Anti-erosive potential of amine fluoride, cerium chloride and laser irradiation application on dentine

Cerium- and samarium-nitrate interaction and accumulation on human dentin

OBJECTIVE

To investigate the accumulation of cerium-nitrate and samarium-nitrate on dentin without or with smear-layer and to test their antibacterial activity.

DESIGN

24 dentin-enamel slices were cut from 24 extracted molars. 12 slices underwent smear-layer creation (320 grit, 200 g, 5 s), the other 12 smear-layer removal (20 % EDTA, 300 s). Slices were halved to 48 semilunar-shaped specimens. One specimen per tooth was treated with either Ce(NO3)3 (50 wt% aqueous solution; pH = 1.29; n = 6) or Sm(NO3)3 (50 wt% aqueous solution; pH = 1.88; n = 6). The other specimen served as control (A. demin). After water rinsing, elemental composition (Ce, Sm, Ca, P, O, N, Na, Mg, C) was measured (EDX; EDAX Octane-Elect, APEX v2.5, low-vacuum) in dentin. Atomic percent (At%), Ca/P- and Ca/N-ratios were calculated and analyzed non-parametrically (α = 0.05, error rates method). Additionally, antibacterial activity (2 min exposure) of Ce(NO3)3 and Sm(NO3)3 against Streptococcus mutans, Actinomyces naeslundii, Schaalia odontolytica, and Enterococcus faecalis was determined (colony forming units) after anaerobic incubation at 37 °C for 24 h (control: 0.2 % CHX).

RESULTS

At% (median) of Ce and Sm were as follows: Ce(NO3)3 3.4 and 0.9 At%Ce with and without smear-layer, respectively; Sm(NO3)3 2.4 and 1.3 At%Sm with and without smear-layer, respectively. Ce(NO3)3 and Sm(NO3)3-application significantly decreased Ca/P-ratios (1.22 - 1.45; p ≤ 0.02) compared to controls (1.47 - 1.63). With smear-layer, significantly higher Ca/N-ratios (5.1 - 29.3) could be detected across all groups (p ≤ 0.004) compared to specimens without smear-layer (0.37 - 0.48). Ce(NO3)3 and Sm(NO3)3 showed reduction rates of up to ≥ 5 log10 steps for S. mutans, A. naeslundii, and S. odontolytica.

CONCLUSIONS

Cerium and samarium nitrate showed accumulation on dentin and certain antibacterial activity and could therefore be identified as potential compounds to treat and prevent dentin and root caries and dentin hypersensitivity.

Surface Accumulation of Cerium, Self-Assembling Peptide, and Fluoride on Sound Bovine Enamel

The accumulation of caries-preventive compounds on sound enamel is crucial in order to improve the inhibition of carious lesion initiation. The aim of this research was to investigate the initial accumulation of cerium, oligopeptide p11-4, and fluoride from NaF or amine fluoride (AmF) on sound enamel in vitro by means of energy dispersive X-ray spectroscopy (EDX). Polished bovine enamel specimens (n = 120 from 60 teeth) were fabricated. Out of these, 12 specimens each were treated with CeCl3 (cerium(III) chloride heptahydrate 25%), oligopeptide p11-4 (Curodont Repair, Credentis), NaF (10,000 ppm F−), AmF (amine fluoride, Elmex Fluid, CP-GABA GmbH, 10,000 ppm F−), or Aqua demin (control). After rinsing with water, the surface elemental composition (Ce, N, F, Ca, P, O, Na, Mg) was measured (EDX; EDAX Octane Elect detector, APEX v2.0), expressed in atomic percent (At%) and analyzed (non-parametric statistics, α = 0.05, error rates method). Another 12 specimens per treatment group were fabricated and used for analyzing accumulation in cross-sections with EDX linescans and two-dimensional EDX-mappings. The surface median atomic percent of cerium (At%Ce) was 0.8 for CeCl3, but no Ce was found for any other group. N, specifically for oligopeptide p11-4, could not be detected. Fluorine could only be detected on fluoridated surfaces. The median atomic percent of fluorine (At%F) was 15.2 for NaF and 17.0 for AmF. The Ca/P ratio increased significantly compared to the control following the application of NaF and AmF (p < 0.001), but decreased significantly for CeCl3 (p < 0.001). In cross-sectioned specimens of the CeCl3-group, 12.5% of the linescans revealed cerium at the enamel surface, whereas 83.3% of the NaF linescans and 95.8% of the AmF linescans revealed fluorine at the enamel surface. Following the application of oligopeptide p11-4, no traces of N were detectable. In the depth of the samples, no signal was detected for any of the corresponding elements exceeding the background noise. Cerium and fluorine (from both NaF and AmF), but not the oligopeptide p11-4, precipitated on sound enamel.

