Protecting primary teeth from dental erosion through bioactive glass

OBJECTIVES

The present study aimed to evaluate the effectiveness of bioactive glass (BAG) in preventing dental erosion in primary teeth.

METHODS

Enamel and dentin specimens (2 × 2 × 2 mm) were obtained from extracted primary teeth, which were randomly divided into the following groups based on the pretreatments (n = 12): DW (deionized water), NaF (2 % sodium fluoride), 2BAG (2 % BAG), 4BAG (4 % BAG), 6BAG (6 % BAG), and 8BAG (8 % BAG). The specimens were immersed in the respective solutions for 2 min and subjected to in vitro erosive challenges (4 × 5 min/d) for 5 d. The erosive enamel loss (EEL), erosive dentin loss (EDL), and the thickness of the demineralized organic matrix (DOM) were measured using a contact profilometer. The surface microhardness (SMH) was measured, and the percentage of SMH loss (%SMHL) was calculated. The surface morphology and mineral composition were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively.

RESULTS

After the erosive challenges, the EEL, EDL, and%SMHL of the 2BAG, 4BAG, 6BAG, and 8BAG groups significantly reduced, with the greatest reduction was observed in the 6BAG (EEL: 6.5 ± 0.2 μm;%SMHL in enamel: 12.8 ± 2.6; EDL: 7.9 ± 0.3 μm; %SMHL in dentin: 22.1 ± 2.7) and 8BAG groups (EEL: 6.4 ± 0.4 μm;%SMHL in enamel: 11.0 ± 1.9; EDL: 7.8 ± 0.5 μm; %SMHL in dentin: 22.0 ± 2.5) (P < 0.05). With increasing BAG concentrations, the number of surface deposits containing Ca, P, and Si increased.

CONCLUSIONS

6BAG was the most effective for preventing dental erosion in primary teeth and showed a particularly strong potential for dentin erosion prevention.

CLINICAL SIGNIFICANCE

Bioactive glass, especially at a 6 % concentration, has proven effective in reducing erosive tooth wear and surface microhardness loss while also protecting demineralized organic matrix in primary dentin.

Analysis of dentin wear and biological properties promoted by experimental inoffice desensitizing materials

BACKGROUND

This study aimed to evaluate dentin wear and biological performance of desensitizing materials.

METHODS

Seventy bovine root dentin blocks were sectioned. Half of the surface of each specimen was untreated (control) and the other half was immersed in EDTA and treated with the following desensitizing materials: placebo varnish (PLA), fluoride varnish (FLU), sodium fluoride (NaF) varnish + sodium trimetaphosphate (TMP), universal adhesive (SBU), S-PRG varnish (SPRG), biosilicate (BIOS), and amelotin solution (AMTN). After application, the specimens were submitted to an erosive-abrasive challenge and the wear analyzed by optical profilometer. Serial dilutions of extracts obtained from the culture medium containing discs impregnated with those desensitizers were applied on fibroblasts and odontoblasts-like cells cultures. Cytotoxicity and production of total protein (TP) by colorimetric assays were determined after 24 h. Data were statistically analyzed using Kruskal-Wallis, Dunn's, One-way ANOVA and Tukey tests (p ≤ 0.05).

RESULTS

No dentin wear was observed only for SBU. The lowest dentin wear was observed for AMTN and TMP. Cell viability was significantly reduced after treatment with undiluted extracts of PLA, FLU, TMP and SBU in fibroblasts and TMP and SBU in odontoblast-like cells. SPRG, BIOS and AMTN were cytocompatible at all dilutions tested. Considering TP results, no statistical difference was observed among the groups and high levels for TP were observed after TMP and FLU treatments.

CONCLUSIONS

Universal adhesive system may protect dentin with opened tubules from wear after challenge. Extracts of adhesive and fluoride varnishes presented cytotoxic mainly on fibroblasts. The enamel protein may be a future alternative to treat dentin with opened tubules because it may cause low wear under erosive-abrasive challenge with low cytotoxic effects.

Fluoride varnishes supplemented with nano-sized sodium trimetaphosphate reduce enamel erosive wear in vitro

OBJECTIVE

To evaluate the effect of fluoride (F) varnishes with sodium trimetaphosphate (TMP) on erosive tooth wear (ETW) in vitro.

