Occluding Efficiency of Different Desensitizing Agents and Er,Cr:YSGG Laser on Dentin Tubules

PURPOSE

This study aimed to evaluate the effects of two desensitizers and the Er,Cr:YSGG laser on human dentin tubules, applied alone or in combination.

METHODS

Ninety-six dentin specimens were obtained from extracted third molars and divided into six groups: Group 1: no-treatment (Control); Group 2: nano-hydroxyapatite desensitizer (NhapD); Group 3: NhapD+Er,Cr:YSGG laser (L); Group 4: Er,Cr:YSGG laser (L); Group 5: glutaraldehyde desensitizer (GD); and Group 6: GD+L, respectively. All specimens were evaluated using scanning electron microscopy. The diameter and the number of open dentin tubules, the tubules' occluding ratio, and the mineral coverage area were measured via the Image J software at 2000× magnification. Atomic force microscopy was used to determine the blocking mechanism of desensitizing treatments and the surface morphology of dentin specimens. One-way ANOVA and Tukey tests were used for statistical analysis.

RESULTS

The number of open tubules and the mean diameter of tubules for all treatment groups showed statistically significant differences from the control group The NhapD+L group had a significantly lower number of open tubules than the L and GD groups. The NhapD+L and L groups significantly had higher occluding ratios than the other groups.

CONCLUSIONS

The present study showed that the Er,Cr:YSGG laser alone was effective in terms of tubule occlusion and also contributed to increasing the occluding ratio of nano-hydroxyapatite. It may be recommended to use the Er,Cr:YSGG laser with nano-hydroxyapatite desensitizers to achieve effective tubule occlusion.

Self-propelled bioglass janus nanomotors for dentin hypersensitivity treatment

Dentin hypersensitivity treatment is not always successful owing to the exfoliation of the blocking layer. Therefore, efficiently delivering a desensitization agent into the dental tubule is critical. Nanomotors are widely used as in vivo drug delivery systems owing to their strong power and good biocompatibility. Herein, we report a kind of self-propelled bioglass Janus nanomotor with a Pt motion unit (nBGs@Pt) for application in dentin hypersensitivity that was prepared via a simple sol-gel method and magnetron sputtering method, with an average size of 290 nm. The Pt layer as the power unit provided the dynamics to deliver the bioglass (desensitization agent). Using hydrogen peroxide as a fuel, the nBGs@Pt could automatically move in different media. In addition, the nBGs@Pt with a mesoporous structure demonstrated good hydroxyapatite formation performance. An in vitro dentin pressure model was used to verify the blocking ability of the nBGs@Pt in dentin tubules. The dynamics of the nBGs@Pt was sufficient to resist the outflow of dentin fluid and movement into the dentin tubules, with a blocking rate of 58.05%. After remineralization, the blocking rate could reach 96.07% and the formation of hydroxyapatite of up to 10 μm or more occurred. It is expected that this study will provide a simple and feasible new strategy for the painless treatment of dentin sensitivity.

Synthesis, Characterization, and Bioactivity of Mesoporous Bioactive Glass Codoped with Zinc and Silver

Due to the overconsumption of antimicrobials, antibiotic-resistant bacteria have become a critical health issue worldwide, especially methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis (VRE). Recently, many efforts have been made to load metals into bioactive glasses to enhance the multifunctionality of materials, such as antibacterial and osteoinductive functions. Zinc has been documented to stimulate the gene expression of various regulatory factors in bone cells. Meanwhile, previous studies have reported that silver and zinc could be a promising antibacterial combination with synergistic antimicrobial effects. Here, we sought to develop a biomaterial coreleasing zinc and silver, designated 80S-ZnAg, and to evaluate its antibacterial activity and biocompatibility. The textural analyses demonstrated different coreleasing patterns of zinc and silver for the materials. The chemical characterization revealed that the zinc in 80S-ZnAg could be the network modifier when its molar ratio was high, releasing more zinc; zinc could also be the network former when its molar ratio was low, showing an extremely low rate of release. However, the ICP results for 80S-Zn3Ag2 demonstrated up to 7.5 ppm of zinc and 67.6 ppm of silver. Among all the 80S-ZnAg materials, 80S-Zn3Ag2 demonstrated more marked antibacterial activity against MRSA and VRE than the others, with inhibition zones of 11.5 and 13.4 mm, respectively. The cytotoxicity assay exhibited nearly 90% cell viability at 20 mg/mL of 80-Zn3Ag2. Further clinical study is needed to develop an innovative biomaterial to address the issue of antibiotic resistance.

