The Power of Licorice (Radix glycyrrhizae) to Improve Oral Health: A Comprehensive Review of Its Pharmacological Properties and Clinical Implications

Licorice (Radix glycyrrhizae) is a plant root extract widely used in various applications, including cosmetics, food supplements, and traditional medicine. It has a long history of medicinal use in different cultures due to its diverse pharmacological properties. Licorice has traditionally been used for treating gastrointestinal problems, respiratory infections, cough, bronchitis, arthritis, and skin conditions. In recent years, the potential therapeutic benefits of licorice for oral health have gained significant interest. This paper aims to provide a comprehensive review of the effects of licorice extracts and their bioactive components on common oral diseases such as dental caries, periodontitis, halitosis, candidiasis, and recurrent aphthous ulcers. The chemical composition of licorice has shown the presence of several bioactive compounds such as glycyrrhizin, glabridin, isoliquiritigenin (ISL), and licochalcone exhibiting various pharmacological activities, including anti-inflammatory, antimicrobial, antioxidative, and immunomodulatory effects. Interestingly, in certain patients, licorice has shown a promising potential to inhibit the spread of viruses, prevent biofilm formation, reduce inflammation, boost immune responses, alleviate pain, and exert antioxidative effects. In this review, we provide a brief overview of the current understanding of licorice's therapeutic benefits in the treatment of oral ailments, emphasising its potential as an alternative treatment option for oral diseases. Further research is warranted to explore its efficacy, safety, and clinical applications using placebo-controlled clinical trials.

Formulation and Evaluation of Prednisolone Sodium Metazoate-Loaded Mucoadhesive Quatsomal Gel for Local Treatment of Recurrent Aphthous Ulcers: Optimization, In Vitro, Ex Vivo, and In Vivo Studies

This study aims to formulate a buccal mucoadhesive gel containing prednisolone sodium metazoate-loaded quatsomes for efficient localized therapy of recurrent aphthous ulcers. Quatsomes were prepared using a varied concentration of quaternary ammonium surfactants (QAS) and cholesterol (CHO). A 2³ factorial design was conducted to address the impact of independent variables QAS type (X₁), QAS to CHO molar ratio (X₂), and sonication time (X₃). The dependent variables were particle size (PS; Y₁), polydispersity index (PDI; Y₂), zeta potential (ZP; Y₃), entrapment efficiency percent (EE%; Y₄) and percent of drug released after 6 h (Q6%: Y₅). Then, the selected quatsomes formula was incorporated into different gel bases to prepare an optimized mucoadhesive gel to be evaluated via in vivo study. The PS of the developed quatsomes ranged from 69.47 ± 0.41 to 113.28 ± 0.79 nm, the PDI from 0.207 ± 0.004 to 0.328 ± 0.004, ZP from 45.15 ± 0.19 to 68.1 ± 0.54 mV, EE% from 79.62 ± 1.44 to 98.60% ± 1.22 and Q6% from 58.39 ± 1.75 to 94.42% ± 2.15. The quatsomal mucoadhesive gel showed rapid recovery of ulcers, which was confirmed by the histological study and the evaluation of inflammatory biomarkers. These results assured the capability of the developed quatsomal mucoadhesive gel to be a promising formulation for treating buccal diseases.

Management of recurrent aphthous ulcers exploiting polymer-based Muco-adhesive sponges: in-vitro and in-vivo evaluation

Recurrent aphthous ulcer (RAU) is a well-known painful, inflammatory disease with uncertain etiology for which local symptomatic therapy is only available. The aim of this study was to formulate and characterize muco-adhesive sponges containing a mixture of tenoxicam and miconazole nitrate to manage pain, inflammation and avoid candida infection that may accompany RAU due to poor oral hygiene. Two polymers at different concentrations were used to prepare sponges applying simple freeze-drying. Medicated chitosan (2%) sponges (mC2) showed acceptable physical appearance, surface pH (6.3 ± 0.042), porosity (25.7% ± 1.8), swelling index (5.7 ± 0.11), in-vivo and ex-vivo muco-adhesion time (115 min.±0.813 and 155 min.±1.537, respectively), ex-vivo muco-adhesion force (0.09 N ± 0.002) and scanning electron microscope (SEM) images. For concurrent clear-cut determination of tenoxicam and miconazole nitrate from mC2, a new UPLC method was developed and validated. mC2 sponges exhibited superior in-vitro drug release profiles where ∼100% of tenoxicam released within 5 min for fast pain relief with a more prolonged miconazole nitrate release. Furthermore, in-vivo animal study revealed that mC2 caused a significant decrease in the acetic acid-induced ulcer size in rats after 6 days of treatment (p < .0001) compared to negative and positive controls. Additionally, histopathological examination showed faster healing with complete restoration of the normal oral histology in rats. The present study concludes that chitosan sponge loaded with a combination of tenoxicam and miconazole nitrate could improve healing of RAU cases.

