8DSS-promoted remineralization of initial enamel caries in vitro

Application of a calcium and phosphorus biomineralization strategy in tooth repair: a systematic review

Biomineralization is a natural process in which organisms regulate the growth of inorganic minerals to form biominerals with unique layered structures, such as bones and teeth, primarily composed of calcium and phosphorus. Tooth decay significantly impacts our daily lives, and the key to tooth regeneration lies in restoring teeth through biomimetic approaches, utilizing mineralization strategies or materials that mimic natural processes. This review delves into the types, properties, and transformations of calcium and phosphorus minerals, followed by an exploration of the mechanisms behind physiological and pathological mineralization in living organisms. It summarizes the mechanisms and commonalities of biomineralization and discusses the advancements in dental biomineralization research, guided by insights into calcium and phosphorus mineral biomineralization. This review concludes by addressing the current challenges and future directions in the field of dental biomimetic mineralization.

The Synergistic Effect of High Intensity Focused Ultrasound on In-vitro Remineralization of Tooth Enamel by Calcium Phosphate Ion Clusters

Background

Remineralization of dental enamel is an important intervention strategy for the treatment of demineralized lesions. Existing approaches have limitations such as failure to adequately reproduce both the ideal structural and mechanical properties of the native tooth. The ability of ultrasound to control and accelerate the crystallization processes has been widely reported. Therefore, a new approach was explored for in-vitro enamel remineralization involving the synergistic effect of high-intensity focused ultrasound (HIFU) coupled with calcium phosphate ion clusters (CPICs).

Methods

The demineralized enamel was treated with CPICs, with or without subsequent HIFU exposure for different periods (2.5, 5, and 10 min). The specimens were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The surface hardness and crystallographic properties of the treated specimens were evaluated using Vickers microhardness testing and X-ray diffraction (XRD), respectively.

Results

SEM revealed distinct, organized, and well-defined prismatic structures, showing clear evidence of remineralization in the combined CPIC/HIFU treatment groups. AFM further revealed a decrease in the surface roughness values with increasing HIFU exposure time up to 5 min, reflecting the obliteration of interprismatic spaces created during demineralization. The characteristic Raman band at 960 cm-1 associated with the inorganic phase of enamel dominated well in the HIFU-treated specimens. Importantly, microhardness testing further demonstrated that new mineral growth also recovered the mechanical properties of the enamel in the HIFU-exposed groups. Critical to our aspirations for developing this into a clinical process, these results were achieved in only 5 min.

Conclusion

HIFU exposure can synergise and significantly accelerate in-vitro enamel remineralization process via calcium phosphate ion clusters. Therefore, this synergistic approach has the potential for use in future clinical interventions.

The Potential of QP3VH-Chitosan Peptide as Biomimetic Remineralization in Early Dental Caries Treatment: An In Vitro Study

OBJECTIVES

 The development of remineralization biomimetics using organic peptide molecules is expected to resemble the hydroxyapatite (HA) mineralization process in tooth enamel. The development of an amelogenin derivative peptide combined with antimicrobial peptide was designed, resulting in QP3VH. This combination then was mixed with chitosan as a carrier. This study aimed to evaluate the biomimetic efficacy of QP3VH as a remineralizing agent combined with chitosan.

MATERIALS AND METHODS

 Fifty deciduous mandibular incisor enamel samples were used in this study. The artificial enamel lesions were created on a buccal surface and were randomly assigned to five groups of 10 each according to the remineralizing agent used: QP3VH, NaF, QP3VH + NaF, QP3VH + CS (QP3VH + chitosan), and saline distilled water (SDW). Each group was performed pH cycling for seven days. Enamel surface morphology and evaluation of mineral content Ca/P (calcium and phosphate) using scanning electron microscopy and energy dispersive X-ray analysis. The assessment was carried out, after demineralization, and after application with remineralization agents.

STATISTICAL ANALYSIS

 Data were analyzed using a one-way analysis of variance followed by least significance difference post-hoc test. The paired t-test was utilized to compare the demineralization and remineralization results. The significance level used was 95%.

RESULTS

 The remineralized group exhibited a significant increase in calcium and phosphate content on the enamel surface (p <0.05), and QP3VH + CS produced the maximum Ca/P mass percent after remineralization.

CONCLUSION

 Combining QP3VH with chitosan produces greatest remineralization than QP3VH, QP3VH + NaF, Naf, and SDW; therefore, QP3VH peptide has potential as a remineralizing agent, in the future.

Remineralizing effects of hydroxypropyl methylcellulose film-loaded amorphous calcium phosphate nanoprecursors on enamel artificial caries lesions

OBJECTIVES

This study was to investigate hydroxypropyl methylcellulose (HPMC) film as a carrier for amorphous fluorinated calcium phosphate (AFCP) nanoprecursors to continuously deliver biomimetic remineralization of enamel artificial caries lesions (ACL).

MATERIALS AND METHODS

The AFCP/HPMC films were comprised of 25 wt% AFCP nanoparticles and 75 wt% HPMC. They were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and biocompatibility tests. Forty enamel ACL were prepared and randomly divided into four groups (n = 10): The enamel surfaces were covered with a pure HPMC film, Tooth Mousse Plus (contains 10% CPP-ACP and 0.2% NaF), and AFCP/HPMC film, or without any things (serving as negative control). Subsequently, all samples were alternatively kept in artificial saliva and a modified pH-cycling before they were characterized by Micro-CT, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), attenuated total reflectance (ATR)-FTIR, XRD, and nanoindentation.

RESULTS

After the enamel ACL was challenged by pH cycling, Tooth Mousse Plus and AFCP/HPMC film groups exhibited less lesion depth and mineral loss than the negative control and pure HPMC film groups. Additionally, the AFCP/HPMC film group revealed a highest remineralization rate of 55.34 ± 3.10 % among the all groups (p < 0.001). The SEM findings showed that the enamel ACL were densely deposited with minerals in the AFCP/HPMC film group, and the EDX results suggested a higher content of fluorine in the remineralized tissues. In particular, the AFCP/HPMC film group exhibited the best nanomechanical performance after 2 weeks of pH cycling (p < 0.05), with the hardness (H) restored from 0.29 ± 0.19 to 2.69 ± 0.70 GPa, and elastic modulus (Er) restored from 10.77 ± 5.30 to 68.83 ± 12.72 GPa.

