Effect of compounds of Galla chinensis on remineralisation of initial enamel carious lesions in vitro

Evaluation of Ilex guayusa and Piper marginatum Extract Cytotoxicity on Human Dental Pulp Mesenchymal Stem Cells

BACKGROUND

Amelogenesis imperfecta is a hereditary disorder affecting dental enamel. Among its phenotypes, hypocalcified AI is characterized by mineral deficiency, leading to tissue wear and, consequently, dental sensitivity. Excessive fluoride intake (through drinking water, fluoride supplements, toothpaste, or by ingesting products such as pesticides or insecticides) can lead to a condition known as dental fluorosis, which manifests as stains and teeth discoloration affecting their structure. Our recent studies have shown that extracts from Colombian native plants, Ilex guayusa and Piper marginatum, deposit mineral ions such as phosphate and orthophosphate into the dental enamel structure; however, it is unknown whether these extracts produce toxic effects on the dental pulp.

OBJECTIVE

To assess cytotoxicity effects on human dental pulp stem cells (hDPSCs) exposed to extracts isolated from I. guayusa and P. marginatum and, hence, their safety for clinical use.

METHODS

Raman spectroscopy, fluorescence microscopy, and flow cytometry techniques were employed. For Raman spectroscopy, hDPSCs were seeded onto nanobiochips designed to provide surface-enhanced Raman spectroscopy (SERS effect), which enhances their Raman signal by several orders of magnitude. After eight days in culture, I. guayusa and P. marginatum extracts at different concentrations (10, 50, and 100 ppm) were added. Raman measurements were performed at 0, 12, and 24 h following extract application. Fluorescence microscopy was conducted using an OLIMPUS fv1000 microscope, a live-dead assay was performed using a kit employing a BD FACS Canto TM II flow cytometer, and data analysis was determined using a FlowJo program.

RESULTS

The Raman spectroscopy results showed spectra consistent with viable cells. These findings were corroborated using fluorescence microscopy and flow cytometry techniques, confirming high cellular viability.

CONCLUSIONS

The analyzed extracts exhibited low cytotoxicity, suggesting that they could be safely applied on enamel for remineralization purposes. The use of nanobiochips for SERS effect improved the cell viability assessment.

The action of microbial collagenases in dentinal matrix degradation in root caries and potential strategies for its management: a comprehensive state-of-the-art review

Conventional views associate microbial biofilm with demineralization in root caries (RC) onset, while research on their collagenases role in the breakdown of collagen matrix has been sporadically developed, primarily in vitro. Recent discoveries, however, reveal proteolytic bacteria enrichment, specially Porphyromonas and other periodontitis-associated bacteria in subgingivally extended lesions, suggesting a potential role in RC by the catabolism of dentin organic matrix. Moreover, genes encoding proteases and bacterial collagenases, including the U32 family collagenases, were found to be overexpressed in both coronal and root dentinal caries. Despite these advancements, to prove microbial collagenolytic proteases' definitive role in RC remains a significant challenge. A more thorough investigation is warranted to explore the potential of anti-collagenolytic agents in modulating biofilm metabolic processes or inhibiting/reducing the size of RC lesions. Prospective treatments targeting collagenases and promoting biomodification through collagen fibril cross-linking show promise for RC prevention and management. However, these studies are currently in the in vitro phase, necessitating additional research to translate findings into clinical applications. This is a comprehensive state-of-the-art review aimed to explore contributing factors to the formation of RC lesions, particularly focusing on collagen degradation in root tissues by microbial collagenases.

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.

