Comparison of in vitro dentinal tubule occluding efficacy of two different methods using a nano-scaled bioactive glass-containing desensitising agent

Biomimetic Dentin Repair: Amelogenin-Derived Peptide Guides Occlusion and Peritubular Mineralization of Human Teeth

Exposure of dentin tubules due to loss of protective enamel (crown) and cementum (root) tissues as a result of erosion, mechanical wear, gingival recession, etc. has been the leading causes of dentin hypersensitivity. Despite being a widespread ailment, no permanent solution exists to address this oral condition. Current treatments are designed to alleviate the pain by either using desensitizers or blocking dentin tubules by deposition of minerals or solid precipitates, which often have short-lived effects. Reproducing an integrated mineral layer that occludes exposed dentin with concomitant peritubular mineralization is essential to reestablish the structural and mechanical integrity of the tooth with long-term durability. Here, we describe a biomimetic treatment that promotes dentin repair using a mineralization-directing peptide, sADP5, derived from amelogenin. The occlusion was achieved through a layer-by-layer peptide-guided remineralization process that forms an infiltrating mineral layer on dentin. The structure, composition, and nanomechanical properties of the remineralized dentin were analyzed by cross-sectional scanning electron microscopy imaging, energy dispersive X-ray spectroscopy, and nanomechanical testing. The elemental analysis provided calcium and phosphate compositions that are similar to those in hydroxyapatite. The measured average hardness and reduced elastic modulus values for the mineral layer were significantly higher than those of the demineralized and sound human dentin. The structural integration of the new mineral and underlying dentin was confirmed by thermal aging demonstrating no physical separation. These results suggest that a structurally robust and mechanically durable interface is formed between the interpenetrating mineral layer and underlying dentin that can withstand long-term mechanical and thermal stresses naturally experienced in the oral environment. The peptide-guided remineralization procedure described herein could provide a foundation for the development of highly effective oral care products leading to novel biomimetic treatments for a wide range of demineralization-related ailments and, in particular, offers a potent long-term solution for dentin hypersensitivity.

Effect of bioactive glass paste on efficacy and post-operative sensitivity associated with at-home bleaching using 20% carbamide peroxide: a randomized controlled clinical trial

Background

The aim of this study was to evaluate the effect of bioactive glass (BAG) 45S5 paste on colour change and tooth sensitivity (TS) when used in combination with 20% carbamide peroxide (CP) during at-home vital tooth bleaching.

Methods

Twenty-four patients were selected and assigned into two experimental groups (n = 12) in a double-blind study design. Each patient received 20% CP followed by the application of either BAG paste or non-active placebo paste. The shade evaluation was performed using a digital spectrophotometer based on the CIE L*a*b* colour space system at different time points and the overall colour changes ΔE were calculated. TS was evaluated using visual analogue scale (VAS). The values of ΔE and TS were statistically analysed using paired t-test. The level of statistical significance was established at p = 0.05.

Results

The overall colour changes (ΔE) between baseline and each time point showed no significant differences between BAG and placebo groups (p > 0.05). The use of BAG paste significantly decreased TS reported by the participants.

Conclusions

The association of BAG paste with at-home bleaching treatment presents a promising method as it decreased TS and did not deteriorate bleaching efficacy.

Trial registration This study was approved and registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under Registration number: ACTRN12621001334897.

Deep and compact dentinal tubule occlusion via biomimetic mineralization and mineral overgrowth

Dentinal tubule (DT) occlusion by desensitizing agents has been widely applied to inhibit the transmission of external stimuli that cause dentin hypersensitivity (DH). However, most desensitizing agents merely accomplish porous blocking or the formation of a superficial tubular occlusion layer, resulting in a lack of mechanical and acid resistance and long-term stability. Herein, combining biomimetic mineralization and mineral overgrowth of the dentinal matrix was shown to effectively occlude DTs, resulting in the formation of a compact and deep occluding mineral layer that is strongly bound to the organic matrix on tubule walls. This DT occlusion method could achieve both mechanical resistance and acid resistance, demonstrating the potential of an inexpensive, long-term, and efficient therapy for treating DH.