Combined signatures of serum proteome and transcriptome in patients with recurrent aphthous ulcer

OBJECTIVES

Recurrent aphthous ulcer (RAU) is a common oral disease with unclear mechanism. This study aimed to explore the serum signatures of RAU patients via proteomic and transcriptomic analysis.

METHODS

This study was based on clinical observation. Part of serum was used for clinical tests, while the rest was processed for isobaric tags for relative and absolute quantitation (ITRAQ) labeling coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS) combined with microRNA (miRNA) microarrays. Bioinformatic analysis was then used to obtain significant signatures, which was verified by ELISA, qRT-PCR, and dual-luciferase reporter gene assays.

RESULTS

Clinical data showed that triglyceride level, white blood cell count, and neutrophils percentage were increased in RAU group, while lymphocytes percentage was decreased. ITRAQ-2D LC-MS/MS identified 22 upregulated and 33 downregulated proteins in RAU group. Simultaneously, miRNA microarrays identified 64 upregulated and 31 downregulated miRNAs. After integrative bioinformatic analysis and verification, three miRNA-protein pairs, mainly involved in oxidative stress and inflammation responses, were obtained. Additionally, the interaction network indicated the crucial role of complement and coagulation cascade pathway in RAU.

CONCLUSIONS

Our study revealed that complement and coagulation cascade pathway, oxidative stress, and inflammation responses may act as vital factors in pathogenesis of RAU.

Lactic acid 5% mouth wash vs Kenalog in Orabase 0.1% for treatment and prophylaxis of recurrent aphthous ulcer

BACKGROUND

The outcomes of most therapeutic modalities for recurrent aphthous ulcer (RAU) are still unsatisfactory.

AIM

To evaluate lactic acid 5% mouth wash vs Kenalog in Orabase for treatment and prophylaxis of RAU.

PATIENTS/METHODS

Forty cases with early-onset idiopathic RAU were enrolled in this study. Patients were divided into two equal groups; group A patients had used Kenalog in Orabase twice daily, and group B patients had used lactic acid 5% mouth wash 3 times daily. All patients had used the therapy for 1-2 weeks according to patients' clinical response that was evaluated according to oral clinical manifestations index (OCMI); before therapy, during course of treatments and in follow-up visits.

RESULTS

At the ends of both first and second weeks, from beginning of therapy, OCMI was reduced more in group B patients than in group A with statistically significant results. These results revealed that group B achieved more reduction in the size, pain, and healing time of RAU. During the follow-up period, group A showed 40% recurrence rate while group B showed 5% only.

CONCLUSIONS

Lactic acid 5% mouth wash is natural, safe, and effective so it is better alternative to corticosteroids for treatment and prophylaxis of RAU without any side effects.

Salivary cortisol and dehydroepiandrosterone as oral biomarkers to determine stress in patients with recurrent aphthous stomatitis

Background

Recurrent aphthous stomatitis (RAS) is one of the most common oral ulcerative diseases with a multifactorial etiology. Although psychological stress is an exacerbating factor, the role of salivary stress hormones, cortisol, and dehydroepiandrosterone (DHEA) in this oral disease has not been extensively reported. The study aimed to estimate and compare the salivary cortisol and DHEA levels in RAS patients and healthy control group with the aid of ELISA microplate reader.

Subjects and Methods

Sixty patients were enrolled in our study, which included 30 patients with clinically diagnosed RAS and 30 healthy controls. Two mL of unstimulated whole saliva was collected and salivary cortisol and DHEA levels were measured using ELISA kit, and the values were read by microplate ELISA reader and recorded in both groups.

Results and Conclusion

The mean salivary cortisol and DHEA levels were elevated in the RAS patients compared to the healthy controls and were statistically significant. Salivary cortisol and DHEA can serve as oral biomarkers to determine stress in patients with RAS. However, the present study necessitates further studies with larger sample size and an improved protocol to ascertain the actual role of these presumed oral biomarkers as well as anxiety and stress as triggers in the pathogenesis of RAS.

[Soluble programmed death-1 and soluble programmed death ligand 1 protein expression and immune status in patients with recurrent aphthous ulcer]

OBJECTIVE

This study aims to investigate the possible role and significance of soluble programmed death-1 (sPD-1)  /soluble programmed death ligand 1 (sPD-L1) in the immune pathogeneses of recurrent aphthous ulcer (RAU).

