Long-term analysis of humoral responses and spike-specific T cell memory to Omicron variants after different COVID-19 vaccine regimens.

Background: The emergence of SARS-CoV-2 variants has raised concerns about the sustainability of vaccine-induced immunity. Little is known about the long-term humoral responses and spike-specific T cell memory to Omicron variants, with specific attention to BA.4/5, BQ.1.1, and XBB.1. Methods: We assessed immune responses in 50 uninfected individuals who received varying three-dose vaccination combinations (2X AstraZeneca + 1X Moderna, 1X AstraZeneca + 2X Moderna, and 3X Moderna) against wild-type (WT) and Omicron variants at eight months post-vaccination. The serum antibody titers were analyzed by enzyme-linked immunosorbent assays (ELISA), and neutralizing activities were examined by pseudovirus and infectious SARS-CoV-2 neutralization assays. T cell reactivities and their memory phenotypes were determined by flow cytometry. Results: We found that RBD-specific antibody titers, neutralizing activities, and CD4+ T cell reactivities were reduced against Omicron variants compared to WT. In contrast, CD8+ T cell responses, central memory, effector memory, and CD45RA+ effector memory T cells remained unaffected upon stimulation with the Omicron peptide pool. Notably, CD4+ effector memory T cells even exhibited a higher proportion of reactivity against Omicron variants. Furthermore, participants who received three doses of the Moderna showed a more robust response regarding neutralization and CD8+ T cell reactions than other three-dose vaccination groups. Conclusion: Reduction of humoral and CD4+ T cell responses against Omicron variants in vaccinees suggested that vaccine effectiveness after eight months may not have sufficient protection against the new emerging variants, which provides valuable information for future vaccination strategies such as receiving BA.4/5 or XBB.1-based bivalent vaccines.

Arecoline Induces ROS Accumulation, Transcription of Proinflammatory Factors, and Expression of KRT6 in Oral Epithelial Cells.

Areca nut is a major contributor to the high prevalence of oral cancer in Asia. The precise mechanisms by which areca nut stimulates mucosal cells and contributes to the progression of oral cancer urgently require clarification. The current study aimed to assess the effects of arecoline on the normal human gingival epithelium cell line S-G. Cell viability, levels of reactive oxygen species (ROS), protein expression, cellular morphology, and gene expression were evaluated using the MTT test, flow cytometry, Western blot analysis, optical or confocal microscopy, and RT-qPCR. Keratin (KRT6) analysis involved matched normal and cancer tissues from clinical head and neck specimens. The results demonstrated that 12.5 µg/mL of arecoline induced ROS production, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) mRNA expression in S-G cells. This activation of the MAPK/ERK pathway increased KRT6 expression while limiting cell migration. In head and neck cancer tissues, KRT6B gene expression exceeded that of normal tissues. This study confirms that arecoline induces ROS accumulation in normal cells, leading to the secretion of proinflammatory factors and KRT6 expression. This impedes oral mucosal healing, thereby promoting the progression of oral cancer.

Combining microfluidic chip and low-attachment culture devices to isolate oral cancer stem cells.

Background/purpose: Cancer stem cells (CSCs) are widely recognized as key drivers of cancer initiation, progression, and therapeutic resistance. Microfluidic chip technology offers a promising approach for CSC isolation and study. This study investigated the efficacy of a microfluidic chip-based method for isolating single cells from oral cancer cell lines characterized by high stem-like phenotypes. Specifically, the study focused on examining the sphere-forming capability and the expression of CSC markers, including aldehyde dehydrogenase 1A1 (ALDH1A1), CD44, and CD133, in isolated cell clones from OECM-1 and SAS cell lines. Materials and methods: Oral cancer cell lines were subjected to isolation using a microfluidic chip. The captured single cells were cultured to assess their sphere-forming capacity in ultra-low binding culture. Furthermore, the protein expression levels of ALDH1A1, CD44, and CD133 in the isolated cell clones were analyzed using western blotting. Results: The microfluidic chip-assisted isolation method significantly enhanced the sphere-forming capability of both OECM-1 and SAS cell clones compared to their parent cell lines. Moreover, the expression levels of CSC markers ALDH1A1, CD44, and CD133 were upregulated in the microfluidic chip-assisted isolated cell clones, indicating a higher stem-like phenotype. Conclusion: This study demonstrates the effectiveness of the microfluidic chip-based approach in isolating oral cancer cell clones with elevated stem-like characteristics. This method offers a valuable tool for further investigation of CSCs and their role in cancer progression, as well as future therapy development for oral cancers.

