Chemical Characterization and Effect of a Lactobacilli-Postbiotic on Streptococcus mutans Biofilm In Vitro.

Postbiotic is the term used to define the soluble factors, metabolic products, or byproducts released by live probiotic bacteria or after its lysis. The objective of this study was to carry out the chemical characterization of the postbiotic of Lacticaseibacillus rhamnosus LR-32 and to evaluate its in vitro effect on the development of the Streptococcus mutans biofilm. After the cultivation of the probiotic strain, the postbiotic was extracted by centrifuging the culture and filtering the supernatant. This postbiotic was characterized by using gas chromatography coupled with mass spectrometry (GC-MS), and then it was used to determine the growth inhibition of S. mutans in its planktonic form; additionally, its effects on the following parameters in 48 h biofilm were evaluated: viable bacteria, dry weight, and gene expression of glucosyltransferases and VicR gene. The control group consisted of the biofilm without any treatment. A paired t-test was performed for statistical analysis, with the p-value set at 5%. Seventeen compounds of various chemical classes were identified in the postbiotic, including sugars, amino acids, vitamins, and acids. The treatment with the postbiotic led to an inhibition of the growth of S. mutans in its planktonic form, as well as a decrease in the number of viable bacteria, reduction in dry weight, and a negative regulation of the gene expression of gtfB, gtfC, gtfD, and vicR in its biofilm state, compared with the nontreated group (p < 0.05). The postbiotic of L. rhamnosus impaired the development of S. mutans biofilm.

Lactobacilli Probiotics Modulate Antibacterial Response Gene Transcription of Dendritic Cells Challenged with LPS.

Probiotics are beneficial bacteria that may modulate the immune response by altering the maturation and function of antigen-presenting cells, such as dendritic cells. This study aimed to evaluate the antibacterial gene expression of dendritic cells challenged with LPS and probiotics. Immature dendritic cells were obtained from human CD14+ monocytes and challenged with E. coli LPS and probiotics Lacticaseibacillus rhamnosus (LR-32) and Lactobacillus acidophilus (LA-5) at a ratio DC:bacteria of 1:10. The analysis of gene expression was performed by RT-qPCR using the Kit RT2 human antibacterial response. In the supernatant, the cytokines secretion was determined by ELISA. Tukey post-ANOVA with p at 5% was used for statistical analysis. LPS showed the higher upregulation of 29 genes compared with the groups where probiotics were added to LPS, including genes related to an inflammatory response like BIRC3, CASP1, CCL5, CXCL1, IL12B, IL18, MYD88, NLRP3, RIPK1, and TIRAP. Similarly, LPS increased the transcription of genes enrolled with apoptosis such as CARD6, CASP1, IRF5, MAP2K1, MAP2K4, MAPK1, MYD88, NLRP3, RIPK2, TNF, TNFRSF1A, and XIAP when compared to probiotics groups (p < 0.05). Although probiotics decrease several genes upregulated by LPS, the transcription of encoded cytokines IL12A, IL12B, IL1B, IL6, CXCL8, and TNF genes was maintained upregulated by probiotics, except for IL18, which was downregulated by LA-5. LA-5 led to a higher transcription of IL1B, IL6, and CXCL-8 which was followed by the secretion of these proteins by ELISA. The results suggest that probiotics attenuate the transcription of inflammatory and immune response genes caused by LPS.

Salivary fluoride bioavailability after use of high-fluoride dentifrices with different compositions: A short-term randomized clinical trial.

