Enamel Demineralization Resistance and Remineralization by Various Fluoride-Releasing Dental Restorative Materials

Evaluation of Broccoli Extract for Enhancing Primary Tooth Enamel Microhardness: An In Vitro Study

Background and Aims

Dental caries remains highly prevalent among children. This study aimed to evaluate the efficacy of aqueous broccoli extract in enhancing the microhardness of demineralized primary tooth enamel compared to a standard fluoride treatment.

Methods

An in vitro study was conducted using 30 extracted primary second molars, which were sectioned and polished. Baseline enamel microhardness was assessed using a Vickers hardness tester. Demineralization was induced using a cola drink (pH 4.5) for 8 min. The broccoli extract was prepared by air-drying fresh florets, stems, and leaves at room temperature, followed by aqueous extraction with distilled water and filtration. The samples were randomly assigned to receive a 10-min treatment with either aqueous broccoli extract (Group B) or 1.23% acidulated phosphate fluoride (APF) gel (Group F). Microhardness was measured posttreatment, and percentage changes between time points were compared using statistical analysis.

Results

After demineralization, broccoli extract, and fluoride gel significantly improved enamel microhardness. The broccoli extract group exhibited a greater recovery in microhardness (+44.95% vs. +20.78%, p = 0.008) compared to the fluoride gel group. However, the overall reduction in microhardness from baseline to final measurement showed no statistically significant difference between the two groups (p = 0.077).

Conclusion

Aqueous broccoli extract demonstrated comparable overall efficacy to fluoride gel in enhancing demineralized primary tooth enamel microhardness despite showing different patterns of demineralization and recovery. These findings suggest that broccoli extract may be a natural and effective alternative for enhancing enamel remineralization in pediatric caries prevention, warranting further clinical investigation.

K. M. B. Biomimetic Effect of Saliva on Human Tooth Enamel: A Scanning Electron Microscopic Study

Introduction: Due to the presence of ion reservoir, saliva may facilitate enamel remineralization and neutralize pH of acidic beverage leads to prevent enamel demineralization. Saliva substitute/artificial saliva has been developed in subsequent years and may differ in physical properties, function, or pH level from 5.0 to 7.3. Objectives: To evaluate the biomimetic effect of saliva (neutralization) on tooth enamel exposed to carbonated beverage (pH 2.44) and to observe therapeutic capability (remineralization) of artificial saliva over previously eroded (grade 3 and grade 5) enamel surface. Methods: After scanning with electron microscope (SEM-EDX), nondemineralized crown samples (n = 40) were randomly grouped into two. Samples (50%) were flushed all around to carbonated beverage with collected natural saliva bathing simultaneously (experimental group, n = 20), and the rest flushed to beverage only without saliva bathing simultaneously (control group, n = 20). Flushing action was performed for 3 min by a customized digital automatic flusher for 30 times for each sample. Samples (n = 40) were further scanned under SEM-EDX to evaluate the demineralization grade and concentration of Ca, P, O, and C elements of crown samples to find out the neutralization effect of saliva. In the second phase, already demineralized crown samples (n = 30) were randomly treated with artificial saliva having two different pH (7 or 6.8, experimental groups) and distilled water (control group) for 15 min 3 times daily for 30 days. The remineralization score of experimental samples was graded, and therapeutic capability was established. Results: Samples, when exposed to a carbonated beverage with saliva bathing simultaneously, showed low level of demineralization (mean 2.9 ± 0.3) than the control (without saliva) (mean 4.8 ± 0.3) (p = 0.01) which indicated neutralization (bioimimetic) effect of natural saliva. All (100%) of demineralized samples treated with both artificial saliva (pH 7 or pH 6.8) showed significant remineralization (p = 0.01), thus revealed biomimetic capacity. SEM-EDX analysis showed initial (before beverage exposure) concentrations of calcium, phosphorus, oxygen, and carbon elements of crown samples were 32.48%, 31.5%, 28.3%, and 5.5%, respectively. The calcium (Ca) (9.7%) and phosphorous (P) (18.5%) values were more decreased after beverage exposure without saliva bathing simultaneously compared to after beverage exposure with saliva bathing simultaneously. The concentration of oxygen (54.4%) and carbon (15.5%) were more increased after beverage exposure without saliva bathing simultaneously compared to after beverage exposure with saliva bathing simultaneously. Though the concentration of calcium (38.5%) of the crown sample was increased after treatment with artificial saliva (pH 7), but the phosphorus (18.5%) concentration of the crown sample was not increased. Conclusion: Within the context of the present study, both natural and artificial saliva showed significant biomimetic effects with respect to neutralization and remineralization.

