Measurement of the efficacy of calcium silicate for the protection and repair of dental enamel

Effect of the calcium silicate and sodium phosphate remineralizing products on bleached enamel

Context and Aims

This study evaluated the effect of calcium silicate and sodium phosphate (CSSP) dentifrice and serum on the surface of enamel bleached with hydrogen peroxide (H2O2).

Materials and Methods

A total of 160 bovine enamel slabs were bleached with 35% H2O2 and treated with sodium fluoride (NaF) dentifrice-GI, CSSP dentifrice-GII; CSSP dentifrice + CSSP serum-GIII, or NaF dentifrice + NaF gel-GIV. The dentifrices were applied using a brushing machine three times daily for 7 days. After brushing, sodium phosphate gel and CSSP serum were applied. The microhardness (KNH, n = 14), surface roughness (Ra, n = 14), energy dispersive spectroscopy (n = 6), and scanning electron microscopy (n = 6) were assessed at t0 (before bleaching), t1 (after bleaching), and t2 (after postbleaching treatments).

Statistical Analysis Used

The data were subjected to a two-way analysis of variance and Bonferroni's test.

Results

The KNH decreased at t1 (P < 0.001) but recovered at t2 for all treatments, although only GII showed restored baseline values (P = 0.0109). The surface roughness increased at t1 (P < 0.001) and reduced at t2 (P < 0.001) for all groups, with no significant differences among groups. Enamel composition and morphology did not differ after the treatments, except for silicon accumulation in GIII.

Conclusions

Postbleaching treatment with CSSP dentifrice and serum yielded superior remineralizing effects on bleached enamel.

Investigation of the constituents of commercially available toothpastes

OBJECTIVES

Toothpaste plays a pivotal role in oral and dental hygiene. This cross-sectional study not only investigates the constituents of toothpastes available in the market and their frequency across different brands but also delves into the potential side effects, irritations, or unfavourable outcomes of these constituents, emphasizing the broader health and environmental implications.

METHODS

The largest of the five major chain markets in each district of Istanbul was visited, and adult toothpastes were included in this study. All the constituents that make up the toothpaste were individually recorded in an Excel database. Subsequently, literature regarding the purposes, toxic and potential side effects of each ingredient was gathered using databases such as Google Scholar, PubMed and ScienceDirect. The percentages of these ingredients' occurrence among all the toothpastes were calculated, and the ingredients were categorized into 15 distinct groups based on their usage purposes.

RESULTS

There were 160 different varieties of toothpaste belonging to 19 different brands on the market shelves. Although a total of 244 different ingredients were identified, only 78 of them were included in the study. Among the analysed toothpaste types, 105 of them were found to contain 1450 ppm fluoride, whilst 26 toothpaste variants were discovered to have fluoride levels below this value. Among the various ingredients analysed, particular attention was drawn to commonly debated compounds in oral care products. Specifically, titanium dioxide was found in 68% (n = 111) of the varieties, sodium lauryl sulphate in 67% (n = 108) and paraben in 2% (n = 4), respectively.

CONCLUSION

Whilst certain ingredients may raise concerns for potential side effects and health considerations within the human body, the toothpaste has long been regarded as an indispensable tool for maintaining optimal oral and dental health. However, gaining a deeper understanding and conducting research on each constituent that comprises the toothpaste, as well as raising awareness in this regard, holds significant importance for human health.

The role of calcium in the prevention of erosive tooth wear: a systematic review and meta-analysis

OBJECTIVES

The loss of hard dental tissue due to recurrent acid challenges and mechanical stresses without bacterial involvement is known as erosive tooth wear (ETW). Many studies in the literature have concentrated on variables that may affect the ETW process and prevent its occurrence or reduce its advancement. However, to date, no previous systematic review has evaluated the role of calcium in preventing ETW. Therefore, the purpose of the present systematic review was to review and critically appraise the scientific evidence regarding the role of calcium formulations in the prevention of ETW.

METHODS

The review protocol was registered in the PROSPERO international prospective register of systematic reviews (Ref: CRD42021229819). A literature search was conducted in electronic databases to identify in situ randomized controlled trials evaluating the prevention of ETW following the application of calcium formulations. The outcomes studied included mean enamel loss, surface microhardness, surface roughness, mean erosion/softening depth, mineral loss/precipitation and remineralization. Study characteristics and outcomes of included studies were summarized. Cochrane's risk-of-bias tool 2.0 was used to assess the quality of eligible studies, and meta-analysis using a random effects model was performed.

RESULTS

The search retrieved 869 studies of which 21 were considered eligible. Regarding the results of the quality assessment for potential risk of bias in all included studies, overall, 5 studies were considered as being at low risk, another 12 at unclear risk and 4 at high risk of bias. The findings of the studies showed that the addition of calcium in juice drinks led to reduced enamel loss, with blackcurrant juice presenting 2.6 times statistically significant less enamel loss compared to orange juice (p = 0.0001, I2 = 89%). No statistically significant difference in mean surface microhardness of eroded enamel was recorded between chewing gum with or without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (p = 0.31, I2 = 71%). Contradictory were the results regarding the effect of milk and CPP-ACP pastes on prevention of ETW.

CONCLUSIONS

Calcium formulations play an important role in ETW prevention, mainly through their addition to acidic drinks.

Enamel remineralization potential and antimicrobial effect of a fluoride varnish containing calcium strontium silicate

OBJECTIVES

To investigate enamel remineralization and antimicrobial effect of sodium fluoride (NaF) varnish containing calcium strontium silicate (CSR).

METHODS

CSR was synthesized by sol-gel process and incorporated in 5 % NaF varnish at three different concentrations (1 %, 2 %, and 4 % w/v). The treatment/control groups were: 1 % CSR+NaF, 2 % CSR+NaF, 4 % CSR+NaF, NaF, and no treatment. Strontium and fluoride release from the varnishes was evaluated. Sound enamel specimens (n = 6) were demineralized, varnish-treated, and subjected to remineralization cycle. Mineral density of enamel specimens was evaluated using micro-CT. Antimicrobial effect of the varnishes on Streptococcus mutans and Lactobacillus acidophilus biofilms was assessed using confocal laser scanning microscopy. The HGF-1 cytotoxicity of the varnishes was examined using CCK-8 assay.

RESULTS

Both 2 % and 4 % CSR+NaF varnishes showed significantly higher F release and remineralization potential than NaF varnish (p < 0.05). Dead bacterial proportion of 4 % CSR+NaF varnish was significantly higher than NaF varnish (p < 0.05). The CFUs values of both S. mutans and L. acidophilus were significantly lower in 4 % CSR+NaF group than NaF group (p < 0.05). No significant difference in cell viability was observed among the groups (p > 0.05).

CONCLUSIONS

Incorporation of 4 % CSR in a NaF varnish significantly enhanced its enamel remineralization and antimicrobial potential with no cytotoxic effect.

