Computational analysis of 3D printing: Selecting the better among newly released materials.

Resin-based three-dimensional (3D) printing finds extensive application in the field of dentistry. Although studies of cytotoxicity, mechanical and physical properties have been conducted for newly released 3D printing resins such as Crowntec (Saremco), Temporary Crown Resin (Formlabs) and Crown & Bridge (Nextdent), the resistance of these materials to esterases in saliva has not been demonstrated at the molecular level. Therefore, in this study, the binding affinities and stability of these new 3D printing resins to the catalytic sites of esterases were investigated using molecular docking and molecular mechanics with Poisson-Bolzmann and surface area solvation (MM/PBSA) methods after active pocket screening. Toxicity predictions of the materials were also performed using ProTox-II and Toxtree servers. The materials were analyzed for mutagenicity, cytotoxicity, and carcinogenicity, and LD50 values were predicted from their molecular structures. The results indicated that out of the three novel 3D printing materials, Nexdent exhibited reduced binding affinity to esterases, indicating enhanced resistance to enzymatic degradation and possessing a superior toxicity profile.

Effect of the application of a hydrogen peroxide home bleaching agent on the cytotoxicity of different CAD-CAM restorative materials.

BACKGROUND: The information regarding the cytotoxicity of ceramic and resin-matrix ceramic materials subjected to over-the-counter bleaching agents is limited in the literature. OBJECTIVES: The aim of the present study was to investigate the cytotoxic effects of lithium disilicate ceramic (LDC), resin nano-ceramic (RNC) and nano-hybrid composite (NHC) computer-aided design/ computer-aided manufacturing (CAD-CAM) block materials subjected to a home bleaching agent and artificial saliva. MATERIAL AND METHODS: A total of 432 specimens were prepared from 3 different CAD-CAM materials. Each material group was divided into 4 groups according to the storage medium (phosphate-buffered saline (PBS) or artificial saliva), and whether the specimens were subjected to a bleaching agent or not. For the bleached groups, hydrogen peroxide (10%) was applied to the specimens for 30 min/day for 15 days, and the specimens were immersed in PBS or saliva after bleaching. The viability of epithelial cells was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at the end of the 5th, 10th and 15th day of the study. The data was statistically analyzed. RESULTS: Regardless of the storage medium and the time period, all restorative materials decreased the viability of cells. The highest cytotoxicity levels were determined on the 15th day of the study. The application of a bleaching agent increased the cytotoxicity of the LDC specimens stored in artificial saliva. The RNC material stored in PBS demonstrated significantly higher cell viability than the LDC and NHC groups. The LDC and RNC specimens stored in artificial saliva did not show any significant difference in cytotoxicity. When the materials were subjected to bleaching, NHC demonstrated the highest cytotoxicity during all periods. No significant difference was found between the LDC and RNC specimens subjected to both artificial saliva and bleaching in terms of cytotoxicity. CONCLUSIONS: The type of restorative material, the immersion medium, the application of a bleaching agent, and the application period affected the cytotoxicity of the materials. Over-the-counter home bleaching agents may induce cellular cytotoxicity due to the existing restorations, and patients should be informed about this potential biological response.

Impact of SARS-CoV-2 Delta and Omicron variants on viral burden and cycle threshold in BNT162b2-vaccinated 12-18 years group.

The SARS-CoV-2 pandemic continues to impact the medical, economic, social, and political areas worldwide. Although it has been claimed that children are the most responsible for the outbreaks as of September 2021, the statistics showed controversary. Although it showed no difference in viral load and Ct values between symptomatic children and symptomatic adults, or between asymptomatic children and asymptomatic adults, the molecular mechanism remains unclear. Here, we aimed to investigate the effects of different strains on infection by comparing viral load levels in pediatric patients aged 12-18 years, infected with different variants of SARS-CoV-2, and vaccinated with full-dose BNT162b2. In this retrospective study, a total of 200 patients aged 12-18 years, who were diagnosed with COVID-19 in our hospital, and vaccinated with full-dose BNT162b2, were analyzed according to their gender, age, viral load, and cycle threshold values. Viral RNA levels were evaluated using Ct values, a semi-quantitative proxy of viral load. While the findings did not show a significant difference between gender and age (P = 0.886 and P = 0.897, respectively), a significant difference was found between the Ct and viral load (P < 0.0001). In conclusion, SARS-CoV-2 viral load was higher in cases infected with SARS-CoV-2 Delta variant than SARS-CoV-2 Omicron variant (mean Ct = 23.05 ± 4.06, viral load = 7.8 × 105 copies/ml and mean Ct = 28.04 ± 3.02, viral load = 7.8 × 103 copies/ml, respectively). These findings indicated that the Delta variant had high viral load and our result could be one of the causes the Delta variant was more effective in the pandemic severity than the other variants in the October-December periods when the Delta variant was dominant in Northern Cyprus. During the same period, the severity of the disease was higher, with higher hospitalization and death rates.

