Galla chinensis Compounds Remineralize Enamel Caries Lesions in a Rat Model

Natural Materials' Potential as Alternative Teeth Remineralization Agents: A Scoping Review

Dental caries is one of the world's major oral health issues. According to The Burden of Disease Study (2016), almost half of the world's population suffers oral health issues, particularly dental caries (3.58 billion individuals). Dental caries treatment through teeth remineralization can be conducted naturally or using remineralization agents. The aim of this study was to map the scientific evidence of natural materials' potential as teeth remineralization agents. The method utilized in this study was the scoping review following the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Review, that is, article searching using search strategies, article screening, data extraction, and conclusion constructing. The searching process was through PubMed, EBSCOhost, and ScienceDirect using keywords and following the inclusion and exclusion criteria. Twenty articles were found and further analyzed. All articles provided the natural materials' potencies in the perspective of antibacterial, increasing saliva pH, remineralization ability, and increasing the hardness of teeth surface. It can be concluded that natural materials can potentially be alternative teeth remineralization agents.

Investigating the efficacy of a varnish containing gallic acid on remineralization of enamel lesions: an in vitro study

This study evaluated the efficacy of a formulated remineralizing gallic acid (GA) varnish in treating artificial enamel caries lesions. Fifty-five intact bovine incisors were collected. Enamel blocks (5 × 9 mm) were prepared. A third of each block's surface remained intact. Primary carious lesions were induced on the middle and bottom thirds of the blocks by immersing the samples in a demineralization solution for 6 h. The bottom third of the blocks were further remineralized by randomly applying 0.5%, 2%, or 8% GA varnishes and 2.26% fluoride varnish (V varnish, Vericom, Seoul, Korea), or the varnish base without active ingredients (n = 11 each). The specimens were immersed in a remineralizing solution for 4 h and then subjected to a 2-hour immersion in the demineralizing solution. After six days of pH cycling, the surface microhardness was measured at depths of 30, 75, and 120 μm. The percentage of surface microhardness recovery (SMHR%) was compared among the groups using the Shapiro-Wilk, ANOVA, and Tukey HSD post-hoc tests (α = 0.05). The SMHR% of all experimental groups was higher than the control group at 30 μm (p < 0.05). The 0.5% GA varnish showed the highest SMHR% at all depths; however, the difference with the other experimental groups was significant at a depth of 30 μm (p < 0.05). The SMHR% of the fluoride and the 2% and 8% GA varnishes was comparable at all depths. All treatments potentially remineralize enamel lesions, with 0.5% GA varnish having the greatest effect, particularly on the top surface layer. As such, this newly developed varnish may emerge as a promising alternative to fluoride varnish.

Encapsulation of a novel peptide derived from histatin-1 in liposomes against initial enamel caries in vitro and in vivo

OBJECTIVES

Biomimetic mineralization mediated by proteins and peptides is a promising strategy for enamel repair, and its specific application model needs more research. In this work, we exploited a liposomal delivery system for a novel peptide (DK5) derived from histatin-1 (DK5-Lips) as a new biomimetic mineralization strategy against initial enamel caries.

MATERIALS AND METHODS

The DK5-Lips was prepared using calcium acetate gradient method and then the in vitro release, salivary stability, and cytotoxicity were studied. Initial enamel caries was created in bovine enamel blocks and subjected to pH-cycling model treated with DK5-Lips. Surface microhardness testing, polarized light microscopy (PLM), and transverse microradiography (TMR) were analyzed. Then the biocompatibility of DK5-Lips was evaluated in the caries model of Sprague-Dawley rats, and the anti-caries effect was assessed using Micro-CT analysis, Keyes scores, and PLM in vivo.

RESULTS

DK5-Lips provided a mean particle size of (97.63 ± 4.94)nm and encapsulation efficiency of (61.46 ± 1.44)%, exhibiting a sustained release profile, excellent stability in saliva, and no significant toxicity on human gingival fibroblasts (HGFs). The DK5-Lips group had higher surface microhardness recovery, shallower caries depth, and less mineral loss in bovine enamel. Animal experiments showed higher volume and density values of residual molar enamel, lower Keyes score, and shallower lesion depth of the DK5-Lips group with good biocompatibility.