The Strong Protective Action of Ce3+/F- Combined Treatment on Tooth Enamel and Epithelial Cells

We studied the toxic effects of cerium and fluoride species on human dental pulp stem cells and epithelial cells of Cercopithecus aethiops as a surrogate for the human oral mucosa. The sequential use of CeCl₃ and NH₄F solutions in equimolar sub-toxic concentrations enabled the possible toxic effects of individual components to be avoided, ensuring the preservation of the metabolic activity of the cells due to the formation of CeF₃ nanoparticles. Cerium fluoride nanoparticles and terbium-doped cerium fluoride nanoparticles exhibited neither cytotoxicity nor genotoxicity to dental pulp stem cells, even at high concentrations (10^-4 M). In millimolar concentrations (from 10^-5-10^-6 M), these nanoparticles significantly increased the expression of genes responsible for the cell cycle, differentiation and proliferation. The formation of cerium fluoride on the surface of the mucous membrane and teeth provided protection against the development of carious lesions, periodontitis, ROS attacks and other inflammatory diseases of the oral cavity. Luminescent CeF₃: Tb nanoparticles enabled the visualization of tooth enamel microcracks.

Topical Agents for Nonrestorative Management of Dental Erosion: A Narrative Review

A nonrestorative approach to the management of dental erosion is the foremost option: controlling dental erosion. The objectives of this study are to provide an overview and to summarise the effects and properties of topical anti-erosive agents as a nonrestorative treatment of dental erosion. A literature search was conducted on five databases of peer-reviewed literature—Cochrane Library, EMBASE, PubMed, Scopus and Web of Science—to recruit articles published between 1 January 2000 and 31 December 2021. The literature search identified 812 studies; 95 studies were included. Topical anti-erosive agents can be broadly categorised as fluorides, calcium phosphate-based agents, organic compounds and other anti-erosive agents. In the presence of saliva, fluorides promote the formation of fluorapatite on teeth through remineralisation. Calcium phosphate-based agents supply the necessary minerals that are lost due to the acid challenge of erosion. Some organic compounds and other anti-erosive agents prevent or control dental erosion by forming a protective layer on the tooth surface, by modifying salivary pellicle or by inhibiting the proteolytic activity of dentine collagenases. Topical anti-erosive agents are promising in managing dental erosion. However, current evidence shows inconsistent or limited results for supporting the use of these agents in clinical settings.

Effect of air-abrasion pretreatment with three bioactive materials on enamel susceptibility to erosion by artificial gastric juice

OBJECTIVE

The purpose of the study was to investigate the protective effect of three in-office preventive treatments with bioactive materials against enamel erosion induced by artificial gastric juice similar to that found in gastroesophageal reflux disease (GERD) patients. The treatments included air-abrasion of enamel with a fluoride-containing bioactive glass (BioMinF®), Bioglass 45S5 (ProSylc) and nano-hydroxyapatite (MI Pearls) to test enamel susceptibility following an erosive challenge.

METHODS

Enamel surface loss was evaluated using confocal microscopy, while changes in enamel surface roughness and morphology were also investigated after the treatments. SEM and EDS were used to observe formation of apatite crystals on enamel and to detect alterations in mineral composition. In Group 1 (negative control) the specimens did not receive any treatment; Group 2 specimens (positive control) treated with 0.4 % SnF₂, while in Groups 3-5 enamel was air-abraded with BioMinF®, ProSylc and MI Pearls, respectively.

RESULTS

All the experimental groups reduced significantly enamel surface loss compared to the negative control group (p < 0.05), except for the MI Pearls treatment (p > 0.05). The most protective behavior against erosion presented the treatment with SnF₂. BioMinF induced the larger amount of apatite crystals on the enamel surface, followed by ProSylc.

SIGNIFICANCE

BioMinF and ProSylc treatments may be beneficial against dental erosion induced by gastric juice in GERD patients, while MI Pearls treatment may not suitable for this indication. Both materials promote formation of apatite crystals on enamel in acidic conditions protecting the surface from the erosion. The tested treatments may be useful in GERD patients who cannot comply with at-home therapies with SnF₂.

