Effect of Erosion/Abrasion Challenge on the Dentin Tubule Occlusion Using Different Desensitizing Agents

Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study

The study aimed to compare various toothpastes and mouthwashes on permanent tooth dentin after erosive and abrasive challenges. 130 sound premolars dentin were randomly submitted to an initial erosive challenge and a cycle of erosive and abrasive challenges for five days. The five experimental groups (n = 26) were: (1) Control group (artificial saliva), (2) Elmex erosion protection toothpaste and mouthwash, (3) Vitis anticaries biorepair toothpaste and mouthwash, (4) Oral B Pro-expert toothpaste and Oral B Fluorinse mouthwash, and (5) MI Paste ONE toothpaste and Caphosol mouthwash. Microhardness, surface roughness values, and the topographical characteristics of the dentin surface were assessed. The highest percentage of recovered dentin microhardness (%RDMH) value was observed in groups 2 and 4, followed by groups 5 and 3, respectively. The %RDMH values in groups 2 and 4 did not demonstrate a significant difference (p = 0.855). The highest percentage of improvement in surface roughness was recorded in groups 2 and 4, with no significant differences (p = 0.989). The atomic force microscopy (AFM) findings were consistent with the surface roughness data. The best recovery of dentin microhardness and roughness were measured with the Elmex and Oral B toothpaste and mouthwash, followed by MI Paste ONE toothpaste and Caphosol mouthwash and Vitis anticaries biorepair toothpaste and mouthwash.

A novel mussel-inspired desensitizer based on radial mesoporous bioactive nanoglass for the treatment of dentin exposure: An in vitro study

OBJECTIVES

The dentin exposure always leads to dentin hypersensitivity and the acid-resistant/abrasion-resistant stability of current therapeutic approaches remain unsatisfatory. Inspired by the excellent self-polymerization/adherence activity of mussels and the superior mineralization ability of bioactive glass, a novel radial mesoporous bioactive nanoglass coated with polydopamine (RMBG@PDA) was developed for prevention and management of dentin hypersensitivity.

METHODS

Radial mesoporous bioactive nanoglass (RMBG) was synthesized by the sol-gel process combined with the cetylpyridine bromide template self-assembly technique. RMBG@PDA was synthesized by a self-polymerization process involving dopamine and RMBG in an alkaline environment. Then, the nanoscale morphology, chemical structure, crystalline phase and Zeta potential of RMBG and RMBG@PDA were characterized. Subsequently, the ion release ability, bioactivity, and cytotoxicity of RMBG and RMBG@PDA in vitro were investigated. Moreover, an in vitro experimental model of dentin hypersensitivity was constructed to evaluate the effectiveness of RMBG@PDA on dentinal tubule occlusion, including resistances against acid and abrasion. Finally, the Young's modulus and nanohardness of acid-etched dentin were also detected after RMBG@PDA treatment.

RESULTS

RMBG@PDA showed a typical nanoscale morphology and noncrystalline structure. The use of RMBG@PDA on the dentin surface could effectively occlude dentinal tubules, reduce dentin permeability and achieve excellent acid- and abrasion-resistant stability. Furthermore, RMBG@PDA with excellent cytocompatibility held the capability to recover the Young's modulus and nanohardness of acid-etched dentin.

CONCLUSION

The application of RMBG@PDA with superior dentin tubule occlusion ability and acid/abrasion-resistant stability can provide a therapeutic strategy for the prevention and the management of dentin hypersensitivity.

Chemical and Ultrastructural Characterization of Dentin Treated with Remineralizing Dentifrices

The aim of this study is to investigate dentin chemical and ultrastructural changes upon exposure to remineralizing dentifrices. Dentin disks were obtained from permanent human molars and treated for 7 days with the dentifrices: (1) C group-control (no dentifrice); (2) S group-Sensodyne Repair & Protect; (3) D group-Dentalclean Daily Regenerating Gel; and (4) DB group-D group + Dentalclean regenerating booster. Afterwards, samples were submitted to an additional 7 days of toothbrushing associated with daily acidic challenge. Samples were imaged and analyzed (days 1, 7, and 14) for Young's modulus by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). SEM and AFM revealed precipitate deposition on dentin surfaces in groups S, D, and DB, formed as early as day 1. Surface elemental analysis showed a Si increase on all brushed surfaces. Similar surface morphology was maintained after the acidic challenge period. Bright-field TEM/SAED revealed the formation of nanocrystalline hydroxyapatite inside the dentin tubules of groups S, D, and DB after day 7. Group C presented a gradual reduction of Young's modulus from days-1-14, whereas all remaining groups had increased values. All evaluated dentifrices led to successful formation of hydroxyapatite and increased dentin stiffness.

