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Barsha Shrestha,1 Sheetal Maria Rajan,1 Sultan Aati,1,2 Emielda Yusiharni,3 Omar Kujan,1 Martin Saunders,4 Amr Fawzy1 1UWA Dental School, The University of Western Australia, Perth, WA, Australia; 2Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; 3UWA XRD Facility, Material & Environmental Analysis Platform, The University of Western Australia, Perth, WA, Australia; 4Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, AustraliaCorrespondence: Amr Fawzy, UWA Dental School, The University of Western Australia, 17 Monash Avenue, Nedlands, WA, 6009, Australia, Tel +61894572434, Email amr.fawzy@uwa.edu.auBackground: Remineralization of dental enamel is an important intervention strategy for the treatment of demineralized lesions. Existing approaches have limitations such as failure to adequately reproduce both the ideal structural and mechanical properties of the native tooth. The ability of ultrasound to control and accelerate the crystallization processes has been widely reported. Therefore, a new approach was explored for in-vitro enamel remineralization involving the synergistic effect of high-intensity focused ultrasound (HIFU) coupled with calcium phosphate ion clusters (CPICs).Methods: The demineralized enamel was treated with CPICs, with or without subsequent HIFU exposure for different periods (2.5, 5, and 10 min). The specimens were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The surface hardness and crystallographic properties of the treated specimens were evaluated using Vickers microhardness testing and X-ray diffraction (XRD), respectively.Results: SEM revealed distinct, organized, and well-defined prismatic structures, showing clear evidence of remineralization in the combined CPIC/HIFU treatment groups. AFM further revealed a decrease in the surface roughness values with increasing HIFU exposure time up to 5 min, reflecting the obliteration of interprismatic spaces created during demineralization. The characteristic Raman band at 960 cm− 1 associated with the inorganic phase of enamel dominated well in the HIFU-treated specimens. Importantly, microhardness testing further demonstrated that new mineral growth also recovered the mechanical properties of the enamel in the HIFU-exposed groups. Critical to our aspirations for developing this into a clinical process, these results were achieved in only 5 min.Conclusion: HIFU exposure can synergise and significantly accelerate in-vitro enamel remineralization process via calcium phosphate ion clusters. Therefore, this synergistic approach has the potential for use in future clinical interventions. Keywords: enamel remineralization, high intensity focused ultrasound, calcium phosphate ion cluster

The variation of stress on faults is important for our understanding of fault friction and the dynamics of earthquake ruptures. However, we still have little observational constraints on their absolute magnitude, or their variations in space and in time over the seismic cycle. Here we use a new geodetic imaging technique to measure the 3D coseismic slip vectors along the 2019 Ridgecrest surface ruptures and invert them for the coseismic stress state. We find that the coseismic stresses show an eastward rotation that becomes increasingly transtensional from south‐to‐north along the rupture, that matches the known background stress state. We find that the main fault near the Mw 7.1 mainshock hypocenter was critically stressed. Coseismic slip was maximum there and decreased gradually along strike as the fault became less optimally oriented due its curved geometry. The variations of slip and stress along the curved faults are used to infer the static and dynamic fault friction assuming Mohr‐Coulomb failure. We find shear stresses of 4–9 MPa in the shallow crust (∼1.3 km depth) and that fault friction drops from a static, Byerlee‐type, value of 0.61 ± $\pm $ 0.14 to a dynamic value of 0.29 ± $\pm $ 0.04 during seismic slip. These values explain quantitatively the slip variations along a transpressional fault bend. Plain Language Summary: Understanding the orientation and magnitude of stresses within the crust are important because they can affect the location, size and spatial extent of earthquake rupture. However, measuring the absolute magnitude and orientation of stresses as well as the frictional properties of the fault surface (i.e., how strongly the fault resists the applied driving forces) is very difficult. Here we use optical images acquired by satellites to measure how the surface deformed in 3D during the 2019 Ridgecrest event. These 3D measurements allow us to extract the direction of fault slip movement along the entire rupture length which we use to estimate the direction of stresses by assuming the shear stress is parallel to the direction of the observed fault slip motion. We find that the main fault near the mainshock epicenter was the most optimally aligned for failure, which could be one contributing reason for the location of rupture initiation. By deriving a relation between how much a fault slips with how well aligned it is to the stress field we can estimate the absolute magnitude of stresses, the frictional resistance at initial fault sliding (finding a static friction = 0.61) and during sliding (a dynamic friction = 0.29). Key Points: Inverting surface coseismic slip vectors show a variable stress state that matches the background stresses constrained by seismicityFaults at the mainshock epicenter were the most critically stressed; we find slip increases linearly as faults become more optimally alignedWe find absolute stress magnitudes of 8–26 MPa in the upper crust, a static frictional coefficient of 0.61 and a dynamic value of 0.29 [ABSTRACT FROM AUTHOR]