CLINICAL SIGNIFICANCE

Dental caries is a major public health problem globally. The study highlights the great potential of CSR-doped NaF varnish as a novel anti-caries agent with synergistic remineralizing and antimicrobial properties to combat early enamel caries lesions in the general population.

Operando Scanning Electrochemical Probe Microscopy during Electrocatalysis

Scanning electrochemical probe microscopy (SEPM) techniques can disclose the local electrochemical reactivity of interfaces in single-entity and sub-entity studies. Operando SEPM measurements consist of using a SEPM tip to investigate the performance of electrocatalysts, while the reactivity of the interface is simultaneously modulated. This powerful combination can correlate electrochemical activity with changes in surface properties, e.g., topography and structure, as well as provide insight into reaction mechanisms. The focus of this review is to reveal the recent progress in local SEPM measurements of the catalytic activity of a surface toward the reduction and evolution of O₂ and H₂ and electrochemical conversion of CO₂. The capabilities of SEPMs are showcased, and the possibility of coupling other techniques to SEPMs is presented. Emphasis is given to scanning electrochemical microscopy (SECM), scanning ion conductance microscopy (SICM), electrochemical scanning tunneling microscopy (EC-STM), and scanning electrochemical cell microscopy (SECCM).

The Effect of a Bioactive Oral System and CO2 Laser on Enamel Susceptibility to Acid Challenge

This study evaluated the structural changes of enamel treated by the Regenerate system and carbon dioxide (CO2) laser against acid challenge. Thirty human enamel slabs were prepared and assigned into three groups: Group I: untreated (control); Group II: treated with the Regenerate system; and Group III exposed to CO2 laser. All specimens were subjected to an acid challenge (pH 4.5–7.0) for 14 days. Specimens were evaluated and compared at 120 points using five Raman microspectroscopic peaks; the phosphate vibrations ν1, ν2, ν3, and ν4 at 960, 433, 1029, and 579 cm−1, respectively, and the carbonate at 1070 cm−1, followed by Vickers microhardness test. The ratio of carbonate to phosphate was correlated to the equivalent microhardness numbers. The intensities of phosphate peaks ν1, ν2, and ν4 were reduced in all groups post-acid challenge, while the carbonate and ν3 were significantly increased (p < 0.000). Surfaces treated by Regenerate exhibited higher peak intensity of phosphate and carbonate before and after pH-cycling (p < 0.05). The mineral content in enamel had a direct effect on tissue microhardness, and the CO2-lased surfaces showed a reduced carbonate content and higher microhardness values. Both approaches induced surface changes that can protect enamel against acid challenge resulting in a significant benefit for dental healthcare.

Effectiveness of fluoride-containing toothpastes associated with different technologies to remineralize enamel after pH cycling: an in vitro study

BACKGROUND

To evaluate the efficacy of fluoride-containing toothpastes with different technologies to remineralize artificial caries lesions in enamel.

METHODS

Bovine enamel blocks were divided into three thirds: intact (untreated), demineralized (artificial caries lesion), and treated (caries lesion, pH cycling with dentifrices). Enamel blocks were randomly distributed into five groups (n = 12): Fluoride-free toothpaste, Colgate Oral Care (NC); Arginine-containing toothpaste, Colgate Total Daily Repair (PC); Silicate-based fluoride toothpaste: REFIX technology, regenerador + sensitive (RDC), NR-5 technology, Regenerate Enamel Science (RES), and NOVAMIN technology, Sensodyne Repair and Protect (SRP). The specimens were submitted to a pH cycling model for 6 days. The efficacy of the toothpastes was estimated by calculating the surface microhardness recovery (%SMHR) and the fluorescence recovery (ΔFRE) with quantitative light-induced fluorescence. The cross-sectional micromorphology of the enamel surface was also assessed using scanning electron microscopy. Elemental analyses (weight%) were determined with an energy-dispersive X-ray spectrometer (EDS). The results were compared to that of the control (NC). Data were statistically analyzed (5%).

RESULTS

%SMHR could be ranked as follows: RDC = PC = RES = SRP > NC. Significantly higher %SMHR and ΔFRE means were observed after enamel treatment with RDC (22.7 and 46.9, respectively). PC (%SMHR = 18.8) was as efficacious as RDC to recover the surface microhardness with a significantly lower mean of ΔFRE (19.5). Only RDC was able to promote the formation of a mineralized layer on the surface of enamel enriched with silicon on the surface.

CONCLUSIONS

The silicate-based fluoride toothpaste containing REFIX technology demonstrated greater efficacy in the remineralizing artificial caries than the other products.

Glass-ionomer and calcium silicate-based cements interactions with human dentine in health and disease: Two-photon fluorescence microscopy and Raman spectroscopy analysis

OBJECTIVES

To investigate the potential mineralising effects of calcium silicate-based dentine replacement material (Biodentine™) in comparison with glass-ionomer cement (GIC) (Fuji IX™) on different human dentine substrates using a multimodal non-invasive optical assessment.

METHODS

Cements were applied on artificially demineralised or naturally carious dentine and stored for 4 weeks in phosphate-rich media +/- tetracycline used for mineralisation labelling. Interfacial dentine was examined from the same sample and location before and after aging using two-photon fluorescence microscopy, fluorescence lifetime imaging (FLIM) and second harmonic generation (SHG) imaging. Additionally, Raman spectroscopy was used to detect changes in the mineral content of dentine.

RESULTS

Significant changes in the fluorescence intensity and lifetime were detected in partially demineralised dentine and caries-affected dentine underneath both tested cements, after storage (p < 0.001). This was associated with a significant increase in the mineral content as indicated by the increased intensity of the phosphate Raman peak located at 959 cm^-1 (p < 0.0001). Caries-infected dentine showed significant fluorescence changes under Biodentine™ after storage (p < 0.001), but not under GIC (p = 0.44). Tetracycline binding induced a reduction in the fluorescence lifetime with comparable increase in the fluorescence intensity in both cements' groups within the affected dentine (p < 0.001). Significance Two-photon fluorescence microscopy can be used efficiently for non-destructive in-vitro dentine caries characterisation providing a technique for studying the same dentine-cement interface over time and detect changes. Biodentine™ demonstrated comparable remineralising potential to GIC, in addition to inducing remineralisation of caries-infected dentine. This may suggest using Biodentine™ as part of minimally invasive operative dentistry (MID) in caries management.

Long-term evaluation of early-enamel lesions treated with novel experimental tricalcium silicate paste: A 2-year randomized clinical trial

OBJECTIVE

The aim of the current study is to evaluate the remineralization potential of experimental tricalcium silicate (TCS) paste in comparison with more popular remineralizing agents like silver diamine fluoride potassium iodide (SDF-KI) and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on early enamel lesions.