Penetration and durability of CPP-ACP paste and sodium fluoride varnish as desensitizing agents: An in vitro comparison

Background

This study aimed to investigate and compare the penetration and durability of two dentin desensitizers, sodium fluoride varnish and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste, using electron microscopy.

Methods

The study was performed on 60 dentin specimens prepared from extracted human premolars. After applying 17% EDTA to remove the smear layer, the specimens were divided into two groups. MI Paste and Bi-fluoride varnish were applied to the specimens. Microscopic images of 20 samples were obtained immediately. Twenty other samples were accessed after 15 days, and the other 20 were accessed after 30 days of toothbrushing and thermal cycling. Both surface and longitudinal cross-sectional images (after sample fracture) were studied. Data were analyzed with two-way ANOVA and Mann-Whitney U test at a significance level of P<0.05.

Results

The mean depth of material penetration was significantly time-dependent and fluctuated in both groups. There was a significant difference between the mean level of plugs between 0, 15, and 30 days (P<0.001). Penetration increased with time for the MI Paste group, while in the Bi-fluoride group, the increase was significant at 15 and 30 days than immediately after application. The mean thickness of the plugs was significantly different at the three time periods, and MI Paste showed a sudden decrease in plug thickness after 15 days.

Conclusion

Immediately after application, Bi-fluoride occluded dentinal tubules more effectively, and its durability after abrasion and thermal fatigue were higher than MI Paste.

Efficacy of a Novel Bioactive Glass-Polymer Composite for Enamel Remineralization following Erosive Challenge

Introduction

Dental caries is the most common cause of tooth loss. However, it can be stopped by enhancing remineralization. Fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) are among the most important remineralizing agents. Recent studies have used bioactive glass as a remineralizing agent in different forms. This study aimed to assess the efficacy of a composite paste (prepared by mixing urethane polypropylene glycol oligomer with bioactive glass powder for easier application).

Materials and Methods

Enamel disks were cut out of the buccal surface of extracted sound third molars. The samples were randomly divided into 3 groups of 15 and underwent Vickers microhardness test. X-ray diffraction (XRD) and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) were performed. All samples were immersed in a demineralizing solution for 14 days. The tests were then repeated. Next, bioactive glass paste, fluoride, and CPP-ACP were applied on the surface of the samples and they were then stored in an artificial saliva for 14 days. The tests were repeated again. The microhardness values were analyzed using repeated measures ANOVA followed by one-way ANOVA and Tukey's post hoc test (P < 0.05).

Results

The microhardness of the bioactive glass group was significantly higher than that of other groups (P < 0.05). XRD revealed an enamel structure more similar to sound enamel in the bioactive glass and CPP-ACP groups compared with the fluoride group. FESEM/EDS revealed higher hydroxyapatite deposition in the bioactive glass group than in the other two groups.

Conclusions

All three remineralizing agents caused remineralization, but bioactive glass paste had a greater efficacy.

Efficacy of CPP-ACP fluoride varnish applied with and without acid etching in preventing enamel demineralization compared to light-curable fluoride varnish

Objectives

To compare efficacy of casein phosphopeptide (CPP)–amorphous calcium phosphate (ACP) fluoride varnish and light-curable resin modified glass ionomer fluoride varnish (FV) in preventing white spot lesions and evaluating acid etching prior to CPP-ACPFV application on its efficacy.

Materials and Methods

Molars and premolars were transected and halves divided into four groups (n = 18/group): (1) resin-modified glass ionomer FV: etched and Clinpro-XT varnish (3M ESPE, Pymble, New South Wales, Australia) application; (2) CPP-ACPFV: MI varnish (GC America, Alsip, IL) application; (3) Etch+CPP-ACPFV: etched and MI varnish application; (4) Control: etched and no surface treatment. To simulate 12 weeks in an intraoral environment, samples were subjected to thermocycling, brushing, and pH cycling. Enamel surface microhardness was evaluated at baseline and after the simulated 12 weeks. Representative samples were also assessed using scanning electron microscopy (SEM).

Results

At baseline there was no significant difference in microhardness among groups. After the simulated 12 weeks, all groups showed significant within-group differences (P &lt; .001). Control showed the highest percentage loss of surface microhardness (89%), followed by CPP-ACPFV (58%), RMGIFV (51%), and Etch+CPP-ACPFV (24%). The control group had a significant decrease in microhardness compared to all experimental groups (P &lt; .001). No difference was found between the RMGIFV and CPP-ACPFV varnish groups. The Etch+CPP-ACPFV group had significantly less decrease in microhardness compared to the RMGIFV (P &lt; .001) and CPP-ACPFV groups (P &lt; .001). With SEM, control samples showed signs of enamel surface damage, while experimental groups showed spherical particles on a relatively intact surface.