CONCLUSION

The AFCP/HPMC film might be used as a promising strategy for arresting or reversing incipient enamel caries lesions.

Reinforced dentin remineralization via a novel dual-affinity peptide

OBJECTIVES

In light of the constantly flowing saliva, anti-caries remineralization agents are inclined to be taken away. Owing to their limited residence time, the remineralization effect is not as desirable as expected. Hence, our study aimed to synthesize a novel peptide (DGP) with high affinity to both collagen fibrils and hydroxyapatite, and investigated its dentin remineralization efficacy in vitro and anti-caries capability in vivo.

METHODS

DGP was synthesized through Fmoc solid-phase reaction. The binding ability and interaction mechanism of DGP to demineralized dentin were investigated. Dentin specimens were demineralized, then treated with DGP and deionized water respectively. The specimens were incubated in artificial saliva and in-vitro remineralization effectiveness was analyzed after 14 days. The rat caries model was established to further scrutinize the in-vivo efficacy of caries prevention.

RESULTS

DGP possesses an enhanced adhesion force of 12.29 ± 1.12 nN to demineralized dentin. The favorable adsorption capacity is ascribed to the stable hydrogen bonds between S2P-101 and ASP-100 of DGP and GLY33 and PRO-16 of collagen fibers. Abundant mineral deposits and remarkable tubule occlusion were observed in the DGP group. DGP-treated dentin obtained notable microhardness recovery and higher mineral content after a 14-day remineralization regimen. DGP also demonstrated potent caries prevention in vivo, with substantially fewer carious lesions and significantly lower Keyes scoring.

SIGNIFICANCE

DGP proves to possess a high affinity to demineralized dentin regardless of saliva flowing, thus enhancing remineralization potency significantly in vitro and in vivo, potential for dental caries prevention and combatting initial dentin caries clinically.

Synthetic extracellular matrices with function-encoding peptides

The communication of cells with their surroundings is mostly encoded in the epitopes of structural and signalling proteins present in the extracellular matrix (ECM). These peptide epitopes can be incorporated in biomaterials to serve as function-encoding molecules to modulate cell-cell and cell-ECM interactions. In this Review, we discuss natural and synthetic peptide epitopes as molecular tools to bioengineer bioactive hydrogel materials. We present a library of functional peptide sequences that selectively communicate with cells and the ECM to coordinate biological processes, including epitopes that directly signal to cells, that bind ECM components that subsequently signal to cells, and that regulate ECM turnover. We highlight how these epitopes can be incorporated in different biomaterials as individual or multiple signals, working synergistically or additively. This molecular toolbox can be applied in the design of biomaterials aimed at regulating or controlling cellular and tissue function, repair and regeneration.

A novel amelogenesis-inspired hydrogel composite for the remineralization of enamel non-cavitated lesions

Enamel non-cavitated lesions (NCLs) are subsurface enamel porosity from carious demineralization. The developed enamel cannot repair itself once NCLs occurs. The regeneration of mineral crystals in a biomimetic environment is an effective way to repair enamel subsurface defects. Previously, an amelogenin-derived peptide named QP5 was proven to repair demineralized enamel. In this work, inspired by amelogenesis, a novel biomimetic hydrogel composite containing the QP5 peptide and bioactive glass (BG) was designed, in which QP5 could promote enamel remineralization by guiding the calcium and phosphorus ions provided by BG. Also, BG could adjust the mineralization micro-environment to alkalinity, simulating the pH regulation of ameloblasts during enamel maturity. The BQ hydrogel composite showed biosafety and possessed capacity for enamel binding, ion release and pH buffering. Enamel NCLs treated with the BQ hydrogel composite showed a higher reduction in lesion depth and mineral loss both in vitro and in vivo. Moreover, compared to the hydrogels containing only BG or QP5, groups treated with the BQ hydrogel composite attained more surface microhardness recovery and color recovery, exhibiting resistance to erosion and abrasion of the remineralization layer. We envision that the BQ hydrogel composite can provide a biomimetic micro-environment to favor enamel remineralization, thus reducing the lesion depth and increasing the mineral content as a promising biomimetic material for enamel NCLs.

Advanced materials for enamel remineralization

Dental caries, a chronic and irreversible disease caused by caries-causing bacteria, has been listed as one of the three major human diseases to be prevented and treated. Therefore, it is critical to effectively stop the development of enamel caries. Remineralization treatment can control the progression of caries by inhibiting and reversing enamel demineralization at an early stage. In this process, functional materials guide the deposition of minerals on the damaged enamel, and the structure and hardness of the enamel are then restored. These remineralization materials have great potential for clinical application. In this review, advanced materials for enamel remineralization were briefly summarized, furthermore, an outlook on the perspective of remineralization materials were addressed.

Dual-functional adhesive containing amorphous calcium phosphate nanoparticles and dimethylaminohexadecyl methacrylate promoted enamel remineralization in a biofilm-challenged environment

OBJECTIVE

The cariogenic biofilm on enamel, restoration, and bonding interface is closely related to dental caries and composite restoration failure. Enamel remineralization at adhesive interface is conducive to protecting bonding interface and inhibiting secondary caries. This study intended to assess the remineralization efficiency of adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) on initial caries lesion of biofilm-coated enamel.

METHODS

Artificial initial carious lesion was created via 72-hour immersion in demineralization solution and cariogenic biofilm was formed after 24-hour culture of Streptococcus mutans (S. mutans). Specimens were then divided into 4 groups: enamel control, enamel treated with NACP, DMAHDM and NACP+DMAHDM respectively. Samples next underwent 7-day cycling, 4 h in BHIS (brain heart infusion broth containing 1 % sucrose) and 20 h in AS (artificial saliva) per day. The pH of BHIS was tested daily. So did the concentration of calcium and phosphate in BHIS and AS. Live/dead staining, colony-forming unit (CFU) count, and lactic acid production of biofilms were measured 7 days later. The enamel remineralization efficiency was evaluated by microhardness testing and transverse microradiography (TMR) quantitatively.

RESULTS

Enamel of NACP+DMAHDM group demonstrated excellent remineralization effectiveness. And the NACP+DMAHDM adhesive released a great number of Ca²⁺ and PO₄^3- ions, increased pH to 5.81 via acid neutralization, decreased production of lactic acid, and reduced CFU count of S. mutans (P < 0.05).

SIGNIFICANCE

The NACP+DMAHDM adhesive would be applicable to preventing secondary caries, strengthening enamel-adhesive interface, and extending the lifespan of composite restoration.