Association of higher transient receptor potential melastatin 8 expression with higher tumor histologic grades, lymph node metastasis, risk factors, and worse survival in patients with head and neck squamous cell carcinoma.

Background/purpose: Transient receptor potential melastatin 8 (TRPM8), a thermosensitive ion channel known for its role in cold sensation and menthol response, has emerged as a potential regulator in various cancers. This study aimed to investigate expression trends of TRPM8 in head and neck squamous cell carcinoma (HNSCC) cases and oral squamous cell carcinoma (OSCC) cell lines and its association with clinicopathological features. Materials and methods: The noncancerous matched tissues and HNSCC paired tissue samples from 84 HNSCC patients were utilized to evaluate the association of TRPM8 with HNSCC clinicopathological features. TRPM8 expression was examined in HNSCC patient tissues and OSCC cell lines treated with arecoline. Results: Kaplan-Meier survival analysis of TCGA data revealed high TRPM8 expression correlated with unfavorable outcomes and higher tumor histologic grades. TRPM8 mRNA expression was upregulated in HNSCC cell lines and patients' tissue samples. Arecoline treatment led to significantly increased TRPM8 mRNA and protein expression in OSCC cell lines. Lymph node metastasis showed a significant association with upregulated TRPM8 expression in combined OSCC and oropharyngeal squamous cell carcinoma (OPSCC) cases. TRPM8 mRNA expression was upregulated in HNSCC and OSCC patients with alcohol drinking and cigarette smoking habits, but not in betel quid chewing. Conclusion: These findings reveal the involvement of TRPM8 in HNSCC's malignant development and metastasis, suggesting that high expression of TRMP8 may be mutually causal with addiction to tobacco, alcohol, and betel nut in HNSCC patients. Further investigations are needed to determine the underlying pathways of TRPM8 in HNSCC's development and progression.

Protective Effect of Electroacupuncture on Chemotherapy-Induced Salivary Gland Hypofunction in a Mouse Model.

Radiotherapy and chemotherapy can impair salivary gland (SG) function, which causes xerostomia and exacerbate other side effects of chemotherapy and oral infection, reducing patients' quality of life. This animal study aimed to assess the efficacy of electroacupuncture (EA) as a means of preventing xerostomia induced by 5-fluorouracil (5-FU). A xerostomia mouse model was induced via four tail vein injections of 5-FU (80 mg/kg/dose). EA was performed at LI4 and LI11 for 7 days. The pilocarpine-stimulated salivary flow rate (SFR) and salivary glands weight (SGW) were recorded. Salivary immunoglobulin A (SIgA) and lysozyme were determined via enzyme-linked immunosorbent assay (ELISA). SG was collected for hematoxylin and eosin staining to measure acini number and acinar cell size. Tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and aquaporin 5 (AQP5) mRNA expressions in SG were quantified via RT-qPCR. 5-FU caused significant decreases in SFR, SGW, SIgA, lysozyme, AQP5 expression, and acini number, while TNF-α and IL-1ß expressions and acinar cell size were significantly increased. EA treatment can prevent 5-FU damage to the salivary gland, while pilocarpine treatment can only elevate SFR and AQP5 expression. These findings provide significant evidence to support the use of EA as an alternative treatment for chemotherapy-induced salivary gland hypofunction and xerostomia.