Conclusions

RMGIFV and CPP-ACPFV are effective in reducing enamel demineralization. Acid etching the enamel surface prior to CPP-ACPFV varnish application increased its efficacy.

Study on Occluding Dentinal Tubules with a Nanosilver-Loaded Silica System In Vitro

The effects of most clinical treatments for dentin hypersensitivity are not long-lasting. To overcome the defects, the mesoporous silica nanoparticles and silver nanoparticles entered the field of oral materials. This study aimed to synthesize a novel, low-cytotoxic dentin desensitizer and investigate its occlusion effects on dentinal tubules. The biphasic stratification approach, a chemical reduction method, and the Stöber method were used to synthesize silver nanoparticle-loaded and nonporous silica-encapsulated mesoporous silica (Ag-MSNs@nSiO₂), which was a noncrystalline structure with an average size of approximately 128 nm and a silver content of 3.506%. Atomic absorption spectrometry and the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide cell viability assay showed that Ag-MSNs@nSiO₂ slowly released silver ions and had nearly no cytotoxicity. An electron microscope was used to observe the blocking effects on the dentinal tubules of sensitive tooth disc models, which were randomly divided into the following four groups: a deionized water group, a 5.9 M silver nitrate solution group, an Ag-MSNs@nSiO₂ group, and a Gluma desensitizer group. There were no significant differences in the relative area of open dentinal tubules between the Ag-MSNs@nSiO₂ group and the Gluma desensitizer group (P > 0.05). Detection of protein structures showed that multilevel structures of bovine serum albumin in dentin tubules were significantly changed by silver ions from Ag-MSNs@nSiO₂. These results suggest that nearly noncytotoxic Ag-MSNs@nSiO₂ was successfully synthesized by a series of methods. Ag-MSNs@nSiO₂ occluded dentin tubules immediately and effectively. Moreover, the blockage effects may be enhanced and maintained by continuous condensation of proteins in dentinal tubules.

Erosive tooth wear inhibition by hybrid coatings with encapsulated fluoride and stannous ions

This study aimed to formulate a hybrid coating material (HC) and to modify this HC with fluoride (NaF) and stannous (SnCl₂) ions, directly or encapsulated in nano containers, testing the effects of these materials against dental erosion and erosion-abrasion. Enamel and dentin specimens were treated with the HCs, and then tested in erosion or erosion-abrasion cycling models of 5 days (n = 10 for each substrate, for each model). Deionized water was the negative control, and a fluoride varnish, the positive control. Surface loss (SL, in µm) was evaluated with an optical profilometer, and data were statistically analyzed (α = 0.05). For enamel, in erosion, the positive control and HC without additives showed significantly lower SL than the negative control (p = 0.003 and p = 0.001). In erosion-abrasion, none of the groups differed from the negative control (p > 0.05). For dentin, in erosion, the positive control, HC without additives, HC with non-encapsulated F, and HC with encapsulated F + Sn showed lower SL than the negative control (p < 0.05). In erosion-abrasion, none of the groups differed significantly from the negative control (p < 0.05). HC without additives showed a promising potential for protecting the teeth against dental erosion (with upward trend for improved protection on dentin), but not against erosion-abrasion. The presence of additives did not improve the protective effect of the HC, on both substrates.

Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses

OBJECTIVES

To evaluate obliterating capability and biological performance of desensitizing agents.

METHODS

50 dentin blocks were distributed according to the desensitizing agent used (n = 10): Control (Artificial saliva); Ultra EZ (Ultradent); Desensibilize Nano P (FGM); T5-OH Bioactive Glass (Experimental solution); F18 Bioactive Glass (Experimental solution). Desensitizing treatments were performed for 15 days. In addition, specimens were subjected to acid challenge to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after desensitizing procedures and acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid assay at 15 min, 24-h and 48-h time points. Scanning electron microscopy and energy dispersion X-ray spectroscopy were performed for qualitative analysis. Data of dentin permeability was analyzed by two-way repeated measures ANOVA and Tukey's test. For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests.

RESULTS

for dentin permeability there was no significant difference among desensitizing agents after treatment, but control group presented highest values (0.131 ± 0.076 Lp). After acid challenge, control group maintained highest values (0.044 ± 0.014 Lp) with significant difference to other groups, except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among groups.

CONCLUSION

Bioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties.