Comparison of calcium-based technologies to remineralise enamel subsurface lesions using microradiography and microhardness

Assessment of enamel subsurface lesion remineralisation is essential for the evaluation of novel remineralisation technologies. The gold standard to assess subsurface mineral gain of enamel lesions is transverse microradiography (TMR). However, some studies have utilised surface microhardness (SMH) to evaluate efficacy of remineralisation agents. The aim of this study was to assess remineralisation of enamel subsurface lesions using TMR and SMH after in vitro treatment with calcium-containing technologies, and to test correlation between the TMR and SMH measurements. The parameters obtained from the TMR and SMH analyses of enamel subsurface remineralisation were not significantly correlated. Furthermore, the enamel subsurface remineralisation as measured by TMR was significantly correlated with the water-soluble calcium concentration of the remineralisation products. Scanning electron microscopy revealed surface precipitates formed by specific remineralisation treatments obfuscated accurate assessment of remineralisation by SMH. It was concluded that TMR is a more appropriate method for analysis of enamel subsurface remineralisation, and that SMH values of remineralised enamel should be interpreted with caution. Using TMR the level of remineralisation (%R) by the different technologies was CPP-ACP/F (31.3 ± 1.4%); CPP-ACP (24.2 ± 1.4%); CaSO₄/K₂HPO₄/F (21.3 ± 1.4%); f-TCP/F (20.9 ± 1.0%); Nano-HA/F (16.3 ± 0.3%); Nano-HA (15.3 ± 0.6%) and F alone control (15.4 ± 1.3%).

Galla Chinensis, a Traditional Chinese Medicine: Comprehensive review of botany, traditional uses, chemical composition, pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Galla chinensis (GC), a traditional Chinese medicine (TCM), has a wide range of pharmacological properties which have been widely used for more than 1400 years. Based on shape, GC is divided into two groups: jiaobei and dubei. It is a bitter, sour, cold and astringent substance which is usually used for treating diarrhea, constipation, bleeding, cough, vomiting, sweating, hemorrhoids, and anal and uterine prolapse. It is distributed in Japan, North Korea, and all parts of China.

AIM OF STUDY

This study was aimed at carrying out a comprehensive overview of the current status of research on Galla chinensis (GC) for better understanding of it characteristics, while providing a clear direction for future studies. It has aroused the interest of researchers, leading to development of medicinal value, expansion of its application, and provision of wider and more effective drug choices. This study was focused on the traditional uses, botany, chemical composition, pharmacology and toxicology of GC. Finally, the study focused on possible future research directions for GC.

MATERIALS AND METHODS

A comprehensive analysis was done based on academic papers, pharmaceutical monographs, ancient medicinal works, and drug standards of China. This review used Galla and Galla chinensis as keywords for retrieval of information on GC from online databases such as PubMed, Elsevier, CNKI, Web of Science, Google Scholar, SCI hub, and Baidu academic.

RESULTS

It was found that the chemical constituents of GC included tannins, phenolic acid, amino acids and fatty acid, with polyphenol compounds (especially tannins and gallic acid) as the distinct components. In vitro and in vivo studies revealed that GC exerted numerous biological effects such as anti-caries, antibacterial, antiviral, anticancer, and antioxidant effects. The therapeutic effect of GC was attributed mainly to the biological properties of its bioactive components.

CONCLUSIONS

GC is an important TCM which has potential benefit in the treatment of a variety of diseases. However, the relationship amongst the structure and biological activity of GC and its components, mechanism of action, toxicity, pharmacokinetics and target organs need to be further studied. Quality control and quality assurance programs for GC need to be further developed. There is need to study the dynamics associated with the accumulation of chemical compounds in GC as well as the original plants and aphid that form GC.

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.

Evaluation of flexural strength and antibacterial effect of orthodontic acrylic resins containing Galla chinensis extract

Objective:

To evaluate different concentrations of Galla chinensis extract (GCE) added to poly(methyl methacrylate) (PMMA), which is widely used for fabrication of removable orthodontic appliances, regarding the effectiveness of this herbal extract on antimicrobial effect and flexural strength of PMMA.

Methods:

Acrylic resin samples containing 0.4%, 0.8% and 1.6% GCE were prepared. Flexural strength was investigated via three-point flexural strength test for the 15 acrylic resin blocks of each concentration. Disk diffusion test was used to evaluate antibacterial effects of incorporating the same concentrations of GCE into acrylic resin. All these three groups were compared with the control group, with no added GCE, regarding flexural strength and antibacterial properties.

Results:

Comparison of flexural strength between the three study groups and the control group showed significant differences between the groups (P=0.018). However, there was no significant difference between the groups containing GCE. There were significant differences in antimicrobial activity between the four groups (P=0.026).