Adverse effects of respiratory disease medicaments and tooth brushing on teeth: A scanning electron microscopy, X-ray fluorescence and infrared spectroscopy study

The present study aims to evaluate the effect of brushing with fluoride dentifrice on teeth severely affected by erosion due to respiratory medicaments. Enamel (n = 50) and dentin (n = 50) bovine specimens were prepared and treated with artificial saliva (S-control), acebrofilin hydrochloride (AC), ambroxol hydrochloride (AM), bromhexine hydrochloride (BR), and salbutamol sulfate (SS) and subjected to cycles of demineralization (immersing in 3 mL, 1 min, three times a day at intervals of 1 hr, for 5 days) followed by remineralization (saliva, 37°C, 1 hr). Simulated brushing with fluoridated toothpaste was performed using 810 strokes in a reciprocal-action brushing simulator. Scanning electron microscopy, micro energy dispersive X-ray fluorescence (μ-EDXRF) spectroscopy and attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy were then performed. μ-EDXRF images showed extensive erosion after treatment with all medicaments. SEM images showed enamel erosion in order SS > BR > AC = AM > S after brushing and fluoridation. FTIR results were in agreement. In case of dentin, μ-EDXRF measurements showed significant difference in mineral content (percent weight of calcium and phosphate) in SS + brushing + fluoridation treated enamel compared to control, while μ-EDXRF images showed erosive effects in the order SS > AM>BR > AC = S post brushing + fluoridation. SEM images showed erosion in the order SS > AM = BR > AC > S post brushing + fluoridation. Again, FTIR multivariate results were in agreement. Overall, our study shows that proper oral care is critical when taking certain medication. The study also demonstrates the possible use of FTIR for rapid clinical monitoring of tooth erosion in clinics.

Chemical and morphological evaluation of enamel and dentin near cavities restored with conventional and zirconia modified glass ionomer subjected to erosion-abrasion

Microenergy dispersive X-ray fluorescence (μ-EDXRF) spectroscopy and scanning electron microscopy (SEM) were used to test the hypothesis that zirconia modified glass ionomer cement (GIC) could improve resistance to erosion-abrasion to a greater extent than conventional cement. Bovine enamel (n = 40) and dentin (n = 40) samples were prepared with cavities, filled with one of the two restorative materials (GIC: glass-ionomer cement or ZrGIC: zirconia-modified GIC). Furthermore, the samples were treated with abrasion-saliva (AS) or abrasion-erosion cycles (AE). Erosive cycles (immersion in orange juice, three times/day for a duration of 1 min over a 5 day period) and/or abrasive challenges (electric toothbrush, three times/day for a duration of 1 min over a 5 day period) were performed. Positive mineral variation (MV%) on the enamel after erosion-abrasion was observed for both materials (p < 0.05), whereas a negative MV% on the dentin was observed for both materials and treatments (p < 0.05). The SEM images showed clear enamel loss after erosion-abrasion treatment and material degradation was greater in GIC_AE compared to those of the other groups. Toothbrush abrasion showed a synergistic effect with erosion on substance loss of bovine enamel, dentin, GIC, and ZrGIC restorations. Zirconia addition to the GIC powder improved the resistance to abrasive-erosive processes. The ZrGIC materials may find application as a restorative material due to improved resistance as well as in temporary restorations and fissure sealants.

[Tooth Erosions Associated with Gastroesophageal Reflux: Cause, Prevention and Restorative Therapy]

Tooth Erosions Associated with Gastroesophageal Reflux: Cause, Prevention and Restorative Therapy Abstract. Dental erosions are caused by the recurring contact of solutions which are unsaturated in tooth minerals,ith hard tooth substances. This initially leads to softening and later to an irreversible loss of hard tooth substance. Erosion is observed particularly with excessive consumption of acidic foods (e.g. soft drinks or citrus fruits) but also in connection with gastrointestinal (gastroesophageal reflux disease) or psychosomatic diseases (anorexia nervosa or bulimia nervosa). The aim of this article is to define dental erosions, their causes, prevalence and consequences as well as possible preventive measures. Based on a clinical example of a patient with reflux-related erosions, a therapy option with direct composite tooth build-up is presented.