Comparative evaluation of remineralizing potential of four enamel remineralising agents using SEM-EDX - An in-vitro study

Objective

Compare the remineralisation potential of four enamel remineralising agents on artificially demineralized enamel surface using Scanning electron microscopy- Energy dispersive x-ray.

Materials and methods

75 extracted maxillary and mandibular premolars coated with acid-resistant nail varnish, were stored in demineralising solution for 96 h to produce artificial caries lesions. The samples were divided into 5 groups (n = 15), Control (Demineralized- No treatment), Group I samples were treated with casein phosphoprotein-amorphous calcium phosphate (CPP-ACP), Group II with self-assembling peptide (SAP-14), Group III with tri-calcium phosphate (f-TCP) and Group IV with Bioactive glass (BAG), respectively. The pH cycling model was followed for 21 days. The samples were analysed via SEM-EDX (Carl Zeiss, Germany; Model: Merlin Compact) for qualitative assessment and quantitative analysis of calcium and phosphorous. The data were analysed for multiple group comparison using IBM SPSS version 20 with one-way ANOVA followed by a paired t-test.

Results

Calcium/Phosphorous ratio of all experimental groups; Group 1(1.92 ± .17), Group 2 (1.98 ± .16), Group 3 (1.81 ± .03), Group 4 (1.75 ± .08) was statistically different (p < 0.0005) from Control; while there was no difference between Group I and Group II (p = 0.33).

Conclusion

All experimental groups showed comparable remineralising potential. Even though no statistically significant difference is seen between Group I and Group II, after correlating with surface analysis it was concluded that Group II showed the greatest remineralising potential.

Silver nanoparticles versus chitosan nanoparticles effects on demineralized enamel

BACKGROUND

To compare the impacts of different remineralizing agents on demineralized enamel, we focused on chitosan nanoparticles (ChiNPs) and silver nanoparticles (AgNPs).

METHODS

This study was conducted on 40 extracted human premolars with artificially induced demineralization using demineralizing solution. Prior to the beginning of the experimental procedures, the samples were preserved in artificial saliva solution. The nanoparticles were characterized by transmission electron microscopy (TEM) and teeth were divided into four equal groups: Group A was utilized as a control group (no demineralization) and received no treatment. Group B was subjected to demineralization with no treatment. Group C was subjected to demineralization and then treated with ChiNPs. Group D was subjected to demineralization and then treated with AgNPs. The teeth were evaluated for microhardness. The enamel surfaces of all the samples were analysed by scanning electron microscopy (SEM) for morphological changes and energy dispersive X-ray analysis (EDX) for elemental analysis.

RESULTS

The third and fourth groups had the highest mean microhardness and calcium (Ca) and phosphorous (P) contents. SEM of these two groups revealed relative restoration of homogenous remineralized enamel surface architecture with minimal micropores.

CONCLUSION

Chitosan nanoparticles (NPs) and silver NPs help restore the enamel surface architecture and mineral content. Therefore, chitosan NPs and AgNPs would be beneficial for remineralizing enamel.

Comparative evaluation of remineralizing efficacy of calcium sodium phosphosilicate, ginger, turmeric, and fluoride

Background

White lesions, also known as white spots, are the earliest signs of tooth decay. At this stage, noninvasive preventive treatments, such as fluoride application, can help to slow down or even reverse the progression of white lesions. For decades, fluoride has held the spotlight as the go-to agent in oral preventive care, demonstrating significant remineralizing power. Recent scientific literature reveals a growing interest in alternative products as natural substances that demonstrate potential remineralizing effects on tooth enamel. This in vitro study aimed to evaluate the potential remineralizing effect of calcium sodium phosphosilicate (CSP), ginger, and turmeric.