Fast Construction of Biomimetic Organic-Inorganic Interface by Crosslinking of Calcium Phosphate Oligomers: A Strategy for Instant Regeneration of Hard Tissue

The organic-inorganic structure in biological hard tissues ensures their marvelous characteristics but these hybrids are easily destroyed by the demineralization of inorganic components, e.g., the damage of dentin. Current clinical materials for hard tissue regeneration commonly act as "fillers" and their therapeutic effect is limited by the failures of biological-linked organic-inorganic interface reconstruction. Herein, a fast in situ crosslinking of calcium phosphate oligomers (CPOs) on collagen matrixes for efficient organic-inorganic interface re-construction, which can result in a biomimetic hybrid, is demonstrated. By using damaged dentin as an example, the inorganic ionic crosslinking can instantly infiltrate into the dentin matrix to rebuild a dense and continuous calcium phosphate-collagen hybrid within only 5 min, where the structurally integrated organic-inorganic interface is identical to natural dentin. As a result, the damaged dentin can be fully recovered to a healthy one, which is superior to any current dentin treatments. The fast construction of biomimetic hybrid by inorganic ionic crosslinking provides a promising strategy for hard tissue repair and follows great potentials of CPOs as advanced biomedical materials in future.

The Effect of Eggshell and Seashell Nanoparticles Alone and Combined With Nd: YAG Laser on Occlusion and Remineralization Potential of Patent Dentinal Tubules: An In Vitro Study

Introduction: There is an interest in developing materials with bioactive potential that could block exposed dentinal tubules. This study compared the effects of eggshell and seashell nanoparticles individually or combined with ND:YAG laser on dentinal tubules occlusion and remineralization. Methods: Fifty radicular dentin discs were prepared from freshly extracted human premolars. The smear layer created by cutting was removed using 37% phosphoric acid gel for 15 sec. The discs were divided into five groups according to the applied treatment(A) (n = 10 each): (A1) control, (A2); Nano eggshells, (A3); Nano seashells, (A4); Nano eggshells + Nd: YAG Laser, and (A5); Nano sea shell + Nd: YAG Laser. Each specimen was evaluated for tubular patency and mineral contents before and after each therapy using ESEM-EDXA energy dispersive spectroscopy for the assessment of tubule occlusion and remineralization. Results: ESEM results revealed a statistically significant decrease in the mean percent changes of the dentinal tubules number after the treatment of the experimental groups compared to the control. The greatest percent decrease was recorded in the seashell NPs + Nd: YAG laser, followed by the eggshell NPs + Nd: YAG laser, then Eggshell NPs only and then Seashell NPs only, while the lowest percentage decrease was recorded in the control group. EDXA revealed that the greatest percentage increase in Ca wt% was recorded in the Eggshell + Nd:YAG laser group, followed by Eggshell only, then Seashell only and then Seashell NPs + Nd: YAG laser, while the lowest percent increase was recorded in the control group. The post hoc test revealed no significant difference between the experimental groups. Conclusions: Both eggshell and seashell nanoparticles are effective in the occlusion and remineralization of dentinal tubules. The combined treatments with Nd: YAG laser had no benefits when compared to the effect of treatments alone.

