Dental plaque disclosure as an auxiliary method for infants' oral hygiene.

AIM: This was to evaluate the effectiveness of plaque disclosure as an auxiliary method for early childhoods' oral hygiene. METHODS: The study was performed with 20 mothers and their children (aged 6-36 months), members of a preventive programme, which two groups used one of two approaches: conventional oral hygiene/group I (tooth brushing) and plaque disclosure with subsequent oral hygiene/group II (tooth brushing with prior plaque disclosure). Ten mothers started the study in group I and the other 10 in group II, after one month interval they changed to be in the alternate group. Each group consisted of baseline and three additional visits at weekly intervals. The effectiveness of oral hygiene was assessed in a blind fashion by plaque quantity estimation, using the Green Vermilion index for smooth surfaces and the plaque thickness index for occlusal surfaces. Statistical comparisons were performed using repeated measures ANOVA/Fisher's post hoc test and paired t-test (p < 0.05). RESULTS: For smooth and occlusal surfaces at first and second visits, group II recorded significantly lower plaque indices when compared with group I. Additionally, when considering the mean dental plaque index of all visits, group II also presented lower plaque scores than group I. CONCLUSION: Dental plaque disclosure before toothbrushing helps mothers to enhance the effectiveness of early childhood oral hygiene. REGISTRATION NUMBER AND NAME OF TRIAL REGISTRY: RBR-7fyc7g; Avaliação do Treinamento e de Métodos Auxiliares na Efetividade da Escovação Dentária Materna em Bebês. Where the full trial protocol can be accessed: http://www.ensaiosclinicos.gov .

Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in situ.

OBJECTIVES: Analyze the effect of varnishes containing xylitol compared to commercial fluoridated varnishes on the remineralization of artificial enamel caries lesions in situ. METHODS: Twenty subjects took part in this crossover, double-blind study performed in four phases of 5days each. Each subject worn palatal appliances containing four predemineralized bovine enamel specimens. Artificial caries lesions were produced by immersion in 30ml of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6µM tetraetil metil diphosphanate (pH 5.0) for 6days. The specimens in each subject were treated once with the following varnishes: 20% xylitol (experimental); Duofluorid™ (6% NaF, 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. Fifteen subjects were able to finish all phases. The 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 analyzed by Friedmann and Dunn's tests test (p<0.05). RESULTS: Enamel surface remineralization was significantly increased by Duraphat™, Duofluorid™ and 20% xylitol formulations. Significant subsurface mineral remineralization could also be seen for the experimental and commercial varnishes, except for Duraphat™, when the parameter "lesion depth" was considered. CONCLUSIONS: 20% xylitol varnish seem to be a promising alternative to increase surface and subsurface remineralization of artificial caries lesions in situ. CLINICAL SIGNIFICANCE: effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in situ, which should be confirmed by 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 Tukey's 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.

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.

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/Tukey's test or Kruskal-Wallis/Dunn's 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.

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.

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.

Cross-sectional hardness of enamel from human teeth at different posteruptive ages.

This study evaluated, by cross-sectional hardness (CSH), enamel maturation at different depths in sound human teeth at different posteruptive ages (12 per age group): unerupted (molars; control), 2-3 years (premolars), 4-10 years (premolars) and >10 years (molars). Cross-sectional Knoop hardness was measured at 10, 30, 50, 70, 90, 110, 220 and 330 mm depth from the surface. The data were subjected to two-way ANOVA followed by Bonferroni's pairwise tests (a = 0.05). The CSH significantly increased with posteruptive age, indicating that the time of exposure in the oral cavity might result in deep enamel maturation.