Materials and Methods

This in vitro study was designed to evaluate the remineralizing effects of various materials on the enamel of extracted human teeth. The aim was to compare the effectiveness of these different substances in promoting enamel remineralization. Enamel blocks were prepared and were divided into seven experimental groups: CSP, fluoride toothpaste, nonfluoride toothpaste, turmeric, ginger, fluoride varnish, and distilled water. In this study, sample mineralization is assessed through the quantitative photo-induced fluorescence test before demineralization, after demineralization, and after remineralization. Statistical analysis of the data was conducted using a one-factor analysis of variance test. The significance level was set at P < 0.05.

Results

The best results were obtained by groups treated with turmeric (P < 0.0001), Enamelast fluoride varnish (P < 0.0001), and NovaMin (P < 0.01), as compared to other remineralizing treatments.

Conclusion

While fluoride has undeniably revolutionized oral preventive care, the exploration of alternative products as natural substances and innovative compounds in recent scientific literature signals a shift in focus toward safer and potentially more diverse options.

Is Cention-N comparable to other direct dental restorative materials? A systematic review with network meta-analysis of in vitro studies

OBJECTIVES

To compare the performance of Cention-N® with direct restorative materials used at the daily practice (e.g., resin-based composites/RBC, glass ionomer cements/GIC, bioactive resins, silver amalgam) via a systematic review study.

METHODS

The review followed the PRISMA-NMA recommendations, and the protocol of the review was published at osf.io/ybde8. The search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Embase, Lilacs, and SciELO databases, as well as in the grey literature (Open Grey, Proquest, and Periódicos CAPES). Studies with an in vitro experimental design evaluating the characteristics and properties of Cention-N in comparison to other restorative materials were included. The risk of bias of included studies was assessed using the RoBDEMAT tool, and meta-analyses were conducted using Review Manager 5.4 and MetaInsight V3 tools.

RESULTS

A total of 85 studies were included in the review, from which 79 were meta-analyzed. Several characteristics of direct restorative materials were analyzed, including physical (color change, degree of conversion, hardness, microleakage, polymerization rate, roughness, water solubility, water sorption), mechanical (bond strength to dentin, compressive strength, diametral tensile strength, flexural modulus, flexural strength, load-to-fracture, wear), and biological (alkalinizing effect, antibacterial activity, calcium and fluoride release) properties.

SIGNIFICANCE

Cention-N presented similar physico-mechanical properties compared to RBCs, but a stronger behavior than GICs. Despite the Alkasite nature of Cention-N, GICs may still demonstrate the greatest fluoride releasing ability from all direct restorative materials. This review confirmed the adequate behavior of Cention-N when compared to several other more traditionally used materials, confirming its applicability for the permanent restoration of decayed or fractured teeth.

Surface and Mineral Changes of Primary Enamel after Laser Diode Irradiation and Application of Remineralization Agents: A Comparative In Vitro Study

OBJECTIVES

The purpose of this study is to evaluate the remineralization potential of primary teeth enamel after being exposed to different laser diode therapies.

METHODS

Ninety-six vestibular primary teeth enamel samples were divided into eight groups (n = 12) with varying treatments: control (G1), CPP-ACP-fluoride varnish (G2), diode lasers at 980 nm (G3), 808 nm (G4), 450 nm (G5), 980 nm + CPP-ACP-fluoride varnish (G6), 808 nm + CPP-ACP-fluoride varnish (G7), and 450 nm + CPP-ACP-fluoride varnish (G8). Each sample was assessed using a DIAGNOdent® (KaVo Dental, Biberach, Germany), at baseline, post-treatment, and post-pH cycle remineralization. SEM imaging was performed before and after treatment and following the pH cycle.

RESULTS

The results indicated that the 980 nm and 808 nm diode lasers, both alone and in combination with CPP-ACP-fluoride varnish, either maintained or increased the calcium (Ca) weight percentage (Wt%) in the enamel. The 980 nm diode laser combined with CPP-ACP-fluoride varnish (G6) showed a significant increase in Ca Wt%, suggesting a strong remineralization effect. Similarly, the 808 nm diode laser alone (G4) also promoted a substantial increase in Ca Wt%. In contrast, the 450 nm diode laser, whether applied alone or in combination with CPP-ACP-fluoride varnish, resulted in a lower Ca Wt% and an increase in phosphorus (P) Wt%. Most groups, except for the CPP-ACP-fluoride varnish alone (G2), demonstrated an increase in P Wt%, indicating a complex interaction between laser therapy and enamel remineralization.