CONCLUSION

As a safe and effective application model, DK5-Lips could significantly promote the remineralization of initial enamel caries both in vitro and in vivo.

CLINICAL RELEVANCE

The potential of liposome utilization as vehicle for oral delivery of functional peptides may provide a new way for enamel restoration.

Biomineral-binding liposomes with dual antibacterial effects for preventing and treating dental caries

Dental caries is a chronic oral disease that results from the demineralization of dental hard tissues caused by the long-term interaction of various pathogenic factors in the human oral cavity. Although magnolol (Mag) and fluconazole (FLC) have shown promising antibacterial activity against Candida albicans (C. albicans) and Streptococcus mutans (S. mutans), their clinical application is limited due to hydrophobicity. In this study, we constructed biomineral-binding liposomes co-loaded with Mag and FLC (PPi-Mag/FLC-LPs) to overcome the hydrophobicity and achieve a dual antibacterial activity in the acidic microenvironment of caries. PPi-Mag/FLC-LPs were characterized by laser particle size analysis, transmission electron microscopy, and high-performance liquid chromatography (HPLC). The ability of PPi-Mag/FLC-LPs to bind hydroxyapatite was assessed in vitro using fluorescence microscopy and HPLC, while the antibacterial activity was examined by measuring drug effects on the acidogenicity, acid resistance, biofilm formation and survival of C. albicans and S. mutans. The pharmacodynamics of PPi-Mag/FLC-LPs was also evaluated in vivo in a rat model of dental caries. Mag and FLC were released rapidly from PPi-Mag/FLC-LPs in a pH-sensitive manner, and they bound effectively to hydroxyapatite, leading to a better antibacterial effect on C. albicans and S. mutans compared to free drugs or liposomes loaded with a single drug. PPi-Mag/FLC-LPs improved the medicinal properties of Mag and FLC and provided a rapid, pH-sensitive release of both drugs in vitro. PPi-Mag/FLC-LPs displayed good antibacterial activity in vivo, showing promise as a dual-drug delivery system for the prevention and treatment of caries.

Water Extract of Gallnut Reduces the Injury of Alveolar Epithelial Cells Induced by Streptococcus pneumoniae by Up-Regulating miRNA-338-3p

Streptococcus pneumoniae (S. pneumoniae) is the primary pathogen causing pneumonia, in addition to lobar pneumonia, meningitis, bronchitis, and other diseases. Inhibiting the apoptosis and inflammation of alveolar epithelial cells is essential for the treatment of pneumonia caused by S. pneumoniae. Traditional Chinese medicine has the characteristics of multiple components, multiple targets, and few adverse reactions. It is recognized by doctors and patients in the treatment of pneumonia and other diseases. We conducted this study to explore the effect of the water extract of gallnut on alveolar epithelial cells affected by S. pneumoniae. Studies have found that the water extract of gallnut can increase the optical density value, Bcl-2 protein expression, IL-10 content, and miRNA-338-3p levels of alveolar epithelial cells affected by S. pneumoniae. Additionally, it can reduce the rate of cell apoptosis, Bax protein expression, and IL-6 content. Further, its effect is dose-dependent: the higher the concentration of gallnut water extract, the more evident its effect on alveolar epithelial cells. Through nano PCR detection, it was found that overexpression of miRNA-338-3p can increase the activity of alveolar epithelial cells affected by S. pneumoniae and promote cell growth. Knockdown of miRNA-338-3p reduced the impact of the water extract of gallnut on the growth of alveolar epithelial cells and the expression of inflammatory factors affected by S. pneumoniae. Therefore, our findings suggest that the water extract of gallnut could inhibit the apoptosis of alveolar epithelial cells affected by S. pneumoniae by up-regulating the expression of miRNA-338-3p.

In vitro mineral apposition analysis of two Colombian plant extracts on Amelogenesis imperfecta teeth

OBJECTIVE

To determine if native Colombian Piper marginatum Jacq. and Ilex guayusa Loes plant extracts have a remineralizing effect on teeth with Amelogenesis imperfecta in comparison with the commercial products Clinpro-3M and Recaldent™.

