Dentin Remineralization Research Articles

Guided tissue remineralization and its effect on promoting dentin bonding

With the deepening of research on condensed matter chemistry, artificially guided demineralized dentin remineralization has changed from a classical remineralization pathway of the thermodynamic deposition mode to a biomimetic mineralization mode. This new mode is more consistent with the biological mineralization process. The biomimetic mineralization model can successfully simulate natural mineralization and restore the microstructure and mechanical properties of demineralized dentin. Therefore, it has a good application value in the treatment of caries and dentin hypersensitivity and adhesive restorations. This paper analyzes the principles of guided tissue remineralization and describes new research findings related to the classical mineralization model and the novel biomaterials developed using the biomimetic mineralization mode in detail. It also describes the application of these principles to improve the dentin bonding system. It thus shares the new findings in guided tissue remineralization applied to dentin bonding systems. Finally, the existing problems in this field and future development directions are proposed.

A novel universal adhesive for improved dentin remineralization with antibiofilm potential against Streptococcus mutans and other cariogenic-pathogens

Dental demineralization is a widespread problem and the main responsible for dental caries and dentin hypersensitivity. Dental caries is a biofilm-driven bacterial infection that causes mineral depletion in enamel and is associated with an increased prevalence of medical rehabilitative polymeric implants. Since existing tissue-engineering methods are incapable of manufacturing synthetic dentin adhesive, modern therapeutic interventions address the remineralization of caries-infected dentin to prevent its inevitable removal. In recent years, magnetic nanoparticle-coated adhesives were known to deliver drugs to the pulp and get better adhesive penetration into dentin. In the present study, we prepared and assessed the effectiveness of antimicrobial peptide (cecropin A) coated Fe3O4-nanoparticle on dentin remineralization, bond strength, and its antibiofilm potential against Streptococcus mutans, is associated with dental caries in humans. Prior to the experiment, the synthesized [email protected]3O4 nanoparticle was characterized and assessed its antibiofilm potential against S. mutans. The transcriptomic approach with qPCR analysis stated that [email protected]3O4 nanoparticle significantly downregulated the expression of biofilm-regulated genes such as GtfB, GtfC, GtfD, VicR, ComDE, and Smu0630 in S. mutans, which validates the outcome of in vitro results. Interestingly, the prepared [email protected]3O4-nanoparticle coated adhesive effectively increased the dentin remineralization and bond strength. Fascinatingly, [email protected]3O4 adhesive significantly hindered the biofilm formation of S. mutans on the dentin surface. Notably, the [email protected]3O4 adhesive accomplished reduced biofilm CFU count, lactic acid production, and biofilm metabolic activity. In addition, the [email protected]3O4 adhesive also reduced the biofilm formation of other caries-associated bacterial pathogens, including S. sobrinus, S. sanguinis, and S. mitis. Overall, the current research found that the [email protected]3O4 adhesive was more effective in remineralizing dentin lesions with antibiofilm potential in order to avoid Streptococcus-derived dental caries.

Aprotinin – Conjugated biocompatible porous nanocomposite for dentine remineralization and biofilm degradation

A nanocomposite (141 nm and +12.46 mV surface charge at pH 2.4) that could provide a single treatment for S. mutans-associated dental carries has been developed. The composite had six components, viz., aprotinin (Apr) that enzymatically inhibits plasmin activity of the bacterium, chitosan (Chi) that inhibits bacterial cell adhesion and biofilm formation, calcium phosphate (CaP) for remineralization of dentine, dexamethasone (DEX) for odontoblast differentiation, collagen (Cen) for crosslinking, and chlorogenic acid (CGA) for bacterial cell death. The structure of nanocomposite (HR SEM) consisted of interconnected pores and was amorphous post incorporation of chitosan. A sustained release of calcium and phosphate ions, lasting from 1 to 20 days at pH 4, an appropriate pH to combat demineralization, was observed, which is essential for remineralization. A 68.79% biofilm degradation was observed after 24 h of treatment, indicating good inhibition of the bacteria. While S. mutans grew well on denture resin specimen, the adhesion was reduced when the specimen was treated with the nanocomposite, indicating deterrence to biofilm formation. 5 Day hemolysis assay revealed red blood cell compatibility of up to 100 μg/25 μL, indicating that the nanocomposite was compatible with RBC. Against L132 cells, cytotoxicity was not observed up to 40 μg/mL for 72 h, a clear indication of non-cytotoxic character of the nanocomposite. CaP(NP)@Chi@CGA@DEX@Cen@Apr nanocomposite thus helps remineralization at cariogenic pH and biofilm degradation of S. mutans.

