Cristiane de Almeida Baldini Cardoso

TiF4 and NaF varnishes as anti-erosive agents on enamel and dentin erosion progression in vitro

Objective This study assessed the effect of fluoride varnishes on the progression of tooth erosion in vitro. Material and Methods: Forty-eight enamel and 60 root dentin samples were previously demineralized (0.1% citric acid, pH 2.5, 30 min), leading to a baseline and erosive wear of 12.9 and 11.4 µm, respectively. The samples were randomly treated (6 h) with a 4% TiF4 varnish (2.45%F-, pH 1.0), a 5.42% NaF varnish (2.45%F-, pH 5.0), a placebo varnish and no varnish (control). The samples were then subjected to erosive pH cycles (4x90 s/day in 0.1% citric acid, intercalated with artificial saliva) for 5 days. The increment of the erosive tooth wear was calculated. In the case of dentin, this final measurement was done with and without the demineralized organic matrix (DOM). Enamel and dentin data were analyzed using ANOVA/Tukey’s and Kruskal-Wallis/Dunn tests, respectively (p<0.05). Results The TiF4 (mean±s.d: 1.5±1.1 µm) and NaF (2.1±1.7 µm) varnishes significantly reduced enamel wear progression compared to the placebo varnish (3.9±1.1 µm) and control (4.5±0.9 µm). The same differences were found for dentin in the presence and absence of the DOM, respectively: TiF4 (average: 0.97/1.87 µm), NaF (1.03/2.13 µm), placebo varnish (3.53/4.47 µm) and control (3.53/4.36 µm). Conclusion The TiF4 and NaF varnishes were equally effective in reducing the progression of tooth erosion in vitro.

Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in vitro

OBJECTIVES Analyse the effect of varnishes containing xylitol alone or combined with fluoride on the remineralization of artificial enamel caries lesions in vitro. METHODS Bovine enamel specimens were randomly allocated to 7 groups (n=15/group). Artificial caries lesions were produced by immersion in 30 mL of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6 μM tetraetil metil diphosphanate (pH 5.0) for 6 days. The enamel blocks were treated with the following varnishes: 10% xylitol; 20% xylitol; 10% xylitol plus F (5% NaF); 20% xylitol plus F (5% NaF); Duofluorid™ (6% NaF, 2.71% F+6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. The blocks were subjected to pH-cycles (demineralization-2h/remineralization-22 h during 8 days) and enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analysed by ANOVA/Tukeys test or Kruskal-Wallis/Dunns test (p<0.05). RESULTS Enamel surface remineralization was significantly increased by Duraphat™, 10% xylitol plus F and 20% xylitol plus F formulations, while significant subsurface mineral remineralization could be seen only for enamel treated with Duraphat™, Duofluorid™ and 20% xylitol formulations. CONCLUSIONS 20% xylitol varnishes seem to be promising alternatives to increase remineralization of artificial caries lesions. CLINICAL SIGNIFICANCE effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in vitro, which should be confirmed by in situ and clinical studies.

The role of matrix metalloproteinases and cysteine-cathepsins on the progression of dentine erosion

OBJECTIVE To evaluate in vitro the effect of the inhibition of endogenous dentinal enzymes (matrix metalloproteinases-MMPs and cysteine cathepsins-CCs) on dentine erosion. DESIGN Dentine blocks (4mm×4mm×2mm) from sound human teeth were randomly divided into 7 groups (n=17) according to the treatment: MMP- and CC-inhibitor chlorhexidine digluconate (CHX, 10mM); MMP-inhibitor galardin (G, 0.2mM); specific cathepsin B inhibitor (CCB, 0.2mM); non-specific CC inhibitor (CCE-64, 0.5μM); fluoride (F, 1.23% NaF); placebo (P) and untreated (UT). Inhibitors were applied as gels once for 1min. Specimens were submitted to 5 days of pH cycling including the erosive challenge (Coke, pH 2.64, 90s/day) and remineralisation (artificial saliva). Demineralised organic surface loss was determined profilometrically. Demineralised organic matrix (DOM) was removed with collagenase and the profile was re-evaluated in the absence of collagen fibrils. The differences in profilometric results and DOM thickness among the groups were analysed with ANOVA and Tukeys test (p<0.05). RESULTS Loss of demineralised tissue (μm, mean±SD) was: CHX 8.4±1.7 b, G 8.6±1.9 b, CCB 9.6±1.4 a, CCE-64 9.9±1.3 a, F 9.9±1.7 a, P 10.9±2.2 a, UT 11.0±1.5 a. Loss of mineralised tissue was: CHX 15.4±2.2 b, G 16.0±1.8 b, CCB 17.6±2.4 a, CCE-64 17.6±2.0 a, F 17.3±2.8 a, P 19.1±2.1 a, UT 18.9±2.4 a. MMP-inhibitors significantly reduced organic matrix and mineral loss in comparison to all the other groups (p<0.05). No statistically significant differences were found in the thickness of the remaining DOM (p=0.845). CONCLUSION Dentine endogenous MMPs seem to be the main enzymes responsible for DOM loss and erosion.