Conclusion:

Within the limitations of this study, it is suggested that incorporation of GCE into PMMA would be beneficial for antimicrobial activity and flexural strength of PMMA, but further studies on other physical properties and antimicrobial effects on other bacterial strain would be beneficial prior to clinical investigations.

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.

Effectiveness of poly-γ-glutamic acid in maintaining enamel integrity

OBJECTIVE

The aim of the study was to determine demineralisation inhibition and remineralisation potential of poly-γ-glutamic acid with its possible mechanism of action on human dental enamel.

METHODOLOGY

Three sodium-fluoride(NaF) concentration(0.01%w/v,0.1%w/v and 0.5%w/v respectively)and two poly-γ-glutamic acid(PGGA)concentration(1%w/v and 2%w/v respectively)were prepared in 0.1 M acetic acid(pH4.0)and deionized distilled water.For de/re-mineralisation study, tooth samples (18 teeth varnished, leaving a 2 mm² window on the mid-buccal surfaces) were immersed in respective acidified NaF and PGGA solutions. The Ca²⁺ release/uptake was monitored with ISE over 72-hr with increasing pH every 24-h from 4.0 to 6.0.These teeth were later subjected to cross-sectional microhardness to determine integrated mineral recovery of enamel on increasing pH of respective acidified solution.In order to determine mechanism of PGGA,two concentrations of PGGA in deionized-water-solutions were used for tooth samples immersion followed by overnight drying then later subjected to Fourier Transform Infra-Red(FT-IR) analysis.The FT-IR analysis was also carried out on PGGA powder.For control,the experiment was repeated using hydroxyapatite(HAp)pellets.The density of PGGA solutions(1%and2%)was also measured to determine their dynamic viscosities.

RESULTS

The ISE and microhardness testing revealed statistically significant (ρ ≤ 0.05) dissolution inhibition and remineralisation potential for tooth sample treated with acidified 2%PGGA. From the FT-IR spectra, it was observed that the profiles of the enamel and HAp surfaces treated with 1%-and 2%-PGGA solutions were similar to those of PGGA powder.It was found that the viscosity of PGGA increases with increasing concentration.

CONCLUSION

The study implies that 2% PGGA is more effective than NaF as forms a coating layer to protect from demineralisation and promote remineralisation of the tooth surface.

Inhibitory ASIC2-mediated calcineurin/NFAT against colorectal cancer by triterpenoids extracted from Rhus chinensis Mill

ETHNOPHARMACOLOGICAL RELEVANCE

Studies have shown that the etiology and pathogenesis of colorectal cancer are closely related to the tumor microenvironment, and the cancer tissue is still in the state of "energy deficit" and has to promote energy generation through high glycolysis. Rhus chinensis Mill is a Chinese herbal medicine used to treat various types of solid tumors in China. Colorectal cancer (CRC) is a heterogeneous disease group caused by abnormal changes in glucose metabolism resulted in lactic acid production, which remodels acidosis.

AIM OF THE STUDY

Although previous studies have shown that the active compounds of Rhus chinensis Mill. can inhibit the proliferation of tumor cells, whether its triterpenoids could effectively regulate glycolysis involved in CRC have not been systematically investigated.

MATERIALS AND METHODS

In this study, the extraction of triterpenoids extract from Rhus chinensis Mill. was obtained, and cell viability assay, the percentage of apoptosis for CRC cells were counted, and matrigel invasion assay and production of lactic acid and glucose uptake assay was determined. we further examined the expression of the key glycolytic enzymes and acid-sending ion channel (ASIC) family members of SW620 cells, and some key proteins in the glycolytic pathway were further verified.

RESULTS

Notably, triterpenoids (TER) of Rhus chinensis Mill. showed effective anti-proliferative activity and significantly altered protein levels associated with CRC cell survival and glycolysis metabolism. TER could down-regulate the expression of ASIC2, in CRC SW620 cell line. Most importantly, the levels of ASIC2 and calcineurin/nuclear factor of activated T cells (NFAT) were also down-regulated by TER. Furthermore, inhibition of activated the ASIC2-mediated calcineurin/NFAT1 pathway and target gene transcript expression of MMP-2 and MMP-9 in parallel to reduce, and resulted in the reduced invasion ability by TER treatment.