Fast self-curing α-tricalcium phosphate/β-dicalcium silicate composites beneficial for root canal sealing treatment

Objectivesα-tricalcium phosphate (α-TCP) and β-dicalcium silicate (β-C2S) have attracted much attention since these two types of self-curing Ca-phosphate and Ca-silicate are valuable biomaterials for bone defect or endodontic therapy. However, the injectable paste of their individual with high liquid/solid ratio is junior for root canal sealing due to very long self-setting time, low pH value and/or much volume shrinkage during paste-to-cement transformation. MethodsOur studies evaluated the effect of biphasic ratio, liquid/solid ratio and pH condition of aqueous medium on setting time and mechanical strength of this biphasic composite cement, and also the hydroxyapatite re-mineralization potential and anti-microleakage level of the cements with different α-TCP/β-C2S ratio were explored in vitro. A control group free of paste filler was included in the extracted teeth model. Dentine re-mineralization and microleakage degree were observed by scanning electron microscopy and microCT reconstruction analysis. ResultsIt indicated that the weak acidic solution with pH value of 6.0 may produce a significantly shorter initial setting time (from 90 min to less 20 min) and expected final setting time (<150 min) for the biphasic composite (2:1 or 1:2) in comparison with the pure β-C2S. Notably, the phasic composites exhibited limited microleakage and induced hydroxyapatite mineralization in the dentine tubules. These hydraulic pastes also produced strong alkaline feature and appreciable compressive resistance (12–18 MPa) after setting for a very short time stage. Moreover, a link between the addition of α-TCP leading to fast re-mineralization reaction was established. SignificanceOur findings suggest that the appreciable self-setting and physicochemical properties adaption to root canal sealability make α-TCP/β-C2S composites as preferential candidates for endodontic treatments.

A Dentin Biomimetic Remineralization Material with an Ability to Stabilize Collagen.

The integrity of collagen matrix structure is a prerequisite for effectively inducing biomimetic remineralization. Repeated low pH stimulation activates matrix metalloproteinases (MMPs) in dental caries. Activated MMPs cause the breakdown of collagen fibrils. Collagen stabilization is a major obstacle to the clinical application of remineralization templates. Here, galardin-loaded poly(amido amine) (PAMAM)-NGV (PAMAM-NGV@galardin, PNG) is constructed to induce collagen stabilization and dentin biomimetic remineralization simultaneously, in order to combat early caries in dentin. PAMAM acts in the role of nucleation template for dentin remineralization, while galardin acts as the role of MMPs inhibitor. NGV peptides modified on the surface of dendrimer core can form small clusters with synergistic movement in short range, and those short-range clusters can form domain areas with different properties on the surface of PAMAM core and restrict the movement of collagen, favoring collagen crosslinking, which can be explained through the computational simulation analysis results. NGV peptides and galardin show a dual collagen-protective effect, laying the foundation for the dentin remineralization effect induced by PAMAM. PNG induces dentin remineralization in an environment with collagenase, meanwhile showsing anti-dentin caries efficacy in vivo. These findings indicate that PNG has great potential to combat early dentin caries for future clinical application.