Effect of Dentin Desensitizer Containing Novel Bioactive Glass on the Permeability of Dentin

The objective of this study was to evaluate the effect of novel bioactive glass (BAG)-containing desensitizers on the permeability of dentin. Experimental dentin desensitizers containing 3 wt% BAG with or without acidic functional monomers (10-MDP or 4-META) were prepared. A commercial desensitizer, Seal & Protect (SNP), was used as a control. To evaluate the permeability of dentin, real-time dentinal fluid flow (DFF) rates were measured at four different time points (demineralized, immediately after desensitizer application, after two weeks in simulated body fluid (SBF), and post-ultrasonication). The DFF reduction rate (ΔDFF) was also calculated. The surface changes were analyzed using field emission scanning electron microscopy (FE-SEM). Raman spectroscopy was performed to analyze chemical changes on the dentin surface. The ΔDFF of the desensitizers containing BAG, BAG with 10-MDP, and BAG with 4-META significantly increased after two weeks of SBF storage and post-ultrasonication compared to the SNP at each time point (p < 0.05). Multiple precipitates were observed on the surfaces of the three BAG-containing desensitizers. Raman spectroscopy revealed hydroxyapatite (HAp) peaks on the dentin surfaces treated with the three BAG-containing desensitizers. Novel BAG-containing dentin desensitizers can reduce the DFF rate about 70.84 to 77.09% in the aspect of reduction of DFF through the HAp precipitations after two weeks of SBF storage.

The Antibacterial and Remineralization Effect of Silver-Containing Mesoporous Bioactive Glass Sealing and Er-YAG Laser on Dentinal Tubules Treated in a Streptococcus mutans Cultivated Environment

The aim of this study was to evaluate the remineralization and antibacterial effect of silver-containing mesoporous bioactive glass (MBG-Ag) sealing combined with Er:YAG laser irradiation on human demineralized dentin specimens in a Streptococcus mutans cultivated environment. A total of 48 human dentin specimens were randomly divided into four groups. The characteristics of MBG-Ag and the occlusion efficiency of the dentinal tubules were analyzed using X-ray diffraction patterns, Fourier-transform infrared spectroscopy, scanning electron microscope images and energy dispersive X-ray spectroscopy. Moreover, the antibacterial activity against Streptococcus mutans was evaluated by colony formation assay. The results showed that the dentin specimens with Er:YAG laser irradiation can form a melted occlusion with a size of 3–4 µm. MBG-Ag promoted the deposition of numerous crystal particles on the dentinal surface, reaching the deepest penetration depth of 70 μm. The results suggested that both MBG-Ag and laser have the ability to enhance the remineralization and precipitation of hydroxyapatite crystals. While the results showed that MBG-Ag sealing combined with the thermomechanical subablation mode of Er:YAG laser irradiation-induced dense crystalline deposition, reaching a penetration depth of more than 300 µm, silver nanoparticles without good absorption of the Er:YAG laser resulted in a heterogeneous radiated surface. Er:YAG laser irradiation with a low energy and pulse rate cannot completely inhibit the growth of S. mutans, but MBG-Ag sealing reached the bactericidal concentration. It was concluded that the simultaneous application of MBG-Ag sealing and Er:YAG laser treatment can prevent the drawbacks of their independent uses, resulting in a superior form of treatment for dentin hypersensitivity.

Antibacterial silver-containing mesoporous bioglass as a dentin remineralization agent in a microorganism-challenged environment

OBJECTIVES

To provide a suitable material capable of treating dentin hypersensitivity with simultaneous active antibacterial activity.

METHODS

We developed silver-containing mesoporous bioglass (MBG-Ag) using the sol-gel technique, which loaded silver nanoparticles as promising bacteriostatic agents. The MBG-Ag with a powder-to-liquid ratio of 0.5 g: 0.01 mL were uniformly mixed with 20 %, 30 %, and 40 % phosphoric acid for 5, 10 and 20 min, respectively. Furthermore, we evaluated the occlusion efficiency, depth of penetration, and antibacterial activity of dentin specimens by simulating a Streptococcus mutans (S. mutans) infection on dentin. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the powders and assess tubule occlusion. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the MBG-Ag against S. mutans were determined via time-killing curves and colony formation assays.

