (SH) and randomly divided into seven groups (n=24/group): Placebo (without F/TMP), 4,500 ppm F (4500F), 4500F + 2.5% TMPnano (2.5% Nano), 4500F + 5% TMPnano (5% Nano), 4500F + 5% TMPmicro (5% Micro), 9,000 ppm F (9000F), and 12,300 ppm F (Acid gel). The gels were applied in a thin layer for one minute. Half of the blocks were subjected to pH cycling for six days, whereas the remaining specimens were used for loosely- (calcium fluoride; CaF2) and firmly-bound (fluorapatite; FA) fluoride analysis. The percentage of surface hardness recovery (%SHR), area of subsurface lesion (ΔKHN), CaF2, FA, calcium (Ca), and phosphorus (P) on/in enamel were determined. Data (log10-transformed) were subjected to ANOVA and the Student-Newman-Keuls’ test (p<0.05). Results We observed a dose-response relation between F concentrations in the gels without TMP for %SHR and ΔKHN. The 2.5% Nano and 5% Micro reached similar %SHR when compared with 9000F and Acid gels. For ΔKHN, Placebo and 5% Nano gels had the highest values, and 5% Micro, 2.5% Nano, 9000F, and Acid gels, the lowest. All groups had similar retained CaF2 values, except for Placebo and Acid gel. We verified observed an increase in Ca concentrations in nano-sized TMP groups. Regarding P, TMP groups showed similar formation and retention to 9000F and Acid. Conclusion Adding 2.5% nano-sized or 5% micrometric TMP to low-fluoride gels lead to enhanced in vitro remineralization of artificial caries lesions.

Resumo Introdução O emprego de biofilmes polimicrobianos, utilizando a saliva como inóculo, é um modelo promissor para o estudo de biofilmes cariogênicos in vitro. Entretanto, ainda não existe uma padronização para seleção de doadores de saliva. Objetivo O objetivo deste estudo foi estabelecer uma metodologia para seleção de doadores de saliva utilizando fatores salivares microbianos e características in vitro do biofilme. Material e método Para doação de saliva foram selecionados vinte voluntários. Os voluntários permaneceram 24 horas sem escovar os dentes e ficaram em jejum por 2 horas antes da coleta da saliva. Foram avaliados os seguintes parâmetros: viabilidade das bactérias anaeróbias totais e mutans streptococci; concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM) da clorexidina; capacidade de formação de biofilme por meio da biomassa; e a suscetibilidade dos biofilmes à clorexidina. Resultado A viabilidade bacteriana da saliva, a capacidade de formação de biofilme e a suscetibilidade do biofilme à clorexidina foram apresentadas como média e intervalo de confiança (95%). A diferença entre a viabilidade do biofilme (mutans streptococci e bactérias totais) após tratamento com NaCl 0,9% e diacetato de clorexidina 0,2% foi comparada pelo teste t de Student com nível de significância estabelecido em 5%. A viabilidade total de bactérias anaeróbias (mediana) foi de 7,28 log 1+UFC/mL (unidades formadoras de colônia/mL). A viabilidade dos mutans streptococci na saliva apresentou mediana de 5,47 log 1+UFC/mL. Para capacidade de formação de biofilme a mediana da biomassa foi de 0,1172 A570. Conclusão O tratamento com clorexidina reduziu significativamente os mutans streptococci e a viabilidade total das bactérias. A metodologia para seleção do doador de saliva foi estabelecida com sucesso.