OBJECTIVE: The objective of the study was to evaluate the kinetics of salivary F bioavailability after the use of high-fluoride dentifrices with different compositions and their amount of total soluble fluoride (TSF). METHODS: A short-term clinical randomized trial was performed in which 15 adult participants were randomly allocated into three groups: 5000 ppm F-dentifrice, 5000 ppm F-dentifrice + TCP (tri-calcium phosphate) and 1450 ppm F-dentifrice. Unstimulated saliva was collected at different times: baseline (before toothbrushing), immediately after brushing/water rinsing and at 5, 15 and 30 min and 1, 2, 4, 8 and 12 h after brushing. The TSF in dentifrices and saliva samples was analysed using an ion-specific electrode. For statistical analysis, the paired t-test and Kruskal-Wallis were used with Dunn's post-test with a 95% confidence interval. RESULTS: There was no significant difference between the declared TSF and that found in 5000 ppm F-dentifrice and 1450 ppm F-dentifrice (p ≥ 0.13); however, in the 5000 ppm F-dentifrice + TCP, approximately 500 ppm less TSF was observed (p = 0.0024). The area under the curve (AUC, µg F/ml min-1 ) of both high-fluoride dentifrices (321.7 ± 84.0 and 223.6 ± 55.1 for the one without and with TCP, respectively) was higher than the conventional one (89.97 ± 15.6) attesting a higher F-bioavailability (p = 0.04). Furthermore, they were able to provide F-salivary levels higher than the baseline for up to 2 h, while this time was 1 h for the 1450 ppm F-dentifrice (p ≤ 0.003). CONCLUSION: Both high-fluoride dentifrices similarly increased the salivary-F bioavailability in comparison with 1450 ppm F-dentifrice, despite the lower TSF presented by the dentifrice containing TCP.

Effect of Probiotics Lactobacillus acidophilus and Lacticaseibacillus rhamnosus on Antibacterial Response Gene Transcription of Human Peripheral Monocytes.

Periodontitis and related systemic inflammatory diseases are characterized by imbalanced ratio between pro- and anti-inflammatory factors. Probiotics may control inflammation by altering the inflammatory phenotype of defense cells. We aimed to evaluate the gene transcription of the antibacterial response of monocytes to exposure to probiotic lactobacilli. CD14 + monocytes were obtained by positive selection from peripheral blood mononuclear cells from healthy donors (5 × 104 CD14 + /mL) and cultured with probiotic strains of Lacticaseibacillus rhamnosus (LR-32) and Lactobacillus acidophilus (LA-5) at a 1:10 multiplicity of infection in 24-well plates for 12 h. The gene expression analysis was performed by RT-qPCR using the Kit RT2 human antibacterial response, and in the supernatant, the cytokines were determined by ELISA. Tukey's post hoc test following an ANOVA with a p value of 5% was used for statistical analysis. Both probiotic strains increased the levels of cytokines TNF-α and CXCL-8 in the supernatant compared to the control of non-challenged cells (p < 0.05), but for IL-1Β and IL-6, this effect was observed only for LA-5 (p < 0.05). The fold-regulation values for the following genes for LA-5 and LR-32 were, respectively, IL-12B (431.94 and 33.30), IL-1Β (76.73 and 17.14), TNF-α (94.63 and 2.49), CXCL-8 (89.59 and 4.18), and TLR-2 (49.68 and 3.40). Likewise, most of the other genes evaluated showed greater expression for LA-5 compared to LR-32 (p < 0.05). The positive regulation of inflammatory factors such as IL-1ß promoted by L. acidophilus LA-5 may increase the antibacterial activity of innate defense in periodontal tissues. However, this property may be deleterious by increasing inflammatory response.

Effect of high-fluoride dentifrice on root dentine de-remineralization exposed to erosion challenge in vitro.

Background: High-fluoride dentifrice can be used to manage dental erosion; however, little is known about it effect on root dentine previously demineralized. This study evaluated the effect of high-fluoride treatment on dentin de/remineralization exposed to an erosion challenge in vitro. Material and Methods: Sound and demineralized dentine blocks were submitted to a 5-days-erosive challenge in soft drink (4/day during 90 s) and treated with fluoride solutions (0, 1,100, or 5,000 µg F/mL). After this, the percentage of surface hardness loss (%SHL) or recovery (%SHR) was calculated. Data were analyzed by one-way ANOVA and Tukey post hoc test with p fixed at 5%. Results: High-fluoride treatment was able to reduce dentine remineralization and increase mineral recovery of previously demineralized dentine compared to other treatments tested (p<0.05). Conclusions: High-fluoride treatment was able to increase the remineralization and reduce the demineralization of root dentine submitted to an erosive challenge in vitro, being an option for the erosion prevention/treatment. Key words:Fluorides, root caries, tooth erosion, toothpastes.