Neutralizing antibodies targeting a novel epitope on envelope protein exhibited broad protection against flavivirus without risk of disease enhancement.

BACKGROUND: Flavivirus causes many serious public health problems worldwide. However, licensed DENV vaccine has restrictions on its use, and there is currently no approved ZIKV vaccine. Development of a potent and safe flavivirus vaccine is urgently needed. As a previous study revealed the epitope, RCPTQGE, located on the bc loop in the E protein domain II of DENV, in this study, we rationally designed and synthesized a series of peptides based on the sequence of JEV epitope RCPTTGE and DENV/ZIKV epitope RCPTQGE. METHODS: Immune sera were generated by immunization with the peptides which were synthesized by using five copies of RCPTTGE or RCPTQGE and named as JEV-NTE and DV/ZV-NTE. Immunogenicity and neutralizing abilities of JEV-NTE or DV/ZV-NTE-immune sera against flavivirus were evaluated by ELISA and neutralization tests, respectively. Protective efficacy in vivo were determined by passive transfer the immune sera into JEV-infected ICR or DENV- and ZIKV-challenged AG129 mice. In vitro and in vivo ADE assays were used to examine whether JEV-NTE or DV/ZV-NTE-immune sera would induce ADE. RESULTS: Passive immunization with JEV-NTE-immunized sera or DV/ZV-NTE-immunized sera could increase the survival rate or prolong the survival time in JEV-challenged ICR mice and reduce the viremia levels significantly in DENV- or ZIKV-infected AG129 mice. Furthermore, neither JEV -NTE- nor DV/ZV-NTE-immune sera induced antibody-dependent enhancement (ADE) as compared with the control mAb 4G2 both in vitro and in vivo. CONCLUSIONS: We showed for the first time that novel bc loop epitope RCPTQGE located on the amino acids 73 to 79 of DENV/ZIKV E protein could elicit cross-neutralizing antibodies and reduced the viremia level in DENV- and ZIKV-challenged AG129 mice. Our results highlighted that the bc loop epitope could be a promising target for flavivirus vaccine development.

Caffeic Acid Phenethyl Ester and Caffeamide Derivatives Suppress Oral Squamous Cell Carcinoma Cells.

Caffeic acid phenethyl ester (CAPE) contains antibiotic and anticancer activities. Therefore, we aimed to investigate the anticancer properties and mechanisms of CAPE and caffeamide derivatives in the oral squamous cell carcinoma cell (OSCC) lines SAS and OECM-1. The anti-OSCC effects of CAPE and the caffeamide derivatives (26G, 36C, 36H, 36K, and 36M) were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Cell cycle and total reactive oxygen species (ROS) production were analyzed using flow cytometry. The relative protein expression of malignant phenotypes was determined via Western blot analysis. The results showed that 26G and 36M were more cytotoxic than the other compounds in SAS cells. After 26G or 36M treatment for 48 h, cell cycle S phase or G2/M phase arrest was induced, and cellular ROS increased at 24 h, and then decreased at 48 h in both cell lines. The expression levels of cell cycle regulatory and anti-ROS proteins were downregulated. In addition, 26G or 36M treatment inhibited malignant phenotypes through mTOR-ULK1-P62-LC3 autophagic signaling activated by ROS generation. These results showed that 26G and 36M induce cancer cell death by activating autophagy signaling, which is correlated with altered cellular oxidative stress.

Effects of Temoporfin-Based Photodynamic Therapy on the In Vitro Antibacterial Activity and Biocompatibility of Gelatin-Hyaluronic Acid Cross-Linked Hydrogel Membranes.