MATERIALS AND METHODS

Forty-five patients in the age range of 15-50 years had early enamel lesions on the buccal surface of molar teeth. The patients were randomly divided into three treatment groups (SDF-KI, CPP-ACP, and TCS group) with 15 patients per group. Lesions were evaluated clinically by DIAGNOdent pen immediately and after 3,6,12, and 24 months of treatment.

RESULTS

The study was completed with 45 patients and 92 teeth. Twice-daily application of CPP-ACP and TCS paste showed a significant remineralization effect on early enamel lesions after 24 months (p < 0.001). Also, annual application of SDF-KI showed a significant remineralization effect after 24 months (p < 0.001). There was a significant difference between (SDF-KI and CPP-ACP) and (SDF-KI and TCS) at the different follow-up periods 3,6,12, and 24 months (p < 0.001). Meanwhile, there was no significant difference between CPP-ACP and TCS at the mentioned follow-up periods (p > 0.05).

CONCLUSION

TCS showed potential remineralization for early enamel lesions.

CLINICAL RELEVANCE

Experimental TCS is a promising remineralizing agent for management of early enamel lesions.

Remineralization of early enamel lesions with a novel prepared tricalcium silicate paste

To evaluate the remineralization potential of prepared tricalcium silicate (TCS) paste compared to silver diamine fluoride-potassium iodide (SDF-KI) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on artificial enamel lesions. Thirty permanent sound molars were collected for the study. After cleaning, root cutting, and applying acid-resistant nail varnish, leaving a 4 × 4 mm buccal window, the teeth were subjected to demineralization process. The teeth were divided into three treatment groups (n = 10). In each group, the teeth were sectioned buccolingually to obtain two halves (30 self-control and 30 experimental halves). The self-control halves were subjected to cross-sectional microhardness (CSMH), energy-dispersive X-ray spectroscopy at 50, 100, and 150 µm from the external enamel surface, and micromorphological analysis at the superficial enamel surface. The experimental halves were subjected to the same tests after 30 days of remineralization. Three-way analysis of variance (ANOVA) outcomes showed no significant difference in CSMH after treatment among the three different groups at the different levels (p > 0.05). Meanwhile, three-way ANOVA outcomes showed a significant difference in calcium/ phosphate ratio after treatment among the three different groups at the different levels. (p < 0.05). The tricalcium silicate paste used in this study showed potential remineralization in subsurface enamel lesions.

Effectiveness of Experimental Whitening Toothpastes Containing Colorants on the Optical Properties of Enamel

Objective. This in vitro study investigated the whitening potential of experimental toothpastes containing optical colorants in their formulations in comparison with commercial products. The chemical and physical characteristics of the toothpastes, the morphology, and elemental analysis of the enamel surface after treatment were also analyzed. Materials and Methods. One hundred twenty-five bovine incisor teeth were randomly divided into five groups according to the treatment: (i) experimental PHTALOX dental gel (PHT); (ii) experimental blue silica dental gel (SDG); (iii) Sensodyne Whitening Repair & Protect (WRP); (iv) Sensodyne True White (STW); (v) Snow White Toothpaste (SWS). The whiteness index differences (ΔWID) and color alteration (CIELab-ΔE, CIEDE2000-ΔE00) were calculated after color change analysis using a spectrophotometer before and after the enamel treatment (n = 25). The surface and cross-sectional micromorphology were assessed using scanning electron microscopy. The elemental analyses were determined with energy-dispersive X-ray spectroscopy (EDS). The pH, particle size, zeta potential, and polydispersity index of toothpaste were evaluated. Data was statistically analyzed (ANOVA/Tukey, 5%). Results. Whitening toothpastes containing optical colorants were effective for whitening the enamel, as whiter teeth were observed following treatment (higher means of ΔWID). In addition, when the parameters ΔEab and ΔE00 were evaluated, these toothpastes were graded as very good effectiveness (grade 4). Other toothpastes were graded as 3 (good effectiveness). PHT had a neutral pH and a larger mean particle size (412.8 nm). Elemental analysis demonstrated enamel with a silicon-enriched mineral layer on the enamel surface treated with SDG. The Ca/P ratio after enamel treatment varied from 1.74 (SWS) to 2.04 (SDG and WRP). Conclusions. Experimental whitening toothpastes containing optical colorants are effective at bleaching the enamel. The synergism among the different parameters analyzed seems to positively affect the color change after brushing with whitening toothpastes containing optical colorants.

Rehardening and the Protective Effect of Gamma-Polyglutamic Acid/Nano-Hydroxyapatite Paste on Surface-Etched Enamel

Many revolutionary approaches are on the way pertaining to the high occurrence of tooth decay, which is an enduring challenge in the field of preventive dentistry. However, an ideal dental care material has yet to be fully developed. With this aim, this research reports a dramatic enhancement in the rehardening potential of surface-etched enamels through a plausible synergistic effect of the novel combination of γ-polyglutamic acid (γ-PGA) and nano-hydroxyapatite (nano-HAp) paste, within the limitations of the study. The percentage of recovery of the surface microhardness (SMHR%) and the surface parameters for 9 wt% γ-PGA/nano-HAp paste on acid-etched enamel were investigated with a Vickers microhardness tester and an atomic force microscope, respectively. This in vitro study demonstrates that γ-PGA/nano-HAp treatment could increase the SMHR% of etched enamel to 39.59 ± 6.69% in 30 min. To test the hypothesis of the rehardening mechanism and the preventive effect of the γ-PGA/nano-HAp paste, the surface parameters of mean peak spacing (Rsm) and mean arithmetic surface roughness (Ra) were both measured and compared to the specimens subjected to demineralization and/or remineralization. After the treatment of γ-PGA/nano-HAp on the etched surface, the reduction in Rsm from 999 ± 120 nm to 700 ± 80 nm suggests the possible mechanism of void-filling within a short treatment time of 10 min. Furthermore, ΔRa-I, the roughness change due to etching before remineralization, was 23.15 ± 3.23 nm, while ΔRa-II, the roughness change after remineralization, was 11.99 ± 3.90 nm. This statistically significant reduction in roughness change (p < 0.05) implies a protective effect against the demineralization process. The as-developed novel γ-PGA/nano-HAp paste possesses a high efficacy towards tooth microhardness rehardening, and a protective effect against acid etching.

Superimposition of sequential scans to measure erosion on unpolished and curved human enamel

OBJECTIVES

To determine if superimposition of sequential scans can discriminate between different fluorides at step heights less than 5 μm on natural human enamel surfaces.

MATERIALS AND METHODS

Natural, unpolished, human enamel specimens (n = 60) were randomly assigned to one of three pre-treatment toothpaste slurries with a calcium silicate/fluoride, fluoride-only and a control. Baseline and post treatment scans, from a non-contacting profilometer with a 0.01 μm z-axis and <1 μm lateral scanning resolution were imported into superimposition software to define change in mean 3D step height and surface roughness following erosion in 0.3 % citric acid for 15 min. Statistical analysis conducted with two-way repeated measures ANOVA and post-hoc Tukey's multiple comparisons.