CONCLUSIONS

The combined use of laser therapy with CPP-ACP-fluoride varnish significantly enhanced the remineralization of temporary teeth enamel. The 980 nm diode laser + CPP-ACP-fluoride varnish showed the most pronounced improvement in remineralization, while the 808 nm diode laser alone also effectively increased calcium solubility. These findings suggest that higher-wavelength diode lasers, particularly when combined with remineralizing agents, can effectively enhance the mineral content of primary teeth and promote enamel remineralization.

Advances in hybridized nanoarchitectures for improved oro-dental health

On a global note, oral health plays a critical role in improving the overall human health. In this vein, dental-related issues with dentin exposure often facilitate the risk of developing various oral-related diseases in gums and teeth. Several oral-based ailments include gums-associated (gingivitis or periodontitis), tooth-based (dental caries, root infection, enamel erosion, and edentulous or total tooth loss), as well as miscellaneous diseases in the buccal or oral cavity (bad breath, mouth sores, and oral cancer). Although established conventional treatment modalities have been available to improve oral health, these therapeutic options suffer from several limitations, such as fail to eradicate bacterial biofilms, deprived regeneration of dental pulp cells, and poor remineralization of teeth, resulting in dental emergencies. To this end, the advent of nanotechnology has resulted in the development of various innovative nanoarchitectured composites from diverse sources. This review presents a comprehensive overview of different nanoarchitectured composites for improving overall oral health. Initially, we emphasize various oral-related diseases, providing detailed pathological circumstances and their effects on human health along with deficiencies of the conventional therapeutic modalities. Further, the importance of various nanostructured components is emphasized, highlighting their predominant actions in solving crucial dental issues, such as anti-bacterial, remineralization, and tissue regeneration abilities. In addition to an emphasis on the synthesis of different nanostructures, various nano-therapeutic solutions from diverse sources are discussed, including natural (plant, animal, and marine)-based components and other synthetic (organic- and inorganic-) architectures, as well as their composites for improving oral health. Finally, we summarize the article with an interesting outlook on overcoming the challenges of translating these innovative platforms to clinics.

The Gloss Retention of Esthetic Restorations Following Simulated Brushing with Charcoal Oral Products: An In-Vitro Study

AIM

To assess the gloss and gloss retention of two esthetic restorative materials after brushing with a charcoal-infused toothbrush and activated charcoal toothpaste compared to their standard counterparts in all possible combinations.

MATERIALS AND METHODS

In this study,104 disc-shaped specimens were prepared, 52 from each of the two materials: Beautifil II LS composite resin (Giomer) and Fuji II LC resin-modified glass ionomer (RMGI). Specimens of each material were divided into 4 groups (n = 13) according to the tested brushing procedure: group A-standard toothbrush + standard non-whitening toothpaste (S-S), group B-standard toothbrush + activated charcoal toothpaste (S-CH), group C-charcoal-infused toothbrush + standard non-whitening toothpaste (CH-S), and group D-charcoal-infused toothbrush + activated-charcoal toothpaste (CH-CH). Gloss was recorded using a gloss meter initially and after each brushing protocol. The data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD post hoc tests using SPSS® v.27 software at 5% significance level.

RESULTS

Beautifil II LS showed the highest gloss values after brushing in group D (44 ± 3.9), which was not significantly different from its initial value (46.1 ± 1.8), followed by groups A (32.2 ± 4), B (23.2 ± 3.6), and C (22.7 ± 3.9), while Fuji II LC showed its highest gloss values after brushing in groups D (16.6 ± 3.7) and a (15.4 ± 8.7), followed by groups C (10.9 ± 6) and B (4.4 ± 2.5), all were significantly lower than their respective initial gloss values.

CONCLUSION

The gloss of Giomer and RMGI reduced significantly following the brushing with the tested brushing procedures except for the Giomer group brushed with a combination of charcoal-infused toothbrush and activated-charcoal toothpaste.