Background: To evaluate the efficacy of probiotics in the treatment of gingivitis.Methods: MEDLINE, EMBASE and CENTRAL were searched up to May 2019. Randomized controlled clinical trials (RCTs) and/or controlled clinical trials were considered. Studies consisting of ≥10 patients per group clinically diagnosed with gingivitis were selected that compared the efficacy of probiotics in any form with placebo. The primary outcome measure was bleeding on probing (BOP) and gingival index (GI), while the secondary outcome measure was plaque index (PI). Forest plots were created reporting weighted mean difference (WMD) of outcomes with 95% confidence intervals (CI).Results: A total of 10 double-blind placebo-parallel RCTs were included. All studies showed that probiotic administration was effective in the treatment of gingivitis at follow-up. The mean percentage of BOP ranged from 11.87% to 21.7% in the probiotics group and from 15% to 33% in the placebo groups at follow-up, respectively. Considering the effects of Lactobacillus reuteri, the overall mean difference for GI (WMD = -0.48, 95% CI = -1.69 to 0.72, P = 0.42) and PI (WMD = 0.18, 95% CI = -0.23 to 0.61, P = 0.37) did not show any statistical significance between probiotic and placebo groups.Conclusions: The outcomes of this review show weak evidence to support the use of probiotics in reducing inflammatory periodontal parameters in gingivitis. Significant heterogeneity and limited available data may reduce the impact of these conclusions. [ABSTRACT FROM AUTHOR]

The anti-cancer and anti-bacterial potential of the Red Sea sponge Phyllospongia lamellosa in its bulk (crude extracts) and gold nanostructure (loaded on gold nanaoparticles) were investigated. Metabolomics analysis was conducted, and subsequently, molecular modeling studies were conducted to explore and anticipate the P. lamellosa secondary metabolites and their potential target for their various bioactivities. The chloroformic extract (CE) and ethyl acetate extract (EE) of the P. lamellosa predicted to include bioactive lipophilic and moderately polar metabolites, respectively, were used to synthesize gold nanoparticles (AuNPs). The prepared AuNPs were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV-vis spectrophotometric analyses. The cytotoxic activities were tested against MCF-7, MDB-231, and MCF-10A. Moreover, the anti-bacterial, antifungal, and anti-biofilm activity were assessed. Definite classes of metabolites were identified in CE (terpenoids) and EE (brominated phenyl ethers and sulfated fatty amides). Molecular modeling involving docking and molecular dynamics identified Protein-tyrosine phosphatase 1B (PTP1B) as a potential target for the anti-cancer activities of terpenoids. Moreover, CE exhibited the most powerful activity against breast cancer cell lines, matching our molecular modeling study. On the other hand, only EE was demonstrated to possess powerful anti-bacterial and anti-biofilm activity against Escherichia coli . In conclusion, depending on their bioactive metabolites, P. lamellosa -derived extracts, after being loaded on AuNPs, could be considered anti-cancer, anti-bacterial, and anti-biofilm bioactive products. Future work should be completed to produce drug leads., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Thevetia peruviana (T. peruviana; Family: Apocynaceae), commonly known as Lucky Nut, is a traditionally and medicinally important plant, and the barks of the plant are traditionally used as anti-inflammatory, anti-diabetic, and antibacterial remedies. Thus, this study aimed to evaluate bioactive phytochemicals and in -vitro biological activities from the bark of T. peruviana using methanolic (TPM) and dichloromethane (TPD) extracts. The GC-MS analysis showed the presence of 54 and 39 bioactive compounds in TPM and TPD, respectively. The TPM extract has a higher level of total polyphenolic contents (TPC: 70.89 ± 1.08 and 51.07 ± 0.78 mg GAE/g extracts, while TFC: 56.89 ± 1.16 and 44.12 ± 1.76 Qu.E/g extracts for TPM and TPD, respectively). Herein, the results of antioxidant activities were also found in correlation with the total polyphenolic contents i.e., depicting the higher antioxidant potential of TPM compared to TPD. The significant inhibitory activities of extracts were observed against tyrosinase (TPM; 59.43 ± 2.87 %, TPD; 53.43 ± 2.65 %), lipoxygenase (TPM; 77.1 ± 1.2 %, TPD; 59.3 ± 0.1 %), and α-glucosidase (TPM; 71.32 ± 2.44 %, TPD; 67.86 ± 3.011 %). Furthermore, in comparison to co-amoxiclave, the antibacterial property against five bacterial strains was significant assayed. The compounds obtained through GC-MS analysis were subjected to in -silico molecular docking studies, and the phyto-constituents with maximum binding scores were then subjected to ADME analysis. The results of in -silico studies revealed that the binding affinity of several phyto-constituents was even greater than that of the standard inhibitory ligands. ADME analysis showed bioavailability radars of phyto-constituents having maximum docking scores in molecular docking. The results of this study indicated that T. peruviana has bioactive phytochemicals and therapeutic potential and may provide a basis for treating metabolic disorders (inflammatory diseases like rheumatism and diabetes), bacterial infections, and skin-related problems., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Huma Rao reports article publishing charges and writing assistance were provided by King Saud University. The authors declare that they have no conflict of interest. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Plants have always been the prime focus in medicine industries due to their enormous ethnobotanical uses and multitude of biological and therapeutic properties. In the current study, preliminary phytochemical composition, Total phenolic content (TPC), and total flavonoid content (TFC) with the antioxidant and antibacterial activity of hydroalcoholic extract and n-hexane, chloroform and n-butanol fractions of five selected medicinal plants [ Tephrosia purpurea (L.) Pers., Lavandula stoechas L., Aesculus indica (Wall. ex Cambess.) Hook, Iris ensata Thunb., and Kalanchoe pinnata (Lam.) Pers.] from Pakistan, have been evaluated. TPC and TFC were determined by Folin-Ciocalteu's and AlCl 3 methods respectively. The antioxidant activity was performed by DPPH, ABTS, FRAP, and CUPRAC while the antibacterial potential of these plants was determined by agar well diffusion assay. K . pinnata (Lam.) Pers. exhibited the highest TPC (695 ± 13.2 mg.GA.Eq.g -1 DE ± SD) in n-butanol fraction and the highest TFC in its chloroform faction (615 ± 6.31 mg Q.Eq.g -1 DE ± SD). The n-butanol fraction and hydroalcoholic extract of I. ensata Thunb. exhibited strong antioxidant potential by DPPH and CUPRAC assays respectively, whereas K . pinnata (Lam.) Pers. n-butanol fraction exhibited the strongest reducing potential. The hydroalcoholic extract of all tested plants exhibited significant antibacterial activity against tested bacterial strains with ZI (12-18 mm). Conclusively, K . pinnata (Lam.) Pers. (Family: Crassulaceae) and I . ensata Thunb. (Family: Iridaceae) exhibited the highest antioxidant and antibacterial potential. They can be explored for the isolation of phytoconstituents responsible for this potential and serve as a lead for the production of new natural antioxidants and antibacterial agents that can be used to cure various diseases., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Objective: The high incidence of endodontic failure is associated with the remnants of Enterococcus faecalis present within the intricate anatomies of the root canal system (RCS), often inaccessible by the current endodontic practices. This study was aimed at evaluating the effect of high-intensity focused ultrasound (HIFU) and photodynamic therapy (PDT) on E. faecalis biofilms in artificially infected root canals for the potential application in current endodontic practices., Methods: Forty-five single-rooted extracted teeth were instrumented using hand files, sterilized in an autoclave, infected with E. faecalis and incubated for 4 wk. The specimens were treated and identified as follows: Control, 4% sodium hypochlorite (NaOCl); riboflavin (1 mg/mL); light only; HIFU (250 kHz, 20 W, 60s); PDT; riboflavin/HIFU; light/HIFU; and riboflavin/HIFU/light. Bactericidal efficacy was determined by colony-forming units (CFU), (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM)., Results: Enterococcus faecalis biofilm exhibited significantly lower metabolic activity when treated with HIFU (250 kHz, 20 W, 60 s) compared with the control (4% NaOCl) and PDT groups. A similar phenomenon was observed with the CFU assay. HIFU remained the most effective treatment modality, with consistent results in CLSM and SEM., Conclusion: This study highlighted the potential application of HIFU as an adjunct drug-free, non-destructive root canal disinfection method for endodontic treatment, suggesting an alternative to the current gold standard of 4% NaOCl and PDT., Competing Interests: Conflict of interest The authors declare no competing interests., (Copyright © 2023 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Objectives: Oral prosthetic rehabilitation has been used for a long time to restore function and natural appearance; however, it is still one of the most challenging areas in dentistry due to its technical fabrication process and biological behavior. Considering the advantages of additive manufacturing technology, this study introduced the feasibility of developing a 3D printed resin-based composition modified with graphene nanoplatelets (GNPs) to improve properties., Methods: Acrylate-based resin was impregnated with different concentrations of GNPs (0.0-0.25 wt%), and then different aspects such as mechanical, physical, biological and antimicrobial were analyzed to evaluate the effectiveness. TEM and SEM were used to characterize GNPs and their existence within the resin. Surface topography and roughness were evaluated using AFM. The degree of conversion and composition were confirmed by FTIR. Mechanical properties were detected using bending strength, microhardness and nanoindentation. Biocompatibility and antimicrobial activities were assessed with oral fibroblast and Candida albicans (C. albicans), respectively. In addition, most of the measurements were performed repeatedly after 3 months of storage in artificial saliva to evaluate performance., Results: GNPs improved strength significantly at low concentrations ≤ 0.05 wt%, while the addition up to 0.25 wt% enhanced printed nanocomposite hardness and elasticity. The modification did not induce a toxic response, as its biocompatibility was within the recommended range of biomedical devices. Antimicrobial activity was of prominence, as GNPs showed an outstanding route of reducing C. albicans activity associated with filler proportion., Significance: The embedment of GNPs in 3D printed resin can become a key material for customized applications that require high antimicrobial, stiffness and strength