Polyzwitterion Manipulates Remineralization and Antibiofilm Functions against Dental Demineralization

Biomineralization technology has become a trend for the arrest and prevention of dental caries. In particular, the bioactivity and ability to release large amounts of Ca²⁺ and PO₄^3- ions make amorphous calcium phosphate (ACP) for hard tissue remineralization are highly desired. However, the instability of ACP limits its clinical application. Under continuous bacterial challenge in the oral cavity, the currently developed ACP-based remineralization system lacks the ability to inhibit bacterial adhesion and biofilm formation. Here, a dual-functional nanocomposite with antibiofilm and remineralization properties was designed by combining zwitterionic poly(carboxybetaine acrylamide) (PCBAA) and ACP. The resulting nanocomposite was stable in solution for at least 3 days without any aggregation. The PCBAA/ACP nanocomposite exerted a significant inhibitory effect on the adhesion and biofilm formation of Streptococcus mutans and exhibited bactericidal activities under acidic conditions resulting from bacteria. Moreover, compared with fluoride, this nanocomposite demonstrated superior effects in promoting the remineralization of demineralized enamel and the occlusion of exposed dentinal tubules in vivo and in vitro. The present work provides a theoretical and experimental basis for the use of the PCBAA/ACP nanocomposite as a potential dual-functional agent for arresting and preventing caries.

Advances in biomineralization-inspired materials for hard tissue repair

Biomineralization is the process by which organisms form mineralized tissues with hierarchical structures and excellent properties, including the bones and teeth in vertebrates. The underlying mechanisms and pathways of biomineralization provide inspiration for designing and constructing materials to repair hard tissues. In particular, the formation processes of minerals can be partly replicated by utilizing bioinspired artificial materials to mimic the functions of biomolecules or stabilize intermediate mineral phases involved in biomineralization. Here, we review recent advances in biomineralization-inspired materials developed for hard tissue repair. Biomineralization-inspired materials are categorized into different types based on their specific applications, which include bone repair, dentin remineralization, and enamel remineralization. Finally, the advantages and limitations of these materials are summarized, and several perspectives on future directions are discussed.

Advanced non-fluoride approaches to dental enamel remineralization: The next level in enamel repair management

In modern dentistry, a minimally invasive management of early caries lesions or early-stage erosive tooth wear (ETW) with synthetic remineralization systems has become indispensable. In addition to fluoride, which is still the non-plus-ultra in these early caries/ETW treatments, a number of new developments are in the test phase or have already been commercialized. Some of these systems claim that they are comparable or even superior to fluoride in terms of their ability to remineralize enamel. Besides, their use can help avoid some of the risks associated with fluoride and support treatments of patients with a high risk of caries. Two individual non-fluoride systems can be distinguished; intrinsic and extrinsic remineralization approaches. Intrinsic (protein/peptide) systems adsorb to hydroxyapatite crystals/organics located within enamel prisms and accumulate endogenous calcium and phosphate ions from saliva, which ultimately leads to the re-growth of enamel crystals. Extrinsic remineralization systems function on the basis of the external (non-saliva) supply of calcium and phosphate to the crystals to be re-grown. This article, following an introduction into enamel (re)mineralization and fluoride-assisted remineralization, discusses the requirements for non-fluoride remineralization systems, particularly their mechanisms and challenges, and summarizes the findings that underpin the most promising advances in enamel remineralization therapy.

Mussel-inspired self-assembly engineered implant coatings for synergistic anti-infection and osteogenesis acceleration

Implant associated infections (IAI) and poor osseointegration are the two major causes for titanium implant failure, leading to subsequent financial burden and physical sufferings. Therefore, advanced implants with excellent anti-infection and osseointegration performance are needed. In this work, mussel-inspired tannic acid (TA) mediated layer-by-layer (LbL) self-assembly was used for fabricating bonded polyethylene glycol (PEG) and 8DSS (8 repeating units of aspartate-serine-serine) coatings (Ti/8DSS/PEG) on the surface of titanium implants. The coating is designed to simultaneously reduce bacterial adhesion through the super-hydrophilic effect of PEG and promote osseointegration through the effective biomineralization of 8DSS. The obtained Ti/8DSS/PEG implant exhibits superior anti-biofouling capabilities (anti-protein adhesion and anti-bacterial adhesion against S. aureus and E. coli) and excellent biocompatibility. Meanwhile, the Ti/8DSS/PEG implant accelerates osteoblast differentiation and presents significantly better osteogenic ability than bare titanium implants in vivo. This mussel-inspired TA mediated LbL self-assembly method is expected to provide a multifunctional and robust platform for surface engineering in bone repair.

Dentin remineralization in acidic solution without initial calcium phosphate ions via poly(amido amine) and calcium phosphate nanocomposites after fluid challenges

OBJECTIVES

A previous study showed that the combination of poly(amido amine) (PAMAM) and rechargeable composites with nanoparticles of amorphous calcium phosphate (NACP) induced dentin remineralization in an acidic solution with no initial calcium (Ca) and phosphate (P) ions, mimicking the oral condition of individuals with dry mouths. However, the frequent fluid challenge in the oral cavity may decrease the remineralization capacity. Therefore, the objective of the present study was to investigate the remineralization efficacy on dentin in an acid solution via PAMAM + NACP after fluid challenges for the first time.

METHODS

The NACP nanocomposite was stored in a pH 4 solution for 77 days to exhaust its Ca and P ions and then recharged. Demineralized dentin samples were divided into four groups: (1) control dentin, (2) dentin coated with PAMAM, (3) dentin with recharged NACP composite, and (4) dentin with PAMAM + recharged NACP. PAMAM-coated dentin was shaken in phosphate-buffered saline for 77 days to desorb PAMAM from dentin. Samples were treated in pH 4 lactic acid with no initial Ca and P ions for 42 days.

RESULTS

After 77 days of fluid challenge, PAMAM failed to prevent dentin demineralization in lactic acid. The recharged NACP nanocomposite raised the pH to above 6.5 and re-released more than 6.0 and 4.0 mmol/L Ca and P ions daily, respectively, which inhibited further demineralization. In contrast, the PAMAM + NACP combined method induced great dentin remineralization and restored the dentin microhardness to 0.54 ± 0.04 GPa, which approached that of sound dentin (P = 0.426, P > 0.05).