Effect of high-fluoride dentifrice on root dentine and bacterial composition in a multispecies biofilm model.

The present study evaluated the effect of high-fluoride dentifrice on dentine demineralization and bacterial composition in a multispecies biofilm model in vitro. A seven-organism bacterial consortium was grown on bovine dentine discs in a high-throughput active attachment model. The biofilms were submitted twice per day to the following dentifrices treatments: 5,000 ppm F, 1,100 ppm F, with placebo as a negative control. After 5 days of biofilm growth, dentine samples were assessed by transversal microradiography, the biofilm was collected for bacterial counts and the pH of the media was determined. Lower integrated mineral loss values were observed when 5,000 ppm F-treatment was used compared to the other treatments. Overall microbiological counts decreased with increasing F-concentration as well the pH of the media throughout the experiment. The 5,000 ppm F-treatment caused a shift in microbial composition and reduced dentine demineralization in the in-vitro experimental model.

Nocturnal Salivary Fluoride Bioavailability After Brushing with a High-fluoride Dentifrice.

The use of fluoridated dentifrices is recognized as the main reason for the decline of dental caries and its effect is associated with the bioavailability of fluoride (F) in the oral cavity. High-fluoride dentifrice has been indicated for patients at high risk of caries and management of root lesions. This study aimed to evaluate the bioavailability of F in saliva after the use of high-fluoride dentifrice during the nocturnal period. Fifteen healthy adults participated in this is in vivo and crossover study in which the concentration of F in their saliva was determined after brushing with the tested dentifrices: a conventional (1450 ppm F) or with high-fluoride concentration (5000 ppm F). Before brushing, the participants collected the non-stimulated saliva (baseline), immediately after brushing (time zero) and after 5min, 2h, 4h, and 8h, during the nocturnal period (between 10:00 pm and 06:00 am). The salivary F concentration was determined using a specific F ion electrode. Regarding statistical analysis, a paired t-test was used to compare dentifrices with p fixed at 5%. At baseline, there was no significant difference between groups (p>0.001). Immediately after brushing, both dentifrices increased the F salivary concentration, with the highest concentration reached in time zero; however, the use of 5000 ppm F dentifrice maintained the higher F salivary concentration at all times evaluated (p<0.001), remaining higher until 8 h after brushing. Furthermore, this treatment showed higher F bioavailability in relation to time, evaluated by the area under the curve (p<0.001). Thus, it can be concluded that the high-fluoride dentifrice increased the bioavailability of salivary F during the nocturnal period in comparison with conventional dentifrice.

Effect of probiotic Lactobacillus rhamnosus by-products on gingival epithelial cells challenged with Porphyromonas gingivalis.

OBJECTIVE: Probiotics are usually given as living cells, but their effects may be also achieved by postbiotics. We hypothesized that probiotics products (spent media and lysate) altered the response induced by P. gingivalis in gingival epithelial cells (GECS). METHODS: Immortalized human OBA-9 GECs (∼2,5 × 105cells/well) were challenged with P. gingivalis ATCC33277, and co-infected with L. rhamnosus Lr-32 for 4 h. L. rhamnosus Lr-32 spent medium or cells lysate was added to GECs co-infected with P. gingivalis. Another set of OBA-9 GECs were first exposed to P. gingivalis ATCC 33277 and then to the living probiotic or probiotic products. Transcription of genes encoding inflammatory mediators (IL-1ß, TNF-α, IL-6, and CXCL-8) and receptors (TLR2 and TLR4) were evaluated by RT-qPCR. P. gingivalis growth under L. rhamnosus Lr-32 postbiotics was also evaluated. RESULTS: L. rhamnosus Lr-32 spent media decreased cell viability, while living cells and cell lysates did not. L. rhamnosus Lr-32 lysate, but not spent media, upregulated transcription of inflammatory mediators (IL-1ß, TNF-α, IL-6, and CXCL-8) in GECs infected with P. gingivalis. Transcription of TRL2 was upregulated in all experimental groups compared to control, whereas TLR4 was upregulated by the probiotic or its postbiotics in P. gingivalis infected cells. Spent media and lysates reduced the growth of P. gingivalis. CONCLUSION: L. rhamnosus Lr-32 cell components rather than live probiotic enhanced the expression of inflammatory mediators in P. gingivalis infected gingival epithelial cells. The increased potential of Lr-32 cell lysates to promote immune response to the periodontopathogen may favor pathogen elimination but may also lead to additional deleterious effects of the exacerbated inflammation.