properties., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The liver is a crucial organ among body organs due to its wide functions, in particular, detoxification and metabolism. Exposure to detrimental chemicals or viral infections may provoke liver dysfunction and ultimately induce liver tissue damage. Finding natural substances for liver disease treatment to overcome the conventional treatments' side effects has attracted the attention of researchers worldwide. Our current work was conducted to investigate the hepato-therapeutic activities of essential oil (EO) isolated from Tagetes patula flowers. EO was extracted using the hydro-distillation (HD) technique and its chemical composition was identified by GC/MS. Then, the hepatic treatment potential of extracted EO was evaluated in vivo against CCL 4 in rats. HD of T. patula flowers yielded highly chemical constituents of EO along with significant antioxidant potential. A coherent molecular network was fashioned via the Global Natural Products Social Molecular Networking (GNPS) to visualize the essential components and revealed that the sesquiterpene ( E )- β -caryophyllene was the most predominant volatile constituent which accounted for 24.1%. The treatment of CCL 4 led to significant induced oxidative stress markers malonaldehyde, total protein, and non-protein sulfhydryl, as well as elevated serum aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, and bilirubin. In addition, it disrupted the level of lipid profile. The post-treatment using T. patula EO succeeded in relieving all toxic effects of CCl 4 and recuperating the histopathological signs induced by CCL 4 . Silymarin was used as a standard hepatoprotective agent. The obtained results demonstrated that the extracted EO exerted high protective activities against the toxicity of CCL 4 . Moreover, the T. patula flowers EO can be used as a natural remedy to relieve many contemporary liver diseases related to oxidative stress., Competing Interests: The authors declare no conflict of interest.

The aim of this study is to develop a novel 3D printed denture base resin material modified with mesoporous silica nanocarrier loaded with silver (Ag/MSN) to enhance mechanical and antimicrobial properties. Acrylate resin-based was incorporated with various proportion of Ag/MSN (0.0-2.0 wt%). Specimens with different geometry were printed and characterized accordingly for the effect of modification on properties such as: mechanical and physical properties, chemical composition and degree of conversion, as well as biological response in term of biocompatibility and antimicrobial against oral fibroblast and candida biofilm (C. albicans), respectively. The consecutive addition of Ag/MSN improved significantly surface hardness and crack propagation resistance, while flexural strength remained similar to control; however, a negligible decrease was observed with higher concentrations ≥1 wt%. No significant difference was noticed with water sorption, while water solubility had a remarkable trend of reduction associated with filler content. The surface roughness significantly increased when concentration of Ag/MSN was ≥1.0 wt%. A significant reduction in C. albicans biofilm mass, as the inhibition proficiency was correlated with the proportion of the filler. With respect to the amount of Ag/MSN, the modification was compatible toward fibroblast cells. The sequential addition of Ag/MSN enhanced significantly the mechanical and antimicrobial properties of the 3D printed resin-based material without affecting adversely compatibility. The acrylic resin denture base material has susceptibility of microbial adhesion which limits its application. Silver loaded MSN showed a significant performance to enhance antimicrobial activity against C. albicans which is the main cause of denture stomatitis. The proposed invention is a promise technique for clinical application to provide an advanced prosthesis fabrication and serve as long-term drug delivery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Ficus vasta Forssk. (Moraceae family) is an important medicinal plant that has not been previously investigated for its phytochemical and biological potential. Phytochemical screening, total bioactive content, and GCMS analysis were used to determine its phytoconstituents profile. Antioxidant, antibacterial, antifungal, anti-viral, cytotoxicity, thrombolytic, and enzyme inhibition activities were examined for biological evaluation. The plant extract exhibited the maximum total phenolic (89.47 ± 3.21 mg GAE/g) and total flavonoid contents (129.2 ± 4.14 mg QE/g), which may be related to the higher antioxidant potential of the extract. The extract showed strong α-amylase (IC 50 5 ± 0.21 µg/mL) and α-glucosidase inhibition activity (IC 50 5 ± 0.32 µg/mL). Significant results were observed in the case of antibacterial, antifungal, and anti-viral activities. The F. vasta extract inhibited the growth of HepG2 cells in a dose-dependent manner. The GCMS analysis of the extract provided the preliminary identification of 28 phytocompounds. In addition, the compounds identified by GCMS were subjected to in silico molecular docking analysis in order to identify any interactions between the compounds and enzymes (α-amylase and α-glucosidase). After that, the best-docked compounds were subjected to ADMET studies which provide information on pharmacokinetics, drug-likeness, physicochemical properties, and toxicity. The present study highlighted that the ethanol extract of F. vasta has antidiabetic, antimicrobial, anti-viral, and anti-cancer potentials that can be further explored for novel drug development.