RESULTS

Confidence and resolution of superimposition and subtraction of repeated profiles from unpolished enamel revealed accuracy within 1-2 μm. The technique was able to discriminate between the fluorides demonstrating statistical differences in mean (SD) 3D step height (μm) of 1.96 (0.40) and 2.75 (0.49) (p=0.0024). There was a statistically significant increase in surface roughness for all groups after 15 min erosion compared to baseline. But no statistically significant difference between the interventions after 15 min erosion but there was compared to no fluoride (p=0.006).

CONCLUSION

Superimposition and subtraction of profiles could discriminate between fluoride interventions, which showed statistical differences in enamel loss differences less than 3 μm.

CLINICAL SIGNIFICANCE

This erosion model and data analysis workflow was able to distinguish differences between scans of 3 μm on unpolished enamel following the interaction with fluoride.

Effects of Remineralizing Agents Based on Calcium Phosphate, Sodium Phosphate, or Sodium Fluoride on Eroded Cervical Dentin

OBJECTIVES

To evaluate the effect of remineralizing agents on collagen matrix pattern, precipitate formation, and dentinal tubule obliteration in eroded cervical dentin.

METHODS AND MATERIALS

One hundred bovine cervical dentin specimens were previously eroded (0.6% hydrochloric acid, pH 2.3, 5 minutes) and then randomized into five groups (n=20): G1, control (without treatment); G2, Desensibilize Nano P (FGM); G3, MI Paste Plus (Recaldent); G4, Regenerate (NR-5); and G5, Desensibilize KF 2% (FGM). These treatments were applied in four sessions with 7-day intervals. During this period, the samples were subjected to an erosive challenge with orange juice (pH 3.8, 5 minutes). The specimens were analyzed by polarized light microscopy with picrosirius red staining, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX).

RESULTS

The G3 showed a higher concentration of type I collagen than G2 and G5 (p<0.05). The G3 showed greater formation of surface precipitates than that of G1 and G5 (p<0.05). In addition, G4 and G5 showed a greater number of open dentinal tubules than that of G3 (p<0.05).

CONCLUSIONS

Calcium phosphate-based remineralizing agents have shown to be a promising alternative treatment for preventing deleterious effects on the eroded dentin collagen matrix. In addition, they promoted precipitate formation and dentinal tubule obliteration on the eroded dentin.

Protection of calcium silicate/sodium phosphate/fluoride toothpaste with serum on enamel and dentin erosive wear

Objective

To evaluate the effect of a toothpaste containing calcium silicate/sodium phosphate/fluoride associated or not to the boost serum (BS) against erosive tooth wear (ETW) on enamel and dentin.

Methodology

Bovine enamel and dentin specimens were subjected to an erosion-abrasion cycling model (1% citric acid - pH 3.6 -2 min / artificial saliva – 60 min, 4×/day, 5 days). Toothbrushing was performed for 15 s (2 min exposed to slurry), 2×/day, with the toothpastes (n=10): control without fluoride (Weleda), Arg/Ca/MFP (Colgate Pro-Relief), Si/PO₄/MFP (Regenerate-Unilever), and Si/PO₄/MFP/BS (Si/PO₄/MFP with dual BS – Advanced Enamel Serum-Unilever). The effect of treatments on the eroded tissues was assessed by surface microhardness in the first day, and surface loss (SL) resulting from ETW was evaluated by profilometry (μm) after three and five days. Additional dentin specimens (n=5/group) were subjected to 20,000 brushing cycles to verify the abrasivity of the toothpastes. Data were subjected to ANOVA and correlation tests (5%).

Results

For enamel, no difference in microhardness was observed among the treated groups, and similar SL was obtained after 5 days. For dentin, Si/PO₄/MFP/BS resulted in higher microhardness values, but none of the groups presented significantly lower SL than the control. There was no significant correlation between SL and abrasiveness.

Conclusion

The calcium silicate/sodium phosphate toothpaste and serum increased microhardness of eroded dentin, but they did not significantly reduce enamel and dentin loss compared to the non-fluoride control toothpaste. The abrasiveness of the toothpastes could not predict their effect on ETW.

Resistance against Erosive Challenge of Dental Enamel Treated with 1,450-PPM Fluoride Toothpastes Containing Different Biomimetic Compounds

OBJECTIVES

 This in vitro study aimed to characterize the superficial and subsurface morphology of dental enamel treated with fluoridated gels containing different biomimetic compounds after erosive challenge.

MATERIALS AND METHODS

Bovine incisor teeth were sectioned to obtain enamel blocks (4 mm × 4 mm × 6 mm; n = 5) that were demineralized to create an artificial caries lesion and treated by pH cycling interspersed with exposure to fluoridated toothpaste slurries under agitation. During pH cycling (demineralization and remineralization for 2 and 22 hours, respectively) for 6 days, the enamel blocks were exposed to toothpaste slurries under agitation with one of the dental gels: Regenerate Enamel Science (NR-5 technology), Daily Regenerator Dental Clean (REFIX technology), and Sensodyne Repair & Protect (Novamin technology). The enamel blocks were subjected to an erosive challenge, immersed in 50% citric acid for 2 minutes, and then washed with plenty of distilled water. The surface and cross-sectional micromorphology were assessed using scanning electron microscope (SEM). The elemental analyses (weight percentage) were determined with an energy-dispersive X-ray spectroscopy (EDS).

RESULTS

 Enamel treated with the product containing REFIX technology presented a smoother surface morphology compared to the other treatments. The higher resistance to the erosive challenge can be attributed to a silicon-enriched mineral layer formed on the enamel induced by the REFIX-based toothpaste. This was not observed in the specimens treated with the other technology-containing toothpastes.

CONCLUSION

 The REFIX technology seemed to be the most promising compared to the Novamin and NR-5 technologies. In addition to forming a surface mineralized layer, the enamel treated with REFIX technology associated with the pH cycling resisted a subsequent erosive challenge.

In situ evaluation of desensitizing toothpastes for protecting against erosive tooth wear and its characterization

OBJECTIVE

This five-phase, single-blind, crossover in situ trial evaluated the effects of desensitizing or anti-erosive toothpastes on dentin erosive wear and tubule occlusion.

MATERIALS AND METHODS

Some characteristics such as relative dentin abrasivity (RDA), viscosity (V), cytotoxicity, and fluoride and calcium (Ca) availability of the toothpastes were also tested. Samples were positioned on removable intraoral appliances from 15 volunteers (n=4), according to the groups, C-control (0 ppm fluoride), F-sodium monofluorophosphate (MFP), A-MFP and arginine+calcium carbonate, CSP-calcium sodium phosphosilicate, and CS-MFP and calcium silicate+sodium phosphate. Erosion-abrasion cycling was performed (1% citric acid, 2min, 6×/day; toothbrushing, 5s, 2×/day). Surface loss (SL) was evaluated by optical profilometry. Environmental scanning electron microscopy images (ESEM) counted the number of open dentin tubules (ODTs). Data were statistically analyzed (α=0.05).