RESULTS

The MIC ranged from 2.5 to 5 mg/mL, and the MBC ranged from 5 to 10 mg/mL. The highest dentinal tubule occlusion efficiency was over 90 %. The colony formation assay confirmed that 5 mg/mL MBG-Ag mixed with phosphoric acid reached the bactericidal concentration.

CONCLUSION

The MBG-Ag 40PA achieved a good occlusion efficiency and deep apatite precipitation in a short time, implying its superiority in clinical applications.

CLINICAL RELEVANCE

The MBG-Ag formed in this study is a promising candidate for the treatment of demineralized dentin and confers antibacterial effects on the remineralized dentin surface against S. mutans.

Advances of nanomaterial applications in oral and maxillofacial tissue regeneration and disease treatment

Using bioactive nanomaterials in clinical treatment has been widely aroused. Nanomaterials provide substantial improvements in the prevention and treatment of oral and maxillofacial diseases. This review aims to discuss new progresses in nanomaterials applied to oral and maxillofacial tissue regeneration and disease treatment, focusing on the use of nanomaterials in improving the quality of oral and maxillofacial healthcare, and discuss the perspectives of research in this arena. Details are provided on the tissue regeneration, wound healing, angiogenesis, remineralization, antitumor, and antibacterial regulation properties of nanomaterials including polymers, micelles, dendrimers, liposomes, nanocapsules, nanoparticles and nanostructured scaffolds, etc. Clinical applications of nanomaterials as nanocomposites, dental implants, mouthwashes, biomimetic dental materials, and factors that may interact with nanomaterials behaviors and bioactivities in oral cavity are addressed as well. In the last section, the clinical safety concerns of their usage as dental materials are updated, and the key knowledge gaps for future research with some recommendation are discussed. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

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.

Evaluation of the Occluding Characteristics of Nanosized Eggshell/Titanium Dioxide with or without Saliva

OBJECTIVES

 The study reports on the effectiveness of a ball-milled nanosized titanium dioxide composite (EB@TiO₂) for DH management in comparison with commercial desensitizing paste with and without saliva.

MATERIALS AND METHODS

  Forty-nine dentine specimens were prepared from extracted bovine anterior teeth. Twenty-one of the specimens were brushed with three desensitizing toothpaste for 7 days, namely: Group 1; EB@TiO₂, Group 2; Colgate Pro-relief; and Group 3; Sensodyne repair (n = 7). Twenty-four specimens were brushed with the toothpaste for 7 days and stored in artificial saliva (control) after brushing. Each specimen was subsequently posttreated in citric acid solution to test its stability in acidic condition. Field scanning electron microscope was used to evaluate the effectiveness of the dentine tubules occlusion. The biocompatibility of the composite was tested using BHK21 cell line.

STATISTICAL ANALYSIS

 One-way analysis of variance was used to analyze the percentage occluded area ratio values for all specimens (α = 0.05). Independent t-test was further used to evaluate the occlusion differences with saliva and without saliva.

RESULTS AND CONCLUSIONS

 The number of dentine tubules decreased significantly after 7 days of brushing. Overall, the occlusion observe for EB@TiO₂ were significantly better than for Colgate Pro-relief and Sensodyne repair (p < 0.05). BHK21 assay suggested that composite had no significant effect on the BHK21 cell line. This study demonstrated that the composite effectively occluded open dentine tubules within 7 days of brushing.

Novel calcium encapsulated mesocellular siliceous foams for crystal growth in dentinal tubules

OBJECTIVES

The aim of this study was to investigate the novel mesocellular siliceous foams (MCF) containing CaCO₃ nanoparticles (denoted as CMCF) combined with phosphoric acid could occlude dentinal tubules through the formation of biomimetic crystal barrier.