Objective: The aim of this study was to investigate the potential antimicrobial and cytotoxic effect of modified 3D printed resin with ZrO 2 nanoparticles, as long-term provisional restoration. In addition, the study involved artificial aging process for three months to observe stability of 3D printed resin., Methods: Functionalized ZrO 2 nanoparticles with γ-MPS were characterized using transmission electron microscopy, scanning electron microscope and Fourier-transform infrared spectroscopy. Dental resin was incrementally impregnated with γ-MPS modified nanoparticles at different concentrations (0, 1, 3, and 5 wt%). Specimens were printed, post-cured and placed in artificial saliva at 37  o C for 48 h or aged for 3 months. Discrepancy in composition and roughness were monitored using FTIR and AFM, respectively. Biocompatibility was evaluated using human oral fibroblasts. Antimicrobials capacity and biofilm adhesion were measured with Streptococcus mutans and Candida albicans., Results: The microscopic and spectroscopic analyses confirmed γ-MPS coating around ZrO 2 nanoparticles. The addition of nanoparticles (>1 wt%) significantly increased the surface roughness. Cytotoxicity results were in agreement with the recommended range of oral biomaterials standard. Moreover, the antimicrobial activity significantly improved with increasing the filler concentration. Despite the decrease in antimicrobial efficacy after 3 months of aging, modified resin revealed a critical ability to dominate biofilm formation., Significance: The addition of ZrO 2 nanoparticles showed significant antimicrobial capability of a 3D printed resin without inducing any cellular side effects. Thus, the modification of a 3D printed resin with ZrO 2 nanoparticles has a promising future in the dental field for fabricating long-term provisional restorations., (Copyright © 2022 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Anethum graveolens L. is a famous aromatic herb that is widely used as a spice and has been applied in folk medicine to cure many diseases. The current work was carried out to compare the chemical composition and antimicrobial potency of essential oils obtained from the different parts of Saudi Arabia. graveolens . The oil constituents were extracted by headspace solid-phase microextraction and were quantified and qualitatively identified using GC/MS. As a result, essential oil isolated from A. graveolens seeds exhibited the highest antimicrobial activity compared to oils isolated from other parts, followed by flowers, leaves and stems. All tested A. graveolens essential oil samples exhibited stronger antifungal activities against Aspergillus parasiticus when compared to itraconazole. To the best of our knowledge, the current work is the first report comparing different parts of Saudi A. graveolens plant with respect to their essential oil chemical composition and antimicrobial potentials. The essential oil of A. graveolens seeds have the highest contents of carvone and limonene and show superior antimicrobial activities compared to other parts of the plant., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)

Objective: The aim of this study was to synthesize and characterize reduced nano graphene oxide (RGO) and graphene nanoplatelets (GNPs) doped with silver nanoparticles (nAg) and to prepare an experimental dentin adhesive modified with RGO/nAg and GNP/nAg nanofillers for studying various biological and mechanical properties after bonding to tooth dentin., Methods: Nanoparticles were characterized for their morphology and chemical structure using electron microscopy and infrared spectroscopy. Experimental dentin adhesive was modified using two weight percentage (0.25% and 0.5%) of RGO/nAg and GNP/nAg to study its degree of conversion (DC), antimicrobial potential, and cytotoxicity. The effect and significance of these modified bonding agents on resin-dentin bonded interface were investigated by evaluating interfacial nanoleakage, micropermeability, nanodynamic mechanical analysis, micro-tensile bond strength (µTBS), and four-point bending strength (BS), RESULTS: Both 0.25% and 0.5% GNP/nAg graphene-modified adhesives showed comparable DC values to the commercial and experimental adhesive (range: 42-46%). The bacterial viability of the groups 0.25% and 0.5% GNP-Ag remained very low under 25% compared to RGO/nAg groups with low cytotoxicity profiles (cell viability>85%). Resin-bonded dentin interface created with GNP/nAg showed homogenous, well-defined hybrid layer and regularly formed long resin tags devoid of any microporosity as evidenced by SEM and confocal microscopy. The lowest nanoleakage and highest bending strength and µTBS was recorded for 0.25% GNP/nAg after 12 months of ageing. A significantly increased nanoelasticity was seen for all experimental groups except for control groups., Significance: The addition of 0.25% GNP/nAg showed optimized anti-biofilm properties without affecting the standard adhesion characteristics., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objective: This study investigated the effect