CLINICAL SIGNIFICANCE

The brushing using a combination of charcoal-infused toothbrush and activated-charcoal toothpaste is recommended for the gloss retention of Beautifil II LS restorations. However, the gloss of the Fuji II LC cannot be retained after any of the brushing procedures. How to cite this article: Farghal NS, Awadalkreem F, Abouelhonoud NA, et al. The Gloss Retention of Esthetic Restorations Following Simulated Brushing with Charcoal Oral Products: An In-Vitro Study. J Contemp Dent Pract 2024;25(5):473-479.

The demineralization resistance and mechanical assessments of different bioactive restorative materials for primary and permanent teeth: an in vitro study

OBJECTIVES

This article examines the efficacy of two bioactive dental composites in preventing demineralization while preserving their mechanical and physical properties.

MATERIALS AND METHODS

The study compares Beautifil Kids and Predicta® Bioactive Bulk-Fill (Predicta) composites with conventional dental composite. Flexural strength and elastic modulus were evaluated using a universal testing machine. A pH-cycling model assessed the composites' ability to prevent dentin demineralization. Color stability and surface roughness were measured using a spectrophotometer and non-contact profilometer, respectively, before and after pH-cycling, brushing simulation, and thermocycling aging.

RESULTS

Beautifil Kids exhibited the highest flexural strength and elastic modulus among the materials (p < 0.05). Predicta demonstrated the highest increase in dentin surface microhardness following the pH-cycling model (p < 0.05). All groups showed clinically significant color changes after pH-cycling, with no significant differences between them (p > 0.05). Predicta exhibited greater color change after brushing and increased surface roughness after thermocycling aging (p < 0.05). While Beautifil Kids had higher surface roughness after pH-cycling (p < 0.05).

DISCUSSION/CONCLUSION

Bioactive restorative materials with ion-releasing properties demonstrate excellent resistance to demineralization while maintaining mechanical and physical properties comparable to the control group.

Developing Bioactive Dental Resins for Restorative Dentistry

Despite its reputation as the most widely used restorative dental material currently, resin-based materials have acknowledged shortcomings. As most systematic survival studies of resin composites and dental adhesives indicate, secondary caries is the foremost reason for resin-based restoration failure and life span reduction. In subjects with high caries risk, the microbial community dominated by acidogenic and acid-tolerant bacteria triggers acid-induced deterioration of the bonding interface and/or bulk material and mineral loss around the restorations. In addition, resin-based materials undergo biodegradation in the oral cavity. As a result, the past decades have seen exponential growth in developing restorative dental materials for antimicrobial applications addressing secondary caries prevention and progression. Currently, the main challenge of bioactive resin development is the identification of efficient and safe anticaries agents that are detrimental free to final material properties and show satisfactory long-term performance and favorable clinical translation. This review centers on the continuous efforts to formulate novel bioactive resins employing 1 or multiple agents to enhance the antibiofilm efficacy or achieve multiple functionalities, such as remineralization and antimicrobial activity antidegradation. We present a comprehensive synthesis of the constraints and challenges encountered in the formulation process, the clinical performance-related prerequisites, the materials' intended applicability, and the current advancements in clinical implementation. Moreover, we identify crucial vulnerabilities that arise during the development of dental materials, including particle aggregation, alterations in color, susceptibility to hydrolysis, and loss of physicomechanical core properties of the targeted materials.

A novel orthodontic adhesive containing zinc-doped phosphate-based glass for preventing white spot lesions

OBJECTIVES

This study aimed at demonstrating the remineralization effect of the enamel around the brackets to aid reduction in white spot lesions (WSLs) with use of zinc-doped phosphate-based glass (Zn-PBG) containing orthodontic adhesives.

METHODS

Zn-PBG powder was synthesized, and particle morphology, size, and density were evaluated. Orthodontic adhesives with increasing loading percentage of Zn-PBG powder were prepared: ZnPG3 (3 wt.%), ZnPG6 (6 wt.%), and ZnPG9 (9 wt.%). Brackets were bonded on the etched enamel surface and stored in distilled water (DW) for 1 h. Following, Shear bond strength (SBS) along with adhesive remnant index were analyzed. The release of calcium (Ca), phosphorus (P), and zinc (Zn) from adhesive specimens in DW was evaluated after 7, 15 and 30 days of immersion. The remineralization effect was confirmed by microhardness and surface morphology analysis with scanning electron microscopy.