MATERIAL AND METHODS

An in vitro study was carried out with 128 human teeth slices (64 healthy and 64 with Amelogenesis imperfecta) on which an initial Raman spectroscopy was performed followed by Raman spectroscopies at 0, 24, 48, and 72 h to determine possible remineralization by observing mineral increase or decrease as a result of P. marginatum Jacq. and I. guayusa Loes extract application in comparison to control substance (Clinpro and Recaldent™) application. Obtained data were analyzed using a bivariate method with a t unidirectional test. Significant differences among groups were determined by an ANOVA with Dunnett post hoc tests.

RESULTS

Native I. guayusa Loes and P. marginatum Jacq. Colombian plants extracts exhibited phosphate and orthophosphate mineral apposition, where P. marginatum Jacq. presented better results.

CONCLUSIONS

Native Colombian I. guayusa Loes and P. marginatum Jacq plant extract might in the future be useful for dental tissue remineralization, as they induced phosphate and orthophosphate mineral apposition, main components of tooth enamel. These types of natural compounds can become an alternative to fluorine, whose ingestion is harmful to the human body.

Influence of Dentin Priming with Tannin-Rich Plant Extracts on the Longevity of Bonded Composite Restorations

Objective

This in vitro study evaluated the influence of bioactive plant extracts as dentin biomodifying agents to improve the longevity of bonded restorations. For that, plant extracts were applied to the dentin surface prior to the adhesive system.

Materials and Methods

Bovine incisors were ground flat to obtain 2 mm thick slices in which conical preparations were made (N = 10). Tannin-containing plant extracts were applied to dentin before the application of the restorative system, as follows: control group (untreated, CTL), chlorhexidine 0.12% (CHX), mastruz (Dysphania ambrosioides, MTZ), cat's claw (Uncaria tomentosa, CTC), guarana (Paullinia cupana, GUA), galla chinensis (Rhus chinensis, GCH), and tannic acid (extracted from Acacia decurrens, TNA). The push-out bond strength test was conducted (0.5 mm/min). Dentin biomodification was assessed by the modulus of elasticity and mass change in bovine tooth sections (0.5 × 1.7 × 7.0 mm). The dentin staining after extract treatments of dentin slices was compared. The dentin surface wettability was also evaluated by means of the contact angles of the adhesive system with the dentin surface and compared with the untreated control group. Data were subjected to ANOVA/Tukey's test (α = 0.05).

Results

The bond strength of the restoratives to dentin was not significantly improved by the plant extracts, irrespective of the evaluation time (p > 0.05). Except for TNA, the elastic modulus of demineralized dentin significantly reduced after treatment with the plant extracts (p < 0.05). The dentin staining correlated with the tannin content of the extracts. The contact angle was significantly reduced when treated with CTC, GCH, and TNA.

Conclusions

The tannin-containing extracts had a questionable effect on the longevity of bonded restorations. The dentin modulus was negatively affected by the extract treatments. Although some of the extracts changed the contact angle, which seems to improve the adhesive monomer permeation, the tannin-rich plant extract application prior to adhesive application was proven to be clinically unfeasible due to dentin staining.

Effects of different remineralizing agents on color stability and surface characteristics of the teeth following vital bleaching

The aim of the study was to investigate the effects of various remineralizing agents on the color stability and surface characteristics of the teeth after vital bleaching. The extracted 96 human incisors were used for the study. Initially, the samples were randomly divided into two groups and exposed to in-office and at-home bleaching agents. Then, the groups were divided into six subgroups (n = 8), including the control group did not undergo remineralization after bleaching, according to five remineralizing agents (Gelato APF Gel, Remin Pro, Tooth Mousse, MI Paste Plus, Curodont Protect). Surface roughness was assessed at baseline, after bleaching and remineralization procedures. Color measurements of the samples were obtained at baseline, after bleaching and then after immersion in the staining solution following remineralization process. Scanning electron microscopy and atomic force microscopy (AFM) analyzes were carried out in order to examine the morphological changes on the surface of the enamel. The independent t-test, paired-samples t-test, and one-way ANOVA was used to compare the data and post-hoc LSD test to compare the difference among the study groups (α = .05). Surface roughness increased following in-office and at-home bleaching in all groups, and reduced after application of remineralizing agents in all groups. Significant differences were found among the groups with respect to changes in surface roughness and color values following treatment with remineralizing agents (p <.05). AFM analyses revealed increased surface roughness after bleaching and a reduction of rough surfaces following treatment with remineralizing agents. Remineralizing agents can be used to reduce postbleaching increase in surface roughness and to maintain color stability after bleaching.