of post curing light exposure time on the physico-mechanical properties and cytotoxicity of a 3D-printed PMMA-based denture material in comparison to a conventional heat-cured alternative as a control., Methods: 3D-printed specimens were fabricated followed by post-curing for 0, 5, 10 or 20 min at 200 W and light wavelength range of 390-540 nm. Heat-cured specimens were fabricated using a standard protocol. Specimens were placed in artificial saliva at 37 ℃ for 48 h (immediate groups) and 6 months (aged group), then evaluated flexural strength/modulus, fracture toughness, microhardness, and degree of conversion. Water sorption and solubility was assessed after 28 days. Flexural strength, flexural modulus, and fracture toughness were tested through three-point bending tests, while the surface hardness was tested using Vickers's test. Fractured specimens were viewed by scanning electron microscope (SEM). Cytotoxicity in term of cell viability was evaluated using human oral fibroblasts., Results: Flexural strength/modulus, fracture toughness and surface hardness significantly improved with the increase in light curing time up to 20 min. The same pattern of improvement was found with degree of conversion, water sorption, solubility, and cell viability. There was no significant difference (p < 0.01) between heat-cured material and 3D specimens post-cured for 20 min in term of flexural strength/modulus, surface hardness, and degree of conversion at the two-storage time points., Significance: Generally, the physico-mechanical properties of the 3D-printed denture base material improve as post curing time increases up to 20 min which exhibited comparable performance as the conventional heat-cured control., Competing Interests: Conflict of interest The authors report no conflict of interest., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

This study synthesized and characterized graphene nanoplatelets silanized with 3-(trimethoxysilyl)propyl methacrylate (MPS-GNP) for morphological and chemical characteristics. In addition, we modified a dentin bonding agent using different concentrations of MPS-GNP to study its interaction within the resin matrix of the adhesive, degree of conversion (DC), biological, and mechanical properties after bonding to tooth. Both 0.25% and 0.5% MPS-GNP-modified bonding agents showed comparable DC values to the unmodified control adhesive (range: 41%-43%). However, a statistically significant reduction in the DC was found when 0.25% and 0.5% non-silanized GNP was doped with the adhesive (<38%) ( p < 0.05). On day 30, the bacterial viability of 0.5% GNP and MPS-GNP groups remained very low under 22% with the highest dead cell count ( p < 0.05). GNP incorporated within the resin matrix of the dentin bonding agent showed clear evidence of several interfacial gap formations and non-union between the GNP surface and resin matrix, while the MPS-GNP modified dentin bonding agent showed MPS-GNP with no gap formation with complete union between the graphene surface and resin matrix. The decrease in the μTBS was least pronounced for 0.25% and 0.5% MPS-GNP groups. After 12 months of ageing, the groups 0.25% and 0.5% MPS-GNP also showed the highest BS as compared to the rest of the groups. Statistically significant reduction was seen in nanohardness at the hybrid layer and adhesive layer for GNP groups after 4 months of storage. The addition of up to 0.5% MPS-GNP showed optimized DC, antibiofilm activity, and micro-tensile bond strength without affecting the standard adhesion characteristics as compared to GNP alone.

The aim of this study was to characterize multiscale interactions between high intensity focused ultrasound (HIFU) and dentin collagen and associated matrix-metalloproteinases, in addition to the analysis of the effect of HIFU on bacterial biofilms and biological properties. Dentin specimens were subjected to 5, 10 or 20 s HIFU. XPS spectra were acquired and TEM was performed on dentin slabs. Collagen orientation was performed using Raman spectroscopy. Calcium measurements in human dental pulpal cells (hDPCs) were carried out after 7 and 14 days. For macrophages, CD36+ and CD163+ were analysed. Biofilms were analyzed using CLSM. Tandem mass spectroscopy was performed for the detection of hydroxyproline sequences along with human MMP-2 quantification. Phosphorus, calcium, and nitrogen were detected in HIFU specimens. TEM images demonstrated the collagen network appearing to be fused together in the HIFU 10 and 20 s specimens. The band associated with 960 cm-1 corresponds to the stretching ν1 PO43-. The control specimens showed intensive calcium staining followed by HIFU 20 s > HIFU 10 s > HIFU 5 s specimens. Macrophages in the HIFU specimens co-expressed CD80+ and CD163+ cells. CLSM images showed the HIFU treatment inhibiting bacterial growth. SiteScore propensity determined the effect of HIFU on the binding site with a higher DScore representing better site exposure on MMPs. Multiscale mapping of dentin collagen after HIFU treatment showed no deleterious alterations on the organic structure of dentin.