CONCLUSION

The potential pathways and targets that involved in glycolysis to excert the anti-CRC effects of main compounds in triterpenoids of Rhus chinensis Mill. were predicted by network pharmacology methods. Our findings thus provided rational evidence that inhibition of the ASIC2-induced calcineurin/NFAT pathway by triterpenoids in Rhus chinensis Mill. profoundly suppressed cell growth and invasion in CRC, which target alternative glycolysis in colorectal tumor cells, may be a useful adjuvant therapy in the treatment of colorectal cancer.

[Prevention of infectious diseases through microecology modulation techniques]

The microbe is small in volume, but large in quantity and species. The symbiotic microbe, which is far more than human cells, code millions times of genes than human being. Somatic cells and these symbiotic microbe distributing in human body skin, respiratory tract, oral cavity and gastrointestinal tract, urinary tract and other parts form a complex ecosystem whose dynamic balance is highly related to body health. With the successful implementation of Human Microbiome Project, more attentions have been paid to the next generation microbiome technologies. New tools and methods for ecological regulation of human microbiome are emerging. The way we improve the world of human microbiology will be more convenient. This paper will make a review on the modulation techniques of human microbiome.

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.

Oral health in China: from vision to action

Chinese president Xi Jinping made clear at the National Health and Wellness Conference that health is the prerequisite for people's all-around development and a precondition for the sustainable development of China. Oral health is an indispensable component of overall health in humans. However, the long neglect of oral health in overall health agendas has made oral diseases an increasing concern. With this perspective, we described the global challenges of oral diseases, with an emphasis on the challenges faced by China. We also described and analyzed the recently released health policies of the Chinese government, which aim to guide mid-term and long-term oral health promotion in China. More importantly, we called for specific actions to fulfill the larger goal of oral health for the nation. The implementation of primordial prevention efforts against oral diseases, the integration of oral health into the promotion of overall health, and the management of oral diseases in conjunction with other chronic non-communicable diseases with shared risk factors were highly recommended. In addition, we suggested the reform of standard clinical residency training, the development of domestic manufacturing of dental equipment and materials, the revitalization traditional Chinese medicine for the prevention and treatment of oral diseases, and integration of oral health promotion into the Belt and Road Initiative. We look forward to seeing a joint effort from all aspects of the society to fulfill the goal of Healthy China 2030 and ensure the oral health of the nation.

Galla chinensis Compounds Remineralize Enamel Caries Lesions in a Rat Model

OBJECTIVES

To investigate the effect of Galla chinensis chemical compounds on enamel caries remineralization in rats.

METHODS

A total of 40 rats were inoculated with Streptococcus sobrinus 6715 and fed a cariogenic diet (Keyes 2000). The rats were randomly divided into 4 groups and treated topically twice a day with each of the following extracts (or control) for 5 weeks: distilled and deionized water (DDW, negative control); 1,000 ppm NaF (positive control); 4,000 ppm G. chinensis crude aqueous extract (GCE), or 4,000 ppm gallic acid (GA). After the experimental period, Keyes' caries diagnosis and scoring technique was applied as a preliminary evaluation on the molar teeth. For more accurate remineralization data, the residual enamel volume of the first molar and the mineral density (MD) of the enamel were further analyzed by micro-CT.

RESULTS

The severity of molar enamel caries decreased in the following order of treatment groups: DDW > GA > GCE > NaF (p < 0.05). In addition, the residual first molar enamel volume and MD values increased in the order of DDW, GA, GCE and NaF treatment groups (p < 0.05). In most molars, remineralization layers were observed on the surface of lesions.