METHODS

Ultrastructures of MCF and CMCF were examined by transmission electron microscopy (TEM). Elemental components were analyzed with energy dispersive X-ray spectrometry (EDX). CMCF was mixed with distilled water, 10%, 20% and 30% phosphoric acid then applied on dentine discs. Crystals were characterized by X-ray powder diffractometry (XRD). The sealing efficacy of the dentinal tubules was examined by scanning electron microscopy.

RESULTS

TEM images showed MCF presented a pore size of approximately 30.0 nm and CMCF contained abundant nano-CaCO₃. Sealing efficacy showed that CMCF, when reacted with 30% phosphoric acid, would form crystals in the dentinal tubules to a depth of 83.2 ± 17.6 μm at an occlusion percentage of 75.6 ± 12.8% on average; both occlusion percentage and depth were higher than those obtained with 10% or 20% phosphoric acid (p < 0.05). The results of XRD and EDS indicated that the crystal growth in the dentinal tubules could be transformed into the biomimetic crystals.

CONCLUSION

This study showed that the CMCF with 30% phosphoric acid could effectively occlude the dentinal tubules through the formation of biomimetic crystal barrier.

CLINICAL SIGNIFICANCE

The novel CMCF combined with phosphoric acid may have potential for the treatment of dentine hypersensitivity.

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.

In Vitro Evaluation of Dentin Tubule Occlusion for Novel Calcium Lactate Phosphate (CLP) Paste

Introduction: The objective of this in vitro study is to evaluate the effective and long-term occlusion of dentinal tubules using a novel calcium lactate phosphate (CLP) based desensitizing agent. Methods: Dentin disks (n = 9) were pre-etched using 1 M lactic acid for 30 s and individually treated with Colgate^® Pro-Relief™ paste, CLP paste, and double distilled water (ddH₂O) by a rubber-cupped handpiece. Dentin disks were analyzed under optical micrographs for pre-treatment, directly after treatment, and 14 days post-treatment. One-way ANOVA and post-hoc Tukey’s test were used to determine whether there were any statistically significant differences in dentinal tubule diameter. Results: A significant decrease occurred in the mean tubule diameter for dentin disks treated with CLP paste. A decrease was observed from 3.52 ± 0.83 µm to 2.62 ± 0.42 µm right after treatment, further decreasing to 1.71 ± 0.45 µm after immersion in artificial saliva for 14 days (p < 0.05). Conclusions: The results suggest that the CLP based desensitizing paste has remineralization properties and provides instant and lasting effectiveness in dentinal tubule occlusion.

Evaluation of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite derived from chicken eggshell powder with and without addition of sodium fluoride: An in vitro study

Aim:

This in vitro study evaluated the degree of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite (nHAp) derived from chicken eggshell powder with and without the addition of 2% sodium fluoride (NaF) using scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM).

Materials and Methods:

nHAp was synthesized and characterized using X-ray diffraction and SEM-energy dispersive spectroscopy. Dentin discs were obtained from extracted teeth, pretreated with 17% ethylenediaminetetraacetic acid for 5 min and were divided into four groups based on the experimental agents as follows: Group 1: Untreated (control), Group 2: 2% NaF, Group 3: nHAp, Group 4: Combination of nHAp and 2% NaF. The treatment protocol was carried out for 7 days, after which the specimens were viewed under SEM and CLSM.

Statistical Analysis Used:

One-way ANOVA and Tukey's post hoc multiple comparison tests (P < 0.05).

Results:

All the experimental agents occluded the dentinal tubules, but to varying degrees and depths. Specimens treated with the combination of nHAp and 2% NaF showed complete dentinal tubular occlusion and significantly greater depth of penetration than those treated with nHAp and 2% NaF alone.

Conclusion:

The combination of nHAp and 2% NaF was the most effective in occluding dentinal tubules.