CONCLUSIONS

The PAMAM + NACP combination achieved dentin remineralization in an acid solution with no initial Ca and P ions, even after severe fluid challenges.

CLINICAL RELEVANCE

The novel PAMAM + NACP has a strong and sustained remineralization capability to inhibit secondary caries, even for individuals with dry mouths.

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

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

A novel anticaries agent, honokiol-loaded poly(amido amine) dendrimer, for simultaneous long-term antibacterial treatment and remineralization of demineralized enamel

OBJECTIVE

Existing agents to induce enamel self-repair and inhibit the progression of dental caries in the early stage have been proven to be inadequate and far from satisfactory. In this study, a honokiol-loaded poly(amido amine) (PAMAM) dendrimer (PAMH) was constructed to combat early caries lesions in enamel.

METHODS

PAMH was prepared via a codissolution method. Computational simulation analysis was used to explore the mechanism of honokiol release. The cytotoxicity of PAMH was tested. The antibacterial effects of PAMH were tested by planktonic growth assays and biofilm formation inhibition assays. The remineralization effect of PAMH was examined via transverse microradiography and scanning electron microscopy after a pH cycling model. The in vivo anti-caries effect of PAMH was carried out in a rat model.

RESULTS

Honokiol released from PAMH was slower but more durable in a cariogenic pH environment than in a neutral pH environment, which could be explained through the computational simulation analysis results. Under electrostatic action, P3 beads with the same charge repelled each other and extended outwards, resulting in the rapid expansion of the PAMAM dendrimer and accelerating the release of the drug. At a low pH of 5.5, the protonated P3 beads were not charged and the protonated P1 beads were positively charged. However, the electrostatic repulsive interaction between protonated P1 beads was restricted by the P3 beads in the outermost layer of the PAMAM dendrimer, so the swelling rate was relatively slow, resulting in the slow release of drug molecules in the acidic environment. The cytotoxicity demonstration and the biocompatibility experiment in animal study showed that PAMH is biologically safe. PAMH showed excellent enamel remineralizing ability after pH cycling and showed a long-term antibacterial effect in vitro. Meanwhile, PAMH showed long-term anticaries efficacy in vivo.

SIGNIFICANCE

Our findings indicated that PAMH had great potential to combat early caries lesions in enamel for future clinical application.

Remineralization effectiveness of adhesive containing amorphous calcium phosphate nanoparticles on artificial initial enamel caries in a biofilm-challenged environment

OBJECTIVES

Dental caries is closely associated with acid-producing bacteria, and Streptococcus mutans is one of the primary etiological agents. Bacterial accumulation and dental demineralization lead to destruction of bonding interface, thus limiting the longevity of composite. The present study investigated remineralization effectiveness of adhesive containing nanoparticles of amorphous calcium phosphate (NACP) in a stimulated oral biofilm environment.

METHODS

The enamel blocks were immersed in demineralization solution for 72 h to imitate artificial initial carious lesion and then subjected to a Streptococcus mutans biofilm for 24 h. All the samples then underwent 4-h demineralization in brain heart infusion broth with sucrose (BHIS) and 20-h remineralization in artificial saliva (AS) for 7 days. The daily pH of BHIS after 4-h incubation, lactic acid production, colony-forming unit (CFU) count, and content of calcium (Ca) and phosphate (P) in biofilm were evaluated. Meanwhile, the remineralization effectiveness of enamel was analyzed by X-ray diffraction (XRD), surface microhardness testing, transverse microradiography (TMR) and scanning electron microscopy (SEM).

RESULTS

The NACP adhesive released abundant Ca and P, achieved acid neutralization, reduced lactic acid production, and lowered CFU count (P < 0.05). Enamel treated with NACP adhesive demonstrated the best remineralization effectiveness with remineralization value of 52.29 ± 4.79% according to TMR. Better microhardness recovery of cross sections and ample mineral deposits were also observed in NACP group.

CONCLUSIONS

The NACP adhesive exhibited good performance in remineralizing initial enamel lesion with cariogenic biofilm.

SIGNIFICANCE

The NACP adhesive is promising to be applied for the protection of bonding interface, prevention of secondary caries, and longevity prolonging of the restoration.

Anticaries activity of GERM CLEAN in Streptococcus mutans and Candida albicans dual-species biofilm

OBJECTIVE

To evaluate the antimicrobial effects of a peptide containing novel oral spray GERM CLEAN on dual-species biofilm formed by Streptococcus mutans and Candida albicans and to investigate whether GERM CLEAN inhibits the demineralization procedure of bovine enamel in vitro.

METHODS

The antimicrobial effects of GERM CLEAN on dual-species biofilm were analyzed by initial adherence rate calculation, water-insoluble exopolysaccharides quantification, total biomass quantification, and colony-forming units (CFUs) counting. Scanning electron microscopy and confocal laser scanning microscopy were applied to evaluate the impacts of GERM CLEAN on the biofilm structure. Further, the effects of GERM CLEAN on acidogenicity of dual-species were appraised via glycolytic pH drop analysis and hydroxyapatite dissolution measurement. The percentage of Surface Microhardness Reduction (%SMHR) evaluation, Atomic Force Micrograph (AFM) examination, and Transverse Microradiography (TMR) analysis after pH cycling were used to determine whether GERM CLEAN inhibited the demineralization of bovine enamel.

RESULTS

GERM CLEAN decreased the adherence rate, water-insoluble EPS production, biofilm formation, and acidogenicity of the dual-species. Moreover, GERM CLEAN significantly inhibited the demineralization status of bovine enamels.

CONCLUSION

This peptide containing novel oral spray GERM CLEAN has antimicrobial potential toward the dual-species. GERM CLEAN can also impede the demineralization procedure of enamel.

Remineralization of enamel subsurface lesions using toothpaste containing tricalcium phosphate and fluoride: an in vitro µCT analysis

Background

This study aimed to compare the efficacies of experimental toothpastes containing functionalized tricalcium phosphate (fTCP) with and without fluoride for in vitro enamel remineralization under pH-cycling conditions.

