BACKGROUND AND OBJECTIVE

Orthodontic brackets predispose dental biofilm accumulation causing caries and gingivitis. Chlorhexidine is an adjunct to mechanical plaque removal, but has side-effects (tooth staining, bacterial resistance) due to long term use. This study tested the efficacy of Photodynamic Therapy, which produces reactive oxygen species, to reduce Streptococcus mutans in dental biofilm on orthodontic brackets.

A 5-day S. mutans biofilm was grown on forty enamel-bracket specimens. Thirty-nine specimens were randomized to three treatment groups: A. Distilled Water; B. 0.12% Chlorhexidine (CHX); C. Photodynamic Therapy (PDT) using Toluidine Blue O (TBO) as a photosensitizer, activated by red LED (630nm). After treatment, one random specimen from each group was viewed under Environmental Scanning Electron Microscopy (ESEM); the other 12 specimens, biofilms were collected, weighed, and cultured onto BHI agar plates to determine the number of CFU/mg. For baseline evaluation, one clean and one untreated specimens were preserved for ESEM.

Based on Tukey HSD test, group A had the most S. mutans (37.0573 CFU/mg) and was significantly different (p < 0.05) from groups B (0.1712 CFU/mg) and C (1.1193 CFU/mg), where both showed less bacteria than group A. The statistical difference between groups B and C was insignificant. ESEM images showed specimen A covered with more abundant and denser S. mutans biofilm than specimens B and C, with almost similar morphology showing sparse, less dense, and disintegrated biofilm with unclear cellular walls and presence of amorphous masses.

Both Photodynamic Therapy and 0.12% Chlorhexidine showed a significant reduction of S. mutans in dental biofilm on orthodontic brackets. However, there is no significant difference between them in reducing S. mutans CFU/mg. Photodynamic therapy could be an alternative adjunctive tool to mechanical removal of plaque adhered to orthodontic brackets.

Nipah virus (NiV) and related viruses form a distinct henipavirus genus within the Paramyxoviridae family. NiV continues to spillover into the humans causing deadly outbreaks with increasing human-bat interaction. NiV encodes the large protein (L) and phosphoprotein (P) to form the viral RNA polymerase machinery. Their sequences show limited homologies to those of non-henipavirus paramyxoviruses. We report two cryo-electron microscopy (cryo-EM) structures of the Nipah virus (NiV) polymerase L-P complex, expressed and purified in either its full-length or truncated form. The structures resolve the RNA-dependent RNA polymerase (RdRp) and polyribonucleotidyl transferase (PRNTase) domains of the L protein, as well as a tetrameric P protein bundle bound to the L-RdRp domain. L-protein C-terminal regions are unresolved, indicating flexibility. Two PRNTase domain zinc-binding sites, conserved in most Mononegavirales, are confirmed essential for NiV polymerase activity. The structures further reveal anchoring of the P protein bundle and P protein X domain (XD) linkers on L, via an interaction pattern distinct among Paramyxoviridae. These interactions facilitate binding of a P protein XD linker in the nucleotide entry channel and distinct positioning of other XD linkers. We show that the disruption of the L-P interactions reduces NiV polymerase activity. The reported structures should facilitate rational antiviral-drug discovery and provide a guide for the functional study of NiV polymerase.
Nipah Virus/chemistry* ; Cryoelectron Microscopy ; Viral Proteins/genetics* ; RNA-Dependent RNA Polymerase/genetics* ; Phosphoproteins/genetics* ; Humans ; Models, Molecular ; Protein Binding

OBJECTIVES: We aimed to compare the apical sealing properties of three endodontic sealers, namely, C-Root SP (C-R), iRoot SP, and GuttaFlow Bioseal (GFB) in vitro. METHODS: Eighty-two single-rooted premolars and anterior teeth were prepared by using M3 machine with nickel-titanium file and randomly divided into six experimental groups (n=12) and two control groups (n=5). Group A1: single-cone technique (SC)+C-R; group B1: SC+iRoot SP; group C1: SC+GFB; group A2: single-cone with ultrasonic activation (SU)+C-R; group B2: SU+iRoot SP; group C2: SU +GFB; group D: positive control group, and group E: negative control group. Dye penetration length and lateral root canal filling in each group were measured by dye penetration test. A scanning electron microscope (SEM) was used to observe the interface between gutta pertscha, root canal sealer, and dentin wall. Dye penetration length was measured and analyzed by Kruskal-Wallis test, and data on lateral root canal filling were evaluated using Chi-square. RESULTS: The dye penetration length in group A1 was lower than that in groups C1 and A2 (P<0.05) but was not significantly different from the other groups (P>0.05). Lateral root canal filling was not significantly different among all groups (P>0.05). SEM showed that GFB was slightly better than C-R and iRoot SP in binding to gutta pertcha and dentin wall. CONCLUSIONS GFB, C-R, and iRoot SP demonstrate excellent apical sealing ability. Under the conditions tested in this study, SU did not yield significantly improve the apical sealing ability of the three root canal sealers.
Root Canal Filling Materials/chemistry* ; Humans ; Gutta-Percha ; Microscopy, Electron, Scanning ; Root Canal Obturation/methods* ; Ceramics ; Dimethylpolysiloxanes ; Drug Combinations