METHODS

Enamel blocks (n = 100) were divided into 5 experimental groups (n = 20/group): Placebo (Pla - without F/TMP); 5 % NaF (NaF); 5 % NaF + 5 % micrometric TMP (NaF+5 %MICRO); 5 % NaF + 2.5 % nano-sized TMP (NaF+2.5 %NANO), and 5 % NaF + 5 % nano-sized TMP (NaF+5 %NANO). Blocks received a single varnish application (6 h contact), and were submitted to 4 daily erosive challenges (ERO, 0.05 M citric acid, pH 3.2, 90 s, under agitation), for 5 days. After ERO, half of the blocks (n = 10/group) were subjected to brushing abrasion (ERO+ABR). Profilometry, surface hardness (SH), and cross-sectional hardness (ΔKHN) were determined. The data were submitted to 2-way ANOVA and Fisher's LSD test (p < 0.05).

RESULTS

Enamel wear was significantly lower for ERO compared with ERO+ABR for all varnishes tested (p < 0.001), following the pattern NaF+5 %NANO < NaF+5 %MICRO < NaF < NaF+2.5 %NANO < Pla (both for ERO and ERO+ABR). The highest SH loss was observed for Pla and the lowest for NaF (ERO) and NaF+2.5 %NANO (ERO+ABR), without significant differences among NaF+2.5 %NANO, NaF, and NaF+5 %MICRO. The highest ΔKHN values were observed for NaF+5 %MICRO and NaF+5 %NANO at 5-30 µm, with less marked differences among the groups at 30-70 µm (ERO and ERO+ABR).

CONCLUSIONS

The addition of TMP to F varnishes significantly improves protection against ETW in vitro. The use of 5 % nano-sized TMP further enhances such effects.

CLINICAL SIGNIFICANCE

F varnishes containing TMP can reduce enamel loss caused by ERO or ERO+ABR.

Effect of sodium hexametaphosphate and quercetin, associated or not with fluoride, on dentin erosion in vitro

OBJECTIVE

to investigate the ability of solutions containing sodium hexametaphosphate, fluoride and quercetin, alone or in association, to prevent dentin erosion and to inhibit matrix metalloproteinases -2 and -9 activity using in vitro protocols.

DESIGN

Root dentin blocks (n = 96) were prepared and divided into 8 experimental groups (n = 12/group), according to the solutions to be tested: Placebo; 0.24% sodium fluoride (F); 1.0% sodium hexametaphosphate (HMP); 0.03% quercetin (QC); F+HMP; F+QC; HMP+QC; and F+HMP+QC. Erosive challenges were performed 4×/day for 5 days. Specimens were treated with the respective solutions for one minute, twice a day. Next, dentin loss (profilometry) and integrated hardness area in depth (KHN × µm) were determined. The antiproteolytic potential was assessed by gelatin zymography. Dentin erosion results (log₁₀-transformed) were submitted to one-way ANOVA, followed by Tukey's test. Integrated hardness area in depth data (raw) were submitted to two-way, repeated-measures ANOVA, followed by Holm-Sidak's test (p<0.05).

RESULTS

Dentin erosion was significantly lower for F+HMP+QC than for all other treatments. At the shallowest depths (5-30 µm), blocks treated with F+HMP+QC had the highest integrated hardness area in depth values. All treatments completely inhibited matrix metalloproteinases-2 activity, except for the group QC (77% inhibition). For matrix metalloproteinases-9, all HMP-containing solutions or F+QC promoted total antiproteolytic activity.

CONCLUSION

The association of fluoride, sodium hexametaphosphate, and quercetin must be considered a valuable strategy for novel product formulation for home and professional use, considering its superior protective effects against dentin erosion and its antiproteolytic potential.

Tooth Age Impact on Dental Erosion Susceptibility and Treatment Efficacy

This laboratory study investigated the impact of tooth age on dental erosion susceptibility and preventive treatment efficacy. Extracted human premolars were selected and had their age estimated (∼10-100 years old) using established dental forensic methods. Enamel and root dentin slabs were prepared, embedded in acrylic blocks, flattened, and polished. The specimens were randomly assigned to one of three treatments (n = 93): Sn+F (800 ppm Sn as SnCl2 and 250 ppm F as NaF, pH 4.5), NaF (250 ppm F, pH 4.5), or deionized water (DIW). Each specimen was subjected for 10 days to a daily cycling protocol consisting of six 5-min erosive challenges (0.3% citric acid, pH 2.6), six 60-min remineralization periods (artificial saliva), and three 2-min treatments with the test solutions. Surface loss (SL) was measured after 3, 5, and 10 days, using optical profilometry. Effects of tooth age, antierosive treatment, and time on SL were evaluated using linear mixed effects regression analysis. SL increased with age for all substrate-treatment-time combinations (p < 0.0001). Sn+F and NaF solutions significantly reduced SL compared to DIW, regardless of substrate, time, or age (p < 0.0001), with best results shown for Sn+F. Efficacy of Sn+F increased with tooth age on enamel, but tooth age did not affect the efficacy of NaF on enamel. For dentin, increased efficacy was observed with age after 5 (for Sn+F) and 10 days (for Sn+F and NaF). In conclusion, increase of tooth age rendered enamel and root dentin more susceptible to dental erosion. NaF preventive efficacy improved with tooth age for dentin, in advanced erosion simulation. Sn+F reduced enamel SL due to erosion regardless of tooth age.