RESULTS

There were no significant differences in SL among groups (p=0.468). The ODT for CSP, CS, and A groups were significantly lower than the control. CSP and CS presented significantly less ODT than F, but they did not significantly differ from A. F and CS were more abrasive than all the other toothpastes; CSP was more abrasive than A, and C was the least abrasive. CSP presented higher V (p<0.05). All toothpastes presented lower cell viability than the control without toothpaste exposure. F and A presented significantly higher values of F^- (p<0.05). All fluoride toothpastes had similar amount of Ca, differing from the control (p<0.05).

CONCLUSION

Although the toothpastes caused similar degree of erosive wear, CSP and CS were able to occlude the dentin tubules.

CLINICAL RELEVANCE

Desensitizing toothpastes containing calcium, sodium, phosphate, and silicate could be a suitable option for treating dentin hypersensitivity.

Protective effect of calcium silicate toothpaste on enamel erosion and abrasion in vitro

Objectives

To compare in vitro the effect of a toothpaste containing fluoride (F), calcium silicate (CaSi) and sodium phosphate salts to conventional toothpaste (NaF) on human enamel specimens submitted to erosive and abrasive challenges.

Methods

48 sound and 48 enamel samples pre-treated with 1% citric acid were divided into 4 groups (n = 12): Group 1- Non-fluoride toothpaste; Group 2- NaF toothpaste (1450 ppmF); Group 3- CaSi toothpaste (1450 ppmF; MFP); Group 4- Erosion only. The samples were subjected to pH cycling (3 cycles/day; 90s; 1% citric acid, pH 3.6) and to abrasion for 7 days. After the 1^st and the last cycle, they were submitted to abrasion (15s, 1.5N load), using a brushing machine, soft toothbrush and toothpaste slurry (1:3; 15ml/sample) and then immersed in the slurry for 45s. Samples were immersed in artificial saliva between the challenges. Enamel loss was evaluated using profilometry on days 3 and 7. Data were analysed by ANOVA and Tukey's test (p < 0.05).

Results

For sound enamel at baseline, mean (±SD) enamel loss (μm) for groups 1-4 on day 3 was 2.15 ± 0.35^a, 1.20 ± 0.22^b, 0.95 ± 0.19^b and 1.98 ± 0.32^a; on day 7 was 3.05 ± 0.40^a, 2.07 ± 0.32^b, 1.36 ± 0.33^c and 3.69 ± 0.27^d respectively. For acid-softened enamel at baseline, enamel loss on day 3 was 3.16 ± 0.19^a, 2.17 ± 0.14^b, 1.70 ± 0.11^c and 3.04 ± 0.19^a; on day 7 was 3.92 ± 0.25^a, 3.07 ± 0.13^b, 2.09 ± 0.15^c and 3.87 ± 0.25^a respectively.

Conclusions

Both F toothpastes led to significantly higher enamel protection from short-term erosion and abrasion in comparison to the non-F toothpaste and erosion only. In the longer term, CaSi toothpaste conferred significantly higher protection than NaF toothpaste.

Clinical significance

The results showed that for the longer term the CaSi toothpaste provided significantly higher protection than the NaF toothpaste, which indicates a good potential of the former to help prevent erosive tooth wear.

Effectiveness of a toothpaste and a serum containing calcium silicate on protecting the enamel after interproximal reduction against demineralization

To evaluate the effectiveness of a calcium silicate/phosphate fluoridated tooth paste and a serum compared with a toothpaste containing hydroxyapatite on protecting the enamel after interproximal reduction against demineralization. 3 sets of eleven incisors were created. The teeth underwent interproximal enamel reduction (IER) of 0.5 mm. Each set was allocated to one of three groups: (1) Brushing without toothpaste (control group); (2) Vitis toothpaste + Remin Pro; (3) Regenerate toothpaste + Regenerate Serum. The agents were applied three times a day and specimens subjected to demineralization cycles for 30 days. The weight percentages of calcium (Ca) and phosphorous (P) were quantified by X-ray microfluorescence spectroscopy. Surface microhardness measurements and electron scanning microscopy (SEM) observations were made. Ca data and the Ca/P ratio were significantly higher in Group 3 than the other groups (p < 0.017), while P was significantly lower in Group 3 (p < 0.017). No significant differences were found between Groups 1 and 2 (p > 0.017). Group 3 showed significantly higher microhardness values (p < 0.05) than Group 1. No significant differences were found for other comparisons between groups (p < 0.05). SEM images showed less demineralization in Group 3. The application of a calcium silicate/phosphate fluoridated tooth paste (Regenerate advance) and a dual serum (Regenerate advance enamel serum) protect the enamel with interproximal reduction against demineralization. Therefore, this treatment could be used to prevent the dissolution of hydroxyapatite after IER.

Tooth Wear: Best Evidence Consensus Statement

PURPOSE

The purpose of this Best Evidence Consensus Statement was to evaluate the impact of wear on teeth.

MATERIALS AND METHODS

A search updated last on the 07th October 2020 using the terms tooth wear, dental erosion, dental abrasion or dental attrition yielded 11,694 results. Limiting the search to clinical trials, cross-sectional investigations, randomized controlled trials, reviews, systematic reviews and meta-analysis yielded 1,769 results. Mechanistic in vitro studies were also added to the list of abstracts supplying additional information of the impact of wear on teeth. All abstracts were reviewed by two authors. Those relating to the focus question formed the evidence base which was used to formulate the response.

RESULTS

From the search results, 212 articles were related to the research question and 60 were included in this paper. Although tooth wear prevalence is over 30% of the population in early adulthood and increases as individual's age, the impact on the dentition is poorly investigated in longitudinal clinical studies. Wear on teeth can result in alterations in shape and potentially dentine hypersensitivity depending on the etiology. However, the process is slow and pulpal death is rare. The impact that tooth wear has on the patient depends on patient characteristics to a greater extent than the severity of wear.

CONCLUSIONS

Tooth wear is a common condition and part of the ageing process. Erosive tooth wear is a term which acknowledges that acids are normally linked to progression, but mechanical actions of attrition and abrasion will cause visible damage. The changes to the shape of teeth on the macro and micro levels are used to investigate the progression, prevention, etiology, and management. The biological impact of wear on teeth is relatively innocuous and management is often a patient driven process. This article is protected by copyright. All rights reserved.

Biomimetic Mechanism of Action of Fluoridated Toothpaste Containing Proprietary REFIX Technology on the Remineralization and Repair of Demineralized Dental Tissues: An In Vitro Study

Objectives  This in vitro study aimed to characterize the mineral content and surface and cross-sectional morphology of enamel and dentin tissues treated with a 1450 ppm fluoride-containing toothpaste with REFIX technology.