Use of poly (amidoamine) dendrimer for dentinal tubule occlusion: a preliminary study

The occlusion of dentinal tubules is an effective method to alleviate the symptoms caused by dentin hypersensitivity, a significant health problem in dentistry and daily life. The in situ mineralization within dentinal tubules is a promising treatment for dentin hypersensitivity as it induces the formation of mineral on the sensitive regions and occludes the dentinal tubules. This study was carried out to evaluate the in vitro effect of a whole generation poly(amidoamine) (PAMAM) dendrimer (G3.0) on dentinal tubule occlusion by inducing mineralization within dentinal tubules. Dentin discs were treated with PAMAM dendrimers using two methods, followed by the in vitro characterization using Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). These results showed that G3.0 PAMAM dendrimers coated on dentin surface and infiltrated in dentinal tubules could induce hydroxyapatite formation and resulted in effective dentinal tubule occlusion. Moreover, crosslinked PAMAM dendrimers could induce the remineralization of demineralized dentin and thus had the potential in dentinal tubule occlusion. In this in vitro study, dentinal tubules occlusion could be achieved by using PAMAM dendrimers. This could lead to the development of a new therapeutic technique for the treatment of dentin hypersensitivity.

Review of nanomaterials in dentistry: interactions with the oral microenvironment, clinical applications, hazards, and benefits

Interest in the use of engineered nanomaterials (ENMs) as either nanomedicines or dental materials/devices in clinical dentistry is growing. This review aims to detail the ultrafine structure, chemical composition, and reactivity of dental tissues in the context of interactions with ENMs, including the saliva, pellicle layer, and oral biofilm; then describes the applications of ENMs in dentistry in context with beneficial clinical outcomes versus potential risks. The flow rate and quality of saliva are likely to influence the behavior of ENMs in the oral cavity, but how the protein corona formed on the ENMs will alter bioavailability, or interact with the structure and proteins of the pellicle layer, as well as microbes in the biofilm, remains unclear. The tooth enamel is a dense crystalline structure that is likely to act as a barrier to ENM penetration, but underlying dentinal tubules are not. Consequently, ENMs may be used to strengthen dentine or regenerate pulp tissue. ENMs have dental applications as antibacterials for infection control, as nanofillers to improve the mechanical and bioactive properties of restoration materials, and as novel coatings on dental implants. Dentifrices and some related personal care products are already available for oral health applications. Overall, the clinical benefits generally outweigh the hazards of using ENMs in the oral cavity, and the latter should not prevent the responsible innovation of nanotechnology in dentistry. However, the clinical safety regulations for dental materials have not been specifically updated for ENMs, and some guidance on occupational health for practitioners is also needed. Knowledge gaps for future research include the formation of protein corona in the oral cavity, ENM diffusion through clinically relevant biofilms, and mechanistic investigations on how ENMs strengthen the tooth structure.

A mesoporous silica biomaterial for dental biomimetic crystallization

The loss of overlying enamel or cementum exposes dentinal tubules and increases the risk of several dental diseases, such as dentin hypersensitivity (causing sharp pain and anxiety), caries, and pulp inflammation. This paper presents a fast-reacting, more reliable and biocompatible biomaterial that effectively occludes exposed dentinal tubules by forming a biomimetic crystalline dentin barrier. To generate this biomaterial, a gelatin-templated mesoporous silica biomaterial (CaCO3@mesoporous silica, CCMS) containing nanosized calcium carbonate particles is mixed with 30% H3PO4 at a 1/1 molar ratio of Ca/P (denoted as CCMS-HP), which enables Ca2+ and PO4(3-)/HPO4(2-) ions to permeate the dentinal tubules and form dicalcium phosphate dihydrate (DCPD), tricalcium phosphate (TCP) or hydroxyapatite (HAp) crystals at a depth of approximately 40 μm (sub-μ-CT and nano-SEM/EDS examinations). In vitro biocompatibility tests (WST-1 and lactate dehydrogenase) and ALP assays show high cell viability and mineralization ability in a transwell dentin disc model treated with CCMS-HP (p<0.05). The in vivo efficacy and biocompatibility analyses of the biomaterial in an animal model reveal significant crystal growth (DCPD, TCP or HAp-like) and no pulp irritation after 70 days (p<0.05). The developed CCMS-HP holds great promise for treating exposed dentin by growing biomimetic crystals within dentinal tubules. These findings demonstrate that the mesoporous silica biomaterials presented here have great potential for serving as both a catalyst and carrier in the repair or regeneration of dental hard tissue.