Effect of high-fluoride dentifrice and bracket bonding composite material on enamel demineralization adjacent to orthodontic brackets in vitro.

BACKGROUND: There is a lack of information about the association of high-fluoride dentrifrice and fluoride-containing bonding material to prevent enamel white spot lesions development adjacent to brackets. The aim of this in vitro study was to evaluate the effect of high-fluoride dentifrice and fluoride-containing bonding material on enamel demineralization adjacent to orthodontic brackets. MATERIAL AND METHODS: Forty-eight enamel specimens with 7x7x2 mm were obtained from bovine incisors. Orthodontic brackets were bonded with fluoride-containing resin composite (OrthoCem®) or fluoride-free low viscosity resin. The specimens were submitted to an 8-day pH cycling that consisted in the daily immersion of specimens in the demineralizing solution for 4 h and in artificial saliva for 20 h in an incubator at 37° C. The treatments consisted in 5 min-immersion between the cycles of fluoride (F) suspensions containing 275 µg F/mL, 1,250 µg F/mL or distilled water (negative control). The 275 and 1,250 µg F/mL concentrations were used to simulate salivary dilution of 1,100 and 5,000 µg F/g dentifrices during toothbrushing. After the experiment, cross-sectional hardness was performed to analyze the lesion area of the specimens. Tukey post hoc test after two-way ANOVA with p at 5% was used as statistical analysis. RESULTS: The specimens treated with high-fluoride dentifrice showed significantly less demineralization in comparison with the other treatments (p>0.05). There was a significant difference in the cross-sectional hardness values for the specimens bonded with OrthoCem when compared to the low viscosity resin (p>0,05). CONCLUSIONS: The use of high-fluoride dentifrice associated with fluoride-containing bonding material promoted a greater reduction of enamel demineralization adjacent to orthodontic brackets. Key words:Demineralization, dentifrice, fluoride, bonding materials, orthodontic brackets.

Effect of over the counter mouthwashes with and without alcohol on sorption and solubility of bulk fill resins.

BACKGROUND: Composites sorption and solubility can be precursors of several chemical and physical processes, which lead to deleterious effects on the polymer structure. This study evaluated the effect of mouthwashes with and without alcohol on the sorption and solubility of conventional and low viscosity bulk fill resins. MATERIAL AND METHODS: Four types of Bulk Fill resins (Filtek™ Bulk Fill, X-tra Fil, Filtek™ Bulk Fill Flow and X-tra Base) were submitted to the following mouthwashes: Listerine Cool Mint and Periogard (containing alcohol) and Listerine Zero and Periogard (alcohol-free). The specimens were stored in the mouthwashes for seven days. Solubility and sorption tests were performed according to ISO 4049. Data were analyzed using two-way-ANOVA, followed by Tukey Test. The data were grouped, and a paired t-test was performed to evaluate the effect of alcohol on the properties studied. The p was fixed at 5%. RESULTS: Resins immersed in alcohol-containing mouthwashes had higher values of sorption and solubility, with the highest sorption rate for X-Tra Base in Listerine Cool Mint treatment (p<0.05). Flow type resins showed higher sorption than conventional viscosity resins, irrespective of the mouthwash used (p<0.05). CONCLUSIONS: Alcohol-containing mouthwashes affected sorption and solubility of bulk fill resins and the composites that presented worse and better performance regarding the studied properties were X-Tra Base and Filtek™ Bulk Fill, respectively. Key words:Solubility, Sorption, Mouthwashes, Bulk-fill composites.