Comparison of metrology created by profilometry and digital microscopy on polished dentine in an erosion/abrasion model

OBJECTIVE

Digital microscopy offers the ability to scan surfaces to produce 3D reconstructions, allowing step height measurements with high accuracy. The aims of this study were to compare the step heights from the gold standard, non-contact profilometry, to digital microscopy in an erosion/abrasion model.

METHODS

Dentine specimens (n = 60) were immersed in deionised water, 1450 ppm and 5000 ppm fluoride as sodium fluoride for 3 min, eroded for a total of 25 min in a cycled protocol in 0.3% citric acid (pH 2.7) and abraded with 120 and 240 brushing strokes. Samples were scanned by a non-contacting profilometer with a 0.1 μm vertical resolution and then the same samples imaged with a digital microscope and the step heights compared. Data were analysed in GraphPad Prism 7.00. Data were normally distributed and a 3 way ANOVA with post hoc analysis used to assess for differences between groups. Agreement between the measurement method was assessed using IntraClass Correlations and Bland Altmans plots.

RESULTS

The mean step heights from the profilometry and the digital microscope on the same samples were not statistically significant different. The magnitude of the differences was less than 0.5 μm. The results of the ANOVA demonstrated that the individual factors fluoride concentration and number of strokes were significant (P<0.05), however, the method of analysis was not (p = 0.74). ICC's between the two methods of analysis were excellent (0.996, p<0.001) with no proportional bias.

CONCLUSIONS

This study reports that step height on dentine from a digital microscopy and non-contact profilometry were not significantly different. The digital microscope, although slower, allows visual inspection of the samples as well as measurement.

SIGNIFICANCE

Digital microscope's offer the ability to scan, 2D or 3D images and perform meteorological analysis of samples. In this investigation both showed that 5000 ppm fluoride prevents erosive tooth wear in vitro.

Effect of TiF4 varnish after pre-treatment with proanthocyanidin or chlorhexidine on the progression of erosive dentin loss in the presence or absence of the demineralized organic matrix

This study evaluated the protective effect of TiF₄ varnish, after pre-treatment with proantocyanidin or chlorhexidine, on the progression of erosive dentin loss (EDL), under the presence or absence of the demineralized organic matrix (DOM). Bovine root dentin samples were eroded for 30 min (0.1% citric acid, pH 2.5) and the loss was measured by profilometry. Half of them were subjected to the DOM removal using collagenase for 4 days, while the other half remained immersed in water. The removal of DOM was checked by profilometry. Samples were divided into 24 groups (n = 15) according to the factors: 1- With or without DOM; 2- Pre-treatment with 0.012% chlorhexidine gel, 10% proanthocyanidin gel or untreated for 1 min; 3-Final Treatment with TiF₄ varnish, NaF varnish, placebo varnish or untreated for 6 h. The samples were submitted to a pH cycling for 5 days: 0.1% citric acid (4 × 90s/day) and artificial saliva between the challenges. The final profile was obtained for the calculation of EDL (μm, three-way ANOVA/Tukey test). When DOM was preserved, the EDL was lower compared to the condition without DOM (7.08 ± 4.03 μm and 9.80 ± 3.79 μm, p < 0.001, respectively), regardless of the treatments. The pre-treatment had no influence on the progression of EDL (p = 0.637), while the final treatment (TiF₄ varnish only, 6.77 ± 4.08 μm) was effective in reducing the progression of EDL (NaF varnish: 9.52 ± 4.02 μm; Placebo varnish: 8.64 ± 4.06 μm and no treatment: 8.80 ± 3.95 μm). It can be concluded that DOM has important protective effect on the progression of EDL. TiF₄ was the unique treatment capable of reducing EDL progression, regardless of the pre-treatment of DOM.