This study was performed to design a hydrogel membrane that exhibits antibacterial properties and guides different tissues. Gelatin and hyaluronic acid were used as the main structures, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) was used as a cross-linker, and temoporfin was used as an antibacterial agent. The results revealed that the hydrogel membrane impregnated with temoporfin (HM-T) had a fixation index of >89%. Temoporfin was used in conjunction with a diode laser and did not significantly affect EDC-induced cross-linking. The inhibitory activity of temoporfin showed that HM-T15 and HM-T30 (light exposure for 15 and 30 min, respectively) had remarkable antibacterial properties. The cell survival rate of HM-T15 was 73% of that of the control group, indicating that temoporfin exposure for 15 min did not exert cytotoxic effects on L-929 cells. HM and HM-T15 hydrogel membranes showed good cell adhesion and proliferation after 14 days of dark incubation. However, the hydrogel membrane containing temoporfin significantly reduced pro-inflammatory gene expression. In summary, the HM-T15 group showed potential as a biodegradable material for biocompatible tissue-guarded regeneration membranes with antibacterial properties. This study demonstrated the potential of temoporfin for innovative biomaterials and delivery systems applied to new regenerative periodontal therapies.

Association of rs9679162 Genetic Polymorphism and Aberrant Expression of Polypeptide N-Acetylgalactosaminyltransferase 14 (GALNT14) in Head and Neck Cancer.

The polypeptide N-Acetylgalactosaminyltransferase 14 (GALNT14) rs9679162 and mRNA expression were associated with treatment outcome in various cancers. However, the relation of GALNT14 and head and neck cancer were nuclear. A total of 199 patients with head and neck squamous cell carcinoma (HNSCC) were collected in this study, including oral SCC (OSCC), oropharyngeal SCC (OPSCC), laryngeal SCC (LSCC), and others. The DNA and RNA of cancer tissues were extracted using the TRI Reagent method. The rs9679162 was analyzed using polymerase chain reaction (PCR) and sequencing methods in 199 DNA specimens, and the mRNA expression was analyzed using quantitative reverse transcription PCR (RT-qPCR) methods in 68 paired RNA specimens of non-cancerous matched tissues (NCMT) and tumor tissues. The results showed that the genotype of TT, TG, and GG appeared at 30%, 44%, and 26%, respectively. Non-TT genotype or G alleotype were associated with alcohol, betel nut, and cigarette using among patients with OSCC, and it also affected the treatment and survival of patients with OSCC and LSCC. High GALNT14 mRNA expression levels increased lymphatic metastasis of patients with HNSCC, and treatment and survival in patients with OPSCC. Overall, the GALNT14-rs9679162 genotype and mRNA expression level can be used as indicators of HNSCC treatment prognosis.

Boosting with Multiple Doses of mRNA Vaccine after Priming with Two Doses of Protein Subunit Vaccine MVC-COV1901 Elicited Robust Humoral and Cellular Immune Responses against Emerging SARS-CoV-2 Variants.

Confronted with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, such as Delta and Omicron, with high infectivity and immune evasion capacity, vaccination remains the most effective tool to prevent infection and severe illness. However, heterologous vaccination of mRNA vaccines primed with protein subunit vaccines had not been evaluated before the current study. Since subunit vaccine MVC-COV1901 (MVC) has been granted emergency use authorization in Taiwan, in this study, we explored the humoral and cellular immune responses to additional third (2× MVC/Mod) and fourth (2× MVC/2× Mod) doses of mRNA-1273 (Mod) after priming with two doses of subunit vaccine MVC against the emerging variants. We found a 12.3- to 16.1-fold increase in antibodies targeting the receptor binding domain (RBD) of the Delta variant with 2× MVC/Mod compared to two doses of MVC (2× MVC) or AZD1222 (2× AZ) regimens and a 26- to 32.2-fold improvement in neutralizing potency against the Omicron variant (BA.1). Besides, the numbers of gamma interferon (IFN-γ)-secreting T cells induced by 2× MVC/Mod were also elevated 3.5-fold and 3.7- to 4.3-fold for the wild type and Delta variant. However, boosting with a fourth dose of Mod (2× MVC/2× Mod) after the 2× MVC/Mod regimen failed to significantly improve the immune responses. Moreover, all vaccination schedules showed reduced neutralizing activity against the Omicron variant. Collectively, our results suggested that the third or fourth dose booster vaccination with mRNA vaccine after priming with two doses of protein subunit vaccine could elicit stronger humoral and cellular immune responses. These findings could provide a future global heterologous boosting strategy against COVID-19. IMPORTANCE Vaccination is the most important strategy to combat the COVID-19 outbreak; however, it remains to be determined whether heterologous prime-boost regimens could induce equal or even stronger immune responses against SARS-CoV-2. Here, we showed that boosting the additional doses of mRNA-1273 (Mod) priming with two doses of MVC-COV1901 (MVC) (2× MVC/Mod) improved humoral and cellular immunity compared to two doses of AZD1222 (2× AZ) or MVC (2× MVC) against SARS-CoV-2 variants. However, the Omicron variant showed strong immune evasion ability for all vaccination schedules. Our findings provided evidence supporting that heterologous vaccination by boosting with mRNA vaccine after priming with two doses of protein subunit vaccine could strongly promote humoral and cellular immune responses against the emerging SARS-CoV-2 variants.