The Efficacy of Selected Desensitizing OTC Products: A Systematic Review

Objectives. The aim of the present study was to review the published literature in order to identify relevant studies for inclusion and to determine whether there was any evidence on the clinical effectiveness of selected desensitizing toothpastes, calcium sodium phosphosilicate (CSPS), amorphous calcium phosphate (ACP), nanohydroxyapatite, and casein phosphopeptide-amorphous calcium phosphate (tooth mousse) on reducing dentine hypersensitivity (DH). Materials and Methods. Following a review of 593 papers identified from searching both electronic databases (PUBMED) and hand searching of relevant written journals, only 5 papers were accepted for inclusion. Results. Analysis of the included studies (3 CSPS and 2 ACP) would suggest that there may be some benefit for patients using these products for reducing DH. No direct comparative studies were available to assess all these products under the same conditions neither were there any comparative randomised controlled studies that compared at least two of these products in determining their effectiveness in treating DH. Conclusions. Due to the small number of included studies, there are limited clinical data to support any claims of clinical efficacy of these OTC products. Further studies are therefore required to determine the efficacy of these products in well-controlled RCT studies with a larger sample size.

Enhancement of nano-hydroxyapatite bonding to dentin through a collagen/calcium dual-affinitive peptide for dentinal tubule occlusion

Calcium phosphate crystals, as the main component of dentin and enamel, have been widely used for the occlusion of dentinal tubules. However, the low bond strength and poor sealing effect limit their clinical practicality. In this study, a collagen/calcium dual-affinitive peptide E8DS (EEEEEEEEDSpESpSpEEDR) and nano-hydroxyapatite (nano-HAp) flocculi were developed to seal dentin tubules for reducing dentin hypersensitivity, whereas the E8DS peptides were pre-applied to improve the adhesion of occlusive hydroxyapatite coating on dentin collagen matrix for the long-lasting sealing effect and relief from hypersensitivity. Our study showed that E8DS peptides had a strong affinity with dentin collageneous matrix that almost 43.7% of initial E8DS peptides immobilized on exposed dentin samples remained detained after continuous washing by distilled water for four weeks at a rate of 1 mL/min. Nano-HAp flocculi were obtained by re-neutralization of HAp-HCl solution and then brushed onto the surfaces of pre-treated human dentin disks with E8DS peptides, which showed a perfect occlusion of exposed dentinal tubules, as compared with Nano-HAp only and a commercial desensitizer, Green Or. With only around 10-min E8DS peptide pre-treatment, the occlusive mineral layers remained intact against consecutively stirred washing in phosphate-buffered saline or coke for 15 min, and 6 min of tooth-brushing, which implied that our E8DS peptide could comparatively improve the durability of sealant-dentin interface bonds for long-lasting dentine desensitization.