Effects of different toothpastes on the prevention of erosion in composite resin and glass ionomer cement enamel and dentin restorations

Objective

This study aimed to evaluate the effects of different toothpastes on the surface wear of enamel, dentin, composite resin (CR), and resin-modified glass ionomer cement (RMGIC), and to perform a topographic analysis of the surfaces, based on representative images generated by atomic force microscopy (AFM) after erosion-abrasion cycles.

Methodology

One hundred and forty bovine incisors were collected and divided into two groups: 72 enamel and 72 dentin blocks (4×4 mm). Half of the specimens were restored with CR (Filtek Z350 XT) and the other half with RMGIC (Fuji II LC). Then, samples were submitted to a demineralization cycle (5 days, 4×2 min/day, 1% citric acid, pH 3.2) and exposed to three different toothpastes (2×15 s/day): without fluoride (WF, n=12), sodium fluoride-based (NaF, n=12), and stannous fluoride-based (SnF₂, n=12). Surface wear, as well as restoration interfaces wear, were investigated by profilometry of the dental substrates and restorative materials. All representative surfaces underwent AFM analysis. Data were analyzed by two-way analysis of variance and Tukey’s tests (α=0.05).

Results

NaF-based toothpaste caused the greater dentin surface wear (p<0.05). Toothpastes affected only enamel-restoration interfaces. AFM analysis showed precipitate formation in dentinal tubules caused by the use of fluoride toothpastes.

Conclusions

NaF-based toothpastes had no protective effect on enamel adjacent to CR and RMGIC against erosion-abrasion challenges, nor on dentin adjacent to RMGIC material. SnF2-based toothpastes caused more damage to interfaces between enamel and RMGIC.

Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion

Objectives

To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Profilometry (CP) measures investigating brushing or dab-on of stannous-fluoride dentifrice on early aggressive dentine erosion.

Methods

75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; artificial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-fluoride NaF (2) or stannous-fluoride SnF₂ (3), and dab-on application of NaF (4) or SnF₂ (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and profiled using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples.

Results

Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p = 0.01). There were no significant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF₂ brushing (3) increased micro-hardness more than control (1) (p = 0.03), NaF (4) and SnF₂ dab-on (5) (p ≤ 0.001), and increased surface roughness more than control (p = 0.02), NaF brushing (2) and NaF dab-on (4) (p ≤ 0.017). Dab-on of SnF₂ (5) produced rougher surfaces than control (1) (p = 0.014) and reduced hardness compared with NaF brushing (p = 0.04).

Conclusions

Good agreement and correlation exists between CLSM and CP measures in dentine. There were no significant differences in surface loss after interventions between groups. Compared with control, SnF₂ application increased dentine surface roughness and SnF₂ controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine.

Clinical significance

Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-fluoride brushing, and dab-on application offer no benefits following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.

Protective Effect of Fluoride Varnish Containing Trimetaphosphate against Dentin Erosion and Erosion/Abrasion: An in vitro Study

This in vitro study evaluated the protective effect of fluoride varnishes containing sodium trimetaphosphate (TMP) against dentin erosion and abrasion. Specimens of coronal dentin were divided into: placebo, 2.5% NaF, 5% NaF, 2.5% NaF + 5% TMP, and 5% NaF + 5% TMP groups (n =24/group). After single application of the varnishes, the samples were immersed in citric acid (0.05 mol/L, pH = 3.2, 5 min) followed or not by brushing, and the dentin wear was assessed after 5 days. Varnishes containing fluoride + TMP led to the lowest wear. TMP varnishes showed a superior effect against dentin erosive wear.

Using fluoride mouthrinses before or after toothbrushing: effect on erosive tooth wear

OBJECTIVES

1. To evaluate the use of fluoridated mouthrinses before or after toothbrushing on erosive tooth wear. 2. To compare the anti-erosive effect of the combination toothpaste and mouthrinse containing fluoride, with or without stannous chloride.

DESIGN

Enamel and dentin specimens were randomly distributed into groups (n = 10 of each substrate/group): B-brushing, B + R-brushing + rinsing, and R + B-rinsing + brushing. The treatments were performed using a fluoride toothpaste (B_F: 1400 ppm fluoride, as amino fluoride-AmF) combined or not with a fluoride mouthrinse (R_F: 250 ppm fluoride, as AmF and sodium fluoride-NaF) or fluoride and stannous toothpaste (B_F+Sn: 1400 ppm fluoride, as AmF and NaF, 3500 ppm stannous, as stannous chloride-SnCl₂ and 0.5% chitosan) combined or not with fluoride and stannous mouthrinse (R_F+Sn: 500 ppm fluoride, as AmF and NaF, 800 ppm stannous, as SnCl₂). As control, brushing was performed with artificial saliva (B_C). Specimens were submitted to a 5-day erosive-abrasive cycling model. Treatments were performed twice daily. Surface loss (SL) was determined by optical profilometry. Data were analyzed by ANOVA and Games-Howell tests (α = 0.05).