Humoral, Cellular and Cytokine Immune Responses Against SARS-CoV-2 Variants in COVID-19 Convalescent and Confirmed Patients With Different Disease Severities.

Objectives: To assess humoral and cellular immune responses against SARS-CoV-2 variants in COVID-19 convalescent and confirmed patients, to explore the correlation between disease severity, humoral immunity, and cytokines/chemokines in confirmed patients, and to evaluate the ADE risk of SARS-CoV-2. Methods: Anti-RBD IgG were quantified using an ELISA. Neutralization potency was measured using pseudovirus and real virus. Cellular immunity was measured using ELISpot. Cytokine/chemokine levels were detected using multiplex immunoassays. In vitro ADE assays were performed using Raji cells. Results: One-month alpha convalescents exhibited spike-specific antibodies and T cells for alpha and delta variants. Notably, the RBD-specific IgG towards the delta variant decreased by 2.5-fold compared to the alpha variant. Besides, serum from individuals recently experienced COVID-19 showed suboptimal neutralizing activity against the delta and omicron variants. Humoral immune response, IL-6, IP-10 and MCP-1 levels were greater in patients with severe disease. Moreover, neither SARS-CoV-1 nor SARS-CoV-2 convalescent sera significantly enhanced SARS-CoV-2 pseudovirus infection. Conclusions: Significant resistance of the delta and omicron variants to the humoral immune response generated by individuals who recently experienced COVID-19. Furthermore, there was a significant correlation among disease severity, humoral immune response, and specific cytokines/chemokine levels. No evident ADE was observed for SARS-CoV-2.

Synergistic Effect of Combination of a Temoporfin-Based Photodynamic Therapy with Potassium Iodide or Antibacterial Agents on Oral Disease Pathogens In Vitro.

5, 10, 15, 20-Tetrakis(3-hydroxyphenyl)chlorin (temoporfin) is a photosensitizer used in photodynamic therapy for oral cancer and periodontal disease treatment. This study determined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of temoporfin. Additionally, the combination of potassium iodide (KI) or antimicrobial agents in oral pathogens under hypoxic or normoxic conditions were determined. We also evaluated the biofilm removal effect and detected the expressions of the antibiotic resistance-related genes and biofilm formation-related genes of methicillin-resistant staphylococcus aureus (MRSA). The results provided reveal that the combination of the temoporfin and KI had a synergistic effect of reducing the MICs and MBCs of Lactobacillus acidophilus and Lactobacillus paracasei under normoxic and hypoxic conditions due to increasing H2O2 production. Temoporfin increased the biofilm removal of Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, and Staphylococcus aureus under normoxic condition, and it reduced the antibiotic resistance-related genes expression of MRSA. The combination of temoporfin with ampicillin or chlorhexidine significantly enhanced the bactericidal effect on MRSA. This study provides a potential application of temoporfin on the clinical side against oral pathogens and the prevention of oral diseases.