Effect of bioactive glasses containing strontium and potassium on dentin permeability

Dentin hypersensitivity (DH) is characterized by pain caused by an external stimulus on exposed dentin. Different therapeutic approaches have been proposed to mitigate this problem; however, none of them provide permanent pain relief. In this study, we synthesized and characterized experimental bioactive glasses containing 3.07 mol% SrO or 3.36 mol% K₂ O (both equivalent to 5 wt% in the glass), and evaluated their effect on dentin permeability to verify their potential to treat DH. The experimental materials were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, micro-Raman spectroscopy, and X-ray diffraction to confirm the respective structures and chemical compositions. The reduction in the hydraulic conductance of dentin was evaluated at the three stages: minimum permeability; maximum permeability (24% ethylenediaminetetraacetic acid [EDTA] treatment); and final dentin permeability after treatment with the bioactive glasses. They all promoted a reduction in dentin permeability, with a significant difference for each sample and posttreatment group. Also, a significant reduction in dentin permeability was observed even after a simulated toothbrushing test, demonstrating effective action of these materials against DH. Besides, incorporating 3.07 mol% SrO was a positive factor. Therefore, strontium's desensitizing and re-mineralizing properties can be further exploited in bioactive glasses to promote a synergistic effect to treat DH.

The Amelogenin-Derived Peptide TVH-19 Promotes Dentinal Tubule Occlusion and Mineralization

In this study, the amelogenin-derived peptide, TVH-19, which has been confirmed to promote mineralization, was evaluated to derive its potential to induce dentinal tubule occlusion. The binding capability of fluorescein isothiocyanate (FITC)-labeled TVH-19 to the demineralized dentin surface was analyzed by confocal laser scanning microscopy (CLSM). Additionally, the sealing function of the peptide was studied through the remineralization of demineralized dentin in vitro. The adsorption results showed that TVH-19 could bind to the hydroxyapatite and demineralized dentin surfaces, especially to periodontal dentin. Scanning electron microscopy analysis further revealed that TVH-19 created mineral precipitates. The plugging rate in the TVH-19 group was higher than that in the PBS group. Moreover, energy-dispersive X-ray spectroscopy (EDX) results indicated that the calcium/phosphorus (Ca/P) ratio of the new minerals induced by TVH-19 was close to that of the hydroxyapatite. Attenuated total internal reflection-Fourier transform infrared (ATR-FTIR) spectrometry and X-ray diffraction (XRD) results indicated that the hydroxyapatite crystals formed via remineralization elongated the axial growth and closely resembled the natural dentin components. These findings indicate that TVH-19 can effectively promote dentin sealing by binding to the periodontal dentin, promoting mineral deposition, and reducing the space between the dentin tubules.

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.

Biomimetic oligopeptide formed enamel-like tissue and dentin tubule occlusion via mineralization for dentin hypersensitivity treatment

OBJECTIVE

Dentin hypersensitivity (DH) is a common oral disease with approximately 41.9% prevalence. Reconstruction of dental hard tissues is the preferred treatment for relieving DH. Here, we applied biomineralization method using oligopeptide simulating cementum protein 1 (CEMP1) to regenerate hard tissues on demineralized dentin.

METHODS

The self-assembly and biomineralization property of the oligopeptide were detected by scanning electron microscopy (SEM), circular dichroism spectroscopy, and transmission electron microscopy. Oligopeptide's binding capacity to demineralized dentin was evaluated by SEM and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Remineralization was characterized using SEM, ATR-FTIR, X-ray diffraction, and nanoindentation. Oligopeptide's biocompatibility was evaluated using periodontal ligament cells.

RESULTS

Oligopeptides self-assembled into nano-matrix and templated mineral precursor formation within 24 h. Moreover, oligopeptide nano-matrix bound firmly on demineralized dentin and resisted water rinsing. Then, bound nano-matrix served as a template to initiate nucleation and transformation of hydroxyapatite on demineralized dentin. After 96 h, oligopeptide nano-matrix regenerated an enamel-like tissue layer with a thickness of 15.35 μm, and regenerated crystals occluded dentin tubules with a depth of 31.27 μm. Furthermore, the oligopeptide nano-matrix had good biocompatibility when co-cultured with periodontal ligament cells.