Dose-Response Effect of Fluoride Dentifrices on De-/Remineralization of Root Dentine in situ.

The present study aimed to evaluate the effect of fluoride (F) dentifrice with different F concentrations on root dentine de-/remineralization. Ten healthy volunteers took part in this randomized, double-blinded, cross-over, and split-mouth in situ experimental study. During 4 phases of 7 days, they wore a palatal appliance containing 4 bovine dentine blocks (2 sound and 2 with caries) of 4 × 4 × 2 mm. Treatments were performed with silica-based dentifrices containing 0, 700, 1,300, and 5,000 µg F/g (F as NaF). To provide a cariogenic challenge, a 20% sucrose solution was dripped 3 and 8 times daily on the carious-like and sound blocks, respectively. After each experimental phase, the percentage of surface hardness loss (%SHL) or recovery (%SHR) was calculated and the fluoride concentration in the biofilm was determined. The statistical analysis was performed using ANOVA and the Tukey post hoc test with p at 5%. The relationship between variables was analyzed by linear regression. The results showed a lower %SHL when 5,000 µg F/g dentifrice was used but without a statistically significant difference from the conventional one (1,300 µg F/g). Regarding remineralization and F in biofilms, the high-fluoride dentifrice was expressively superior in mineral replacement on the surface and in the F concentration in the biofilms, respectively, compared to the other 3 products (p < 0.05). Also, a significant linear fit between mineral loss/gain, F in biofilms, and fluoride concentration in the dentifrices could be observed. In conclusion, a dose-response F effect was observed, and the high-fluoride dentifrice was effective in enhancing root dentine remineralization in this short-term in situ study.

Development of an Experimental Dentifrice with Hydroxyapatite Nanoparticles and High Fluoride Concentration to Manage Root Dentin Demineralization.

BACKGROUND: High-fluoride dentifrice is used to manage root caries, but there is no evidence whether its association with nanohydroxyapatite could provide an additional protection for root caries. Therefore, this study aimed to develop and evaluate the effect of an experimental dentifrice with high fluoride (F-) concentration and nanohydroxyapatite (nano-HA) on root dentin demineralization. MATERIALS AND METHODS: After formulation of dentifrices, root dentin specimens were randomly assigned to six groups (n = 10) using different dentifrice treatments: placebo; nano-HA without F-; 1,100 µg F-/g; 1,100 µg F-/g + nano-HA; 5,000 µg F-/g; and 5,000 µg F-/g + nano-HA. A pH cycling model was performed for 10 days, in which treatments were performed twice a day. After that period, the longitudinal hardness was evaluated and the area of demineralization (ΔS) was calculated. The formulated dentifrices were evaluated for primary stability, cytotoxicity, and other technical parameters. Two-way ANOVA and Tukey's test with p set at 5% were used for data analysis. RESULTS: The experimental dentifrices were stable and had no cytotoxicity. Regarding dentin demineralization, the placebo group significantly increased ΔS compared to all other treatment groups (p<0.001). The dentifrices containing 5,000 µg F-/g, regardless of the presence of nano-HA, led to a smaller lesion area in relation to the other treatments (p<0.001). CONCLUSION: The findings of this study suggest that nano-HA reduced dentin demineralization, and dentifrice with 5,000 µg F-/g dentifrices, regardless of the presence of nano-HA, showed a greater reduction in root dentin demineralization.

Chemokines and cytokines profile in whole saliva of patients with periodontitis.