Methods

To create artificial white spot lesions, 36 bovine enamel specimens were immersed in a demineralization solution for 10 days. During pH-cycling for 12 days, the specimens were divided into four groups based on the experimental toothpaste type used: (a) fTCP-free, fluoride-free (fTCP − F −); (b) fTCP-containing, fluoride-free (fTCP + F −); (c) fTCP-free, fluoride-containing (fTCP − F +); and (d) fTCP-containing, fluoride-containing (fTCP + F +). Micro-focus X-ray computed tomography (μCT) scans of all specimens were obtained before demineralization, after demineralization, and after pH-cycling. The mineral density and mineral loss (ΔZ) in the enamel subsurface lesions were measured and the percentage of remineralization (%R) was calculated from ΔZ after demineralization and pH-cycling. One-way ANOVA with Tukey’s test was used for statistical analysis of the %R values. The treated enamel surface was investigated via scanning electron microscopy (SEM).

Results

The fTCP − F − group presented with the lowest amount of mineral gain after pH-cycling. In contrast, the fTCP + F + group showed the highest degree of remineralization within all lesion parts. The %R was highest in the fTCP + F + group (38.2 ± 7.8, all P < 0.01). SEM revealed the presence of small crystals on the enamel rods in the fTCP + F − and fTCP + F + groups.

Conclusions

The experimental toothpaste containing fTCP and fluoride increased remineralization of the artificial enamel subsurface lesions during pH-cycling. Furthermore, fTCP and fluoride appear to act independently on the remineralization of enamel subsurface lesions, although they coexisted in one toothpaste type.

Trial registration: This is not a human subject research.

Two-in-one strategy: a remineralizing and anti-adhesive coating against demineralized enamel

Tooth enamel is prone to be attacked by injurious factors, leading to a de/remineralization imbalance. To repair demineralized enamel and prevent pulp inflammation caused by biofilm accumulation, measures are needed to promote remineralization and inhibit bacterial adhesion on the tooth surface. An innovative material, poly (aspartic acid)-polyethylene glycol (PASP-PEG), was designed and synthesized to construct a mineralizing and anti-adhesive surface that could be applied to repair demineralized enamel. A cytotoxicity assay revealed the low cytotoxicity of synthesized PASP-PEG. Adsorption results demonstrated that PASP-PEG possesses a high binding affinity to the hydroxyapatite (HA)/tooth surface. In vitro experiments and scanning electron microscopy (SEM) demonstrated a strong capacity of PASP-PEG to induce in situ remineralization and direct the oriented growth of apatite nanocrystals. Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and Vickers hardness tests demonstrated that minerals induced by PASP-PEG were consistent with healthy enamel in Ca/P ratio, crystal form and surface micro-hardness. Contact angle tests and bacterial adhesion experiments demonstrated that PASP-PEG yielded a strong anti-adhesive effect. In summary, PASP-PEG could achieve dual effects for enamel repair and anti-adhesion of bacteria, thereby widening its application in enamel repair.

Nano-calcium phosphate and dimethylaminohexadecyl methacrylate adhesive for dentin remineralization in a biofilm-challenged environment

OBJECTIVE

Dentin remineralization at the bonded interface would protect it from external risk factors, therefore, would enhance the longevity of restoration and combat secondary caries. Dental biofilm, as one of the critical biological factors in caries formation, should not be neglected in the assessment of caries preventive agents. In this work, the remineralization effectiveness of demineralized human dentin in a multi-species dental biofilm environment via an adhesive containing nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) was investigated.

METHODS

Dentin demineralization was promoted by subjecting samples to a three-species acidic biofilm containing Streptococcus mutans, Streptococcus sanguinis, Streptococcus gordonii for 24h. Samples were divided into a control group, a DMAHDM adhesive group, an NACP group, and an NACP+DMAHDM adhesive group. A bonded model containing a control-bonded group, a DMAHDM-bonded group, an NACP-bonded group, and an NACP+DMAHDM-bonded group was also included in this study. All samples were subjected to a remineralization protocol consisting of 4-h exposure per 24-h period in brain heart infusion broth plus 1% sucrose (BHIS) followed by immersion in artificial saliva for the remaining period. The pH of BHIS after 4-h immersion was measured every other day. After 14 days, the biofilm was assessed for colony-forming unit (CFU) count, lactic acid production, live/dead staining, and calcium and phosphate content. The mineral changes in the demineralized dentin samples were analyzed by transverse microradiography.

RESULTS

The in vitro experiment results showed that the NACP+DMAHDM adhesive effectively achieved acid neutralization, decreased biofilm colony-forming unit (CFU) count, decreased biofilm lactic acid production, and increased biofilm calcium and phosphate content. The NACP+DMAHDM adhesive group had higher remineralization value than the NACP or DMAHDM alone adhesive group.

SIGNIFICANCE

The NACP+DMAHDM adhesive was effective in remineralizing dentin lesion in a biofilm model. It is promising to use NACP+DMAHDM adhesive to protect bonded interface, inhibit secondary caries, and prolong the longevity of restoration.

Tuftelin-derived peptide facilitates remineralization of initial enamel caries in vitro

With the gradual discovery of functional domains in natural proteins, several biologically inspired peptides have been designed for use as biomaterials for hard tissue regeneration and repair. In this study, we designed a tuftelin-derived peptide (TDP) and tested its effects on hydroxyapatite crystallization and remineralization of initial enamel carious lesions in vitro. Using circular dichroism spectroscopy, we found that TDP contained 36.1% β-sheets and β-turns, which could be influenced by calcium ions. We verified the ability of TDP to crystallize hydroxyapatite using transmission electron microscopy and its ability to bind to the enamel surface and hydroxyapatite using confocal laser scanning microscopy and Langmuir adsorption isotherms (K = 881.56, N = 1.41 × 10^-5 ). Artificial enamel lesions were generated on human enamel blocks and subjected to a 12-day pH cycling model and were treated with 25 μM TDP, 1 g/L sodium fluoride (NaF), or deionized water. We analyzed the results of remineralization by surface microhardness testing, polarized light microscopy, and transverse microradiography. The TDP group showed significantly higher surface microhardness recovery (49.21 ± 1.66%), shallower lesions (34.89 ± 4.05 μm), and less mineral loss (871.33 ± 81.49 vol%·μm) after pH cycling than the deionized water group (p < .05). There were no significant differences between the TDP and NaF groups. Our experiment indicated that TDP could regulate hydroxyapatite crystallization and promote remineralization of enamel caries in vitro.

Remineralising effect of 45S5 bioactive glass on artificial caries in dentine

BACKGROUND

This study investigated the remineralisation effect of bioactive glass on artificial dentine caries.