CONCLUSIONS

This biomimetic oligopeptide simulating CEMP1 effectively induced remineralization and reconstructed hard tissues on demineralized dentin, providing a potential biomaterial for DH treatment.

Acidic Monetite Complex Paste with Bleaching Property for In-depth Occlusion of Dentinal Tubules

Background

Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no treatment regimen demonstrates long-lasting efficacy in treating DH, and unesthetic yellow tooth color is a concern to many patients with DH.

Aim

To develop a bi-functional material which can occlude dentinal tubules in-depth and remineralize dentin for long-lasting protection of the dentin–pulp complex from stimuli and bleach the tooth at the same time.

Methods

A mixture containing CaO, H₃PO₄, polyethylene glycol and H₂O₂ at a specific ratio was mechanically ground using a planetary ball. The mineralizing complex paste was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dentin was exposed to the synthesized paste for 8 h and 24 h in vitro. The mineralizing property was evaluated using SEM and microhardness tests. Red tea-stained tooth slices were exposed to the synthesized paste for 8 h and 24 h in vitro. The bleaching effect was characterized by a spectrophotometer.

Results

The complex paste had very a fine texture, was injectable, and had a gel-like property with 2.6 (mass/volume) % H₂O₂ concentration. The X-ray diffraction pattern showed that the inorganic phase was mainly monetite (CaHPO₄). The mineralizing complex paste induced the growth of inorganic crystals on the dentin surface and in-depth occlusion of dentin tubules by up to 80 μm. The regenerated crystals were integrated into the dentin tissue on the dentin surface and the wall of dentinal tubules with a microhardness of up to 126 MPa (versus 137 Mpa for dentin). The paste also bleached the stained dental slices.

Conclusion

The mineralizing complex paste is a promising innovative material for efficient DH management by remineralizing dentin and in-depth occlusion of dentin tubules, as well as tooth bleaching.

Efficacy of nano-carbonate apatite dentifrice in relief from dentine hypersensitivity following non-surgical periodontal therapy: a randomized controlled trial

Background

Dentine hypersensitivity (DH) could occur or intensify after non-surgical periodontal therapy because of the exposure of dentine tubules, but currently no gold standard exists to treat DH. It has been demonstrated that nano-sized particles presented potential for dentine tubules blocking and remineralization. This randomized controlled trial aimed to investigate the efficacy of dentifrice containing nano-carbonate apatite (n-CAP) in reducing dentine hypersensitivity (DH) after non-surgical periodontal therapy.

Methods

48 periodontitis patients with DH were included in this clinical trial. After non-surgical periodontal therapy, patients included were randomized to test and control group and the respective dentifrices were applied at chairside, after which they were instructed to brush teeth with the allocated dentifrices twice a day at home. Periodontal parameters were recorded at baseline and the last follow-up. DH was measured by air-blast test and recorded by visual analogue scale (VAS) and Schiff sensitivity scale at baseline, after polishing (0 week) and 2/4/6 weeks.

Results

45 participants completed the follow-up. Periodontal parameters were improved and comparable between groups. Significant reduction in DH was observed in both groups at all time-points compared to baseline in terms of VAS and Schiff score. The test group achieved significantly greater relief from hypersensitivity compared with the control group after 4-week at-home use (for change of VAS, test group: 2.27 ± 2.47 versus control group: 1.68 ± 2.24, p = 0.036; for change of Schiff, test group: 0.94 ± 0.92 versus control group: 0.61 ± 0.83, p < 0.001). The 6-week results showed borderline significance between groups in terms of change of Schiff (p = 0.027) and no significance in terms of change of VAS (p = 0.256).

Conclusions

Home-use of n-CAP based dentifrice had some benefit on alleviation of DH following non-surgical periodontal therapy after 4 weeks compared to the control product.

Trial registration

Chinese Clinical Trials Registry (No. ChiCTR-IPR-17011678, http://www.chictr.org.cn/, registered 16 June, 2017).