CONCLUSION

G. chinensis compounds remineralize enamel caries lesions in a rat model.

Antibacterial effect and shear bond strength of an orthodontic adhesive cement containing Galla chinensis extract

Galla chinensis extract (GCE), a naturally-derived agent, has a significant inhibitory effect on cariogenic bacteria. The present study aims to evaluate the antibacterial effect and shear bond strength of an orthodontic adhesive cement containing GCE. A resin-modified glass ionomer cement incorporated GCE at five mass fractions (0, 0.1, 0.2, 0.4, and 0.8%) to prepare GCE-containing cement for analysis. For the agar diffusion test, cement specimens were placed on agar disk inoculated with Streptococcus mutans (strain ATCC 25175). Following 48 h incubation, the inhibition halo diameter was measured. To assess bacteria colonization susceptibility, S. mutans adhesion to cement specimens was detected by scanning electron microscopy (SEM) following 48 h incubation. To evaluate bond strength, a total of 50 metal brackets were bonded on premolar surfaces by using cement (10 teeth/group). Following immersion in an artificial saliva for 3 days, shear bond strength (SBS) was measured. The results demonstrated that GCE-containing samples exhibited a larger bacterial inhibition halo than control, and the inhibition zone increased as the GCE mass fraction increased. SEM analysis demonstrated that S. mutans presented a weaker adherent capacity to all GCE-containing cements compared with control, but the difference between each GCE-containing group was not significant. SBS values of each GCE-containing group exhibited no difference compared with the control. In conclusion, GCE-containing adhesive cement exhibits a promising inhibitory effect on S. mutans growth and adhesion. Without compromising bond strength, adding GCE in adhesive cement may be an attractive option for preventing white spot lesions during orthodontic treatment.

Natural products and caries prevention

Dental caries is considered as the most common polymicrobial oral disease in the world. With the aim of developing alternative approaches to reduce or prevent the decay, numerous papers showed the potential anticaries activity of a number of natural products. The natural products with anticaries effects are selected from e.g. food, beverages, flowers or traditional herbs. Most of the effective components are proven to be polyphenol compounds. Many of the natural products are studied as antibacterial agents, while some of them are found to be effective in shifting the de-/remineralization balance. However, the mechanisms of the anticaries effects are still unclear for most of the natural products. In the future, more efforts need to be made to seek novel effective natural products via in vitro experiment, animal study and in situ investigations, as well as to enhance their anticaries effects with the help of novel technology like nanotechnology.

Control of hydroxyapatite crystal growth by gallic acid

The purpose of this study is to detect the effect of gallic acid (GA) on hydroxyapatie crystal growth and find the mechanism of the regulation. We evaluated the morphology of HAP crystals grown under various amounts of GA (0, 0.05, 1, and 4 gL(-1)). Subsequently, the chemical composition, crystal size and the morphology were investigated via the energy-dispersive X-ray spectrometer, attenuated total fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, transmission electron microscope and scanning electron microscopy. In all groups, the Ca/P ratio was closed to 1.67. In the absence of GA, crystals did not arrange, while in the presence of GA, crystals tended to form spherules. The size of the crystals decreased with the concentration of GA increased. These results indicated the role of GA on the growth and morphology of hydroxyapatite crystals, which might be the key mechanism for gallic acid regulating the mineralization.

Effect of Galla сhinensis on the Wear Resistance of Dentine

The aim of this study was to investigate the effect of natural herb material Galla Chinensis extraction (GCE) on the wear resistance of dentine in vitro. Forty sound bovine dentine blocks were prepared and randomly divided into two groups. The samples were first treated with 4000 ppm aqueous solution of Galla chinensis and distilled deionized water (DDW) was used as a control. Then the samples were subjected to 5,000 cycles of attrition bathed under artificial saliva with 150 N loads. Wear measurement, scanning electron microscopy (SEM) examination and energy-dispersive X-ray spectrometry (EDX) analysis were utilized to evaluate the effects of GCE on the wear resistance. The depth of the wear scar of DDW-treated surface (mean = 32.5 μm, SD = 11.8 μm) was significantly greater than that of GCE-treated surface (mean = 26.4 μm, SD = 13.9 μm) (p < 0.05). Furthermore, the SEM images showed severe wear on the DDW specimens and less wear on the GCE-treated samples. Finally, from EDX data, GEC group had higher percentage of Ca and P than the control. In conclusion, our study suggested that Galla chinensis could enhance wear resistance of dentine.