Current strategies for biomimetic remineralization of human dentin: a scoping review

The purpose of this scoping review was to present the published successful techniques and strategies for biomimetic remineralization of human dentin. Studies whose primary objective was to present the strategy of successful dentin biomimetic remineralization were included. No language, participant age, or time restrictions were set. Stud-ies were retrieved via CENTRAL, LILACS, PubMed/MEDLINE, SciELO, SCOPUS and Web of Science. Gray literature searches on Google Scholar and OpenGrey were also conducted to find additional references. Based on the main research objectives, articles were classified by technique according to the methodology used for the research. One hundred forty-five articles, published be-tween 2003 and 2019, were included in the final scoping review. Protocols that imitate dentin's natural mineralization seek to restore lost minerals in dental tissues. Biomimetic remineralization proposes different ways to replace demineralized collagen in dentin by using inorganic materials like natural minerals, with the primary purpose of optimizing the clinical longevity of restorations and improving dental treatment.

The impact of an alkasite restorative material on the pH of Streptococcus mutans biofilm and dentin remineralization: an in vitro study

BackgroundIt has been claimed that an alkasite restorative material can neutralize acids produced by cariogenic bacteria from released hydrogen ions and enable to remineralization via calcium and fluoride ions. However, there is no evidence to support this assertion. Therefore, the aims of this study were to investigate the effect of the alkasite restorative material on the pH of Streptococcus mutans biofilm and dentin hardness.MethodsStreptococcus mutans biofilms were formed on Filtek™ Z350 (FZ, a resin composite) and Cention® N (CN, the alkasite restorative material) and their pH determined after 24 h. Hydroxide, fluoride, and calcium-ions released from the materials were determined at 6 h, 1, 3, 7, 14, and 28 days. Dentin specimens were prepared from 14 human molars and divided into four quadrants. Quadrant 1 was a sound dentin control, quadrants 2–4 were chemically demineralized, and a cylinder of FZ and CN placed on the surfaces of quadrants 2 and 4, respectively. The microhardness of quadrants 1 and 3 were measured at depths of 20, 40, and 60 µm from the occlusal surface, and similarly of quadrants 2 and 4, after 30 days. Independent t-test, Mann–Whitney-U, and repeated-measure-ANOVA were used for data analysis.ResultsThe pH of biofilm on CN (4.45) was significantly higher (p < 0.05) than that on FZ (4.06). The quantity of all ions released from CN was significantly higher than from FZ. The hardness of demineralized dentin under CN was significantly higher than that of demineralized dentin at all depths, and higher than that of demineralized dentin under FZ at 20 and 40 µm.ConclusionsCN released hydroxide, fluoride, and calcium ions, which was associated with raising the biofilm pH and the hardness of demineralized dentin. All results indicated that CN had the potential to reduce the incidence of secondary caries.

Evaluation of the effect of a glass ionomer cement containing fluoro-zinc-silicate glass on dentin remineralization using the ultrasonic pulse-echo method

The purpose of this study was to investigate the protective effect of a glass ionomer cement (GIC) consisting of fluoro-zinc-silicate glass on the demineralization of bovine dentin using the ultrasonic pulse-echo method. The findings were compared with those obtained using a conventional GIC. Slabs of dentin from bovine teeth were sliced, shaped into a rectangular form, and immersed in 0.5 M ethylenediaminetetraacetic acid solution at 25ºC for 6 days, followed by storage in distilled water for 3 days. After demineralization, they were immersed in artificial saliva with and without the GIC specimens. The propagation times of the longitudinal ultrasonic waves in the samples were measured. The ultrasonic velocities of the fluoro-zinc-silicate glass-containing GICs were significantly increased 2-3 days after the start of the experiment and showed an upward trend thereafter. These findings indicate that the GICs containing fluoro-zinc-silicate glass might exhibit the potential to promote remineralization in the dentin.

Fluoride and trimetaphosphate association as a novel approach for remineralization and antiproteolytic activity in dentin tissue