CLINICAL SIGNIFICANCE

There is no gold standard protocol for dentin sensitivity. The study of novel desensitizing agents that can obliterate dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.

Association of Nd:YAG laser and calcium-phosphate desensitizing pastes on dentin permeability and tubule occlusion

Objective

To evaluate the efficacy of Nd:YAG laser associated with calcium-phosphate desensitizing pastes on dentin permeability and tubule occlusion after erosive/abrasive challenges.

Methodology

Dentin specimens were exposed to 17% ethylene diamine tetra-acetic acid (EDTA) solution for 5 min and randomly allocated into five groups: G1, control (no treatment); G2, Nd:YAG laser (1 W, 10 Hz, 100 mJ, 85 J/cm2); G3, Laser + TeethmateTM Desensitizer; G4, Laser + Desensibilize Nano P; and G5, Laser+Nupro^®. Specimens underwent a 5-day erosion-abrasion cycling. Hydraulic conductance was measured post-EDTA, post-treatment, and post-cycling. Post-treatment and post-cycling permeability (%Lp) was calculated based on post-EDTA measurements, considered 100%. Open dentin tubules (ODT) were calculated at the abovementioned experimental moments using scanning electron microscopy and ImageJ software (n=10). Data were analyzed using two-way repeated measures ANOVA and Tukey’s test (α=0.05).

Results

G1 presented the highest %Lp post-treatment of all groups (p<0.05), without significantly differences among them. At post-cycling, %Lp significantly decreased in G1, showed no significant differences from post-treatment in G3 and G4, and increased in G2 and G5, without significant differences from G1 (p>0.05). We found no significant differences in ODT among groups (p>0.05) post-EDTA. At post-treatment, treated groups did not differ from each other, but presented lower ODT than G1 (p<0.001). As for post-cycling, we verified no differences among groups (p>0.05), although ODT was significantly lower for all groups when compared to post-EDTA values (p<0.001).

Conclusion

All treatments effectively reduced dentin permeability and promoted tubule occlusion after application.

Combining Nd

YAG laser with calcium-phosphate pastes did not improve the laser effect. After erosive-abrasive challenges, treatments presented no differences when compared to the control.

Microshear bond strength of composite resin to demineralized dentin after remineralization with sodium fluoride, CPP-ACP and NovaMin containing dentifrices

Background

Bonding composite to remineralized dentin is challenging. The aim of this study was to evaluate the microshear bond strength (μSBS) of composite to demineralized dentin, which had been remineralized with sodium fluoride (NaF), CPP-ACP and NovaMin containing dentifrices.

Materials and methods

108 extracted human premolars or molars were sectioned longitudinally into buccal and lingual halves (n = 216). Dentin (3 × 3 mm) was exposed on the cervical aspect of teeth and the samples were allotted randomly to six groups (n = 36) according to the remineralizing agent used namely, group 1 (sound dentin), group 2 (demineralized dentin), group 3 (NaF), group 4 (CPP-ACP), group 5 (NovaMin) and group 6 (non-fluoridated). The type of bonding system (total-etch or self-etch) formed the subgroups. Samples in groups 2-6 were submitted to an acid challenge for 3 days followed by remineralization in groups 3-6 for 90 days. Etching pattern (n = 3) was observed under SEM. μSBS of the bonded samples (n = 15) were evaluated. The data were statistically analyzed using Kruskal Wallis and Dunn's Post Hoc tests (p < 0.05).

Results

SEM micrographs of remineralized samples showed varying degrees of partially occluded and exposed dentinal tubules. Under both the adhesives, the mean μSBS of composite in groups 2-6 was lesser than that of group 1. Among self-etch subgroups, μSBS of NaF group was not significantly different from that of normal dentin.

Conclusion

Composite forms a weaker bond to remineralized dentin. Self-etch bonding system is capable of achieving acceptable bond strength to dentin remineralized with NaF and NovaMin.

Morphological and chemical effects of in-office and at-home desensitising agents containing sodium fluoride on eroded root dentin

OBJECTIVE

The aim of this study was to evaluate the morphological and chemical effect of in-office and at-home desensitising agents containing sodium fluoride (NaF) on eroded root dentine in vitro.

METHODS

Fifty bovine dentine samples were pre-eroded and randomised into five groups (n = 10): G1 (Control) - milli-Q water; G2 - fluoride varnish containing NaF 22,500 ppm; G3 - desensitising cream containing NaF 9,000 ppm associated with 20% nanohydroxyapatite; G4 - toothpaste with NaF 5,000 ppm associated to tricalcium phosphate; G5 - toothpaste containing NaF 900 ppm and casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF). The specimens were submitted to erosive challenge for three days. The analyses were performed using non-contact profilometry for volumetric (Sa) and linear roughness (Ra) followed by scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The data were analysed by Kruskal-Wallis and Wilcoxon tests (α = 0.05).