Materials and Methods  Bovine enamel blocks ( n = 5) were obtained (4 × 4 × 6 mm), demineralized (artificial caries lesion), and treated (pH cycling and brushing with the toothpaste). During the pH cycling, which lasted for 7 days (demineralization and remineralization took 6 and 18 hours, respectively), the enamel was brushed for 5 minutes using an electric toothbrush before being immersed in a remineralizing solution. The dentin blocks were acid-etched for 2 minutes (0.05 M citric acid, pH 1.8) to expose the dentinal tubules ( n = 5). Morphological analysis of the dentin was performed immediately and after 7 days of brushing with the dentifrice, and compared with the control group. The specimens were then cross-sectioned. The surface and cross-sectional micromorphology were assessed using scanning electron microscopy (SEM). The elemental analyses (weight%) were determined with an energy-dispersive X-ray spectroscopy (EDS).

Results  The toothpaste with REFIX technology remineralized and repaired the surface enamel effectively. The elemental analysis also demonstrated that treating the enamel with the toothpaste formed a silicon-enriched mineral layer on the enamel surface. Elemental analysis of the enamel cross-sections showed that the toothpaste induced a mineral change. The results were also consistent in the dentin, where the dentinal tubules were progressively occluded until there was complete occlusion after 7 days.

Conclusions  We prove the biomimetic mechanism of action of fluoridated toothpaste containing proprietary REFIX technology for obtaining silicon-enriched, remineralized and repaired dental tissues.

Fluoride dentifrice containing calcium silicate and sodium phosphate salts on dental erosion: In vitro study

OBJECTIVE

To investigate the effect of a commercial dentifrice containing fluoride, calcium silicate, and sodium phosphate and its dual phase gel serum to prevent erosive tooth wear in enamel.

METHODS

Forty-eight enamel specimens were selected by surface hardness and randomly allocated into 4 groups (n = 12) according to the commercial toothpastes: non-fluoridated (NF); 1100 ppm Stannous fluoride (SnF₂); 1450 ppm MFP + calcium silicate + sodium phosphate (CSSP); CSSP + dual-phase gel (CSSP + Serum). Cyclic experiments were repeated 3x / day for five days, including an erosive challenge with 0.05 M citric acid (pH 3.75 for 30 s), treatment with toothpaste slurries (1 min), and remineralization with artificial saliva (pH 7.0 for 60 min). Surface alterations were determined by stylus profilometry (μm) and scanning electron microscopy (SEM). Data were analyzed by ANOVA and Tukey tests (α = 0.05).

RESULTS

SnF₂, CSSP and CSSP + Serum significantly reduce surface wear compared to NF treated group. Besides, there were no significant differences among SnF₂, CSSP and CSSP + Serum. In micrographs of both groups treated with CSSP, the surface demonstrates the presence of a protective layer as a deposition of particles.

CONCLUSIONS

Dentifrice containing calcium silicate and sodium phosphate with or without the dual-phase gel was able to prevent the erosive tooth wear.

Effects of 1450-ppm Fluoride-containing Toothpastes Associated with Boosters on the Enamel Remineralization and Surface Roughness after Cariogenic Challenge

OBJECTIVES

 This in vitro study investigated the remineralization potential of 1450 ppm, fluoride-containing toothpastes containing different active remineralization agents after cariogenic challenge with pH cycling. The enamel surface roughness after brushing and the chemical and physical characteristics of the toothpastes tested were also analyzed.

MATERIALS AND METHODS

 Fifty-six bovine enamel blocks were obtained (4 × 4 × 6 mm) and divided into three thirds: intact (untreated), demineralized (artificial caries lesion), and treated (caries lesion, pH cycling, and brushing with dentifrices). Seven commercially available fluoride toothpastes (1450 ppm F): three with anti-erosion claims (Candida Professional [CPP], Colgate Total 12 Daily Repair [CDR], Regenerate Enamel Science [RES]); three with desensitizing claims (Bianco Pro Clinical [BPP], Elmex Sensitive [ESS], and Regenerador Diário DentalClean [RDC]); and one standard regular-fluoride toothpaste Colgate Total 12 (CTT) were selected. During pH cycling (demineralization 6 h/remineralization 18 h) for 7 days, the treated third was brushed with the different dentifrices for 10 minutes in a brushing machine before immersion in a remineralizing solution. The Knoop hardness (25 g, 10 second of the surface, and longitudinal section were then evaluated at eight depths (10 to 330 μm). Mean and percentage of surface hardness recovery (% SHR) were calculated. Surface enamel roughness (Ra) was also evaluated. The pH, %weight of particles, zeta potential, and polydispersity index of toothpaste slurries were also evaluated.

STATISTICAL ANALYSIS

 Data were statistically analyzed (ANOVA/Tukey, 5%).

RESULTS

 The %SHR of CPP was significantly lower than the others (p < 0.05). The enamel subsurface was more effectively remineralized when treated with BPP, ESS, and RDC. The surface roughness was higher when the demineralized third was treated with CTT, RDC, and RES and after the cariogenic challenge (p < 0.05). For some of the products tested, there was no relationship between surface remineralization and subsurface remineralization. Although toothpastes CPP and RDC present the lowest %SHR means, both products effectively remineralize within the subsurface carious lesion. Regression analysis demonstrated no strong correlations of the enamel surface roughness with the chemical and physical parameters.

CONCLUSIONS

 Most but not all the fluoride toothpastes were able to remineralize the enamel surface. No specific chemical or physical parameter alone correlated with the surface roughness.

Preventive effect of remineralizing materials on dental erosion lesions by speckle technique: An in vitro analysis

The aim of this in vitro study was to evaluate the preventive effect of different materials on dental erosion lesions by speckle coherent light scattering analysis. Forty bovine teeth were divided in the following groups (n = 10): 1) DURA- Preventive Treatment with Fluoride Varnish (Duraphat, Colgate-Palmolive); 2) ELX- Preventive treatment with Elmex® Erosion Protection Toothpaste (GABA International AG, Therwil, Switzerland); 3) MP- Preventive treatment with MI Paste® (GC America); and 4) REG- Preventive Treatment with Regenerate Enamel Science™ (Unilever). For all groups, each sample was divided into 3 areas: non-treatment (control); preventive treatment + erosive challenge; non-treatment + erosive challenge. The erosive challenge was carried out using Sprite® Zero soft drink (pH 2.58). After the erosive challenge, the samples were evaluated by speckle coherent light scattering method in the eroded area compared to the sound area. The results showed that there was a statistically significant difference between eroded area with and without preventive treatment, however, there was no statistically significant difference among the different preventive materials tested.