METHODS

Dentine disks with artificial caries were treated with bioactive glass (group BAG), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (group CPP-ACP), sodium fluoride glycerol (group F) or deionized water (group W). All disks were subjected to pH cycling for 28 days subsequently. The topography, microhardness and remineralisation depth of the dentine carious lesion were assessed by atomic force microscopy (AFM), microhardness testing and confocal laser scanning microscope (CLSM), respectively.

RESULTS

AFM images indicated mineral depositions on the surface of the carious lesion in group BAG. The changes of Vickers hardness number (ΔVHN, mean ± SD) after pH cycling were 9.67 ± 3.60, 6.06 ± 3.83, 5.00 ± 2.19 and - 1.90 ± 2.09 (p < 0.001) in group BAG, group CPP-ACP, group F and group W, respectively. The remineralisation depth (mean ± SD) of the carious lesion in group BAG, group CPP-ACP, group F and group W were 165 ± 11 μm, 111 ± 11 μm, 75 ± 6 μm and 0 μm (p < 0.001), respectively.

CONCLUSION

Bioactive glass possessed a promising remineralisation effect on artificial dentine caries and could be a therapeutic choice for caries management.

Natural protein bioinspired materials for regeneration of hard tissues

This review describes the protein bioinspired materials for the repair of hard tissues such as enamel, dentin and bone.

Repair of tooth enamel by a biomimetic mineralization frontier ensuring epitaxial growth

The regeneration of tooth enamel, the hardest biological tissue, remains a considerable challenge because its complicated and well-aligned apatite structure has not been duplicated artificially. We herein reveal that a rationally designed material composed of calcium phosphate ion clusters can be used to produce a precursor layer to induce the epitaxial crystal growth of enamel apatite, which mimics the biomineralization crystalline-amorphous frontier of hard tissue development in nature. After repair, the damaged enamel can be recovered completely because its hierarchical structure and mechanical properties are identical to those of natural enamel. The suggested phase transformation-based epitaxial growth follows a promising strategy for enamel regeneration and, more generally, for biomimetic reproduction of materials with complicated structure.

The effects of 8DSS peptide on remineralization in a rat model of enamel caries evaluated by two nondestructive techniques

Nowadays, dental caries is one of the most common oral health problems, affecting most individuals. It has been found that, by remineralizing enamel at an early stage in the formation of enamel caries, teeth can be effectively protected from dental caries. In this work, a peptide with eight repetitive sequences of aspartate-serine-serine (8DSS) is applied as the bio-mineralizer in an in-vivo rat enamel caries model. Nondestructive quantitative light-induced fluorescence-digital (QLF-D) imaging and micro-computed tomography (micro-CT) are used to evaluate the remineralization of enamel carious lesions by measuring the total fluorescence radiance loss of the molar area (Δ Q_Total), acquired using QLF-D imaging, and the mineral density and residual molar enamel volume, acquired using micro-CT. Correlations are explored between Δ Q_Total and mineral density (strong correlation, r = 0.8000, p < 0.001) and Δ Q_Total and residual molar enamel volume (moderate correlation, r = 0.6375, p < 0.001). Our results demonstrate that 8DSS is a promising in-vivo remineralization agent that exhibits comparable effects to NaF ( p < 0.05), which has been verified using the classical Keyes method. Moreover, the nondestructive QLF-D and micro-CT methods can be combined to quantify the remineralization of enamel carious lesions three-dimensionally in vivo, making them broadly applicable in quantifying hard tissues.

Peptide-Mediated Biomimetic Regrowth of Human Enamel In Situ

Mimicking the dynamics of mineral loss and gain involved in dental caries formation can help us evaluate and compare the mineralization efficacy of different treatment agents used in enamel remineralization. Here, we offer an abridged study design outlining the preparation of tooth samples, creation of artificial dental lesions, application of a peptide, and characterization of the regrown enamel-like mineral layer.

State of the Art Enamel Remineralization Systems: The Next Frontier in Caries Management

The principles of minimally invasive dentistry clearly dictate the need for clinically effective measures to remineralize early enamel caries lesions. While fluoride-mediated remineralization is the cornerstone of current caries management philosophies, a number of new remineralization strategies have been commercialized or are under development that claim to promote deeper remineralization of lesions, reduce the potential risks associated with high-fluoride oral care products, and facilitate caries control over a lifetime. These non-fluoride remineralizing systems can be broadly categorized into biomimetic enamel regenerative technologies and the approaches that repair caries lesions by enhancing fluoride efficacy. This paper discusses the rationale for non-fluoride remineralization and the mechanism of action, challenges, and evidence behind some of the most promising advances in enamel remineralization therapies.

Anti-biofilm and remineralization effects of chitosan hydrogel containing amelogenin-derived peptide on initial caries lesions

In this study, we have designed a more clinically powerful anti-caries treatment by applying the amelogenin-derived peptide QP5 to the antibacterial carrier material chitosan in a hydrogel (CS-QP5 hydrogel), and characterized its effects on the inhibition of a cariogenic biofilm and the promotion of the remineralization of the initial caries lesions. The results indicated that the CS-QP5 hydrogel sustainably inhibited the growth of the Streptococcus mutans biofilm, lactic acid production and the metabolic activity over a prolonged period of time. Moreover, the CS-QP5 hydrogel promoted the remineralization of early enamel lesions, which were indicated by surface micro-hardness (, polarized light microscopy and transverse microradiography. In conclusion, the CS-QP5 hydrogel shows good potential for caries control in the clinic because of its antibacterial effects as well as the remineralization of initial enamel carious lesions even in a biofilm model over a prolonged period of time.

A statherin-derived peptide promotes hydroxyapatite crystallization and in situ remineralization of artificial enamel caries

In situ remineralization of hydroxyapatite on a human tooth enamel surface induced by anti-caries bioactive components is an alternative restorative strategy against dental caries. In this study, a novel biomimetic peptide DE-11, inspired by the salivary phosphoprotein statherin, was developed, and it showed beneficial potentials for the restoration of demineralized tooth enamel in vitro. The peptide DE-11 contained the initial six-peptide sequence of N-terminus of statherin extended by a mineralization hydrophilic tail composed of consecutive acidic amino acids capable of adsorbing calcium and phosphate ions. A strong adsorption capacity of DE-11 to hydroxyapatite was confirmed through Langmuir adsorption isotherm experiment and confocal laser scanning microscopy. Then, the nucleation and crystallization of hydroxyapatite due to DE-11 was characterized by scanning and transmission electron microscopy and selected-area electron diffraction. Moreover, the ability of DE-11 to promote the remineralization of initial enamel caries lesions was further evaluated. Initial lesions were created in bovine enamel blocks, which were then exposed to the peptide solution and finally immersed in artificial saliva. After 7 days, a higher percentage of surface microhardness recovery, a lower mineral loss, a shallower lesion depth, and a higher mineral content were found on the surface of the lesion body in the DE-11 group as compared to that in the negative group using surface microhardness testing, polarized light microscopy, and transverse microradiography; this indicated that DE-11 could induce in situ remineralization of hydroxyapatite on the demineralized enamel surface. Overall, these findings suggest that DE-11 is highly promising as a restorative biomaterial for enamel remineralization in the anti-caries applications.