Abstract Introduction The utilization of polymicrobial biofilms, with saliva as an inoculum, represents a promising model for in vitro studies on cariogenic biofilms. However, there is still no standardization for selecting saliva donors. Objective The aim of this study is to establish a methodology for the selection of saliva donors using microbial salivary factors and in vitro biofilm characteristics. Material and method For saliva donation, twenty volunteers were selected. Volunteers remained 24 h without brushing their teeth and fasted for 2 h before saliva collection. The following parameters were evaluated: total anaerobic bacteria and mutans streptococci viability; minimum inhibitory concentration (MIC) and minimum bactericide concentration (MBC) of chlorhexidine; biofilm forming capacity by biomass assessment; and the susceptibility of biofilms to chlorhexidine. Result Saliva bacterial viability, biofilm forming capacity and biofilm susceptibility to chlorhexidine were presented as mean and confidence interval (95%). The difference between biofilm (mutans streptococci and Total bacteria) viability after treatment with NaCl 0.9% and 0.2% chlorhexidine diacetate was compared using the Student t-test with a significance level established at 5%. Total anaerobic bacteria viability (median) was 7.28 log 1+CFU/mL (colony forming units/ mL). Mutans streptococci viability in the saliva showed a median of 5.47 log 1+CFU/mL. Biofilm forming capacity showed that biomass had a median of 0.1172 A570. Conclusion Treatment with chlorhexidine significantly reduced mutans streptococci and total bacteria viability. The methodology for the selection of the saliva donor was successfully established.

Abstract The present study evaluated the ability of Bifidobacterium and Lactobacillus species associated with streptococci to increase insoluble extracellular polysaccharide (EPS) production and initial caries lesion progression. Bovine enamel blocks (n = 190; 4 mm x 4 mm) were prepared, selected according to initial surface hardness (SH), and divided into two groups: a) double combinations: S. mutans with Bifidobacterium or Lactobacillus, and b) triple combinations: S. mutans and S. sobrinus with Bifidobacterium or Lactobacillus species. The blocks were exposed to the bacterial associations for 7 days. Subsequently, quantity of EPS from biofilms and caries lesion depth were determined by means of colorimetric and cross-sectional enamel hardness (ΔKHN) analysis. The data were submitted to one-way analysis of variance, followed by the Bonferroni test (p < 0.05). S. mutans with B. animalis or B. dentium produced a higher quantity of EPS; S. mutans + B. animalis led to the highest ∆KHN. S. mutans + S. sobrinus + B. longum induced greater EPS and ∆KHN values. In conclusion, associations of B. animalis and B. longum with streptococci promoted EPS production and caries lesion progression.

Abstract Dental applications based on the unique characteristics of amorphous calcium phosphate stabilized by casein phosphopeptides (CPP-ACP) have been proposed, as well as the improvement of its properties. Objectives: The objective of this study was to determine the ability of topically applied CPP-ACP from a commercial product to remineralize subsurface lesions when applied for extended periods of time (3 h and 8 h). Material and Methods: Artificially induced carious lesions were produced in 50 bovine enamel blocks previously selected by surface hardness. After treatments with gel without F and CPP-ACP applied for 1 minute (Placebo); 2% NaF neutral gel applied for 1 minute (Fluoride 1 min); CPP-ACP applied for 3 min (ACP 3 min); and CPP-ACP applied for 3 h (ACP 3 h) and for 8 h (ACP 8 h), the enamel blocks were submitted to the remineralization pH-cycling. Surface hardness and synchrotron micro-tomography were used to determine the percentage of surface hardness recovery (%SHR) and to calculate mineral concentration (gHAp.cm−3), respectively. The data were submitted to ANOVA followed by the Student-Newman-Keuls test (p<0.05). Results: Fluoride gel presented higher %SHR followed by ACP 3 min (p<0.001). No difference (p = 0.148) was found for Placebo, ACP 3 h and ACP 8 h groups for %SHR. Fluoride gel showed greater mineral concentration (p<0.001) when compared with the other groups. ACP 3 min demonstrated a significant difference (p<0.001) from ACP 3 h and ACP 8 h. The ACP 3 h and 8 h presented a subsurface lesion with development of laminations in all blocks. Conclusion: In this in vitro study the use of CPP-ACP for extended periods of time did not produce an additive effect in the remineralization process.