Clinical features suggest differences in immune response among periodontitis forms, albeit a large number of cytokines and chemokines remain to be evaluated. The saliva is an available source of mediators and its analysis would be valuable in order to understand pathophysiological differences. The objective of this study was analyze chemokines/cytokines profile in whole saliva of individuals with severe periodontitis (Stage III) presenting moderate [Grade B; GB] or rapid progression rate with a localized incisor-molar pattern [Grade C; GC/IMP]. A case-control study was designed for each periodontitis group. GB (n = 9) and GC/IMP (n = 7) patients and their healthy controls (C-GB, n = 9 and C-GC, n = 7) were evaluated. Non-stimulated saliva samples were assessed by a multiplex assay for a total of 40 cytokines, C-C and C-X-C motif chemokines. GC/IMP group presented higher levels of CCL17 and CCL27 (p = 0.04, FDR > 0.05), and lower levels of CCL2 (p = 0.04, FDR > 0.05) and CCL25 (p = 0.006, FDR < 0.05) when compared to its control. GB patients had higher levels of IL-6, IL-1ß (p = 0.04, FDR > 0.05), and elevated pro-inflammatory (TNF-α,IL-1ß,INF-γ,IL-6, IL-16): anti-inflammatory (IL-2, IL-4, IL-10) ratio (p = 0.01, FDR < 0.05) compared to its control [p-values by Mann-Whitney test, and False Discovery Rate (FDR) by Benjamini-Hochburg corrections]. CCL-chemokines and cytokines contributed to differences between GC/C-GC and GB/C-GB, respectively (p < 0.05, PERMANOVA test). These preliminary data revealed that each periodontitis phenotype presented distinct immune profiles differentially expressed in saliva compared to their related controls, suggesting differences in the etiopathogenesis of GB and GC/IMP.

Effect of high-fluoride dentifrice and bracket bonding composite material on enamel demineralization in situ.

OBJECTIVE: This in situ study evaluated the effect of high-fluoride dentifrice (5000 µg F-/g) and fluoride-containing bonding composite resin on enamel demineralization adjacent to orthodontic brackets. METHODS: Ten volunteers wore palatal appliances containing bovine enamel blocks with metallic brackets bonded with fluoride-free or fluoride-containing composite resin. During three phases of 14 days each, three dentifrices with different fluoride concentrations (0, 1100, and 5000 µg F-/g) were tested. The cariogenic challenge consisted of 20% sucrose solution dripped 8x/day onto the dental blocks. At the end of each phase, biofilm formed was collected for fluoride analysis. Cross section hardness was performed in enamel blocks, and the lesion area was calculated. Data were analyzed by two-way ANOVA followed by Tukey post hoc test (α = 5%). RESULTS: The only signicant factor for all the variables under study was the dentifrice. Smaller lesion area and higher fluoride concentration on biofilm were found in 5000 µg F-/g group, irrespective of bonding composite resin (p < 0.001). Neither bracket-bonding composite resin nor the interaction between the factors was statistically significant (p > 0.05) for all the variables. CONCLUSION: High-fluoride dentifrice is effective in reducing demineralization on enamel adjacent to orthodontic brackets, while the fluoride-containing bonding composite resin does not influence it. CLINICAL SIGNIFICANCE: Since high-fluoride dentifrice was able to reduce demineralization adjacent to brackets, it can be an option to caries management in orthodontics patients.

Fluoride Release of Fresh and Aged Glass Ionomer Cements after Recharging with High-Fluoride Dentifrice.

OBJECTIVE: This study aimed to evaluate F release from GICs before and after recharging with F-dentifrices and after aging process. METHODS: Fifteen specimens of GICs (conventional, resin modified, and high viscosity) and composite resin were stored individually in a polystyrene tube containing 2 ml of deionized water (DW), with water replacement every 24 hours. After 15 days, the specimens were treated with a dentifrice suspension (1 : 3 by volume) containing 0 µg F/g (n = 5), 1,100 µg F/g (n = 5), or 5,000 µg F/g (n = 5). After 3 min, the specimens were rinsed and replaced in new tubes with 2 ml of DW. This procedure was performed 2x/day for 2 days. The readings were taken on days 1, 5, 10, and 15 before and after the treatments. A second experiment was performed, using the same specimens of the previous study that were submitted to an aging process (specimens were kept in 2 ml of DW, remaining at 37°C for 36 weeks). Readings using specific electrode for F detection were taken on days 1, 5, 10, and 15 after treatment of the samples as described above. Data were analyzed by ANOVA and Tukey's test with α fixed at 5%. RESULTS: It was observed that the highest release of F for all the GICs occurred on the first day after the treatments, especially when using a high-fluoride dentifrice, with decreasing release over time. Also, although aged GICs still recharge with F treatments, the amount of F released was lower than fresh materials. CONCLUSION: GICs present a high F recharge and release capacity, especially in the first 24 hours and after the treatment with a high-fluoride dentifrice, even after material aging.