RESULTS

There was a significant reduction of Ra and Sa for the eroded samples from the G2 and G5 (p < 0.05) after an erosive challenge. The dentine surface topography pattern showed partially or totally occluded dentinal tubules after treatments, except in the control group. The control, G4 and G3 groups showed a reduction in the dentine inorganic content percentage of Ca (Calcium) and P (Phosphorus) minerals.

CONCLUSION

The fluoride varnish and CPP-ACPF toothpaste were able to prevent morphological changes and were the only materials that showed the Ca and P content increased after treatment. These materials may be promising alternatives in the clinical control of dentin erosion.

In Vitro Effect of Innovative Desensitizing Agents on Dentin Tubule Occlusion and Erosive Wear

Purpose:

The purpose of this study was to evaluate the effects of four in-office desensitizing products on dentin tubule occlusion and erosive wear.

Methods:

Dentin hypersensitivity was simulated by EDTA application for five minutes. The specimens were randomly allocated into five groups (n=11), according to treatment: No treatment - Control (C), Duraphat (DUR), Desensibilize Nano P (NP), ClinPro XT Varnish (XTV), and ClinPro White Varnish (CWV). They were then submitted to erosive/abrasive cycling for five days. After EDTA, treatment, and cycling, the specimens were analyzed with an environmental scanning electron microscope (ESEM) to verify the number of opened dentin tubules (ODT) which were counted by using ImageJ software, and with a profilometer to determine the surface curvature/loss. ESEM data were analyzed with two-way repeated measure analysis of variance and Tukey tests. For the profilometer, data were analyzed with Kruskal-Wallis, Tukey, and Mann-Whitney tests.

Results:

After treatment, all groups showed lower ODT than the control, without significant differences between them. After cycling, the only group that showed lower ODT than the control was group XTV; however, it did not significantly differ from the other groups. For the profilometric analysis, there were significant differences in SL between the experimental times after treatment and after cycling for all groups (p&lt;0.05). After cycling, no surface loss was detected in groups DUR and XTV, which presented a significantly different curvature than group NP and the control group, but not from group CWV. Surface loss was detected for the control and groups NP and CWV, without difference among them.

Conclusion:

All desensitizing agents tested presented promising results concerning the obliteration of dentin tubules immediately after treatment. XTV was the only desensitizer capable of preventing the reopening of the tubules after the erosive/abrasive challenges. XTV and DUR presented a protective effect against dentin erosive wear.

Dentin sealing and antibacterial effects of silver-doped bioactive glass/mesoporous silica nanocomposite: an in vitro study

OBJECTIVES

To synthesize a silver-doped bioactive glass/mesoporous silica nanoparticle (Ag-BGN@MSN), as well as to investigate its effects on dentinal tubule occlusion, microtensile bond strength (MTBS), and antibacterial activity.

MATERIALS AND METHODS

Ag-BGN@MSN was synthesized using a modified "quick alkali-mediated sol-gel" method. Demineralized tooth disc models were made and divided into four groups; the following treatments were then applied: group 1-no treatment, group 2-bioglass, group 3-MSN, group 4-Ag-BGN@MSN. Next, four discs were selected from each group and soaked into 6 wt% citric acid to test acid-resistant stability. Dentinal tubule occlusion, as well as the occlusion ratio, was observed using field-emission scanning electron microscopy. The MTBS was also measured to evaluate the desensitizing effect of the treatments. Cytotoxicity was examined using the MTT assay. Antibacterial activity was detected against Lactobacillus casei, and ion dissolution was evaluated using inductively coupled plasma optical emission spectrometry.

RESULTS

Ag-BGN@MSN effectively occluded the dentinal tubule and formed a membrane-like layer. After the acid challenge, Ag-BGN@MSN had the highest rate of dentinal tubule occlusion. There were no significant differences in MTBS among the four groups (P > 0.05). All concentrations of Ag-BGN@MSN used had a relative cell viability above 72%.

CONCLUSIONS

Ag-BGN@MSN was successfully fabricated using a modified sol-gel method. The Ag-BGN@MSN biocomposite effectively occluded dentinal with acid-resistant stability, did not decrease bond strength in self-etch adhesive system, had low cytotoxicity, and antibacterial effect.

CLININAL RELEVANCE

Dentinal tubule sealing induced by Ag-BGN@MSN biocomposite with antibacterial effect is likely to increase long-term stability in DH.