Enhanced effect of nano-monetite hydrosol on dentin remineralization and tubule occlusion

OBJECTIVES

We aim to investigate the dentin tubule occlusion and remineralization potential of a novel nano-monetite hydrosol (nMH).

METHODS

First, nano-monetite hydrosol (nMH) was fabricated by homogeneous precipitation method. Then, the effectiveness of toothpaste with nMH on improving remineralization was evaluated by the measurement of tubule occluding ratio and acid-resistant stability compared with dentifrices comprising nano-hydroxyapatite hydrosol (nHH) and bioactive glass (BG). To explain this result, we studied the ions releasing and remineralization based on gelatin scaffold among nMH, nHH and BG. Finally, the cytotoxicity of these three minerals on Human dental pulp stem cells (HDPSCs) was evaluated.

RESULTS

Processing for more than 7 days, the toothpaste containing nMH exhibited the significant remineralization potential and acid-resistant compared with two commercial de-sensitive dentifrices comprising nHH and BG. In addition, cytotoxicity test resulted that nMH has good cell compatibility to HDPSCs below extracts concentration of 3.12mg/mL.

SIGNIFICANCE

Small size, the release of Ca²⁺ and PO₄^3- with high concentration, strongly binding on dental surface, and fast transformation to HAp, were all needed in the preparation of effective dentin tubule occluding biomaterials.

Impact of transparent tray-based application of bioactive glasses desensitizer on the permeability of enamel and dentin to hydrogen peroxide: an in vitro study

BACKGROUND

To investigate the effect of transparent tray-based application of bioactive glasses (BGs) desensitizer on the permeability of enamel and dentin to hydrogen peroxide (H₂O₂).

METHODS

Freshly extracted human first premolars were divided into 6 groups (n = 8). Group A and B: without pretreatments; Group C and E: treated with BGs desensitizer only; Group D and F: treated with BGs desensitizer dispensed with a transparent tray. After roots and pulp tissues of the treated tooth specimens were thoroughly removed, acetate buffer was added into pulp chambers and the treated specimens were immersed in distilled water (Groups A, E, and F) or 30% H₂O₂ (Groups B, C, and D) for 30 min at 37 °C. The amount of H₂O₂ in the pulp chamber of each group was measured using ultraviolet-visible spectrophotometry.

RESULTS

In control groups (Group A, E, and F), H₂O₂ was not detected. The amount of pulpal H₂O₂ in Group B, C, and D were 21.149 ± 0.489 μg, 9.813 ± 0.426 μg, and 4.065 ± 0.268 μg respectively. One-way ANOVA analysis indicated that significant differences existed in these groups (F = 459.748, p < 0.05).

CONCLUSIONS

The effect of BGs desensitizer in reducing the permeability of enamel and dentin to H₂O₂ could be enhanced when dispensed with a transparent tray.

Remineralization of dentin slices using casein phosphopeptide-amorphous calcium phosphate combined with sodium tripolyphosphate

Background

The remineralization approach mechanically occludes the exposed dentinal tubules mechanically, reduces the permeability of dentinal tubules and eliminates the symptoms of dentin hypersensitivity. The aim of the present study was to investigate the remineralization of demineralized dentin slices using CPP–ACP combined with TPP, and the research hypothesis was that CPP–ACP combined with TPP could result in extrafibrillar and intrafibrillar remineralization of dentin.

Methods

Demineralized dentin slices were prepared and randomly divided into the following groups: A (the CPP–ACP group), B (the CPP–ACP + TPP combination group), C (the artificial saliva group), D (the negative control group), and E (the positive control group). Dentin slice samples from groups A, B and C were remineralized and the remineralization effect was evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR) and X-ray diffraction (XRD).

Results

Treatment with CPP–ACP combined with TPP occluded the dentinal tubules and resulted in remineralization of collagen fibrils. The hydroxyapatite crystals formed via remineralization were found to closely resemble the natural dentin components.

Conclusion

CPP–ACP combined with TPP has a good remineralization effect on demineralized dentin slices.