Mechanisms of action of fluoridated acidic liquid dentifrices against dental caries

OBJECTIVE This study attempted to clarify the mechanisms of action of fluoridated acidic liquid dentifrices against dental caries. DESIGN In the in vitro leg, enamel specimens were submitted to a pH-cycling model, treated with distinct dentifrices (0, 550 μgF/g pH 4.5 and pH 7.0, 1100 or 5000 μgF/g pH 7.0) and analyzed using hardness. Alkali-soluble fluoride (F) deposition was quantified on pre-demineralized specimens treated with the dentifrices. In the clinical leg, 2-to-4-year-old children who had been using liquid dentifrices for 6 months (550 μgF/g pH 4.5 or pH 7.0 or 1100 μgF/g pH 7.0) had their plaque samples collected 5 and 60 min after the last brushing. Fluoride uptake in whole plaque was evaluated. RESULTS The reduction of the pH had a partial preventive effect on subsurface hardness loss only. [F] had a significant influence on the deposition of fluoride, surface and subsurface hardness loss. In vivo, the reduction of the pH was able to significantly increase plaque F uptake, leading to similar levels as those found for the neutral dentifrice containing twice [F]. CONCLUSION The results obtained from in vitro studies whose design does not include the presence of dental plaque should be interpreted with caution.

Total fluoride intake and excretion in children up to 4 years of age living in fluoridated and non-fluoridated areas.

Fractional fluoride retention is important during the early years of life when considering the risk of development of dental fluorosis. This study aimed to measure fractional fluoride retention in young children. The objectives were to investigate the relationships between fractional fluoride retention and total daily fluoride intake, age, and body mass index (BMI). Twenty-nine healthy children, up to 4 yr of age, participated; 14 lived in a fluoridated area (0.64 μg ml(-1) of fluoride in drinking water) and 15 lived in a non-fluoridated area (0.04 μg ml(-1) of fluoride in drinking water). The total daily fluoride intake of each child was calculated from the daily dietary fluoride intake and toothpaste ingestion (if fluoride toothpaste was used). Total daily fluoride excretion was measured by collecting voided urine and faeces over a 24-h period, and fractional fluoride retention was calculated by dividing the amount of fluoride retained in the body (total daily fluoride intake minus total daily fluoride excretion) by the total daily fluoride intake. Nine children were excluded from data analysis because of suspected invalid samples. Mean (range) fractional fluoride retention for the remaining 20 children was 0.61 (0.06-0.98). There were no statistically significant correlations between fractional fluoride retention and either age or BMI. However, fractional fluoride retention was correlated with total daily fluoride intake: fractional fluoride retention = 1 - exp (-C × total daily fluoride intake), where C = 28.75 (95% CI = 19.75-37.75). The wide variation in fluoride retention in young children could have important implications when recommendations for fluoride use are being considered.

Preventive effect of toothpastes with MMP inhibitors on human dentine erosion and abrasion in vitro

ABSTRACT The use of gels and mouthrinses with MMP inhibitors (chlorhexidine, and green tea extract) was shown to prevent erosive wear. The aim of this study was to analyze the protective effect of toothpastes containing MMP inhibitors on dentine loss induced by erosion in vitro. Material and Methods Five groups each containing 12 specimens of human root dentine were prepared. The specimens were subjected to 1 min erosion by immersion in a cola drink, 4 times a day, for 5 d. Each day, after the first and last erosive challenges, the specimens were brushed for 15 s with a slurry of dentifrice and water (1:3) containing placebo, 1,100 ppm fluoride, 0.61% green tea extract, 0.12% chlorhexidine or 0.004% chlorhexidine (commercial toothpaste). Between the acid challenges, the specimens were stored in artificial saliva with remineralizing potential until the next treatment. Dentine loss was determined using profilometry. Data were analyzed using one-way ANOVA after log transform (p<0.05). Results The mean wear values (μm) were as follows: placebo 1.83±0.53; 0.61% green tea extract 1.00±0.21; fluoride 1.27±0.43; 0.12% chlorhexidine 1.19±0.30; and 0.004% chlorhexidine 1.22±0.46. There was a significant difference in wear between placebo and all the treatment toothpastes, which did not differ from each other. Conclusion The results suggest that toothpastes containing MMP inhibitors are as effective as those based on NaF in preventing dentine erosion and abrasion.

Inhibition of tooth erosion by milk containing different fluoride concentrations: An in vitro study