Root dentine demineralisation according to frequency of sucrose exposure using high-fluoride dentifrice.

OBJECTIVE: To evaluate root dentine demineralisation, biomass and loosely bound fluoride (CaF2 ) concentration according to different frequencies of sucrose exposure using a high-fluoride dentifrice. BACKGROUND: Although high-fluoride dentifrice has been recommended to arrest root dentine lesions, it is not clear whether it can protect dentine from increased frequencies of sucrose exposure. METHODS: An in situ, crossover, split-mouth study was conducted in 3 phases with 7 days each, in which 10 volunteers used a palatal device containing 4 bovine root dentine slabs (2 on each side) with predetermined initial hardness. Cariogenic challenge consisted in dripping a 20% sucrose solution 0 (control), 2, 4, 6, 8 or 10 times/d in each block. Volunteers used high-fluoride dentifrice (NaF, 5000 µg F/g) 3 times/d. After each phase, final hardness was measured and the percentage of surface hardness loss (%SHL) calculated. Also, biomass and CaF2 concentration on dentine were determined. The data were processed and analysed by ANOVA and Tukey test with significance level set at 5%. The relationship between the variables was analysed by linear regression and Pearson correlation (r). RESULTS: %SHL and biomass were significantly greater than control for sucrose frequencies higher than 6 times/d (P < 0.001), while CaF2 concentration decreased from sucrose frequency higher than 2 times/d (P < 0.001). Regression analysis data showed a significant linear fit between sucrose exposure frequency and the studied variables with a strong correlation (r) for %SHL and CaF2 and moderate for biomass (P < 0.05). CONCLUSION: High-fluoride dentifrice is able to reduce root dentine demineralisation if sucrose consumption is not higher than 6 times/d.

Effect of Sweeteners on Root Dentine Demineralization Using a Microcosm Biofilm Model / Efecto de los Edulcorantes en la Desmineralización de la Dentina Radicular Utilizando un Modelo de Biofilm Microcosmo

ABSTRACT: The aim of the present study was to evaluate the effect of commercial sweeteners on root dentin demineralization using a microcosm biofilm model. Bovine dentin specimens with pre-determined surface hardness were randomized into six groups according to the studied sweeteners: sucralose, stevia, saccharin, aspartame. Sucrose was used as a positive control and an untreated group as a negative control. The specimens were submitted to biofilm development from one saliva donor and the cariogenic challenge occurred on subsequent five days, twice a day. At the end, the percentage of surface hardness loss (%SHL) and biomass was determined and submitted to ANOVA followed by Tukey's test. Sucrose presented the highest rate of demineralization, however, all sweeteners tested lead to a statistically higher root demineralization compared to the negative control (p <0.05). Sucrose caused greater demineralization in root dentin, however, the sweeteners were also able to induce it under this biofilm model.