Variation on Molecular Structure, Crystallinity, and Optical Properties of Dentin Due to Nd:YAG Laser and Fluoride Aimed at Tooth Erosion Prevention

This in vitro study evaluated the compositional, crystalline, and morphological effects promoted by Nd:YAG laser on root dentin, and verified the effects of laser and topical acidulated phosphate fluoride application (APF-gel) on dentin erosion. 180 bovine dentin slabs were randomized into 4 groups (n = 45): G1–untreated, G2–APF-gel (1.23% F⁻, 4 min), G3–Nd:YAG (1064 nm, 84.9 J/cm², 10 Hz), and G4–APF-gel application followed by Nd:YAG laser irradiation. The compositional, crystalline, and morphological effects promoted by treatments were investigated on five samples of each experimental group. The other samples were submitted to a 5-day, 10-day, or 15-day erosive and abrasive demineralization and remineralization cycling in order to create erosion lesions. The area and depth of lesions, as well as the optical attenuation coefficient, were assessed, and all data were statistically analysed (p < 0.05). Nd:YAG laser promoted the reduction of carbonate, the formation of tetracalcium phosphate, as well as the melting and recrystallization of the dentin surface. Laser significantly decreased the area and depth of erosion lesions and altered the optical attenuation coefficient when compared to untreated and APF-gel groups, but the association of APF-gel and laser did not promote an additional effect. Nd:YAG laser irradiation can be a promissory treatment to prevent dentin erosion and the abrasion process.

Cerium Chloride Application Promotes Wound Healing and Cell Proliferation in Human Foreskin Fibroblasts

This study investigated the effect of cerium chloride (CeCl₃) on cell migration and gene expression of human foreskin fibroblasts (HFF). HFF were exposed to three different CeCl₃ solutions (1%, 5% and 10%, w/v %) for three different time durations (1, 5 and 10 min). 72 h after exposure to CeCl₃, cell viability was assessed by MTT test. A scratch-wounded assay determined the cell migration and the width of the wound, measured at 24 h. Gene expression patterns for cyclins B1, D1 and E1 were analyzed by RT-PCR (p < 0.05, t-test). The viability proliferation increased at 1- and 5-min exposures for all CeCl₃ concentrations, in contrast to no treatment (p < 0.05 at 24 h). No influence of CeCl₃ was found after 10 min. The scratch assay showed increased cell migration up to 60% at 1 and 5 min after 24 h at 5% and 10%. Cyclin B1, D1 and E1 all showed upregulation, confirming an increase in cell proliferation. This study demonstrates that exposure time and concentration of CeCl₃ may have a positive effect on fibroblast viability and migration. Application of CeCl₃ may be beneficial as a cell-stimulating agent leading to therapeutic tissue fibrosis or more resistant tissue around teeth, when warranted, during different periodontal therapies.

Evaluation of ex vivo effectiveness of commercial desensitizing dentifrices

BACKGROUND

Dentin hypersensitivity is a short, severe pain with fast onset. Therapy aims to either prevent or decrease neural transmission or physically occlude the dentinal tubules. This study aimed to evaluate the effectiveness of commercial desensitizing dentifrice by means of an ex vivo method.

MATERIAL AND METHODS

Samples (n=8 lower human premolars for each group) were randomly allocated into: G1- brushing with Colgate®Sensitive Pro-Relief; G2- brushing with Sensodyne®Rapid Relief; G3- brushing with Sensodyne®Repair & Protect; and G4- brushing with Colgate®Maximum Cavity Protection. The test bodies were submitted to simulated toothbrushing and dentifrices were analyzed regarding their hydrodynamic size, polydispersity index (PI) and zeta potential. Specimens were evaluated using: scanning electron microscopy (SEM); spectroscopy energy dispersive X-ray (EDS); and profilometry. A qualitative analysis of the photomicrographs and topographies was performed.

RESULTS

The dentifrices showed statistical similar physical and chemical characteristics. They also demonstrated obliteration of dentinal tubules when micrographs were observed. Regarding the chemical elements present in the dentin samples, there was a statistically significant difference between the control and experimental surfaces in the four groups.

CONCLUSIONS

Joint data analysis shows that the desensitizing dentifrice showed better results with regards to the obliteration of dentinal tubules compared to positive and negative controls. Key words:Dentin hypersensitivity, dentin desensitizing agents, toothpastes.

Effect of 10% cerium chloride on artificial caries lesions of human enamel evaluated using quantitative light-induced fluorescence: an in vitro study

AIM

To evaluate the effect of 10% cerium chloride intervention on pre-demineralised human enamel subjected to cycles of de- and remineralisation.