METHODS

A total of 30 RAU cases (18 cases of minor RAU, 5 cases of major RAU, and 7 cases of herpetiform ulcers) were enrolled in this study. A total of 18 healthy people served as controls. Lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD16⁺+56⁺) were investigated by flow cytometric analysis. Humoral immunity (IgG, IgA, IgM, C3, and C4) was explored by nephelometry immunoassay. The sPD-1 and sPD-L1 protein levels in the sera of RAU patients were investigated by enzyme-linked immunosorbent assay. The correlations of the sPD-1 and sPD-L1 protein levels with the immune status and clinical characteristics of the RAU patients were analyzed by SPSS 19.0.

RESULTS

The number of CD4+ T cells decreased and the levels of IgM antibodies increased in the RAU patients relative to those in the normal controls (P<0.05). The sPD-1 and sPD-L1 protein levels in the RAU patients were significantly higher than those in the control group (P<0.05). Meanwhile, the sPD-1 and sPD-L1 protein levels in the patients with minor and major RAU were significantly higher than those in the control group (P<0.05). By contrast, no significant difference was found in the patients with herpetiform RAU (P>0.05). Positive correlations were noted between the sPD-1 protein level and the CD19+ cell frequency or C4 level (r₁=0.389, P₁=0.034; r₂=0.382, P₂=0.037).

CONCLUSIONS

Cellular immune hypofunction and humoral immunity disorders were found in the RAU patients. The PD-1/PD-L1 signaling pathway, which might be influenced by the involvement of sPD-1 and sPD-L1 proteins to a certain extent, may play some roles in the immune pathogenesis of RAU.

[Relationship between transforming growth factor-β1 and interleukin-10 single nucleotide polymorphism and susceptibility of recurrent aphthous ulcer]

OBJECTIVE

To explore the possible relationship between recurrent aphthous ulcer (RAU) and single nucleotide polymorphism (SNP) of transforming growth factor-β1 (TGF-β1)-509T/C and interleukin-10 (IL-10)-1082A/G sites.

METHODS

A total of 138 RAU patients were recruited for this study. The control group consisted of 124 subjects. TGF-β1-509T/C and IL-10-1082A/G sites were detected by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) and sequence specific primer-polymerase chain reaction (SSP-PCR). Relative risk ratios were estimated by odds ratios (OR) and 95% confidence interval (95%CI).

RESULTS

Significant differences were found in the genotype frequencies or allele frequencies of TGF-β1-509T/C and IL-10-1082A/G sites between the RAU patients and controls (P < 0.05). CT genotype (OR = 1.231, 95% CI = 0.702-2.160), TT genotype (OR = 2.482, 95% CI = 1.250-4.927), and T allele (OR = 1.465, 95% CI = 1.036-2.074) at the TGF-β1-509 site exhibited high risks. AG genotype (OR = 1.391, 95% CI = 0.808-2.396), GG genotype (OR = 4.165, 95% CI = 1.944-8.924), and G allele (OR = 2.134, 95% CI = 1.474-3.089) at the IL-10-1082A/G site also showed high risks.

CONCLUSION

TGF-β1-509T/C and IL-10-1082A/G sites are associated with the risk of RAU. The TGF-β1 gene-509T allele and IL-10 gene-1082G allele may serve as genetic determinants for RAU.

[Relationship between transforming growth factor-β1 and interleukin-10 single nucleotide polymorphism and susceptibility of recurrent aphthous ulcer]

OBJECTIVE

To explore the possible relationship between recurrent aphthous ulcer (RAU) and single nucleotide polymorphism (SNP) of transforming growth factor-β1 (TGF-β1)-509T/C and interleukin-10 (IL-10)-1082A/G sites.

METHODS

A total of 138 RAU patients were recruited for this study. The control group consisted of 124 subjects. TGF-β1-509T/C and IL-10-1082A/G sites were detected by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) and sequence specific primer-polymerase chain reaction (SSP-PCR). Relative risk ratios were estimated by odds ratios (OR) and 95% confidence interval (95%CI).

RESULTS

Significant differences were found in the genotype frequencies or allele frequencies of TGF-β1-509T/C and IL-10-1082A/G sites between the RAU patients and controls (P < 0.05). CT genotype (OR = 1.231, 95% CI = 0.702-2.160), TT genotype (OR = 2.482, 95% CI = 1.250-4.927), and T allele (OR = 1.465, 95% CI = 1.036-2.074) at the TGF-β1-509 site exhibited high risks. AG genotype (OR = 1.391, 95% CI = 0.808-2.396), GG genotype (OR = 4.165, 95% CI = 1.944-8.924), and G allele (OR = 2.134, 95% CI = 1.474-3.089) at the IL-10-1082A/G site also showed high risks.

CONCLUSION

TGF-β1-509T/C and IL-10-1082A/G sites are associated with the risk of RAU. The TGF-β1 gene-509T allele and IL-10 gene-1082G allele may serve as genetic determinants for RAU.

Increased beta 2 defensin in recurrent aphthous ulcer

OBJECTIVES

It was hypothesized that beta 2 defensin (BD-2) is increased in RAU lesions compared with healthy controls to promote anti-microbial host defence.

