Effect of enamel organic matrix on the potential of Galla chinensis to promote the remineralization of initial enamel carious lesions in vitro

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.

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.

Sealing effects of different Chinese herbal medicines on dentinal tubules: a scanning electron microscopic observation

BACKGROUND AND OBJECTIVES

To evaluate the sealing effects of different Chinese herbal medicines on dentinal tubules, and to provide a reference for the clinical treatment of dentin hypersensitivity.

METHODS

Forty dentin slices prepared by freshly extracted bovine mandibular central incisors were randomly assigned to procyanidins, tannic acid, gallic acid, naringin, epigallocatechin gallate (EGCG), glycyrrhizic acid, paeonol, and blank groups. Dentin slices in each Chinese herbal medicine group were treated three times a day, each for 5 min, and then immersed in a remineralization solution for the rest of the time. Dentin slices in the blank group were directly immersed in the remineralization solution for 7 days. The dentinal tubule sealing effect was observed under the scanning electron microscope (SEM).

RESULTS

SEM results showed that the dentinal tubules were almost completely open in the blank group, which was mostly open in the gallic acid, EGCG, glycyrrhizic acid, and paeonol groups, and were sealed in procyanidins, tannic acid, and naringin groups. Significant differences were detected in mean area, mean diameter of dentinal tubules, and mean plugging rate of dentinal tubules between the remaining Chinese herbal medicine groups and blank group (P < .05). Among them, the dentinal tubule sealing effect of procyanidins, tannic acid, and naringin was obvious.

CONCLUSION

The findings suggested that procyanidins, tannic acid, and naringin can effectively seal dentinal tubules, which provided a basis for clinical treatment of dentin hypersensitivity.

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.

Comparison of Composition and Anticaries Effect of Galla Chinensis Extracts with Different Isolation Methods

Objectives:

Galla chinensis water extract (GCE) has been demonstrated to inhibit dental caries by favorably shifting the demineralization/remineralization balance of enamel and inhibiting the biomass and acid formation of dental biofilm. The present study focused on the comparison of composition and anticaries effect of Galla chinensis extracts with different isolation methods, aiming to improve the efficacy of caries prevention.

Methods:

The composition of water extract (GCE), ethanol extract (eGCE) and commercial tannic acid was compared. High performance liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (HPLC-ESI-TOF-MS) analysis was used to analyze the main ingredients. In vitro pH-cycling regime and polymicrobial biofilms model were used to assess the ability of different Galla chinensis extracts to inhibit enamel demineralization, acid formation and biofilm formation.

Results:

All the GCE, eGCE and tannic acid contained a high level of total phenolics. HPLC-ESI-TOF-MS analysis showed that the main ingredients of GCE were gallic acid (GA), while eGCE mainly contained 4-7 galloylglucopyranoses (GGs) and tannic acid mainly contained 5-10 GGs. Furthermore, eGCE and tannic acid showed a better effect on inhibiting enamel demineralization, acid formation and biofilm formation compared to GCE.

Conclusions:

Galla chinensis extracts with higher tannin content were suggested to have higher potential to prevent dental caries.

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 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.