In Vitro Antimicrobial Potential of CAPE and Caffeamide Derivatives against Oral Microbes.

Caffeic acid phenethyl ester (CAPE) is a natural component isolated from propolis and used in traditional medicine. We aimed to investigate the antimicrobial properties and action mechanism of CAPE and caffeamide derivatives (26G and 36M) against oral disease microbes. We resolved the minimum inhibitory and bactericidal concentrations of 26G and 36M and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation and antibiotic resistance gene expression in methicillin-resistant Staphylococcus aureus (MRSA). Our results revealed that 26G and 36M showed the best anticancer and antimicrobial activities, respectively, compared with the other four caffeamide derivatives. Both 26G and 36M showed heat-dependent decreases in antimicrobial activity. The 36M derivative was stable irrespective of pH, whereas 26G was not stable under high pH conditions. Biofilm formation and antibiotic resistance-related gene expression were consistent with their respective phenotypes. This study provides evidence for the potential application of CAPE and caffeamide derivatives in dental medicine to cure or prevent oral diseases.

The relation between NEAT1 expression level and survival rate in patients with oral squamous cell carcinoma.

BACKGROUND/PURPOSE: Numerous studies have shown that long noncoding RNAs (lncRNAs) are involved in cancer progression and chemotherapy resistance. Nuclear enriched abundant transcript 1 (NEAT1) is an lncRNA. It affects tumor cell progression and drug resistance in various tumors. However, the relation of NEAT1 and survival rate in oral squamous cell carcinoma (OSCC) requires further study. MATERIALS AND METHODS: One normal gingival epithelium cell line, SG, three oral cancer cell lines (HSC3, OEC-M1, and SAS), 34 paired non-cancerous matched tissues (NCMT), and OSCC tissues were used in this study. Tri-reagent was used for total RNA extraction. NEAT1 expression was assessed by reverse transcription-quantitative PCR (RT-qPCR). RESULTS: NEAT1 expression in oral cancer cell lines was lower than that in normal cells and was significantly downregulated in OSCC. NEAT1 upregulation reduced the survival rate of patients with OSCC. NEAT1 upregulation also reduced the survival rate of OSCC patients treated with chemotherapy and radiotherapy. CONCLUSION: These results indicate that NEAT1 expression is a valuable biomarker for the prediction and prognosis of oral cancer.

Risk of anxiety and depression in patients with lichen planus: A nationwide population-based study.

BACKGROUND: This study aims to determine the risk of developing anxiety and/or depression among patients with lichen planus. METHODS: Based on the Longitudinal Health Insurance Database of Taiwan National Health Insurance Research Database, a total of 4012 patients with lichen planus and 16,048 matched controls (1:4) were enrolled between January 1, 2000, and December 31, 2015. After controlling for the risk variables, multivariate Cox proportional hazard regression and the log-rank test with Kaplan-Meier method were performed to assess the influence of anxiety/depression among individuals with lichen planus under a maximum follow-up period of 16 years. RESULTS: The subsequent anxiety or depression incidence of the lichen planus group and the comparisons was 19.67% (1962.70 per 105 person-years) and 10.11% (982.23 per 105person-years), respectively. Additionally, after adjustment of the risk variables, the hazard ratios for anxiety, depression, anxiety without depression, depression without anxiety, anxiety or depression, and both anxiety and depression combined were 1.779 (95%CI: 1.289-2.477, p < 0.001), 2.010 (95%CI: 1.454-2.790, p < 0.001), 2.015 (95%CI: 1.463-2.799, p < 0.001), 2.356 (95%CI: 1.705-3.286, p < 0.001), 2.011 (95%CI: 1.457-2.793, p < 0.001), and 1.515 (95%CI: 1.100-2.134, p < 0.001), respectively. LIMITATIONS: Individuals with lichen planus were unable to be classified into oral subtype and cutaneous subtype based on the ICD-9-CM. Moreover, the results of our study could not demonstrate the mechanism between lichen planus and anxiety and/or depression. CONCLUSION: Patients with lichen planus was positively associated with developing anxiety or depression. Physicians should to be aware of the signs of anxiety and/or depression while facing the patients with lichen planus during the clinical practices.