METHODS

RAU and control mucosa samples were subjected to quantitative real-time PCR and immunostained for BD-2, CD68, mast cell tryptase and 4-hydroxynonenal (4HNE). The effect of tumour necrosis factor-α (TNF-α) ± interleukin-17C (IL-17C), without and with vitamin K3, was studied on BD-2 expression in epithelial SCC-25 cells.

RESULTS

Although BD-2 mRNA did not differ between healthy and RAU mucosa, BD-2 stained strongly in acute-phase RAU epithelium (P = 0.001). In controls, subepithelial BD-2(+) cells were mast cells and macrophages, whereas in RAU, most infiltrating leucocytes were BD-2(+) (P = 0.004). In cell culture, BD-2 was increased 124-fold by TNF-α (P < 0.0001) and 208-fold synergistically together with IL-17C (P < 0.0001). 4HNE staining of RAU epithelium was not significantly increased, and vitamin K3-induced reactive oxygen species (ROS) did not affect BD-2.

CONCLUSIONS

Anti-microbial BD-2 was not affected by oxidative stress but was highly increased in the epithelial and immigrant cells in the acute-phase RAU lesions, probably in part synergistically by TNF-α and epithelial IL-17C, which are known to be induced by activation of danger-signal receptors by pathogen- and/or damage-associated molecular patterns.

IL-17C and its receptor IL-17RA/IL-17RE identify human oral epithelial cell as an inflammatory cell in recurrent aphthous ulcer

BACKGROUND

Recurrent aphthous ulcer (RAU) is an ulcerative disease of non-keratinized oral mucosa. Colon and bronchial epithelial cells produce interleukin-17C (IL-17C) upon stimulation of Toll-like receptor 2 (TLR2), TLR3 and TLR5, which are highly expressed in epithelial cells in RAU lesions. We therefore investigated the eventual presence and function of IL-17C in cultured human oral keratinocytes (HOK) and control biopsies compared to RAU lesions.

METHODS

Expression of IL-17A, IL-17C, IL-17RA and IL-17RE was analysed in cultured HOK cells using quantitative real-time polymerase chain reaction (qRT-PCR). HOK cells were stimulated with IL-17C and analysed for IL-8 and tumour necrosis factor-α (TNF-α) using qRT-PCR. Control mucosa (n = 5) was immunostained for IL-17A, IL-17C, IL-8, TNF-α and mast cell tryptase and compared with RAU lesions (n = 5) using the mean grey scale value.

RESULTS

IL-17C, but no IL-17A, mRNA was found in cultured HOK cells. Components of the heterodimeric IL-17RA/IL-17RE receptor for IL-17C were also highly expressed. Stimulation of HOK with IL-17C increased TNF-α mRNA (P = 0.03; IL-8 increase was not statistically significant). HOK in RAU lesions stained intensively for IL-17C compared to controls (P = 0.006). This was associated with increased epithelial immunostaining of TNF-α (P = 0.04) and IL-8 (P = 0.02). Most of the inflammatory cells which stained for IL-17A in control mucosa and RAU lesions were also mast cell tryptase positive.

CONCLUSION

IL-17C is highly expressed in epithelial cells in RAU lesions, where it seems to stimulate oral keratinocytes via IL-17RA/IL-17RE to produce pro-inflammatory cytokines. Human oral epithelial cells are probably important inflammatory cells in RAU.

Determination of levels of salivary IgA subclasses in patients with minor recurrent aphthous ulcer

Context:

Recurrent Aphthous Ulcer (RAU) is an inflammatory disease characterized by recurrent, painful oral ulcers. It is of multifactorial etiology. Salivary immunoglobulins have important role in the protection of mucosal surfaces.

Aim:

The aim of this study was to determine salivary immunoglobulin A1 (IgA1) and IgA2 in acute and remission phases of the disease.

Materials and Methods:

Thirty clinically confirmed cases of RAU and 30 age-and sex-matched controls were included in the study. After detailed case history and thorough clinical examination, 2 mL of saliva was collected in both acute and remission phases of the disease. The obtained saliva samples were subjected to quantification of IgA1 and IgA2 levels using RID kit.

Results:

The mean IgA2 level was significantly higher (P<.001) in both acute and remission phase of the study group. The mean IgA1 level also showed a significant increase in the acute phase compared to remission as well as controls (P<.05). Females exhibited a higher level in acute phase for IgA1 and in both phases for IgA2 (P<.05).

Conclusion:

The results associated with clinical observations suggest that acute phase is characterized with increase in IgA2 that might reflect increased immune response as a possible result of the microbial stimulation seen in the acute phase in comparison to the remission period. IgA plays an important role in the pathogenesis of RAU and it can be used as a parameter to assess the mucosal immune status