ObjectiveThe study evaluated the effect of solutions containing fluoride (F) and/or sodium trimetaphosphate (TMP) and F/TMP on the inhibition of MMP-2 and MMP-9, and on dentin remineralization in vitro. DesignBovine root dentin blocks were prepared, and caries-like lesions were induced in two thirds of the surface. Blocks were then randomly divided into 13 groups/solutions (n = 10): Placebo; 0.3 %, 1 % and 3 % NaOH-hydrolyzed TMP; 0.3 %, 1 % and 3 % TMP; 250, 500 and 1100 ppm F; 250 ppm F + 0.3 % TMP; 500 ppm F + 1 % TMP and 1100 ppm F + 3 % TMP. One third of each specimen was treated with the respective solutions in pH-cycling. The mineral concentration (gHAp × cm−3 × µm) was determined by computed X-ray microtomography, and data submitted to ANOVA and Student-Newman-Keuls’ test (p < 0.05). The ability of the solutions to inhibit MMP-2 and MMP-9 activity was assessed by zymography. ResultsF/TMP association led to less mineral loss in the deeper region of the lesion and reduced the depth of lesions when compared to its counterpart without TMP (p < 0.001). 3 % TMP (hydrolyzed or not), 500 ppm F and 1100 ppm F completely inhibited MMP-2 activity, while for MMP-9 such effects were only achieved by treatment with 1100 ppm F + 3 % TMP. ConclusionTreatment with 1100 ppm F + 3 % TMP fully inhibits the gelatinolytic activity of MMPs-2 and − 9 and shows greater remineralizing capacity in artificial caries lesions in dentin. However, hydrolyzing TMP does not improve its anti-proteolytic activity and its remineralizing capacity.

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.

Caries-affected dentin remineralization using Natural marine-based gels

Caries-affected dentin remineralization using Natural marine-based gels

Assessment of the remineralisation induced by contemporary ion-releasing materials in mineral-depleted dentine.

Evaluate the ability of currention-releasing materials to remineralise bacteria-driven artificial caries lesions. Standardised class I cavities were obtained in 60 extracted human molars. Specimens underwent a microbiological cariogenic protocol (28days) to generate artificial caries lesions and then were randomly divided into four restorative groups: adhesive + composite (negative control); glass ionomer cement (GIC); calcium silicate cement (MTA); and resin-modified calcium silicate cement (RMTA). Microhardness analysis (ΔKHN) was performed on 40 specimens (10/group, t = 30days, 45days, 60days in artificial saliva, AS). Micro-CT scans were acquired (3/group, t = 0days, 30days, and 90days in AS). Confocal microscopy was employed for interfacial ultra-morphology analysis (2/group, t = 0days and 60days in AS). Additional specimens were prepared and processed for scanning electron microscopy (SEM) and FTIR (n = 3/group + control) to analyse the ability of the tested materials to induce apatite formation on totally demineralised dentine discs (60days in AS). Statistical analyses were performed with a significance level of 5%. Adhesive + composite specimens showed the lowest ΔKHN values and the presence of gaps at the interface when assessed through micro-CT even after storage in AS. Conversely, all the tested ion-releasing materials presented an increase in ΔKHN after storage (p < 0.05), while MTA best reduced the demineralised artificial carious lesions gap at the interface. MTA and RMTA also showed apatite deposition on totally demineralised dentine surfaces (SEM and FTIR). All tested ion-releasing materials expressed mineral precipitation in demineralised dentine. Additionally, calcium silicate-based materials induced apatite precipitation and hardness recovery of artificial carious dentine lesions over time. Currention-releasing materials can induce remineralisation of carious dentine. MTA shows enhanced ability of nucleation/precipitation of hydroxyapatite compared to RMTA and GIC, which may be more appropriate to recover severe mineral-depleted dentine.

Recent Advances in Direct Adhesive Restoration Resin-Based Dental Materials With Remineralizing Agents

Resin-based dental materials are popular restorative materials especially in direct adhesive restoration because of the excellent mechanical and esthetic properties. Toward the realization of minimally invasive dental procedures, direct composite resin adhesive restoration has become the main treatment for dental defects. In addition, for caries-affected dentin close to the pulp, conservation remineralization has been advocated to save the living pulp. However, the resin–dentin interface can be destabilized by various factors, especially the enzymatic degradation of collagen fibrils within the hybrid layer and polymer hydrolysis. Furthermore, for resin-based restorative materials, the marginal gap remains a major problem that can lead to the occurrence of secondary caries. To address these issues, research efforts have focused on the remineralization of mineral-depleted dental hard tissues using remineralizing bioactive substances. In this review, we first described various bioactive agents with remineralizing properties. Furthermore, we discussed recent advances in resin-based dental materials for enamel or dentin remineralization. Finally, we examined the current challenges and prospects of these emerging materials. This work aims to provide a theoretical foundation for the future development of resin-based dental materials in direct adhesive restoration with remineralizing agents.