In Vitro Assessment of the Cell Metabolic Activity, Cytotoxicity, Cell Attachment, and Inflammatory Reaction of Human Oral Fibroblasts on Polyetheretherketone (PEEK) Implant-Abutment.

The purpose of this research is to compare the cytotoxicity of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) with conventional dental implant-abutment materials, namely titanium alloy (Ti-6Al-4V) and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), to evaluate the cell metabolic activity, cytotoxicity, and inflammation potential of human oral fibroblasts (HOF) on these materials. Disk-shaped specimens were designed and prepared via a dental computer-aided manufacturing technology system. Surface topography, roughness, and free energy were investigated by atomic force microscope and contact angle analyzer; cell metabolic activity and cytotoxicity by MTT assay; and morphological changes by scanning electron microscopy (SEM). The effect of pro-inflammatory gene expression was evaluated by RT-qPCR. The obtained data were analyzed with one-way analysis of variance and post-hoc Tukey's honest significant difference tests. PEEK and PEKK exhibited higher submicron surface roughness (0.04 µm) and hydrophobicity (>80°) than the control. Although the cell activity of PEEK was lower than that of Ti-6Al-4V and Y-TZP for the first 24 h (p < 0.05), after 48 h there was no difference (p > 0.05). According to the cell cytotoxicity and the pro-inflammatory cytokine gene expression assays, there was no difference between the materials (p > 0.05). SEM observations indicated that HOF adhered poorly to PEKK but properly to Ti-6Al-4V, Y-TZP, and PEEK. PEEK and PEKK show comparable epithelial biological responses to Ti-6Al-4V and Y-TZP as implant-abutment materials. Between the two polymeric materials, the PEEK surface, where the HOF showed better cell metabolic activity and cytotoxicity, was a more promising implant-abutment material.

Biofilm Formation on the Surface of (Poly)Ether-Ether-Ketone and In Vitro Antimicrobial Efficacy of Photodynamic Therapy on Peri-Implant Mucositis.

Poly-ether-ether-ketone (PEEK) is an aesthetically pleasing natural material with good biocompatibility and shock absorption characteristics. The application of PEEK as a dental implant or abutment is expected to reduce the risk of failure and enhance aesthetics. Given that approximately one in 15 patients have allergic reactions to antibiotics, photodynamic therapy (PDT) has been gaining attention as an alternative treatment. Herein, the applicability of PEEK dental implants or abutments was investigated using material analyses, biofilm formation assay, and cell viability tests. The possible use of PDT for peri-implant mucositis was evaluated with the biofilm removal assay. The obtained data were analyzed based on the multivariate analysis of variance, paired t-tests, and the Pearson correlation coefficient (α = 0.05). The results revealed that PEEK was significantly less conducive to the formation of biofilms with S. mutans and A. actinomycetemcomitan (p < 0.001) but exhibited comparable MG-63 (human osteoblast-like) osteoblast cell viability (p > 0.05) to the other materials. PDT had similar antimicrobial efficacy and yielded similar biofilm removal effects to antibiotics. Altogether, these findings suggest that PEEK has attractive features and can serve as an alternative material for dental implants or abutments. In cases where peri-implant mucositis occurs, PDT can be used as an accessible therapeutic approach.

Effects of melatonin to arecoline-induced reactive oxygen species production and DNA damage in oral squamous cell carcinoma.