Designing In-House SARS-CoV-2 RT-qPCR Assay for Variant of Concerns.

Variants (Alfa, Gamma, Beta, and Delta) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are circulating worldwide. These variants of concerns share some common mutations but they also have distinguishing mutations. These mutations affect transmissibility of virus and cause evasion from neutralizing antibodies. Monitoring and identification of circulating variants is of great importance for public health. In this study, an in-house SARS-CoV-2 reverse transcription quantitative polymerase chain reaction (RT-qPCR) kit was designed to detect variants of concerns by the World Health Organization. Primer sets and probes were designed to target presence of virus along with mutations for identifying different variants (for N501Y, HV69-70del, K417N, and T478K). Reactions were set by using commercially available master mixes without a reference dye. The RT-qPCR conditions were optimized by using commercially available ribonucleic acid samples of wild-type, Alfa, Beta, Gamma, and Delta variants. Several samples were also analyzed by the in-house kit after optimization studies. All Alfa variant and wild-type samples were also double confirmed with a commercially available variant detection kit demonstrating a 100% consistence with the in-house kit. Beta, Gamma, and Delta variants could not be confirmed with any other commercially available kits as there is not any available one in the market. SARS-CoV-2 variants are gaining importance during the pandemic and shaping the fight against the virus. RT-qPCR kits detecting different variants would provide a significant advantage while screening the population.

Detection of SARS-CoV-2 N501Y mutation among SARS-CoV-2 variants of concern circulating in Northern Cyprus.

Aim: SARS-CoV-2 variants of concern (VOCs) carry signature mutations particularly in the spike protein. Most VOCs lineages that carry N501Y substitution have been reported to evade viral diagnostic tests and have impact on vaccine effectiveness. Therefore, monitoring the circulating variants represents a major requirement for a public health response worldwide. We aimed to investigate the prevalence of N501Y bearing SARS-CoV-2 samples in Northern Cyprus. Materials & methods: Reverse transcription quantitative PCR technique was used to identify N501Y mutation from 658 samples. Results: Our results indicate that the proportion of N501Y-bearing lineages increased significantly from January through May 2021 (45.2-75.5%) in the region. Conclusion: These results indicate that VOCs are dominant lineages in the country and highlight an alarming situation which require strict governmental measures to minimize COVID-19 morbidity and mortality.

Evaluation of Antibacterial and Antifungal Effects of Calcium Hydroxide Mixed with Two Different Essential Oils.

BACKGROUND: Calcium hydroxide is a routinely used material for root canal disinfection during root canal treatment. Natural products have great potential in terms of their antibacterial effects. This study aimed to establish an effective alternative intracanal medicament using Origanum dubium (O. dubium) and Mentha spicata (M. spicata) essential oils. MATERIALS AND METHODS: O. dubium and M. spicata, collected from Lefke, Cyprus, were separately subjected to hydrodistillation. The obtained essential oil compositions were analysed simultaneously by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The compositions were then divided into groups and mixed with calcium hydroxide at a 1:1 concentration; after that, the pastes were tested on Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans), which are the most common resistant pathogenic microorganisms in the root canal. The antibacterial activity of the pastes was measured using a disk diffusion assay. RESULTS: The GC and GC-MS analyses revealed that O. dubium and M. spicata had major compositions of carvacrol (75.8%) and carvone (71.3%), respectively. Antimicrobial activity was found to be significantly higher when study groups with O. dubium essential oil were applied to both E. faecalis and C. albicans. The results also show that M. spicata, together with calcium hydroxide, demonstrated a significant antifungal effect on C. albicans when incubated for 72 h. CONCLUSIONS: M. spicata was found to be an effective antimicrobial agent on C. albicans, whereas O. dubium was found to be very effective on both E. faecalis and C. albicans. These data demonstrate that these natural essential oils may be promising candidates for alternative intracanal medicament in future routine clinical applications.

Comparative evaluation of low-level laser therapy on proliferation of long-term cryopreserved human dental pulp cells isolated from deciduous and permanent teeth.