Self-assembly peptide P11-4 induces mineralization and cell-migration of odontoblast-like cells

ObjectivesSelf-assembling peptide P11-4 is amphiphilic and pH-triggered, effective on repairing early enamel carious lesions and dentin remineralization. However, P11-4 effects on dentin biomineralization and repair ability remain unexplored. Thus, cytocompatibility and effectiveness of P11-4 on inducing mineralization and migration of odontoblast-like cells (MDPC-23) were investigated. MethodsMDPC-23 were seeded in contact with P11-4 (0.5 and 1 µg/ml), Dentin Matrix Protein 1 (DMP1 0.5 and 1 µg/ml) or Calcium hydroxide (Ca(OH)2 100 µg/ml) solutions. Cell viability was verified using MTT (n = 6/group). Mineral deposition was tested using Alizarin Red (n = 4/group). Cell migration was assessed by light microscopy (n = 2/group). MTT and Alizarin Red data were compared using Kruskal-Wallis and Mann-Whitney (α=0.01). ResultsP11-4 (0.5 and 1 µg/ml) and DMP1 (0.5 and 1 µg/ml) resulted the highest cell viability; Ca(OH)2 presented the lowest. 1 µg/ml DMP1 and 1 µg/ml P11-4 promoted the highest mineral deposition. Ca(OH)2 presented lower values of mineral deposits than DMP1 1 µg/ml (p < 0.01), but similar to P11-4 1 µg/ml. P11-4 and DMP1 at 0.5 µg/ml induced lesser mineral precipitation than P11-4 and DMP1 at 1 µg/ml (p < 0.01), with no difference to Ca(OH)2. All materials stimulated cell migration, however, lower concentrations of DMP1 and P11-4 demonstrated a higher migration potential. ConclusionP11-4 did not affect cell viability, induces mineral deposition and MDPC-23 migration like DMP1. Clinical significanceSelf-assembling peptide P11-4 does not affect the cell viability and induces mineral deposition comparable to native protein involved in biomineralization. Combined with its ability to bind type I collagen, P11-4 is a promising bioinspired molecule that provides native-tissue conditions and foster further studies on its ability to form dentin bridges in pulp-capping strategies.

Chlorhexidine-loaded poly (amido amine) dendrimer and a dental adhesive containing amorphous calcium phosphate nanofillers for enhancing bonding durability

ObjectiveA novel method of combining chlorhexidine (CHX) loaded poly (amido amine) (PAMAM) dendrimers with a dental adhesive containing amorphous calcium phosphate (ACP) nanofillers are proposed for etch-and-rinse bonding system to enhance resin-dentin bonding durability. MethodsThe CHX-loaded PAMAM and ACP nanofillers were synthesized and characterized. Their effects on the cytotoxicity were tested by MTT assay. Micro-tensile bond strength (μTBS) before and after thermomechanical challenges were used to evaluate the bonding durability. Anti-matrix metalloproteinase (MMPs) property was examined using in-situ zymography. A double-fluorescence technique was used to examine interfacial permeability after bonding. Dentin remineralization in Ca/P lacking solution was observed under scanning electron microscopy. ResultsCompared with a 0.2 wt% CHX solution, the PAMAM loaded CHX had less cytotoxicity, while the in situ zymography showed it could still inhibit MMPs activity within the hybrid layer after released from PAMAM. The application of the novel method maintained the μTBS better than the control group after thermomechanical challenges, and it did not negatively affect water permeability of the bonding interfaces. CHX-loaded PAMAM regulated the calcium (Ca) and phosphate (P) ions provided by the ACP-containing adhesives to remineralize the demineralized dentin surfaces without initial Ca/P in the environment. SignificanceThe novel method can reduce the cytotoxicity of CHX, inhibit MMPs activities, maintain μTBS, and induce dentin remineralization, which are crucial factors for enhancing bonding durability.