No in situ protocol has assessed the dose-response effects of fluoride dentifrices involving low-fluoride formulations. Objective: To assess the ability of an in situ remineralization model in determining dose-response effects of dentifrices containing low fluoride concentrations ([F]) on bovine enamel. Material and Methods: Volunteers wore palatal appliances containing demineralized enamel blocks and brushed their teeth and devices with the dentifrices supplied (double-blind, crossover protocol) separately for 3 and 7 days. Surface hardness (SH), integrated subsurface hardness (ΔKHN) and [F] in enamel were determined. Data were analyzed by ANOVA, Tukey's test and Pearson's correlation (p<0.05). Results: Dose-response relationships were verified between [F] in dentifrices and SH, ΔKHN and enamel [F]. Higher correlation coefficients between enamel [F] and SH and ΔKHN were obtained for the 3-day period. Significant differences in SH and ΔKHN were observed among all groups for the 3-day period, but not between 0-275, 275-550, and 550-1,100 µg F/g dentifrices for the 7-day period, nor between 3- and 7-day periods for the 1,100 µg F/g groups. Conclusions: Considering that the peak remineralization capacity of the conventional dentifrice (1,100 µg F/g) was achieved in 3 days, this experimental period could be used in future studies assessing new dentifrice formulations, especially at low-fluoride concentrations.

O objetivo do presente trabalho foi avaliar in vitro o efeito de um dentifrício com reduzida concentração de fluoreto (450 µgF/g, NaF) associado ao citrato de cálcio (Cacit) e trimetafosfato de sódio (TMP) na remineralização do esmalte. Blocos de esmalte bovino tiveram sua superfície de esmalte polida seqüencialmente para determinação da dureza de superfície. Após o desenvolvimento de lesões artificiais de cárie, os blocos selecionados através da dureza de superfície foram submetidos a ciclagem de remineralização e tratamento diário com suspensões de dentifrícios (diluição em água deionizada ou saliva artificial): placebo, 275, 450, 550 e 1.100 µgF/g e com dentifrício comercial (controle positivo, 1.100 µgF/g). Ao término, determinou-se a dureza de superfície e em secção longitudinal, para cálculo da variação da dureza de superfície (%SH) e do conteúdo mineral (%∆Z). O fluoreto presente no esmalte também foi determinado. Os dados de %SH, %∆Z e fluoreto foram submetidos a análise de variância a dois critérios seguido pelo teste de Student-Newman-Keuls (p<0,05). O ganho mineral (%SH e %∆Z) foi maior para os dentifrícios diluídos em saliva (p<0,05), exceto para os dentifrícios 450 µg F/g com Cacit/TMP (p>0,05). Os dentifrícios 450 Cacit/TMP e controle positivo apresentaram resultados semelhantes (p>0,05) quando diluídos em água. Uma relação dose-resposta foi observada entre a concentração de fluoreto nos dentifrícios e o fluoreto presente no esmalte, independente da diluição. Concluiu-se que é possível melhorar a capacidade de remineralização de dentifrícios com reduzida concentração de fluoreto pela adição de compostos orgânico (Cacit) e inorgânico (TMP) com afinidade a hidroxiapatita.

The objective of this study was to evaluate in vitro the effect of a low fluoride toothpaste (450 µgF/g, NaF) combined with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel remineralization. Bovine enamel blocks had the enamel surface polished sequentially to determine the surface hardness. After production of artificial carious lesions, the blocks selected by their surface hardness were submitted to remineralization pH cycling and daily treatment with dentifrice suspensions (diluted in deionized water or artificial saliva): placebo, 275, 450, 550 and 1,100 µgF/g and commercial dentifrice (positive control, 1,100 µgF/g). Finally, the surface and cross-section hardness was determined for calculating the change of surface hardness (%SH) and mineral content (%∆Z). Fluoride in enamel was also determined. The data from %SH, %∆Z and fluoride were subjected to two-way analysis of variance followed by Student-Newman-Keuls's test (p<0.05). The mineral gain (%SH and %∆Z) was higher for toothpastes diluted in saliva (p<0.05), except for the 450 µgF/g dentifrice with Cacit/TMP (p>0.05). The 450 Cacit/TMP toothpaste and the positive control showed similar results (p>0.05) when diluted in water. A dose-response was observed between fluoride concentration in toothpastes and fluoride present in enamel, regardless of dilution. It was concluded that it is possible to enhance the remineralization capacity of low F concentration toothpaste by of organic (Cacit) and inorganic (TMP) compounds with affinity to hydroxyapatite.