The aim of the current study was to evaluate the proliferative effect of low-level laser therapy on long-term cryopreserved dental pulp stem cells (DPSCS) and stem cells from human exfoliated deciduous teeth (SHEDS). The DPSCS and SHEDS were divided into 2 main groups according to gallium aluminum arsenide (GaAIAs) diode laser irradiation densities as 5 J/cm2 and 7 J/cm2. Each main group was further divided into 4 groups according to laser irradiation periods as 0, 24, 48, 72 h groups. During the incubation periods, cells received laser irradiation in every 24 h according to their groups and were put into incubator after irradiation. Cell groups that were not subjected to laser irradiation were served as control groups. Viabilities of cells were determined via MTT assay at the end of all incubation periods, and data were statistically analyzed. Laser irradiation demonstrated significant effects on proliferation rate of DPSCs and SHEDs in comparison with control. Intragroup comparison data of DPSCS revealed that repetitive laser irradiation for long term (72 h) increased the cellular viability significantly in comparison with all other treatment groups; however, no significant differences were found when energy densities were compared within each time interval, except for 48 h group at which irradiation with 7 J/cm2 provided significantly higher cell viability rates of SHEDS. DPSCs showed significantly higher cellular viability than SHEDs only for the 7 J/cm2 energy density in 72 h. Longer term (72 h) repetitive laser irradiation with energy densities of 5 and 7 J/cm2 (wavelength of 980 nm) may be recommended to induce the proliferative effect on long-term cryopreserved DPSCS and SHEDS.

Investigation of the combination of anti-PD-L1 mAb with HER2/neu-loaded dendritic cells and QS-21 saponin adjuvant: effect against HER2 positive breast cancer in mice.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2) is overexpressed in a subset of cancers including 25% of breast cancers. Since combination therapy consisting of multiple therapeutic approaches is considered a promising regimen, we examined combination treatment modalities in a xenograft model in Balb/c mice injected with 4T1-HER2 cells. We used HER2/neu-loaded bone marrow-derived dendritic cells (BM-DC's) along with anti-PD-L1 monoclonal antibody in a new combination immunotherapy model. METHODS: The combination was composed of an active immunotherapy (i.e. BM-DC-based vaccine) designed to boost the immune response against target antigen and was augmented by using anti-PD-L1 mAb to prevent immune evasion by the xenografted tumors. The vaccine combination was further supported using a QS-21 saponin adjuvant and the immune response was evaluated. RESULTS: Mice treated with HER2/neu-loaded BM-DCs, combined with QS-21 and anti-PD-L1 mAb had significantly decreased tumor sizes and their splenocytes had enhanced cytotoxic activity, based on the lactate dehydrogenase (LDH) assay, compared to vaccine and adjuvant groups alone. The same vaccination group demonstrated a remarkable increase in IFN-γ secreting CD8+ T-cells analyzed by flow cytometry. ELISA data also revealed a significant increase in the serum anti-HER2 IgG1 response; in addition, there was significant splenocyte proliferation upon stimulation with antigen compared to vaccine and adjuvant groups. Consistently, a significant infiltration of CD4+, CD8+ immune cells in and around the tumors was observed. CONCLUSIONS: Our data suggest that the BM-DC + HER2/neu + QS-21 + anti-PD-L1 vaccine combination paradigm synergistically generates anti-tumor activity and immune responses against HER2 overexpressing breast cancer in mice.

Investigating the cytotoxic effects of the venom proteome of two species of the Viperidae family (Cerastes cerastes and Cryptelytrops purpureomaculatus) from various habitats.

Animal secretions are of great interest in terms of drug development due to their complex protein and peptide composition. Especially, in the field of therapeutic medications such as anti-cancer drugs snake venoms receive attention. In this study, we address two Viperidae species from various habitats with a particular focus on the cytotoxic potential along with the decomplexation of the venom proteome: the horned desert viper (Cerastes cerastes), native to desert regions of North Africa and the mangrove pit viper (Cryptelytrops purpureomaculatus), found in coastal forests of Southeast Asia. Initial cytotoxic screenings of the crude venoms revealed diverse activity, with the highest effect against SHSY5Y human glioblastoma carcinoma cells compared to other cancerous and non-cancerous cell lines. In-depth cytotoxicity studies of SHSY5Y cells with purified venom fractions revealed heterodimeric disintegrins from C. cerastes venom, which exerted a high cytotoxic activity with IC50 values from 0.11 to 0.58 µM and a disintegrin-like effect on SHSY5Y morphology was observed due to cell detachment. Furthermore, two polyproline BPP-related peptides, one PLA2 and a peptide-rich fraction were determined for C. purpureomaculatus with moderate IC50 values between 3 and 51 µM. Additionally, the decryption of the venom proteomes by snake venomic mass spectrometry and comparison of the same species from different habitats revealed slight differences in the composition.