Chemical composition of Galla chinensis extract and the effect of its main component(s) on the prevention of enamel demineralization in vitro

To determine the chemical composition of Galla chinensis extract (GCE) by several analysis techniques and to compare the efficacy of GCE and its main component(s) in inhibition of enamel demineralization, for the development of future anticaries agents, main organic composition of GCE was qualitatively determined by liquid chromatography–time of flight–mass spectrometry (LC–TOF–MS) and quantified by high-performance liquid chromatography–diode array detector (HPLC–DAD). Inorganic ions were tested by inductively coupled plasma–atomic emission spectroscopy and F was especially measured by ion chromatography. Then, bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times. Each cycle included 5-min applications with one of four treatments: 4 g⋅L⁻¹ GCE solution, 4 g⋅L⁻¹ gallic acid (GA) solution, 1 g⋅L⁻¹ NaF solution (positive control), deionized water (DDW, negative control), and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer. Acidic buffers were retained for calcium analysis. The main organic composition of GCE were GA and its isomer, and, to a lesser extent, small molecule gallotannins. The content of GA in GCE was 71.3%±0.2% (w/w). Inorganic ions were present in various amounts, of which Ca was (136±2.82) µg⋅g⁻¹, and Zn was (6.8±0.1) µg⋅g⁻¹. No F was detected in GCE. In pH cycling, GA showed an effect similar to GCE in inhibiting enamel demineralization (P>0.05). GA was found to be the main effective, demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.

In vitro inhibitory effect of clove essential oil and its two active principles on tooth decalcification by apple juice

The dental erosion or decalcification of enamel is a significant clinical problem. Apple acidic beverages are thought to increase the potential for dental erosion. The purpose of this in vitro study was to investigate the effect of clove essential oil (CEO) and its active principles on tooth decalcification of apple juices. On GC-MS analysis, CEO showed a high content of eugenol (58.29%) and eugenyl acetate (19.10%). Teeth specimens were randomly divided into 5 treatment groups: control, CEO, eugenol, eugenyl-acetate, and fluoride. The specimens were exposed for 24 h and were analyzed for calcium contents using Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES). Data were analyzed using student t-test (P < 0.05). CEO, eugenol, and eugenyl-acetate significantly decreased the decalcification of tooth by the apple juice to only 17, 24, and 21 mgL⁻¹, respectively. Hemolytic activity on human erythrocytes was studied to exclude the possibility of further associated cytotoxicity. It was observed that the CEO and its two lead molecules inhibit the decalcification and/or promote the remineralization caused by the apple juices. The effect of the test compounds appears to be distinct like that of fluoride treatment. CEO may, therefore, serve to be a promising adjunct to fluoride in the treatment of root caries during minimally invasive therapy.

Natural enamel caries in polarized light microscopy: differences in histopathological features derived from a qualitative versus a quantitative approach to interpret enamel birefringence

Lesion area measurement of enamel caries using polarized light microscopy (PLM) is currently performed in a large number of studies, but measurements are based mainly on a mislead qualitative interpretation of enamel birefringence in a single immersion medium. Here, five natural enamel caries lesions are analysed by microradiography and in PLM, and the differences in their histopathological features derived from a qualitative versus a quantitative interpretation of enamel birefringence are described. Enamel birefringence in different immersion media (air, water and quinoline) is interpreted by both qualitative and quantitative approaches, the former leading to an underestimation of the depth of enamel caries mainly when the criterion of validating sound enamel as a negatively birefringent area in immersion in water is used (a current common practice in dental research). Procedures to avoid the shortcomings of a qualitative interpretation of enamel birefringence are presented and discussed.