RESULTS

The SBS value was observed between 20 and 22 MPa on enamel surface. The concentration of Ca, P and Zn released in DW increased with loading percentage of Zn-PBG. The microhardness increased in the experimental groups after immersion in artificial saliva for 7 days. Apatite-like crystal formation was observed after 30 days in the ZnPG 9 group.

CONCLUSIONS

The orthodontic adhesive containing Zn-PBG with an optimal SBS performance has an enamel remineralization effect, and therefore can aid in prevention of WSLs.

CLINICAL SIGNIFICANCE

The orthodontic adhesive containing Zn-PBG is clinically advantageous as it can promote remineralization and resist the formation of WSLs that may occur during orthodontic therapy.

Inorganic Compounds as Remineralizing Fillers in Dental Restorative Materials: Narrative Review

Secondary caries is one of the leading causes of resin-based dental restoration failure. It is initiated at the interface of an existing restoration and the restored tooth surface. It is mainly caused by an imbalance between two processes of mineral loss (demineralization) and mineral gain (remineralization). A plethora of evidence has explored incorporating several bioactive compounds into resin-based materials to prevent bacterial biofilm attachment and the onset of the disease. In this review, the most recent advances in the design of remineralizing compounds and their functionalization to different resin-based materials' formulations were overviewed. Inorganic compounds, such as nano-sized amorphous calcium phosphate (NACP), calcium fluoride (CaF₂), bioactive glass (BAG), hydroxyapatite (HA), fluorapatite (FA), and boron nitride (BN), displayed promising results concerning remineralization, and direct and indirect impact on biofilm growth. The effects of these compounds varied based on these compounds' structure, the incorporated amount or percentage, and the intended clinical application. The remineralizing effects were presented as direct effects, such as an increase in the mineral content of the dental tissue, or indirect effects, such as an increase in the pH around the material. In some of the reported investigations, inorganic remineralizing compounds were combined with other bioactive agents, such as quaternary ammonium compounds (QACs), to maximize the remineralization outcomes and the antibacterial action against the cariogenic biofilms. The reviewed literature was mainly based on laboratory studies, highlighting the need to shift more toward testing the performance of these remineralizing compounds in clinical settings.

Remineralization of Artificially Demineralized Human Enamel and Dentin Samples by Zinc-Carbonate Hydroxyapatite Nanocrystals

(1) Background: Decalcified enamel and dentin surfaces can be regenerated with non-fluoride-containing biomimetic systems. This study aimed to investigate the effect of a zinc carbonate-hydroxyapatite-containing dentifrice on artificially demineralized enamel and dentin surfaces. (2) Methods: Human enamel and dentin discs were prepared and subjected to surface demineralization with 30% orthophosphoric acid for 60 s. Subsequently, in the test group (n = 20), the discs were treated three times a day for 3 min with a zinc carbonate-hydroxyapatite-containing toothpaste (biorepair^®). Afterwards, all samples were gently rinsed with PBS (5 s) and stored in artificial saliva until next use. Samples from the control group (n = 20) received no dentifrice-treatment and were stored in artificial saliva, exclusively. After 15 days of daily treatment, specimens were subjected to Raman spectroscopy, energy-dispersive X-ray micro-analysis (EDX), white-light interferometry, and profilometry. (3) Results: Raman spectroscopy and white-light interferometry revealed no significant differences compared to the untreated controls. EDX analysis showed calcium phosphate and silicon dioxide precipitations on treated dentin samples. In addition, treated dentin surfaces showed significant reduced roughness values. (4) Conclusions: Treatment with biorepair^® did not affect enamel surfaces as proposed. Minor mineral precipitation and a reduction in surface roughness were detected among dentin surfaces only.