Inhibitory Effect of Lactobacillus plantarum CCFM8724 towards Streptococcus mutans- and Candida albicans-Induced Caries in Rats

Streptococcus mutans is a recognized cariogenic bacterium and a major producer of biofilm matrix. The presence of Candida albicans in dental plaque with S. mutans enhances the virulence leading to the onset of rampant caries which is similar to early childhood caries (ECC). The purpose of this study was to explore the effect of Lactobacillus plantarum CCFM8724 (CCFM8724) on the treatment and prevention of dental caries induced by S. mutans and C. albicans in vivo. Rats were divided into 6 groups: the control group and model group, 2 treatment groups, and 2 prevention groups (0.02% chlorhexidine or CCFM8724). The fluctuation of microbial colonization and the change of bacteria flora in rat oral cavity after sowing of L. plantarum CCFM8724 were investigated by colony-forming units (CFU) and microflora analysis. The caries of rats were assessed by microcomputed tomography (micro-CT) and Keyes scoring method. The results showed that L. plantarum CCFM8724 in both the treatment and prevention groups could significantly decrease the population of S. mutans and C. albicans in the rats' oral cavity (p < 0.001), the mineral loss of enamel (p < 0.05), and the scores of caries (p < 0.05). Besides, L. plantarum CCFM8724 exhibited better effects than chlorhexidine. Hence, L. plantarum CCFM8724 was proved to be a potential oral probiotic on caries treatment and prevention in vivo and it may have the prospect of application in dental caries (especially ECC) prevention products.

Current herbal medicine as an alternative treatment in dentistry: In vitro, in vivo and clinical studies

Since the time that human population comprehended the importance of general health maintenance and the burden of disease, there has been a search for healing properties in the natural environment. Herbal medicine is the use of plants with medical properties for prevention and treatment of conditions that can affect general health. Recently, a growing interest has been observed toward the use of traditional herbal medicine alongside synthetic modern drugs. Around 80% of the population, especially in developing countries relies on it for healthcare. Oral healthcare is considered a major part of general health. According to the world health organization (WHO), oral health is considered an important part of general health and quality of life. The utilization of natural medications for the management of pathologic oro-dental conditions can be a logical alternative to pharmaceutical methods due to their availability, low costs, and lower side effects. The current literature review aimed at exploration of the variety and extent of herbal products application in oral health maintenance including different fields of oral healthcare such as dental caries, periodontal maintenance, microbial infections, oral cancers, and inflammatory conditions.

Effect of Galla Chinensis on Remineralization of Early Dentin Lesion

Objective  This study aimed to investigate the efficacy of the Galla chinensis extract (GCE) on early dentin lesion remineralization.

Materials and Methods  Seventy-two dentin specimens were divided into three groups according to the treatment solution. In group S1, specimens were treated with GCE; in group S2, the specimens were treated with sodium fluoride (NaF); meanwhile, specimens of group S3 were treated with distilled water (DW). Each group was further subdivided into two subgroups according to the treatment time (1 minute and 5 minutes). An in vitro pH-cycling model for 12 days was done. Subsequently, surface microhardness (SMH) of the specimens, elemental analysis, and their micromorphological appearance were evaluated.

Statistical Analysis  Data were statistically analyzed. One-way analysis of variance was used to compare numerical (parametric) data between more than two separate groups followed by post hoc Tukey.

Results  There was no significant difference between the mean SMH of dentin between NaF and GCE groups. Regarding the time, the 5-minute treatment with NaF and DW groups recorded higher mean SMH value of dentin than the 1-minute treatment group. Meanwhile, for GCE groups, the 1-minute immersion recorded higher mean SMH value than the 5-minute immersion without any significant difference between them. The microhardness results were confirmed by environmental scanning electron microscope and energy dispersive X-ray analysis results.

Conclusion  GCE could be used as an effective alternative for dentin remineralization.