Rhus chinensis and Galla Chinensis--folklore to modern evidence: review

The species Rhus chinensis Mill. (Anacardiaceae) is an important representative of the genus Rhus, which contains over 250 individual species found in temperate and tropical regions worldwide. Rhus chinensis has long been used by folk medicine practitioners in Asia. Leaves, roots, stem, bark, fruit and particularly the galls on Rhus chinensis leaves, Galla chinensis, are recognized to have preventative and therapeutic effects on different ailments (such as diarrhea, dysentery, rectal and intestinal cancer, diabetes mellitus, sepsis, oral diseases and inflammation). However, it is critical to separate evidence from anecdote. Fortunately, recent scientific research has revealed that Rhus chinensis compounds possess strong antiviral, antibacterial, anticancer, hepatoprotective, antidiarrheal and antioxidant activities. Moreover, compounds isolated from the stem of Rhus chinensis significantly suppressed HIV-1 activity in vitro. Compounds from this plant were also found to inhibit enamel demineralization in vitro and enhance remineralization of dental enamel with fluoride. This review highlights claims from traditional and tribal medicinal lore and makes a contemporary summary of phytochemical, biological and pharmacological findings on this plant material. It aims to show that the pharmaceutical potential of this plant deserves closer attention.

Effect of compounds of Galla chinensis on remineralization of enamel surface in vitro

OBJECTIVE

The aim of the study was to investigate the effect of chemical compounds of Galla chinensis on in vitro the remineralization of enamel surface.

METHOD

Bovine enamel blocks with in vitro produced initial lesions were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4x1 min applications with one of four treatments: Group A: 1000 ppm F aq. (as NaF, positive control); Group B: deionized water (DDW, negative control); Group C: 4000 ppm crude aqueous extract of G. chinensis (GCE); Group D: 4000 ppm gallic acid. The enamel specimens were analysed by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray microdiffraction (XRD).

RESULTS

The morphology of surface enamel was different in each group. The mineral composition was identified as similar to hydroxylapatite, but the crystallite sizes of enamel in different groups were significantly different. In addition, the Ca/P ratios were significantly lower in GCE group.

CONCLUSION

GCE could affect the mineral ions deposit on the surface layer and then modified the remineralization of initial dental caries. The mechanism seems to be different between GCE and gallic acid.

Chemical and crystallographic study of remineralized surface on initial carious enamel treated with Galla chinensis

To investigate the morphologic, chemical and crystallographic characters of remineralized surface on initial carious enamel treated with Galla chinensis, scanning electron microscopy equipped with energy dispersive analysis spectroscopy were used, and X-ray microdiffraction (microzone XRD) was used for the first time to analyze in situ the microzone crystallite of remineralized surface on carious enamel. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH-cycling regime for 12 days of remineralization. Each daily cycle included 4x1 min applications with one of the three treatments: distilled and deionized water (DDW); 1 g/L NaF; 4 g/L G. chinensis extract (GCE). After the treatments, some rod-like deposits and many irregular prominences were found on GCE-treated enamel surface, and the intensities of Ca and P signals showed a tendency to increase; Ca:P ratio was significantly higher than that of DDW-treated enamel. X-ray microdiffraction showed hydroxyapatite was still the main component of GCE-treated enamel, and the crystallinity was increased, the crystal lattice changed gently with decreased lattice parameter a. These results indicated the potential of GCE in promoting the remineralization of initial enamel carious lesions, and supported the previous hypothesis about GCE mechanism. Combined with the anti-bacteria and demineralization inhibition properties of GCE, the natural G. chinensis may become one more promising agent for caries prevention.

Effects of Galla chinensis on the surface topography of initial enamel carious lesion: an atomic force microscopy study

To investigate the effect of Galla chinensis on the surface topography of initial enamel carious lesion, atomic force microscope (AFM) was used, and it was a new AFM application in enamel de-/remineralization research. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH-cycling regime for 12 days. Each daily cycle included 4x1 min applications with one of three treatments: negative control group: deionized water; positive control group: 1 g/L aqueous solutions of NaF; experimental group: 4 g/L aqueous solutions of G. chinensis extract (GCE). The surface topography and roughness were investigated on the enamel slabs before and after pH-cycling by AFM. 3D AFM images revealed the surface topographical changes of GCE-treated enamel. Significant difference existed before and after the pH-cycling among the groups. AFM offers a powerful tool for enamel de-/remineralization research. The surface roughness results provide the evidences to remineralization of carious lesion, and indicate the potential of G. chinensis in promoting the remineralization. G. chinensis may become one more promising agent for caries prevention.