Promotion Effect of Carboxymethyl Chitosan on Dental Caries via Intrafibrillar Mineralization of Collagen and Dentin Remineralization

Objective: To observe ultrastructural changes during the process of carboxymethyl chitosan (CMC)-mediated intrafibrillar mineralization, we evaluated the biomimetic remineralization potential of CMC in type-I collagen fibrils and membranes, and further explored the bond strength as well as the bond interfacial integrity of the biomimetic remineralized artificial caries-affected dentin (ACAD). Methods: A mineralized solution containing 200 μg/mL CMC was used to induce type-I collagen biomimetic remineralization in ACAD, while traditional mineralization without CMC was used as a control. The process and pattern of mineralization were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) as well as structured illumination microscopy (SIM). The Vickers hardness test was used to quantify the dentin hardness, while the microtensile bond strength (µTBS) test was used to assess the bond strength and durability. The bond interfacial integrity was evaluated by a confocal laser scanning microscope (CLSM). Results: TEM, SEM, and SIM images showed that CMC had a positive effect on stabilizing amorphous calcium phosphate (ACP) and promoting intrafibrillar mineralization, while extrafibrillar mineralization was formed without CMC. Furthermore, hardness evaluation and µTBS proved that CMC significantly increased dentin hardness and bond strength. CLSM indicated that CMC could create a significantly better bond interfacial integrity with less of a micro-gap in ACAD. Significance: CMC possessed the ability to promote intrafibrillar mineralization and remineralization in demineralized caries dentin lesions, as well as improve bond performance, which implied its potential in carious dentin demineralization or dentin hypersensitivity and possibly even as a possible material for indirect pulp-capping, to deal with deep caries. Highlights: CMC possessed the ability to induce intrafibrillar mineralization effectively; the bond strength and bond durability of demineralized caries dentin were improved via CMC-induced remineralization; the CMC-induced remineralization complex is a potential material for indirect pulp-capping, to deal with deep caries.

Remineralization Efficacy of Four Remineralizing Agents on Artificial Enamel Lesions: SEM-EDS Investigation

Dental remineralization represents the process of depositing calcium and phosphate ions into crystal voids in demineralized enamel, producing net mineral gain and preventing early enamel lesions progression. The aim of the present study was to qualitatively and quantitatively compare the remineralizing effectiveness of four commercially available agents on enamel artificial lesions using Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) techniques. Thirty-six extracted third molars were collected and randomly assigned to six groups (n = 6), five of which were suspended in demineralizing solution for 72 h to create enamel artificial lesions, and one serving as control: G1, treated with a mousse of casein phosphopeptide and amorphous calcium−phosphate (CPP-ACP); G2, treated with a gel containing nano-hydroxyapatite; G3, treated with a 5% SF varnish; G4, treated with a toothpaste containing ACP functionalized with fluoride and carbonate-coated with citrate; G5, not-treated artificial enamel lesions; G6, not demineralized and not treated sound enamel. G1−G4 were subjected to pH cycling over a period of seven days. Analyses of the specimens’ enamel surfaces morphology were performed by SEM and EDS. Data were statistically analyzed for multiple group comparison by one-way ANOVA/Tukey’s test (p < 0.05). The results show that the Ca/P ratio of the G5 (2.00 ± 0.07) was statistically different (p < 0.05) from G1 (1.73 ± 0.05), G2 (1.76 ± 0.01), G3 (1.88 ± 0.06) and G6 (1.74 ± 0.04), while there were no differences (p > 0.05) between G1, G2 and G6 and between G4 (2.01 ± 0.06) and G5. We concluded that G1 and G2 showed better surface remineralization than G3 and G4, after 7 days of treatment.

Effect of adhesive coating on calcium, phosphate, and fluoride release from experimental and commercial remineralizing dental restorative materials

This study investigated the potential of adhesive coating for hindering the reactivity of ion-releasing dental restorative materials. Experimental composites were prepared by replacing 10 or 20 wt% of reinforcing fillers with two types of bioactive glass. A glass ionomer, a giomer, and an alkasite were used as representatives of commercial ion-releasing materials. Restorative material specimens were coated with an etch-and-rinse adhesive, 1-step self-etch adhesive, 2-step self-etch adhesive, or left uncoated. The specimens were immersed in a lactic acid solution and ion concentrations were measured in 4 days intervals for 32 days (atomic absorption spectrometry for calcium, UV–Vis spectrometry for phosphate, ion-selective electrode for fluoride, and pH-meter for pH values). The adhesive coating reduced ion release between 0.3 and 307 times, in a significantly material- and adhesive-dependent manner. Fluoride release was most highly impaired, with the reduction of up to 307 times, followed by phosphate and calcium release, which were reduced up to 90 and 45 times, respectively. The effect of different adhesive systems was most pronounced for phosphate release, with the following rankings: uncoated ≥ 2-step self-etch adhesive ≥ 1-step self-etch adhesive ≥ etch-and-rinse adhesive. The differences among adhesives were less pronounced for calcium and fluoride. It was concluded that the resinous adhesive layer can act as a barrier for ion release and diminish the beneficial effects of remineralizing restorative materials.