BACKGROUND/PURPOSE: Arecoline, the major alkaloid of areca nut, is known to induce reactive oxygen species (ROS) and DNA damage during oral cancer progression. This study aim to evaluate whether melatonin, an antioxidant, supported or repressed the arecoline-induced carcinogenesis phenotypes in oral squamous cell carcinoma (OSCC). METHODS: The cytotoxicity of arecoline or melatonin treatment alone and their co-treatment in the OSCC cell line OEC-M1 were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cell cycle, cell death, and total ROS production were analyzed using flow cytometer. The protein expression was determined using western blot analysis. The genotoxicity and mutation rate were determined using micronucleus assay and hypoxanthine phosphoribosyl transferase (HPRT) forward mutation assay, respectively, in CHO-K1 cells. The ataxia telangiectasia mutated (ATM) promoter activity and DNA repair ability were determined through reporter assay. RESULTS: The result showed that both the arecoline and melatonin induced ROS production and antioxidant enzymes expression. Melatonin treatment enhanced arecoline-induced ROS production, cytotoxicity, G2/M phase arrest, and cell apoptosis in OSCC cells. On the other hand, melatonin treatment activated DNA repair activity to reverse arecoline-induced DNA damage and mutation. CONCLUSION: These results indicated that melatonin is a potential chemopreventive agent for betel quid chewers to prevent OSCC initiation and progression.

In vitro antimicrobial and antipro-inflammation potential of honokiol and magnolol against oral pathogens and macrophages.

BACKGROUND/PURPOSE: Honokiol and magnolol are natural components isolated from Magnolia bark that is used in traditional Chinese and Japanese herbal medicine. These two isomers are used as a component of dietary supplements and cosmetic products. In this study, we investigated the antimicrobial effect of honokiol and magnolol on pathogens causing oral diseases, their mechanism of action in biofilm formation and drug resistance of oral pathogens, and inflammatory regulation in mammalian cells. METHODS: We determined the minimum inhibitory concentration and minimum bactericidal concentration of honokiol and magnolol, and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation, antibiotic-resistance gene expression in MRSA, and pro-inflammatory gene expression in mammalian cells. RESULTS: Honokiol showed better antimicrobial activity than magnolol. Both honokiol and magnolol showed stable bacterial inhibitory activity over a wide range of temperature and pH, reduced biofilm formation, and antibiotic resistance in oral pathogens. The biofilm formation- and antibiotic resistance-related gene expression was consistent with the respective phenotypes. Furthermore, these two isomers repressed the expression of pro-inflammatory genes in RAW264.7 cells. CONCLUSION: Our study provides evidence of the potential application of honokiol and magnolol in dental medicine to cure or prevent oral diseases.

Effects of unilateral posterior missing-teeth on the temporomandibular joint and the alignment of cervical atlas.

Cervical atlas alignment changes are associated with craniofacial development. Disturbance of craniofacial development may be associated with temporal mandibular joint function. Therefore, we examined the possibility of a correlation between unilateral missing teeth and morphologic changes of the spine and posture. We collected eighty-nine patients (38 men and 51 women) with unilateral posterior missing teeth and twenty patients without previous orthodontic treatment or missing posterior teeth by tracing and analyzing their panoramic and cephalometric film. We measured the angulations of articular eminence, cranio-cervical angle, and the percentage of the occlusal plane passing through the first and second cervical vertebrae with other morphologic geometric data. The angle of articular eminence inclination was higher in the non-missing teeth group than the missing teeth group (46.66° and 42.28°, respectively). The cranio-cervical angle was smaller in the missing posterior teeth group than the non-missing posterior teeth group (99.81° and 103.27°, respectively). The missing teeth group also showed fewer occlusal planes passing through the intersection of the first and second cervical vertebrae compared to the non-missing teeth group (28.9% and 65%, respectively). Individuals with unilateral missing teeth had lower articular eminence inclination, smaller cranio-cervical angle, and a lower percentage of the occlusal plane passing through the intersection of the first and second cervical vertebrae.