Mechanisms of Bioactive Glass on Caries Management: A Review

This review investigates the mechanisms of bioactive glass on the management of dental caries. Four databases (PubMed, Web of Science, EMBASE (via Ovid), Medline (via Ovid)) were systematically searched using broad keywords and terms to identify the literature pertaining to the management of dental caries using "bioactive glass". Titles and abstracts were scrutinized to determine the need for full-text screening. Data were extracted from the included articles regarding the mechanisms of bioactive glass on dental caries management, including the aspect of remineralizing effect on enamel and dentine caries, and antimicrobial effect on cariogenic bacteria. After removal of duplicates, 1992 articles were identified for screening of the titles and abstracts. The full texts of 49 publications were scrutinized and 23 were finally included in this review. Four articles focused on the antimicrobial effect of bioactive glass. Twelve papers discussed the effect of bioactive glass on demineralized enamel, while 9 articles investigated the effect of bioactive glass on demineralized dentine. In conclusion, bioactive glass can remineralize caries and form apatite on the surface of enamel and dentine. In addition, bioactive glass has an antibacterial effect on cariogenic bacteria of which may help to prevent and arrest dental caries.

Therapeutic Management of Demineralized Dentin Surfaces Using a Mineralizing Adhesive To Seal and Mineralize Dentin, Dentinal Tubules, and Odontoblast Processes

Dentin hypersensitivity is attributable to the exposed dentin and its patent tubules. We proposed the therapeutic management of demineralized dentin surfaces using a mineralizing adhesive to seal and remineralize dentin, dentinal tubules, and odontoblast processes. An experimental self-etch adhesive and a mineralizing adhesive consisting of the self-etch adhesive and 20 wt % poly-aspartic acid-stabilized amorphous calcium phosphate (PAsp-ACP) nanoparticles were prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy. After 60 acid-etched midcoronal dentin disks were treated with distilled water (control), a desensitizing agent (Gluma), the experimental self-etch adhesive, and the mineralizing adhesive, dentin permeability was measured and mineralization was evaluated by Raman, FTIR, XRD, TEM, and selected-area electron diffraction, irrespective of abrasive and acidic challenges. In vitro cytotoxicity of the adhesive and the mineralizing adhesive was assessed by Cell Counting Kit-8. The mineralizing adhesive possessed excellent biocompatibility. We proposed a hybrid mineralization layer composed of the light-cured mineralizing adhesive and the mineralized dentin surfaces, as well as interiorly mineralized resin tags and odontoblast processes inside of the dentinal tubules. This hybrid mineralization not only reduced dentin permeability but also resisted abrasive and acidic attacks.

Nanogels of carboxymethyl chitosan and lysozyme encapsulated amorphous calcium phosphate to occlude dentinal tubules

This study aimed to develop of a rapid and effective method to occlude dentinal tubules using carboxymethyl chitosan and lysozyme (CMC/LYZ) nanogels with encapsulated amorphous calcium phosphate (ACP) based on the transformation of ACP to HAP. In this work, CMC/LYZ was used to stabilize ACP and form CMC/LYZ-ACP nanogels, and then the nanogel-encapsulated ACP was applied to exposed dentinal tubule surfaces. The morphology of the nanogels was examined by transmission electron microscopy (TEM). Distribution and quantity of elements in CMC/LYZ-ACP nanogels were determined by element mapping and energy dispersive X-Ray spectroscopy (EDX). Scanning electron microscopy (SEM) images, XRD measurements and nanoindentation were applied to check the efficacy of tubular occlusion. TEM revealed that CMC/LYZ-ACP nanogels were spherical dense gel particles with size approximately 50-500 nm. Element mapping and EDX indicated that C, N, O, Ca, P, and S in the microspheres are thoroughly represented. SEM images shows that the thickness of the coating layer was approximately 1-2 μm and the depth to which the mineralized substance enters the dentinal tubule was approximately 4-8 μm. XRD measurements and nanoindentation indicated that the occluding mineralized substance observed were similar to nature dentin. CMC can form spherical dense nanogels loaded with ACP under the participation of lysozyme. The CMC/LYZ-ACP nanogels could increase the dentinal tubule occluding effectiveness. These results indicated that finding and developing novel nanomaterials of CMC/LYZ-ACP would be an effective strategy for the treatment of dentin hypersensitivity.