Effect of gallic acid on the wear behavior of early carious enamel

The purpose of this research was to investigate the wear behavior of early carious enamel remineralized with gallic acid. Forty natural human premolar specimens with early caries lesions were prepared. A remineralization pH-cycling treatment agent of 4000 ppm gallic acid was used for 12 days to treat the early lesions. The changes in microhardness were monitored. Nanoscratch tests were used to evaluate wear resistance. The experimental data were analyzed by using a t-test. The widths of traces were measured by an AMBIOS XP-2 stylus profilometer. After remineralization, all samples re-hardened significantly. The coefficients of friction became higher, and the widths of scratches were larger than they were before remineralization. Gallic acid significantly improved the early carious enamel's hardness. The wear damage of the samples treated with gallic acid was more severe than that of the control group. There were more obvious cracks and delaminations on the traces of the treated group. Compared with the control group, the enamel remineralized with gallic acid had inferior wear resistance. After remineralization, the dominant damage mechanisms of early carious enamel had changed from plastic deformation and adhesive wear to a combination of brittle cracks and delamination of enamel.

Anticaries effect of compounds extracted from Galla chinensis in a multispecies biofilm model

INTRODUCTION

Galla Chinensis is a leaf gall known to have some antibacterial effects. Using an in vitro biofilm model of dental plaque, the present study aimed to evaluate the anticaries effects of Galla Chinensis and its chemical fractions.

METHODS

A four-organism bacterial consortium (Streptococcus sanguis, Streptococcus mutans, Actinomyces naeslundii, Lactobacillus rhamnosus) was grown on hydroxyapatite (HA) discs, bovine enamel blocks, and glass surfaces in a continuous culture system and exposed to repeated solution pulses. Galla Chinensis extracts, sucrose solutions, and sodium fluoride solutions were pulsed into different flow cells. The pH value of the planktonic phase in each flow cell was recorded and the bacteria colonizing the biofilm on the HA discs were counted. Enamel blocks were observed using a polarized microscope and lesion depth was evaluated. The biofilm morphology was examined with a fluorescence microscope and the images captured were analyzed on an image analysis system.

RESULTS

When Galla Chinensis extract, its chemical fraction, or fluoride was added to the sucrose solution, the planktonic phase pH remained higher than that in the sucrose alone. A lower level of colonization on the HA surface was also observed in the groups to which Galla Chinensis and fluoride were added compared with the control sucrose group, and this was reflected in both the total viable count and the biofilm imaging, which showed fewer cariogenic bacteria and a less compact biofilm, respectively. Enamel demineralization in both the fluoride group and the Galla Chinensis group was significantly less than that in the sucrose group.

CONCLUSIONS

Galla Chinensis and fluoride may inhibit the cariogenicity of the oral biofilm. Galla Chinensis appears to be a promising source of new agents that may prevent dental caries.

In vitro remineralization effects of grape seed extract on artificial root caries

Grape seed extract (GSE) contains proanthocyanidins (PA), which has been reported to strengthen collagen-based tissues by increasing collagen cross-links. We used an in vitro pH-cycling model to evaluate the effect of GSE on the remineralization of artificial root caries. Sound human teeth fragments obtained from the cervical portion of the root were stored in a demineralization solution for 96 h at 37 degrees C to induce artificial root caries lesions. The fragments were then divided into three treatment groups including: 6.5% GSE, 1,000 ppm fluoride (NaF), and a control (no treatment). The demineralized samples were pH-cycled through treatment solutions, acidic buffer and neutral buffer for 8 days at 6 cycles per day. The samples were subsequently evaluated using a microhardness tester, polarized light microscopy (PLM) and confocal laser scanning microscopy (CLSM). Data were analyzed using ANOVA and Fisher's tests (p<0.05). GSE and fluoride significantly increased the microhardness of the lesions (p<0.05) when compared to a control group. PLM data revealed a significantly thicker mineral precipitation band on the surface layer of the GSE-treated lesions when compared to the other groups (p>0.05), which was confirmed by CLSM. We concluded that grape seed extract positively affects the demineralization and/or remineralization processes of artificial root caries lesions, most likely through a different mechanism than that of fluoride. Grape seed extract may be a promising natural agent for non-invasive root caries therapy.