Nonprescription Bleaching versus Home Bleaching with Professional Prescriptions: Which One is Safer? A Comprehensive Review of Color Changes and Their Side Effects on Human Enamel

OBJECTIVES

 This study evaluates the efficacy and safety of the professionally prescribed and nonprescription over-the-counter (OTC) bleaching agents.

MATERIALS AND

METHODS:  Extracted human upper central incisors were prepared and stained with red wine for 14 days before being subjected to four different bleaching agents: professionally prescribed opalescence PF 15%, VOCO Perfect Bleach 10%, nonprescription OTC Crest 3D Whitestrips, and Whitelight Teeth Whitening System. Colorimetric measurement was performed with Vita Easyshade Handheld Spectrophotometer, enamel surface microhardness measured using Vickers Hardness machine, and surface roughness was evaluated with profilometer, before and after bleaching. Scanning electron microscope (SEM) evaluation and atomic force microscopy were conducted postbleaching.

STATISTICAL ANALYSIS

 The data were analyzed with t-test, two-way ANOVA, one-way ANOVA, and Turkey's test at a significance level of 5%.

RESULTS

 All bleaching products have the same efficacy to whiten stained enamel. Opalescence PF 15% showed significant increase in the microhardness (92.69 ± 68.316). All groups demonstrated significant increase in surface roughness (p < 0.05). SEM evaluation showed that Opalescence PF 15% resulted in same microscopic appearance as unbleached enamel, while VOCO Perfect Bleach 10%, Whitelight Teeth Whitening System and Crest 3D Whitestrips demonstrated mild to moderate irregularities and accentuated irregularities, respectively.

CONCLUSION

 Professionally prescribed bleaching agent of Opalescence PF 15% is effective tin whitening the teeth, while the other bleaching products may be effective but also have deleterious effects on the enamel.

Influence of desensitizing and anti-erosive toothpastes on dentine permeability: An in vitro study

OBJECTIVE

This study analyzed the effect of desensitizing and/or anti-erosive toothpastes on dentine permeability.

METHODS

One-mm dentin discs were prepared from human molars and exposed to EDTA solution (5 min, 17%). Initial dentine permeability was measured, under constant pressure. Specimens were randomly allocated into 10 groups: four anti-erosive toothpastes (calcium silicate + sodium phosphate, potassium nitrate, stannous chloride + chitosan, oligopeptide-104); four desensitizing toothpastes (arginine + calcium carbonate, calcium sodium phosphosilicate, strontium acetate, stannous fluoride); and two controls (regular fluoridated toothpaste, and human saliva). They were submitted to a 5-day erosion-abrasion cycling model. Erosion consisted of immersion in citric acid (2 min, 0.3%, natural pH ˜ 2.6, 4x/day), followed by 1 h exposure to human saliva. Specimens were brushed for 15 s (2 N, 45 strokes) with the toothpaste slurries (total exposure time of 2 min). After 5 cycles, the final dentine permeability was determined. Dentine permeability change was calculated as a percentage of the initial hydraulic conductance (%Lp). Data were analyzed with one-way ANOVA and Tukey tests (α=0.05).

RESULTS

The toothpastes calcium silicate + sodium phosphate and potassium nitrate, showed significant decrease in %Lp, with no difference between them. The regular fluoridated toothpaste also decreased the %Lp, not differing from potassium nitrate. No desensitizing toothpaste showed change in %Lp. Human saliva, oligopeptide-104 and stannous chloride + chitosan presented significant increase in %Lp, without difference between them.

CONCLUSION

Calcium silicate + sodium phosphate, potassium nitrate, and the regular fluoridated toothpaste decreased dentine permeability, whereas the desensitizing toothpastes tested did not.

CLINICAL RELEVANCE

Toothpastes had distinct impacts on dentine permeability, which may reflect a variable effect on the treatment of dentine hypersensitivity. Within the limitations of a laboratory-based study, toothpastes with an anti-erosive claim could also be effective in reducing the pain in dentine hypersensitivity.

Color change of the bleached enamel treated with calcium silicate- sodium phosphate-sodium monofluorophosphate-based system

Background

The increasing demand of tooth bleaching has also increased the need of researches focusing on the durability of the resultant color. The aim of this study was to evaluate the effect of a system based on calcium silicate, sodium phosphate and sodium monofluorophosphate (Regenerate™) on color maintenance of bleached enamel considering two waiting times for the contact with a cola drink.

Material and Methods

This in vitrostudy was performed on bovine enamel specimens (n = 100), bleached with 35% H2O2 and treated with: G1 Distilled water; G2 Artificial saliva; G3 RegenerateTM Serum and Toothpaste; G4 RegenerateTM Toothpaste; G5 RegenerateTM Serum. The groups G3, G4 and G5 received one application of the respective products for 3 min, in 3 consecutive days. The color parameters (ΔE, L*, a*, b*) were evaluated by spectrophotometry before and after bleaching and after surface treatments and immersion (15min) in cola drink, on the waiting times of 24 hours (T1) and 7 days (T2). The effect of surface treatments and waiting times was evaluated by Two-Way ANOVA, Kruskal-Wallis, Wilcoxon and T test (p<0.05).

Results

There was no significant effect of the surface treatments (p=0.57), waiting times (p=0.97) and their interaction (p=0.47) considering ΔE. The analysis of repeated measures of the color coordinates L*, a* and b* showed a decrease of chromaticity (a*, b*) for G3, G4 and G5 and an increase of lightness (L*) for G5, after immersion in cola drink, suggesting some protection against bleached enamel pigmentation.

Conclusions

RegenerateTM has a potential protective effect on bleached enamel color maintenance. The waiting times of 24 hours and 7 days for the contact with the cola drink did not influence bleached enamel color maintenance.

Key words:Tooth bleaching, hydrogen peroxide, spectrophotometry, pigmentation.

Bioactive injectable polymethylmethacrylate/silicate bioceramic hybrid cements for percutaneous vertebroplasty and kyphoplasty

Polymethylmethacrylate (PMMA) cement has been widely used to fill and stabilize hard tissue defects in clinical surgery, especially in percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP). However, the dense body of pure PMMA in defects has no ability to promote bone regeneration. We herein aim to fabricate novel PMMA/silicate bioceramic hybrid cements by adding bioactive calcium silicate (CS) particles into PMMA to endow PMMA/CS hybrid cements with bioactivity and biodegradability without losing the excellent mechanical strength and injectability. Following comprehensive characterization of the physicochemical properties and in vitro bioactivity study, our results showed compared with PMMA cement, the constructed PMMA/CS hybrid cements possessed significantly lower curing temperatures and simultaneously retained the acceptable mechanical strength and injectability. Moreover, obvious bioactive ion release and hydroxyapatite formation could be detected and observed after the PMMA/CS hybrid cements were soaked in simulated body fluid, indicating their pronounced bioactivity. A further in vivo study of the PMMA/CS hybrid cements on goat vertebral body defect models reflected that the PMMA/CS hybrid cements could be biodegraded well and could significantly promote new bone formation in defects 6 months of post-injection. Our results suggest that PMMA/CS hybrid cements may be promising candidates for PVP and PKP in clinic.