A novel biomimetic peptide inspired by salivary statherin was developed and exhibited beneficial potentials in promoting remineralization of hydroxyapatite on tooth enamel surface, providing a desirable alternative restorative strategy against dental caries.

Effects of Fluoride on Two Chemical Models of Enamel Demineralization

This study evaluated the effects of fluoride on subsurface enamel demineralization induced by two commonly used chemical models. Forty-eight enamel blocks were demineralized at pH = 5.0 by an acetate buffer (Group 1), a lactate buffer (Group 2), an acetate buffer with 0.02 ppm fluoride (Group 3) and a lactate buffer with 0.02 ppm fluoride (Group 4) at 25 °C for 3 weeks. The surface destruction percentage (SDP), mineral loss and lesion depth of the blocks were studied using micro-computed tomography. An elemental analysis of the enamel surface was evaluated using an energy-dispersive X-ray spectroscopy. Surface micro-hardness was determined by the Knoop Hardness Test. The mean lesion depth of Groups 1 through 4 were 134.1 ± 27.2 μm, 96.1 ± 16.5 μm, 97.5 ± 22.4 μm and 91.1 ± 16.2 μm, respectively (p < 0.001; group 1 > 2, 3 > 4). The SDPs of groups 1 through 4 were 7.8 ± 8.93%, 0.71 ± 1.6%, 0.36 ± 1.70% and 1.36 ± 2.94% (p < 0.001; group 1 > 2, 3, 4). The fluoride in mean weight percentages of groups 1 through 4 were 1.12 ± 0.24%, 1.10 ± 0.20%, 1.45 ± 0.40% and 1.51 ± 0.51%, respectively (p < 0.001; group 3, 4 > 1, 2). The mean Knoop hardness values of groups 1 through 4 were 27.5 ± 13.3, 39.7 ± 19.3, 73.6 ± 44.2 and 91.0 ± 57.2, respectively (p < 0.001; group 4 > 3 > 2 > 1). The chemical model using an acetate buffer solution created significantly deeper zones of subsurface demineralization on enamel than the lactate buffer solution. An acetate buffer may damage the enamel surface, but the surface damage can be prevented by adding fluoride.

From molecules to macrostructures: recent development of bioinspired hard tissue repair

This review summarizes the bioinspired strategies for hard tissue repair, ranging from molecule-induced mineralization, to microscale assembly to macroscaffold fabrication.

Assembly of Layered Monetite-Chitosan Nanocomposite and Its Transition to Organized Hydroxyapatite

Bioinspired synthesis of hierarchically structured calcium phosphate (CaP) material is a highly promising strategy for developing improved bone substitute materials. However, synthesis of CaP materials with outstanding mechanical properties still remains an ongoing challenge. Inspired by the formation of lamellar structure in nacre, we designed an organic matrix composed of chitosan and cis-butenediolic acid (maleic acid, MAc) that could assemble into a layered complex and further guide the mineralization of monetite crystals, resulting in the formation of organized and parallel arrays of monetite platelets with a brick-and-mortar structure. Using the layered monetite-chitosan composite as a precursor, we were able to synthesize hydroxyapatite (HAp) with multiscale hierarchically ordered structure via a topotactic phase transformation process. On the nanoscale, needlelike HAp crystallites assembled into organized bundles that aligned to form highly oriented plates on the microscale. On the large-scale level, these plates with different crystal orientations were stacked together to form a layered structure. The organized structures and composite feature yielded CaP materials with improved mechanical properties close to those of bone. Our study introduces a biomimetic approach that may be practical for the design of advanced, mechanically robust materials for biomedical applications.

Efficacy of amelogenin-chitosan hydrogel in biomimetic repair of human enamel in pH-cycling systems

Amelogenin-chitosan (CS-AMEL) hydrogel has shown great potential for the prevention, restoration, and treatment of defective enamel. As a step prior to clinical trials, this study aimed to examine the efficacy of CS-AMEL hydrogel in biomimetic repair of human enamel with erosive or caries-like lesions in pH-cycling systems. Two models for enamel defects, erosion and early caries, were addressed in this study. Two pH-cycling systems were designed to simulate the daily cariogenic challenge as well as the nocturnal pH conditions in the oral cavity. After pH cycling and treatment with CS-AMEL hydrogel, a synthetic layer composed of oriented apatite crystals was formed on the eroded enamel surface. CS-AMEL repaired the artificial incipient caries by re-growing oriented crystals and reducing the depth of the lesions by up to 70% in the pH-cycling systems. The results clearly demonstrate that the CS-AMEL hydrogel is effective at the restoration of erosive and carious lesions under pH-cycling conditions.

Synergistic Inhibition of Enamel Demineralization by Peptide 8DSS and Fluoride

The biomimetic peptide 8DSS has shown beneficial effects in promoting remineralization of demineralized enamel in vitro. Here we examined the ability of 8DSS alone and in combination with fluoride to inhibit enamel demineralization during pH-cycling mimicking intraoral conditions. Enamel blocks were subjected to 9 days of pH-cycling in the presence of 1,000 ppm NaF (positive control), distilled-deionized water (DDW; negative control), 25 μM 8DSS alone, 25 μM 8DSS with 500 ppm NaF (8DSS-FL) or 25 μM 8DSS with 1,000 ppm NaF (8DSS-FH) twice daily for 1 min each time. The blocks were analyzed in terms of surface microhardness (SMH), fluoride uptake and mineral content. The 8DSS-treated blocks showed significantly lower mineral loss, shallower lesions and higher SMH than the DDW-treated blocks. No significant differences were observed between the blocks treated with 8DSS alone or fluoride alone. The blocks treated with 8DSS alone or DDW showed similar amounts of fluoride uptake, which was the lowest of all the treatment groups. The blocks treated with 8DSS-FL or 8DSS-FH did not differ significantly, and both groups showed significantly greater SMH and fluoride uptake as well as significantly lower mineral loss and shallower lesions than the NaF-treated blocks. Mineral content was significantly higher in the 8DSS-treated blocks than in the DDW-treated blocks from the surface layer (10 µm) to the lesion depth (110 µm), and it was significantly higher in the blocks treated with 8DSS-FL or 8DSS-FH than in the NaF-treated blocks from 10 to 90 µm. These findings illustrate the potential of 8DSS for inhibiting enamel demineralization and for enhancing the anticaries effect of NaF.