RESULTS

For enamel, R_F+B_F and R_F+Sn+B_F+Sn presented significantly lower SL than the control, with R_F+B_F being significantly lower than R_F+Sn+B_F+Sn. For dentin, B_C had the lowest SL, not differing from B_F+Sn+R_F+Sn, R_F+Sn+B_F+Sn and B_F. Groups R_F+B_F and B_F+R_F showed highest SL, not differing from B_F+Sn and B_F+Sn.

CONCLUSIONS

For enamel, the use of a mouthrinse before brushing was able to reduce erosive wear for both fluoride and stannous products. For dentin, the use of stannous-containing products, irrespective of the order of application, presented superior effects.

Do fluoride toothpastes have similar preventive effect in permanent and primary teeth against erosive tooth wear?

BACKGROUND

Little is known about fluoride toothpastes effect on primary teeth submitted to erosive tooth wear.

OBJECTIVES

To evaluate the preventive effect of different toothpastes on surface loss (SL) after severe erosion/abrasion model and to compare this effect between permanent (PT) and primary teeth (pt).

DESIGN

Enamel samples were randomly divided according toothpastes groups (n = 17). G1: placebo; G2: NaF; G3: AmF-NaF-SnCl2 anti-erosion; G4: SnF2 ; and G5: NaF anti-erosion for children. Samples were incubated in artificial saliva (1 hour), submitted to erosive challenge (3 minutes; 1% citric acid; pH3.6; at 25°C) and to toothbrush abrasion (2 minutes slurry immersion; 50 strokes; 200 g) during 30 cycles. Surface loss (μm; mean ± SD) was quantified by contactless profilometry. The effects of the two covariables "tooth" and "toothpaste" were analysed by non-parametric ANOVA, variables with significant effects were tested by Wilcoxon tests.

RESULTS

pt showed significantly higher surface loss than PT in all groups (P < 0.001). The mean values of SL of each group were: G1 PT 18.18(±3.98), pt 25.65(±9.21); G2 PT 14.76(±2.82), pt 18.11(±3.92); G3 PT 12.62(±5.29), pt 15.61(±6.70); G4 PT 17.12(±2.24), pt 23.41(±7.9); G5 PT 13.24(±1.29), pt 18.28(±8.96).

CONCLUSIONS

In permanent teeth, G3 showed the best preventive effect. In primary teeth, G1, G3, and G5 showed similar effect.

Effect of Proanthocyanidin-enriched extracts on the inhibition of wear and degradation of dentin demineralized organic matrix

OBJECTIVES

The aim of this study was to evaluate the effect of Cranberry and Grape seed-enriched extract gels in inhibiting wear and degradation of demineralized organic matrix (DOM).

DESIGN

225 dentin specimens obtained from bovine incisors were randomly allocated into 5 groups (n=45): 10% Grape seed extract gel (GSE), 10% Cranberry extract gel (CE), 0.012% Chlorhexidine gel (CX), 1.23% NaF gel (F), and no active compound gel (P, placebo). Before the treatments, samples were demineralized by immersion in 0.87M citric acid, pH 2.3 (36h). Then, the studied gels were applied once over dentin for 1min. Next, the samples were immersed in artificial saliva containing collagenase obtained from Clostridium histolyticum for 5days. The response variable for dentin wear was depth of dentin loss measured by profilometry and for collagen degradation was hydroxyproline determination. Data were analyzed by ANOVA followed by Tukey's test and Pearson Correlation Test (p<0.05).

RESULTS

Grape seed extract significantly reduced dentin wear compared to the other groups (p<0.05). Cranberry extract and Chlorhexidine did not differ statistically and were able to reduce wear when compared to NaF and placebo treatments. The hydroxyproline analysis showed that there was no significant difference among groups for all treatments (p<0.05). Correlation analysis showed a significant correlation between the amount of degraded DOM evaluated by profilometry and the determination of hydroxyproline.

CONCLUSION

Cranberry extract was able to reduce the dentin wear and collagen degradation, likely due to the proanthocyanidin content and its action. Therefore, Cranberry could be suggested as an interesting natural-based agent to prevent dentin erosion.