Phosphorus Effects of Mesoporous Bioactive Glass on Occlude Exposed Dentin

In recent studies, sealing of exposed dentinal tubules is generally considered as one of the most effective strategies to treat dentin hypersensitivity. Mesoporous bioactive glass (MBG) is a potential material for treating dentin hypersensitivity due to its highly specific areas for dissolution and re-precipitated reaction for reduction in dentin permeability. The groups of commercial products of PerioGlas®, synthetic MBG and MBG without phosphorus (MBGNP) were compared. The MBG and MBGNP powders were prepared by the sol-gel method and mixed with different calculated ratios of phosphoric acid (PA) and then was brushed onto dentin surfaces. We used X-ray diffractometer (XRD), scanning electronic microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) to investigate the physiochemistry and the occlusion ability of dentinal tubules. The results showed that MBG paste mixed with PA solution has a better ability for occluding dentinal tubules than MBGNP; it has a short reaction time and good operability. The major crystallite phase of MBG agents was monocalcium phosphate monohydrate [Ca(H₂PO₄)₂·H₂O] in the early stages of the reactions. MBG pastes that were mixed with 30% and 40% PA had the ability to create excellent penetration depth greater than 80 μm. These agents have the potential to treat dentin hypersensitivity.

Dental applications of nanostructured bioactive glass and its composites

To improve treatments of bone or dental trauma and diseases such as osteoporosis, cancer, and infections, scientists who perform basic research are collaborating with clinicians to design and test new biomaterials for the regeneration of lost or injured tissue. Developed some 40 years ago, bioactive glass (BG) has recently become one of the most promising biomaterials, a consequence of discoveries that its unusual properties elicit specific biological responses inside the body. Among these important properties are the capability of BG to form strong interfaces with both hard and soft tissues, and its release of ions upon dissolution. Recent developments in nanotechnology have introduced opportunities for materials sciences to advance dental and bone therapies. For example, the applications for BG expand as it becomes possible to finely control structures and physicochemical properties of materials at the molecular level. Here, we review how the properties of these materials have been enhanced by the advent of nanotechnology, and how these developments are producing promising results in hard-tissue regeneration and development of innovative BG-based drug delivery systems.

Seal that Heals

Introduction

Dentinal hypersensitivity can be treated by dentinal tubule occlusion which prevents any stimuli from causing dentinal fluid movement. This in vitro study aims to compare the dentinal tubule occluding capability of four chemical compounds, a bonding agent, a compound of fluoride and hydroxyapatite, potassium oxalate gel and sodium fluoride varnish.

Materials and methods

Forty dentin samples were divided into four groups of 10 samples each. Group A (treated with Clearfil SE Bond), Group B (treated with Remin Pro), Group C (treated with Potassium Oxalate, Vi-sense,) and Group D (treated with Pro Fluoride varnish). The samples were treated with ethylene diamine tetraacetic acid (EDTA) gel prior to application of desensitizing agents to remove the smear layer and open the dentinal tubule orifice. Following the desensitizing treatment the specimens were washed and dehydrated using graded series of ethanol treatments (25, 50, 75, 90 and 100%). After each treatment tubule occlusion was analyzed by scanning electron microscope.

Results

Qualitative and quantitative analysis demonstrated potassium oxalate gel to cause maximum tubule occlusion followed by Remin Pro > Sodium fluoride varnish > Clearfil SE Bond.

Conclusion

Life expectancy is increasing and patients are retaining their natural teeth for a longer time due to effective treatment strategies. The results showed the potential use of these products as an effective means of tubule occlusion.

How to cite this article

Benjamin S, Roshni, Pradhan S, Nainan MT. Seal that Heals. World J Dent 2012;3(3):243-246.

Treatment of dentin hypersensitivity

Dentinal hypersensitivity is exemplified by brief, sharp, well-localized pain in response to thermal, evaporative, tactile, osmotic, or chemical stimuli that cannot be ascribed to any other form of dental defect or pathology. Pulpal pain is usually more prolonged, dull, aching, and poorly localized and lasts longer than the applied stimulus. Up to 30% of adults have dentinal hypersensitivity at some time. Current techniques for treatment may be only transient in nature and results are not always predictable. Two methods of treatment of dentin hypersensitivity are tubular occlusion and blockage of nerve activity. A differential diagnosis needs to be accomplished before any treatment.