Farnesal-loaded pH-sensitive polymeric micelles provided effective prevention and treatment on dental caries

BACKGROUND

Farnesol is a sesquiterpene from propolis and citrus fruit that shows promising anti-bacterial activity for caries treatment and prevention, but its hydrophobicity limits the clinical application. We aimed to develop the novel polymeric micelles (PMs) containing a kind of derivative of farnesol and a ligand of pyrophosphate (PPi) that mediated PMs to adhere tightly with the tooth enamel.

RESULTS

Farnesal (Far) was derived from farnesol and successfully linked to PEG via an acid-labile hydrazone bond to form PEG-hyd-Far, which was then conjugated to PPi and loaded into PMs to form the aimed novel drug delivery system, PPi-Far-PMs. The in vitro test about the binding of PPi-Far-PMs to hydroxyapatite showed that PPi-Far-PMs could bind rapidly to hydroxyapatite and quickly release Far under the acidic conditions. Results from the mechanical testing and the micro-computed tomography indicated that PPi-Far-PMs could restore the microarchitecture of teeth with caries. Moreover, PPi-Far-PMs diminished the incidence and severity of smooth and sulcal surface caries in rats that were infected with Streptococcus mutans while being fed with a high-sucrose diet. The anti-caries efficacy of free Far can be improved significantly by PPi-Far-PMs through the effective binding of it with tooth enamel via PPi.

CONCLUSIONS

This novel drug-delivery system may be useful for the treatment and prevention of dental caries as well as the targeting therapy of anti-bacterial drugs in the oral disease.

Early Caries in an In Vivo Model: Structural and Nanomechanical Characterization

The utilization of rat models in cariology research has made substantial contributions to decipher mechanisms of caries formation and to develop preventive treatments. The existing rat models still have potential for improvement toward establishing a more accurate standard caries protocol to utilize in testing and/or developing new dental technologies. The current caries-scoring methods rely on optical microscopy-based techniques, which necessitates formation of highly advanced lesions. Moreover, models that facilitate the implementation of cariogenic bacteria by shifting the balance of oral flora through desalivation and/or antibiotic treatment create a nonnatural environment. Furthermore, there is a paucity of detailed structural and mechanical characterization on the resulting carious lesions. The purpose of this study was to develop a rat model that induces formation of mild carious lesions and to provide comprehensive structural and mechanical characterization. With this aim in mind, an in vivo model promoting progression of mild lesions was established with specific pathogen-free Sprague-Dawley rats. Cariogenic bacteria, Streptococcus mutans, was implemented into the oral flora without the use of antibiotics or desalivation surgery. During caries formation, progression of the infection was monitored by quantifying the relative abundance of S. mutans in oral flora with quantitative real-time polymerase chain reaction. A significant increase in colonization efficacy of S. mutans was detected during cariogenic challenge ( P < 0.01). The resulting carious lesions were analyzed by conventional light optical and scanning electron microscopy. A detailed structural and morphological characterization on fissure caries with different degrees of severity was provided. The changes in the morphology and demineralization state of the sound and carious tissues were quantified by energy-dispersive X-ray spectroscopy, and local mechanical properties were acquired with nanoindentation. The principles laid out in this work can be utilized in cariology research and developed into a standard protocol for future studies.

Remineralization Efficacy of an Amelogenin-Based Synthetic Peptide on Carious Lesions

Objective: The aim of this study was to evaluate the remineralization efficacy of an amelogenin-based peptide on initial enamel carious lesions in vitro. Furthermore, we attempted to provide insights into the possible mechanism of the remineralization, including determining the calcium-binding properties of the peptide and its effects on calcium phosphate mineralization.

Methods: The peptide comprising the N-terminus and the C-terminus of porcine amelogenin was synthesized by Synpeptide Co., Ltd. Fifty specimens were randomly assigned to five immersing treatment groups for 12 days: remineralizing medium only; 12.5 μg/mL peptide + remineralizing medium; 25 μg/mL peptide + remineralizing medium; 50 μg/mL peptide + remineralizing medium; fluoride + remineralizing medium. After immersion, mean mineral loss before and after remineralization of each specimen was determined using micro-CT. Mean mineral gain after remineralization was calculated. Calcium binding properties were measured by Isothermal titration calorimetry (ITC). TEM and Fourier transform-infrared were used to determine the effects of the peptide on calcium phosphate mineralization.