METHODS

This was an in vitro, comparative type study of 60 human enamel samples that were randomly divided into control and test groups. The samples were then subjected to a cycle of demineralisation followed by intervention with respective treatment solutions (control group: placebo solution; test: 10% cerium chloride) for 30 s under constant agitation and then to a 2nd cycle of demineralisation followed by remineralisation using artificial saliva. After the first and second cycles of demineralisation (4th and 8th day) and a cycle of remineralisation (22nd day), the samples were evaluated for fluorescence values using a quantitative light-induced fluorescence camera. The data was analysed using paired t test and ANOVA.

RESULTS

Comparing the fluorescence values and mean difference of lesion area between the first cycle of demineralisation to the cycle of remineralisation and the second cycle of demineralisation to the cycle of remineralisation, the test group showed a statistically significant reduction in loss of fluorescence values and lesion area compared to the control group (p < 0.001). Mean fluorescence values and lesion area comparison between cycles of de- and remineralisation for control and test groups (inter-group comparison) showed a statistically significant difference (p < 0.001).

CONCLUSIONS

Cerium chloride alone reduced demineralisation and improved remineralisation of artificial caries lesions in human enamel when subjected to pH cycling in vitro.

In Vitro Effects of Resin Infiltration on Enamel Erosion Inhibition

Resin-based materials that show promising effects for preventing the progression of erosion have been studied. This in vitro study evaluated the effects of applying resin-based materials, including resin infiltration, on previously eroded enamel subjected to erosive challenges. The influence of enamel surface etching prior to application of the material was also studied. Bovine enamel blocks were immersed in hydrochloric acid (HCl), 0.01 M (pH 2.3), for 30 seconds in order to form a softened erosion lesion. The blocks were then randomly divided into nine groups (n=12) and treated as follows: C = control without treatment; Hel = pit & fissure resin sealant (Helioseal Clear); Adh = two-step self-etching adhesive system (AdheSe); Tet = two-step conventional adhesive system (Tetric N-bond); and Inf = infiltrant (Icon). The Helno, Adhno, Tetno, and Infno groups received the same materials without (or with no) surface conditioning. The depth of the material's penetration into softened erosion lesions was qualitatively analyzed using reflection and fluorescence confocal microscopy. After application of the materials, the blocks were immersed in HCl for two minutes; this step was followed by immersion in artificial saliva for 120 minutes four times a day for five days (erosive cycling). Both the enamel alteration and material thickness were analyzed using profilometry, and the results were submitted to Kruskal-Wallis and Dunn tests (p>0.05). Images from the confocal microscopy showed minimal penetration of Adh/Adhno and deep penetration of Inf/Infno into the erosive lesions. The groups Hel, Adh, Inf, Tetno, and Infno resulted in the formation of a layer of material over the enamel, which was effective in inhibiting the progression of erosion. In conclusion, the infiltrant, with or without etching, was able to penetrate and protect the enamel against dental erosion. The other resin-based materials, except for the two-step conventional adhesive, were able to penetrate and inhibit the progression of erosive lesions only when they were applied after enamel etching.

Long-term protective effect of surface sealants against erosive wear by intrinsic and extrinsic acids

OBJECTIVE

To test sealants to prevent erosive tooth wear caused by extrinsic and intrinsic acids under long-term exposition.

METHODS

144 bovine enamel samples were randomly allocated to twelve groups (1-12). Samples of groups 1, 5 and 9 remained unsealed (positive controls), 2, 6 and 10 were sealed with Silicon Seal Nano Mix and 3, 7 and 11 with Seal&Protect. Groups 4, 8 and 12 were sealed with flowable composite (negative controls). Groups 1-4 were immersed in artificial saliva, 5-8 in hydrochloric acid and groups 9-12 in citric acid for 28 days, respectively. After 1, 2, 4, 7, 11, 14, 21 and 28 days, solutions were renewed and enamel wear was quantified by assignation of (32)P in the solutions.

RESULTS

In all immersion solutions, lowest mineral loss was observed for the negative controls whilst highest loss was observed for unsealed positive controls. In artificial saliva and citric acid, the loss from samples sealed with Seal&Protect was not significantly different compared with negative controls whilst loss in groups sealed with Silicon Seal Nano Mix was significantly higher. In hydrochloric acid, loss from samples sealed with Seal&Protect was not different compared with that of negative controls up to 4 days. Except day 1, the mineral loss in the Seal&Protect group was significantly lower compared with that of the Silicon Seal Nano Mix group.

CONCLUSION

The tested resin based surface sealant is able to significantly reduce the erosive demineralisation of enamel caused by hydrochloric and citric acid even under long-term exposition.