Objectives: To longitudinally evaluate the periodontal parameters and MMP-8 and CTX (C-terminal crosslinked telopeptide of type I collagen) levels from diseased and healthy sites from cigarette and electronic cigarette (e-cig) smokers and characterize the gingival crevicular fluid (GCF) samples using Raman spectroscopy In addition, to longitudinally determine if MMP-8 and CTX are predictive factors for attachment loss in periodontitis sites., Methods: Sixty periodontally healthy and 60 periodontitis/diseased sites from 30 e-cig and 30 cigarette smokers were monitored at baseline, 3 months, and 6-months. GCF was sampled to study the MMP-8 and CTX concentrations using enzyme-linked immunosorbent assay. Infra-red absorption spectra of GCF were acquired at all time points and processed to identify key functional groups., Results: A significantly increased attachment loss was observed at 6 months for both smokers when compared with baseline (p < 0.01). This difference was significantly high for cigarette smokers compared with e-cig users (p < 0.01). MMP-8, CTX, smoking pack-years were significantly correlated with probing depth and clinical attachment loss among both e-cig and cigarette smokers. For MMP-8 and CTX, the periodontitis sites showed a statistically significant difference between e-cig and cigarette smokers at both 3- and 6 months follow-up. From baseline to 6 months follow-up, periodontitis sites from both groups showed higher spectral band intensities with deconvulations and Raman shifts for Amide I and Amide II peaks., Conclusion: Cigarette smokers showed higher periodontal worsening than e-cig smokers. Smoking, MMP-8, CTX are prognostic factors for clinical attachment loss in cigarette and e-cig smokers., Clinical Significance: Data for Raman scattering and spectral information identifying collagen degradation among e-cig and cigarette smokers have been analyzed. This type of analysis proves a robust diagnostic and prognostic tool for periodontal diseases. Smoking, MMP-8, and CTX are prognostic factors for clinical attachment loss in cigarette and e-cig smokers., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objective: To characterize and investigate efficacy of loading functionalized ZrO 2 nanoparticles in 3-dimensional (3D) printed acrylate ester-based resin subjected to accelerated aging in artificial saliva. As well as to evaluate the effect of ZrO 2 nanoparticle volume fraction addition on mechanical and physical properties of printed composite., Methods: Functionalized ZrO 2 nanoparticles were characterized using TEM and Raman spectroscopy. 3D printed dental resin was reinforced, with ZrO 2 nanoparticles, in the concentration range (0-5wt.%). The resulted nanocomposites, in term of structure and physical/mechanical properties were evaluated using different mechanical testing, microscopic and spectroscopic techniques., Results: ZrO 2 based nanocomposite was successful and formed composites were more ductile. Degree of conversion was significant at the highest level with blank resin and 1wt.%. Sorption revealed reduction associated with volume fraction significant to neat resin, however solubility indicated neat and 4wt.% had the lowest significant dissolution. Vickers represented critical positive correlation with filler content, while nanohardness and elasticity behaved symmetrically and had the maximum strength at 3wt.% addition. In addition, 3wt.% showed the highest fracture toughness and modulus. Improvement of flexural strength was significantly linked to filler concentration. Overall properties dramatically were enhanced after 3 months aging in artificial saliva, especially degree of conversion, microhardness, nanoindentation/elasticity, and flexural modulus. However, significant reduction was observed with flexural modulus and fracture toughness., Significance: The outcomes suggest that the newly developed 3D printed nanocomposites modified with ZrO 2 nanoparticle have the superior potential and efficacy as long-term provisional dental restoration materials., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

We formulated a pH-sensitive chlorhexidine-loaded mesoporous silica nanoparticles (MSN) modified with poly-(lactic-co-glycolic acid) (CHX-loaded/MSN-PLGA) and incorporated into experimental resin-based dentin adhesives at 5 and 10 wt%. Nanocarriers were characterized in terms of morphology, physicochemical features, spectral analyses, drug-release kinetics at varying pH and its effect on dentin-bound proteases was investigated. The modified dentin adhesives were characterized for cytotoxicity, antimicrobial activity, degree of conversion (DC) along with CHX release, micro-tensile bond strength (μTBS) and nano-leakage expression were studied at different pH values and storage time. CHX-loaded/MSN-PLGA nanocarriers exhibited a significant pH-dependent drug release behavior than CHX-loaded/MSN nanocarriers without PLGA modification. The highest percentage of CHX release was seen with 10 wt% CHX-loaded/MSN-PLGA doped adhesive at a pH of 5.0. CHX-loaded/MSN-PLGA modified adhesives exhibited more profound antibiofilm characteristics against S. mutans and more sustained CHX-release which was pH dependent. After 6 months in artificial saliva at varying pH, the 5 wt% CHX-loaded/MSN-PLGA doped adhesive showed excellent bonding under SEM/TEM, higher μTBS, and least nano-leakage expression. The pH-sensitive CHX-loaded/MSN-PLGA could be of crucial advantage for resin-dentin bonding applications especially in reduced pH