Correlation between Two Evaluation Methods for the Effect of Two Desensitizing Materials: An In Vitro Study

AIM: This study was conducted to assess the efficiency of enamel matrix derivative (EMD) on dentin remineralization at two different application times. MATERIALS AND METHODS: Thirty-two human dentin specimens of 1 mm thickness were prepared and randomly divided into two groups according to the treatment material (M) used: fluoride varnish with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (M1) and Enamel matrix derivative (EMD) (M2). Following treatment, each group was subdivided into two subgroups (n = 8) based on the storage time in artificial saliva into: (S); subgroup (S1); storage for 15 days and subgroup (S2); storage for 30 days. Dentin permeability was measured for all specimens at baseline and after applying the treatment protocol. All specimens were photomicrographed using ESEM before and after the treatment protocol. RESULTS: The highest permeability reduction percent mean value was recorded for M1S2 specimens (90% ± 20), with a statistically significant difference with other subgroups, followed by subgroup M2S2 (56% ± 8) and subgroup M1S1 (51% ± 11), respectively. Meanwhile, the subgroup M2S1 had the lowest mean value (36% ± 9). In addition, the dentin permeability test was confirmed by the ESEM results. CONCLUSION: EMD could be used as a promising remineralizing agent for dentin remineralization.

Effect of Diode Laser versus a Combination of Sodium Trimetaphosphate with Polyacrylic Acid on Obliteration of Dentinal Tubules: An In Vitro Study

BACKGROUND: Irradiation with diode laser and biomimetic remineralization are important methods in the treatment of hypersensitivity and dentin remineralization. AIM: The aim of the study was evaluation of the effect of diode laser versus the effect of sodium trimetaphosphate (STMP) with polyacrylic acid (PAA) on obliteration of dentinal tubules (DT). MATERIALS AND METHODS: Sixty dentin discs with a thickness of 2 mm were prepared and conditioned with EDTA for 15 s. Then, all dentin discs were divided into three main groups (20 discs each) according to the treatment method; control, diode laser treated, and STMP with PAA group (biomimetic group). Each group was subdivided into four subgroups (five discs each) according to the storage time; 2 h (To), 1 month (T1), 2 months (T2), and 3 months (T3), respectively. All samples were prepared to be analyzed after each time interval using environmental scanning electron microscope (ESEM). Comparison of differences of DT obliteration percentage made on each group before and after the treatment were performed using computer-assisted digital image analysis. RESULTS: Control group showed the least DT obliteration percentage, the samples of laser group recorded statistically significant increase in DT obliteration percentage at To in comparison to the biomimetic group. Meanwhile, at T1, there was no statistically significant difference between both laser and biomimetic groups. However, statistically significant decrease was recorded in laser group at T2 and T3, respectively. CONCLUSION: Irradiation with diode laser and biomimetic remineralization using PAA with STMP are a promising methods to obliterate opened DT effectively.

Remineralization of caries-affected dentin and color stability of teeth restored after treatment with silver diamine fluoride and bioactive glass–ceramic

The aim of this study was to evaluate the microhardness of caries-affected dentin and color stability of teeth restored after treatments with silver diamine fluoride (SDF) associated to potassium iodide (KI) and Biosilicate. Different samples from bovine teeth were obtained. For color readings, 80 cavities (6mm × 6mm × 2mm) were prepared, and for microhardness, teeth were flattened into dentine to obtain 40 samples. All samples were submitted to cariogenic challenge and separated in 4 groups, according to the treatment used: 12% SDF + KI; 38% SDF; Biosilicate and control (no treatment). Cavities were restored with resin-modified glass-ionomer cement (RMGIC, Vitremer, 3M ESPE) or composite resin (CR, Z350, 3M ESPE). After restoration, the samples were submitted to thermo-mechanical cycling (TMC) for 1,200,000 cycles. Color readings (EasyShade, Vita) were performed after restorations, after TMC, and 30days after TMC. Knoop microhardness was evaluated on the planned samples before and after cariogenic challenge, after treatments, and after 30days. Scanning electron microscopy (SEM) evaluated the dentine surface after treatments. Data were analyzed (ANOVA, Bonferroni, p < .05). The results showed a higher color alteration for RMGIC than CR. The time of analysis was significant (p < .05) for the 12% SDF + KI and control group. There was no difference (p < .05) in microhardness between groups. However, there was evidence of dentin remineralization after treatments. It was concluded that the samples treated with Biosilicate resulted in a color alteration similar to control. The treatments presented dentin remineralizing potential for microhardness, below the demineralization level, caused by the cariogenic challenge. Considering the remineralizing potential presented by Biosilicate, this agent is a promising alternative that overcomes the SDF adverse effects such as tooth staining.