Effect of Remineralizing Gels on Microhardness, Color and Wear Susceptibility of Bleached Enamel

Objectives:

To evaluate the effect of a remineralizing gel combining fluoride and calcium silicate/phosphate or a sodium fluoride gel on bleached enamel microhardness, color, and wear susceptibility.

Methods and Materials:

Two hundred forty bovine enamel-dentin samples were prepared. Baseline analysis of Knoop microhardness, color coordinates (L*a*b*), and surface profile were performed. According to the baseline microhardness values, specimens were stratified into six groups (n=40): NC (negative control)—no treatment; BL (positive control)—bleaching with 40% hydrogen peroxide gel (Opalescence Boost, Ultradent); BL/Rs—bleaching + application of calcium silicate/phosphate gel (Regenerate Serum, Unilever - Rs); Rs/BL—Rs + bleaching; Rs/BL/Rs—Rs + bleaching + Rs; and BL/F—bleaching + 2% sodium fluoride gel. After the treatment described for each group, color change (ΔE) and microhardness were evaluated again. To evaluate abrasion susceptibility, samples were randomly divided into two subgroups, according to the toothpaste used (Cp—Close Up or Rt—Regenerate), and underwent 100,000 brushing strokes. The profile of each sample was evaluated and the mean wear calculated. The data were analyzed by ANOVA and Tukey tests.

Results:

All bleached groups showed a significant reduction of microhardness in relation to the negative control. The groups treated with remineralizing gels showed a significantly higher microhardness and less wear than the positive control, although nonsignificant differences were observed among them. Nonsignificant differences in ΔE were found among bleached groups. The groups brushed with Regenerate toothpaste showed significantly less wear than those brushed with Close Up toothpaste.

Conclusions:

The remineralizing gels did not interfere with bleaching efficacy. However, all the treatments minimized the surface hardness reduction caused by the bleaching procedure and enamel loss after abrasion. Regenerate toothpaste resulted in less enamel abrasion.

In-vitro apatite formation capacity of a bioactive glass - containing toothpaste

OBJECTIVES

The in-vitro dissolution of bioactive glass-based toothpastes and their capacity to form apatite-like phases in buffer solutions have been investigated.

MATERIALS AND METHODS

The commercial toothpaste samples were tested on immersion in artificial saliva, Earle's salt solution and Tris buffer for duration from 10min to four days. The powder samples collected at the end of the immersion were studied using solid-state ³¹P and ¹⁹F nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction and Fourier transform infrared (FTIR) spectroscopy. The fluoride concentration in the solution remained after the immersion was measured.

RESULTS

In artificial saliva and in presence of sodium monofluorophosphate (MFP), the bioactive glass and bioactive glass-based toothpastes formed fluoridated apatite-like phases in under 10min. A small amount of apatite-like phase was detected by ³¹P NMR in the toothpaste with MFP but no bioactive glass. The toothpaste with bioactive glass but no fluoride formed an apatite-like phase as rapidly as the paste containing bioactive glass and fluoride. By contrast, apatite-like phase formation was much slower in Earle's salt solution than artificial saliva and slower than Tris buffer.

CONCLUSIONS

The results of this lab-based study showed that the toothpaste with MFP and bioactive glass formed a fluoridated apatite in artificial saliva and in Tris buffer, as did the mixture of bioactive glass and MFP.

CLINICAL SIGNIFICANCE

The presence of fluoride in bioactive glass-containing toothpastes can potentially lead to the formation of a fluoridated apatite, which may result in improved clinical effectiveness and durability. However, this should be further tested intra-orally.

Effect of self-assembling peptide P11 -4 on enamel erosion: AFM and SEM studies

The aim of the present in vitro study was to evaluate the protective effect of self-assembling peptide P11 -4 (Curodont™ Protect/Credentis) on enamel erosion produced by a soft-drink, by using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Thirty human incisors were equally and randomly assigned to 6 groups. Group 1: intact enamel, group 2: soft drink, group 3: Curodont(™) Protect applied, group 4: Curodont(™) Protect applied + soft drink, group 5: soft drink + Curodont(™) Protect applied, group 6: soft drink + Curodont(™) Protect applied + soft drink. Specimens were observed through atomic force microscopy (AFM). The root mean-square roughness (Rrms) was obtained from the AFM images and the differences in the averaged values among the groups were analyzed by Shapiro-Wilk test in order to assess the normality of the distribution. Parametric ANOVA and post hoc Tuckey test were performed to assess the differences between the different groups. After demineralization process, enamel demonstrated a high degree of surface porosity. This morphological aspect was reflected in the increase of Rrms values. No significant differences (p > 0.05) were reported between intact enamel and enamel only treated with P11 -4 and between eroded enamel and enamel treated with P11 -4 and then demineralized. However significant differences (p < 0.05) were recorded when comparing softened enamel with softened enamel further remineralized with biomimetic self-assembling peptides and enamel treated with the protective paste between two acid attacks. The use of P11 -4 remineralizing may offer a degree of protection from enamel erosion. SCANNING 38:344-351, 2016. © 2015 Wiley Periodicals, Inc.

Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments

A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient.

Protective effect of casein phosphopeptide-amorphous calcium phosphate on enamel erosion: Atomic force microscopy studies

The aim of this study was to investigate the in vitro effect of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (GC Tooth Mousse- TM, GC Corporation, Tokyo, Japan) on preventing enamel erosion, by using Atomic Force Microscopy (AFM). 30 human incisors, were equally assigned to 6 groups: intact enamel, enamel + soft drink, enamel + TM, enamel + TM + soft drink, enamel + soft drink + TM, enamel + soft drink + TM + soft drink. Specimens were observed through atomic force microscopy (AFM). The most common topographical parameters were determined, such as the surface roughness (Rrms ). The use of soft drink on intact enamel has roughened the surface of the sample. The application of the CPP-ACP paste on non-treated enamel made the surface smoother. A significant decrease in roughness was seen after remineralization with CPP-ACP paste. Significant differences were recorded when comparing softened enamel with softened enamel remineralized with CPP-ACP paste. Comparing eroded enamel with demineralized/remineralized specimens, the application of a CPP-ACP paste leads to a significant reduction in roughness values. AFM images of enamel surface treated with CPP-ACP resulted in less morphological changes of the tooth substrate when compared with the only eroded enamel surface morphology; thus, indicating that CPP-ACP paste promoted remineralization. Specimens' surface roughness remained similar regardless that the protective agent is used before or after exposure to coke or between two demineralizing cycles. The results confirmed the effectiveness of the CPP-ACP paste on preventing enamel erosion produced by soft drinks.