microenvironment resulting from biofilm formation; and the activation of dentin-bound proteases as a consequence of acid etching and acidic content of bonding resin monomers., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: A low pH environment is created due to the production of acids by oral biofilms that further leads to the dissolution of hydroxyapatite crystal in the tooth structure significantly altering the equilibrium. Although the overall bacterial counts may not be eradicated from the oral cavity, however, synthesis of engineered anti-bacterial materials are warranted to reduce the pathogenic impact of the oral biofilms. The purpose of this study was to synthesize and characterize chlorhexidine (CHX)-loaded mesoporous silica nanoparticles (MSN) grafted with poly-L-glycolic acid (PGA) and to test the in vitro drug release in various pH environments, cytotoxicity, and antimicrobial capacity. In addition, this study aimed to investigate the delivery of CHX-loaded/MSN-PGA nanoparticles through demineralized dentin tubules and how these nanoparticles interact with tooth dentin after mixing with commercial dentin adhesive for potential clinical application., Results: Characterization using SEM/TEM and EDX confirmed the synthesis of CHX-loaded/MSN-PGA. An increase in the percentage of drug encapsulation efficiency from 81 to 85% in CHX loaded/MSN and 92-95% in CHX loaded/MSN-PGA proportionately increased with increasing the amount of CHX during the fabrication of nanoparticles. For both time-periods (24 h or 30 days), the relative microbial viability significantly decreased by increasing the CHX content (P < 0.001). Generally, the cell viability percentage of DPSCs exposed to MSN-PGA/Blank, CHX-loaded/MSN, and CHX-loaded/MSN-PGA, respectively was > 80% indicating low cytotoxicity profiles of experimental nanoparticles. After 9 months in artificial saliva (pH 7.4), the significantly highest micro-tensile bond strength value was recorded for 25:50 CHX/MSN and 25:50:50 CHX/MSN-PGA. A homogenous and widely distributed 50:50:50 CHX-loaded/MSN-PGA nanoparticles exhibited excellent bonding with the application of commercially available dentin adhesive., Conclusions: A pH-sensitive CHX release response was noted when loaded in MSN grafted PGA nanoparticles. The formulated drug-loaded nanocarrier demonstrated excellent physicochemical, spectral, and biological characteristics. Showing considerable capacity to penetrate effectively inside dentinal tubules and having high antibacterial efficacy, this system could be potentially used in adhesive and restorative dentistry.

On July 4 2019, a M w 6.5 earthquake, followed 34 h later by a M w 7.1 event, struck Searles Valley, California. These events are part of a long-lived cluster of historical earthquakes along the Eastern California Shear Zone (ECSZ) which started in 1872 and are associated with temporarily elevated strain rates. We find that the M w 6.5 event initiated on a right-lateral NW striking fault and then ruptured a left-lateral fault to the surface. This event triggered right-lateral slip during the M w 7.1 earthquake. It started as a bilateral, crack-like rupture on a segment brought closer to failure by the M w 6.5 event. The rupture evolved to pulse-like as it propagated at a relatively slow velocity (2 km/s) along a segment that was unloaded by the M w 6.5 event. It stopped abruptly at the Coso volcanic area and at the Garlock Fault and brought some neighbouring faults closer to failure.

Aim of the Study: The aim of this laboratory study was to evaluate the effect of ethanol treatment on the surface roughness (S a ), nano-mechanical properties (NMP) and surface characterization of dental fiber reinforced composite (FRC) with semi-interpenetrating polymer network (IPN)., Materials and Methods: A total of 240 FRC specimens with bisphenol A-glycidyl methacrylate - triethyleneglycol dimethacrylate - Poly (methylmetahcrylate) (bis-GMA-TEGDMA-PMMA) IPN matrix system were light cured for 40 s and divided into 2 groups (L and LH). The group LH was further post-cured by heat at 95 °C for 25 min. The specimens were exposed to 99.9%, 70% and 40% for 15, 30, 60 and 120 s respectively. The treated specimens were evaluated for S a using non-contact profilometer. NMP were determined using nanoindentation technique and chemical characterization was assessed by Fourier Transform-Infrared (FTIR) spectroscopic analyses. Scanning electron microscopic (SEM) images were made to evaluate the surface topographical changes., Results: Both the L and LH group showed changes in the S a and NMP after being treated by different concentrations of ethanol and at different time interval. The highest S a was observed with L-group (0.733 μm) treated with 99.9% ethanol for 120 s. Specimens in LH-group treated with 99.9% ethanol for 120 s (1.91 GPa) demonstrated increased nano-hardness, and group treated with 40% ethanol for 120 s demonstrated increased Young's modulus of elasticity (22.90 GPa). FTIR analyses revealed changes in the intensity and bandwidth in both the L and LH groups., Conclusion: The present study demonstrated that both light-cured and heat post-cured FRC were prone for ethanol induced alteration in the surface roughness (S a ), nano-mechanical properties (NMP) and chemical characterization. The interphase between the glass fibers and the organic matrix was affected by ethanol. The changes were considerably less in magnitude in the heat post-cured FRC specimens., (Copyright © 2019 Elsevier Ltd. All rights reserved.)