Chlorhexidine gluconate enhances the remineralization effect of high viscosity glass ionomer cement on dentin carious lesions in vitro

BackgroundTo compare the mean mineral density (MMD) and examine the remineralization of carious dentin after cavity disinfection with chlorhexidine gluconate (CHX) and restoration with high viscosity glass ionomer cement (H-GIC) in vitro.MethodsSelective caries removal to leathery dentin was performed in 40 extracted primary molars. The samples were scanned using micro-computed tomography (micro-CT) to determine the MMD baseline and randomly divided into 4 groups (n = 10): Equia™ group, applied dentin conditioner and restored with H-GIC (Equia Forte™), CHX-Equia™ group, disinfected the cavity with 2% CHX before applying dentin conditioner and restored with H-GIC (Equia Forte™), Ketac™ group, restored with H-GIC (Ketac Universal™) and CHX-Ketac™ group, disinfected the cavity with 2% CHX before restored with H-GIC (Ketac Universal™). The samples underwent micro-CT scanning post-restoration and post-pH-cycling to determine their respective MMDs. One sample from each group was randomly selected to analyze by scanning electron microscopy (SEM).ResultsThe MMD gain in the 4 groups post-restoration was significantly different between the Equia™ and CHX-Ketac™ groups (oneway ANOVA with Post hoc (Tukey) test, P = 0.045). There was a significant difference in MMD gain post-restoration between the Equia™ and CHX-Equia™ groups (Independent t-test, P = 0.046). However, the Ketac™ and CHX-Ketac™ group’s MMD were similar. The SEM images revealed that the CHX-Ketac™ group had the smallest dentinal tubule orifices and the thickest intertubular dentin among the groups. However, the CHX-Equia™ group had thicker intertubular dentin than the Equia™ group.ConclusionApplying 2% CHX on demineralized dentin enhances the remineralization of the dentin beneath the restoration.

Biomimetic remineralization of human dentine via a “bottom-up” approach inspired by nacre formation

Nacre exhibited noticeable similarities in fundamental material buildup and biological characteristics with tooth hard tissue, so the present study aims to achieve bionic dentine remineralization by duplicating nacre's “bottom-up” assembly concept. Inspired by nacre's mineralization mechanism, the present project starts to synthesize a “seawater-like” mineralizing precursor medium, then monitor its in vitro dentinal tubules occlusion effect, acid-resistant stability, the “fingerprint” dynamic components change in real time on in vitro sensitive tooth model as well as its in vitro cellular biological response towards human dental pulp stem cells. For the further exploration, a single-layer fibrillar collagen model was established to simulate the exposed collagen of demineralized dentine to appraise its intrafibrillar mineralization effect. The results demonstrated that the application of “seawater-like” mineralizing precursor medium effectively occluded dentinal tubules, reduced dentine permeability, increased surface microhardness, provided certain acid-resistant stability and possessed favorable in-vitro biocompatibility. In addition, the dynamic procedure of hierarchical intrafibrillar nanocrystalline assembly was observed, which offered a clue to uncover its remineralizing mechanism. It is attainable to realize the biomimetic remineralization of human dentine via the “bottom-up” concept inspired by nacre structure duplication, suggesting great potential for providing dentists a therapeutic strategy to counter dentine hypersensitivity in the future.