RESUMEN: El objetivo del presente estudio fue evaluar el efecto de los edulcorantes comerciales en la desmineralización de la dentina radicular utilizando un modelo de biofilm microcosmo. Se asignaron al azar muestras de dentina bovina con una dureza de la superficie predeterminada de acuerdo con los edulcorantes estudiados: sucralosa, estevia, sacarina, aspartame. La sacarosa se utilizó como control positivo y un grupo no tratado como control negativo. Las muestras se enviaron al desarrollo de biopelículas de un donante de saliva y el desafío cariogénico se produjo en los siguientes cinco días, dos veces al día. Al final, se determinó el porcentaje de pérdida de dureza de la superficie (% PDS) y biomasa y se aplicó un estudio estadístico de ANOVA seguido de la prueba de Tukey. La sacarosa presentó la mayor tasa de desmineralización; sin embargo, todos los endulzantes probados condujeron a una desmineralización de la raíz estadísticamente mayor en comparación con el control negativo (p<0,05). La sacarosa causó una mayor desmineralización en la dentina de raíz, sin embargo, los edulcorantes también fueron capaces de inducirla bajo este modelo de biofilm.

Gastrointestinal Absorption and Renal Excretion of Fluoride After Ingestion of a High-Fluoride Dentifrice.

This study aimed to evaluate the gastrointestinal absorption and renal excretion of fluoride after the ingestion of high-fluoride dentifrice. Twelve volunteers participated in this in vivo, crossover, and blinded study. In three experimental phases, the volunteers were randomly assigned to one of three treatment groups, who ingested either the following: distilled and deionized water (control), conventional dentifrice (1100 µg/g), or high-fluoride dentifrice (5000 µg/g). Both dentifrices contained fluoride in the form of NaF/SiO2. To determine the rate of fluoride absorption, non-stimulated saliva was collected for up to 120 min after ingestion and the area under the curve of the salivary fluoride concentration was plotted as a function of time and the maximum concentration determined. All urine produced during the 24 h before and after ingestion was collected, and urinary excretion was calculated from the difference between the urinary fluoride concentrations in the two periods. A specific ion electrode coupled to an ion analyzer was used to measure fluoride concentrations. Statistical analysis was performed by ANOVA followed by Tukey's test with p set at 5%. All measured parameters were highest after the ingestion of the dentifrice with 5000 µg/g (p < 0.001), confirming that this has an increased level of bioavailable fluoride compared with the conventional dentifrice. The high-fluoride dentifrice increases the concentration of salivary fluoride, which may explain its greater anticaries effect. However, it poses a potential risk of causing dental fluorosis and so should not be used by children.

Is the fluoride intake by diet and toothpaste in children living in tropical semi-arid city safe?

Data about total fluoride intake in children living in a tropical semi-arid climate city is scarce, thus we conducted this study. Fifty-eight children aged two to five years, living in a Brazilian tropical city with optimally fluoridated water were selected. Dietary samples were collected using the duplicate diet method on two non-consecutive days in the children's home toothpaste was determined by subtracting the amount of fluoride recovered after brushing from the amount placed on the toothbrush. The mean total dose (SD) of fluoride intake was 0.043(0.016) mg F·kg-1·d-1, with the major (60.6%) contribution from water. The factors associated with the ingestion of fluoride from toothpaste were fluoride concentration of the toothpaste (p = 0.03) and the use of kids toothpaste (p = 0.02). The findings suggest that children have a low fluoride intake, measured by at-home meals and use of fluoride toothpaste; drinking water is the main source of fluoride ingestion.

Is the fluoride intake by diet and toothpaste in children living in tropical semi-arid city safe?

Abstract: Data about total fluoride intake in children living in a tropical semi-arid climate city is scarce, thus we conducted this study. Fifty-eight children aged two to five years, living in a Brazilian tropical city with optimally fluoridated water were selected. Dietary samples were collected using the duplicate diet method on two non-consecutive days in the children's home toothpaste was determined by subtracting the amount of fluoride recovered after brushing from the amount placed on the toothbrush. The mean total dose (SD) of fluoride intake was 0.043(0.016) mg F·kg-1·d-1, with the major (60.6%) contribution from water. The factors associated with the ingestion of fluoride from toothpaste were fluoride concentration of the toothpaste (p = 0.03) and the use of kids toothpaste (p = 0.02). The findings suggest that children have a low fluoride intake, measured by at-home meals and use of fluoride toothpaste; drinking water is the main source of fluoride ingestion.