OBJECTIVES This in vitro study assessed the effect of milk containing different fluoride concentrations on tooth erosion. METHODS Bovine enamel and root dentine specimens were treated with: (1) bovine whole milk with 0ppm F; (2) 2.5ppm F; (3) 5ppm F; (4) 10ppm F (all after erosion); (5) whole milk with 0ppm F (before erosion); (6) NaF (0.05% F, positive control, after erosion) or (7) 0.9% NaCl (negative control, after erosion). The specimens were submitted to pH cycles (4× 90s in soft drink) and treatments for 5 days. The specimens were immersed in the treatment solutions for 1min (only at the first cycle each day) with further exposition to 1:1 milk:saliva slurry for 10min. The tooth loss was measured using a contact profilometer and statistically analysed (p<0.05). RESULTS Rinsing with milk before erosive challenge significantly reduced tooth loss compared to negative control (67% and 24% reduction in dentine and enamel loss, respectively) and to milk after erosive challenge, only for dentine. The addition of fluoride to milk also reduced tooth loss compared to negative control, but with no significant differences among fluoride concentrations for enamel and dentine (μm), respectively: 0ppm (3.63±0.04 and 2.51±0.53), 2.5ppm F (2.86±0.42 and 1.96±0.47), 5ppm F (2.81±0.27 and 1.77±0.44), 10ppm F (2.03±0.49 and 1.68±0.59). There was a negative and significant correlation between [F] and the tooth loss. CONCLUSIONS Daily rinse with milk containing F is able to reduce both enamel and dentine erosion in vitro. CLINICAL SIGNIFICANCE Since the prevalence of dental erosion is steadily increasing, rinse with milk or its derivate might be an important strategy to reduce the progression of tooth erosion.

Frequency of intake and amount of fluoride in milk for remineralisation of artificial caries on enamel and dentine: Ex vivo/in situ study

OBJECTIVES This study analysed the effect of frequency of intake and amount of fluoride in milk on the remineralisation of artificial enamel and dentine caries lesions ex vivo/in situ. MATERIALS AND METHODS Pre-demineralised bovine enamel and dentine slabs were randomly allocated into 5 groups and fixed in removable appliances used by subjects for 7days in each phase. Each treatment comprised milk containing 2.5ppm fluoride daily (T1), or every other day (T2), 5.0ppm F daily (T3), or every other day (T4) or no treatment (T5). RESULTS Enamel alterations were quantified by surface hardness recovery (%SHR) and transversal microradiography (TMR), and in dentine by TMR only. Data were analysed by ANOVA and Tukeys test (p<0.05). For enamel, the highest %SHR was found for T1 and T3 compared to control, without significant differences between them. All groups showed positive values of ΔΔZ - T1 (247.3±198.5); T2 (110.9±303.2); T3 (226.0±299.2); T5 (5.0±288.0), except T4 (-274.5±407.3). For dentine, the only group that presented remineralisation was T2 (350.0±657.5). CONCLUSIONS Fluoridated milk daily seems to have higher remineralising effect on enamel than its use every other day. Dentine, does not seem to benefit from daily use of fluoridated milk.

Prevention and control of dental erosion: Patient self-care

This chapter presents new insights into the self-applied preventive strategies, comprising of both home-use products and recommended behavioral modifications to prevent dental erosion. It important to emphasize that these products should be delivered with counselling by motivational interview. Dental erosion is a multifactorial condition dependent on the interaction of chemical, biological and behavioral factors. Preventive measures are established according to the causal factors, which may include the dietary intervention, modification of acidic drinks and behavioral changes, in order to reduce the contact between acid and teeth. The modification of the tooth surface, by increasing its resistance against acidic attacks, is one of the most studied strategies. Many available active agents as fluoride, polyvalent metal cations, calcium phosphates in different forms, proteins, protease inhibitors and biopolymers (as chitosan) have been demonstrated to have some protective effect against erosion. Amongst them, the daily application of fluoride, especially those containing titanium or tin (as dentifrice or mouthrinse), has shown the best effect in reducing dental erosion. However, there is need for further clinical trials to better establish the protocols for the use of some of these agents.

Dentifrice pH but not consistency may affect fluoride uptake in plaque

OBJECTIVE Test the ability of acidic fluoridated solutions to enhance fluoride (F) bound on bacteria (1) and the effect of dentifrice consistency on plaque fluid F uptake (2). METHODS (1) Streptococcus mutans isolates were grown in BHI medium (37°C/18h). Bacteria were washed either with EDTA or CaCl2 both at 1mM to remove or add calcium, respectively. Pellets were incubated with 12 mM NaF at pH 4.5 or 7 for 1 min and F was quantified in the lysates and supernatants with the electrode, after HMDS-facilitated diffusion. (2) A randomized, double-blind, crossover clinical trial was performed in three phases with nineteen adults (20-35 years) that used one of the dentifrices: commercial toothpaste (1100 ppm F, pH7.0 and conventional viscosity (Sorriso Fresh(®))); experimental liquid dentifrice (ELD) (1100 ppm F, pH7.0 and low viscosity [1.1% carboxymethylcellulose (CMC)]) and ELD (1100 ppm F and high viscosity pH7.0 (2.2% CMC)). F concentration in plaque fluid was analyzed using an inverted F electrode. RESULTS (1) Significantly higher F amounts were detected in the lysates of bacteria incubated with NaF solution at pH4.5 compared to the supernatant, which was not seen at pH7.0, being this effect calcium-dependent. (2) Significantly higher F concentrations in plaque fluid were found 1h after toothbrushing compared to 12h, but no significant differences were seen among the toothpastes. CONCLUSIONS F at low pH binds more efficiently to S. mutans than at neutral pH and dentifrice viscosity does not interfere in plaque fluid fluoride incorporation. CLINICAL SIGNIFICANCE pH of the dentifrice but not consistency may be important to F uptake in plaque.