Effect of enamel-surface modifications on shear bond strength using different adhesive materials

BACKGROUND

This study aimed to investigate the effect of enamel-surface modifications on the shear bond strength between ceramic brackets bonded using different adhesive materials and the enamel surface and to identify the most suitable clinical adhesive and bonding method. Whether the non-acid-etching treatment met the clinical bond strength was also determined.

METHODS

A total of 108 extracted premolars were divided into nine groups (n = 12) based on the different enamel-surface modification techniques (acid etching, deproteinization, and wetting). Group 1 was bonded with Transbond™ XT adhesive, whereas groups 2-9 were bonded with resin-modified glass ionomer cement (RMGIC). The treatment methods for each group were as follows: groups 1 and 2, acid etching; group 3, acid etching and wetting; group 4, acid etching and deproteinization; group 5, acid etching, deproteinization, and wetting; group 6, deproteinization; group 7, deproteinization and wetting; group 8, without treatment; and group 9, wetting. The samples' shear bond strength was measured using an universal testing machine. Adhesive remnant index (ARI) was examined using a stereomicroscope. The enamel-surface morphology was observed with a scanning electron microscope. One-way ANOVA with Tukey's post-hoc test and chi-square test were used for statistical analysis, and p < 0.05 and α = 0.05 were considered statistically significant.

RESULTS

The ARIs of groups 1-5 and 6-9 were statistically significant (p = 0.000). The enamel surface of groups 1-5 was demineralized, and only a tiny amount of protein remained in groups 7 and 8, whereas a thick layer of protein remained in groups 8 and 9.

CONCLUSIONS

RMGIC adhesive did not damage the enamel surface and achieved the required clinical bond strength. The enamel surface was better treated with 5.25% sodium hypochlorite preferably under non-acid-etching conditions.

Nano-Hydroxyapatite Gel and Its Effects on Remineralization of Artificial Carious Lesions

Introduction

Nano-hydroxyapatite gel (NHG) has never been investigated for enamel remineralization. This study evaluated the effects of two concentrations of NHG on remineralization of an artificial carious lesion in comparison with nano-HA toothpaste (NHT) and fluoride varnish (FV).

Materials and Methods

Carious lesions were prepared on 100 enamel samples and divided into 5 groups: FV, NHT, 20% NHG, and 30% NHG. One untreated (NT) group was left as control. The hardness of the surface was evaluated before, during, and after remineralization. Microhardness at various phases and the percent recovery of hardness (%HR) were determined and analyzed with ANOVA. Polarized-light micrographs (PLM) were evaluated for depth of the carious lesion.

Results

Significantly different remineralization capability was indicated for tested agents (p < 0.05). NHT was significantly capable of remineralization greater than NHG, FV, and NT (p < 0.05). No noticeable difference in %HR between 20% NHG and 30% NHG (p > 0.05) was found. Decreasing in the depth of caries lesion was notified by PLM as applying either NHT or NHG as greater than FV, with no reduction in the depth for NT.

Conclusions

Nano-HA both in toothpaste and gel form was capable of remineralization better than fluoride varnish. Comparable remineralization of 20% versus 30% NHG was evidenced. NHG for both concentrations was recommended as a capable remineralizing agent for caries remineralization. Clinical Significance: This study indicated that an application of nano-HA gel is an attractive route to deliver the material and can be more effective and less toxic than conventional formulations and provide its effectiveness directly at the site of action, especially for a noncooperative young child and medicinally intimidated patients who may face with inconvenience in using toothbrush and toothpaste for hygiene control.