Amelogenin and Enamel Biomimetics

Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.

Potential of an amelogenin based peptide in promoting reminerlization of initial enamel caries

OBJECTIVE

In this study we give a preliminary study of a rationally designed small peptide, which is based on the enamel matrix protein amelogenin, to investigate its effect on remineralization of initial enamel caries lesions.

DESIGN

A novel peptide was designed and synthesized to investigate its effects on the remineralization of initial enamel carious lesions during pH cycling that simulates intra-oral conditions. Initial lesions were created in bovine enamel blocks, which were then pH-cycled for 12 days in the presence of 25μM peptide, 1g/L NaF (positive control), 50mM HEPES buffer(negative control). Before and after pH cycling, enamel blocks were analyzed by surface microhardness testing, polarized light microscopy and transverse microradiography.

RESULTS

Percentage of surface microhardness recovery (SMHR%) after pH cycling was significantly higher in peptide group than HEPES group. Lower lesion depth and less mineral mineral loss were found in peptide or NaF treatment groups after the cycling, and were significantly different to HEPES group. No significant differences were observed between the blocks treated with peptide and those treated with NaF.

CONCLUSSION

This study provides in vitro evidence that this amelogenin based peptide promotes enamel caries remineralization, offering a promising remineralizing biomaterial in initial enamel carious treatment.

Study on the influence of leucine-rich amelogenin peptide (LRAP) on the remineralization of enamel defects via micro-focus x-ray computed tomography and nanoindentation

Regeneration of severely damaged enamel (e.g. deep demineralized lesions) is currently not possible, because the structural units of enamel crystal construction are removed after its maturation. The aim of this in vitro study was to evaluate the effect of surface impregnation by leucine-rich amelogenin peptide (LRAP) on the remineralization of eroded enamel using micro-focus x-ray computed tomography (µCT). Fifteen bovine enamel blocks were embedded in resin and three zones (sound, demineralization, and remineralization) were defined on each specimen. Lesions were prepared by immersing the samples in demineralization solution for 7 d. The samples were soaked in distilled water or 60 or 120 µg mL(-1) solution of LRAP in water for 30 min. After the surface treatment, specimens were incubated in artificial saliva for either 5 or 10 d at 37 °C. The amount of mineral gain (dΔZ%) and the relative changes in the lesion depth (dLD%), obtained from µCT, were used to evaluate the effect of LRAP on the remineralization of lesions. The effects of LRAP on cross-sectional integrated hardness ΔINH were studied after 10 d using nanoindentation. ANOVA test was used to determine the effect of time and/or LRAP concentration on dΔZ%, dLD% and ΔINH mean values. Tukey's analysis was used for multiple comparison testing (α = 0.05). Analysis of µCT data showed significant effect of time and LRAP concentration on the dΔZ% (p = 0.013, p = 0.003) and the dLD% (p  <  0.001, p = 0.002) mean values. The nanoindentation hardness was significantly improved by 120 µg mL(-1) LRAP (p = 0.02). Also, the peptide treatment affected the mineral distribution throughout the lesion by inhibiting of superficial deposition. This study showed that the treatment of eroded lesions in enamel by LRAP can improve and regulate the pattern of remineralization in vitro.

Leucine-rich amelogenin peptide (LRAP) as a surface primer for biomimetic remineralization of superficial enamel defects: An in vitro study

This study was carried out to obtain more information about the assembly of hydroxyapatite bundles formed in the presence of Leucine-Rich Amelogenin Peptide (LRAP) and to evaluate its effect on the remineralization of enamel defects through a biomimetic approach. One or 2 mg/mL LRAP solutions containing 2.5 mM of Ca(+2) and 1.5 mM phosphate were prepared (pH = 7.2) and stored at 37 °C for 24 h. The products of the reaction were studied using atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Vickers surface microhardness recovery (SMR%) of acid-etched bovine enamel, with or without LRAP surface treatment, were calculated to evaluate the influence of peptide on the lesion remineralization. Distilled water and 1 or 2 mg/mL LRAP solution (pH = 7.2) were applied on the lesions and the specimens were incubated in mineralization solution (2.5mM Ca(+2) , 1.5mM PO4 (-3) , pH = 7.2) for 24 h. One-way ANOVA and Tukey's multi-comparison tests were used for statistical analysis. The pattern of enamel surface repair was studied using FE-SEM. AFM showed the formation of highly organized hierarchical structures, composed of hydroxyapatite (HA) crystals, similar to the dental enamel microstructure. ANOVA procedure showed significant effect of peptide treatment on the calculated SMR% (p < 0.001). Tukey's test revealed that peptide treated groups had significantly higher values of SMR%. In conclusion, LRAP is able to regulate the formation of HA and enhances the remineralization of acid-etched enamel as a surface treatment agent.

Noninvasive Dentistry: A Dream or Reality?

Various caries prevention and repair strategies are reviewed in this article ranging from the use of fluoride to nanohydroxyapatite particles. Several of the strategies which combine fluoride and calcium and phosphate treatments have both in vitro and in vivo data showing them to be efficacious if the surface integrity of the lesion is not breached. Once this has occurred, the rationale for cutting off the nutrient supplies to the pathogenic bacteria without the removal of the infected dentine, a noninvasive restorative technique, is discussed using existing clinical studies as examples. Finally two novel noninvasive restorative techniques using fluorohydroxyapatite crystals are described. The need for clinical data in support of emerging caries-preventive and restorative strategies is emphasized.

Amelogenin and enamel biomimetics

Mature tooth enamel is acellular and does not regenerate itself.

8DSS-promoted remineralization of demineralized dentin in vitro

The 8DSS peptide successfully induced nano-crystals precipitation on the collagen matrix. The completely demineralized dentin was effectively remineralized and its mechanical properties were significantly improved.