Results: A significant decrease in mineral loss after remineralization process in all groups was observed (p < 0.05). Treatment in remineralizing medium resulted in the lowest mineral gain while the fluoridated treatment exhibited the highest mineral gain among all groups. Inclusion of synthetic peptide in the remineralizing medium exhibited a higher mineral gain and the gain of 50 μg/mL group was greater than that of the 25 μg/mL group. No significant difference in mineral gain was observed between the remineralizing medium only group and the 12.5 μg/mL peptide group (p > 0.05). ITC values showed that the Ca²⁺-binding affinity of the peptide is about 9.914 × 10⁴M⁻¹. Furthermore, the peptide was found to inhibit calcium phosphate precipitation and stabilize amorphous calcium phosphate formation for more than 2 h and finally transform into ordered hydroxyapatite crystals.

Conclusion: Specific concentrations of the amelogenin-based synthetic peptide promoted in vitro remineralization, with higher concentrations exhibiting significantly greater remineralization. This study presented evidence suggesting that the peptide may act as a Ca²⁺carrier as well as a regulating factor. When the stabilizing calcium and phosphorus ions bind with the peptide they become biologically available for the remineralization of deeper carious lesions, while also regulated by the peptide to transform into ordered hydroxyapatite crystals.

Bioinspired heptapeptides as functionalized mineralization inducers with enhanced hydroxyapatite affinity

The regeneration of mineral crystals under physiological conditions is an efficient way to repair defects in hard tissues. To achieve robust mineralization on surfaces such as the tooth enamel, an inducer requires strong affinity with the substrates and should be able to induce mineralization. Thus far, most studies used a single molecule containing two components to realize the above functions separately, which might be troublesome to synthesize and purify. In this work, inspired by the statherin in the salivary acquired pellicle, we designed a simple peptide sequence, Asp-Asp-Asp-Glu-Glu-Lys-Cys (peptide-7), to accomplish the dual tasks of adsorption and mineralization on enamel surfaces. We speculate the calcium binding ability of the negatively charged carboxylic acid groups in the peptide itself contributes to the dual functions of peptide-7. In vitro and in vivo experiments demonstrated its excellent repair effect on enamel as compared to fluoride. More importantly, due to the strong affinity between peptides and hydroxyapatite, a compact mineralized crystal layer and a strong adhesion between the regenerated minerals and the bottom substrates were observed, similar to the effect induced by fluoride. This work sheds light on the interaction mechanism between peptide-7 and minerals. In addition, since it is safer than fluoride, peptide-7 may have potential applications in the repair of other hard tissues and the functionalization of biomaterials.

Salivary acquired pellicle-inspired DpSpSEEKC peptide for the restoration of demineralized tooth enamel

Salivary acquired pellicle (SAP) is a layer of proteins and glycoproteins of salivary origin that tightly coat the tooth surface. Statherin is an important part of the SAP. The initial six-peptide sequence DpSpSEEK (where pS denotes phosphorylated serine) of the N-terminus of statherin can be immobilized on a hydroxyapatite (HAP) surface and the negatively charged domains of the DpSpSEEK side chain can catch free Ca²⁺ in saliva due to the charge adsorption effect. In order to prepare more functional materials based on DpSpSEEK, we designed a cysteine-labeled peptide sequence DpSpSEEKC, which could conjugate other macromolecules by forming a sulfur-based linkage. In this work, we measured the adsorption of DpSpSEEKC to HAP by various methods. We also coated DpSpSEEKC on a demineralized tooth enamel surface to evaluate its biomineralization capacity. The DpSpSEEKC-coated samples were characterized after immersion in artificial saliva for 2 weeks. The results showed that DpSpSEEKC has a strong adsorption capacity to HAP and could induce remineralization on the demineralized tooth enamel surface due to its carboxyl and phosphate groups. Compared with the control samples, the mechanical properties of the DpSpSEEKC-coated samples were obviously improved. In conclusion, DpSpSEEKC can provide a potential method for restoring demineralized tooth enamel.