OBJECTIVES: This study aimed to compare the osteogenic performance differences of titanium surface coatings modified by dopamine or silanized graphene oxide, and to provide a more suitable modification scheme for titanium surface graphene oxide coatings. METHODS: Titanium was subjected to alkali-heat treatment and then modified with dopamine and silanization, respectively, followed by coating with graphene oxide. Control and experimental groups were designed as follows: pure titanium (Ti) group; titanium after alkali-heat treatment (Ti-NaOH) group; titanium after alkali-heat treatment and silanization modification (Ti-APTES) group; titanium after alkali-heat treatment and dopamine modification (Ti-DOPA) group; titanium with silanization-modified surface decorated with graphene oxide (Ti-APTES/GO) group; titanium with dopamine-modified surface decorated with graphene oxide (Ti-DOPA/GO) group. The physical and chemical properties of the material surfaces were analyzed using scanning electron microscopy (SEM), contact angle goniometer, X-ray photoelectron spectroscopy (XPS), and Raman spectrometer. The proliferation and adhesion morphology of mouse embryonic osteoblast precursor cells MC3T3-E1 on the material surfaces were observed by cell viability detection and immunofluorescence staining followed by laser confocal microscopy. The effects on the osteogenic differentiation of MC3T3-E1 cells were studied by alkaline phosphatase (ALP) staining, alizarin red staining and quantification, and real-time quantitative polymerase chain reaction. RESULTS: After modification with graphene oxide coating, a thin-film-like structure was observed on the surface under SEM. The hydrophilicity of all experimental groups was improved, among which the Ti-DOPA/GO group had the best hydrophilicity. XPS and Raman spectroscopy analysis showed that the modified materials exhibited typical D and G peaks, and XPS revealed the presence of a large number of oxygen-containing functional groups on the surface. CCK8 assay showed that all groups of materials had no cytotoxicity, and the proliferation level of the Ti-APTES/GO group was higher than that of the Ti-DOPA/GO group. Under the laser confocal microscope, the cells in the Ti-DOPA/GO and Ti-APTES/GO groups spread more fully. The Ti-DOPA/GO and Ti-APTES/GO groups had the deepest ALP staining, and the Ti-APTES/GO group had the most alizarin red-stained mineralized nodules and the highest quantitative result of alizarin red staining. In the Ti-DOPA/GO and Ti-APTES/GO groups, the expression of the early osteogenic-related gene RUNX2 reached a relatively high level, while in the expression of the late osteogenic-related genes OPN and OCN, the Ti-APTES/GO group performed better than the Ti-DOPA/GO group. CONCLUSIONS Ti-APTES/GO significantly outperformed Ti-DOPA/GO in promoting the adhesion, proliferation, and in vitro osteogenic differentiation of MC3T3-E1 cells.
Titanium/chemistry* ; Graphite/chemistry* ; Dopamine/chemistry* ; Animals ; Mice ; Osteogenesis ; Osteoblasts/cytology* ; Surface Properties ; Cell Proliferation ; Silanes/chemistry* ; Cell Adhesion ; Coated Materials, Biocompatible/chemistry* ; Cell Differentiation ; Alkaline Phosphatase/metabolism* ; Microscopy, Electron, Scanning

OBJECTIVES: Through the investigation of the microhardness and microstructure of permanent tooth enamel at various eruption stages during childhood, this research offers references for the early prevention of childhood dental caries. METHODS: Forty-five premolars extracted due to orthodontic reasons were collected and screened. These premolars were divided into three experimental groups according to the time since eruption: Group A (erupted for 0-1 year), Group B (erupted for 1-3 years), and Group C (erupted for 3-5 years). Additionally, the third molars that were extracted due to impaction and had not erupted were selected as the control group, with 15 teeth in each group. Samples were prepared, and the surface microhardness, microstructure, and elemental composition of the enamel were measured using Vickers microhardness tester, scanning electron microscope, and electron probe, respectively. RESULTS: Compared with that in the control group, the microhardness of enamel in groups A, B, and C increased with prolonged eruption time, the surface porosity structure decreased considerably, the contents of Na and Mg on the surface decreased, and that of F increased (P<0.05). CONCLUSIONS The microhardness and microstructure of enamel in permanent teeth at different stages vary. Permanent teeth are at a substantially higher risk of caries within one year after eruption, and early prevention should be emphasized.
Dental Enamel/ultrastructure* ; Humans ; Hardness ; Dental Caries/prevention & control* ; Microscopy, Electron, Scanning ; Tooth Eruption ; Bicuspid/chemistry* ; Dentition, Permanent ; Child ; Child, Preschool

OBJECTIVES: Calcium silicate (CSO) is modified to give it photothermal antibacterial properties. Its application potential in tooth mineralization and oral antibacterial is evaluated. METHODS: Based on defect-engineering modification strategy, a series of CSO-T samples (CSO-300, CSO-400, CSO-500, CSO-600) was obtained by introducing oxygen vacancy into CSO through thermal reduction using sodium borohydride. The samples were tested using scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet near-infrared absorption spectroscopy, and infrared thermography. The powder samples with the best photothermal performance and the most suitable material concentration (CSO-500, 500 μg/mL) were selected for subsequent experiments. High resolution transmission electron microscopy was used to analyze the microstructure and morphology of the sample, and MTT assay and Calcein AM/PI live/dead cell staining were used to evaluate the toxicity and compatibility of the sample to human oral keratinocytes. Escherichia coli and Staphylococcus aureus were selected for photothermal antibacterial experiments to evaluate their in vitro antibacterial performance. SEM, energy dispersive spectrometer, and micro Vickers hardness tester were used to evaluate the ability of materials to induce in vitro remineralization of detached teeth. RESULTS: Oxygen vacancies changed the crystal type and lattice spacing of CaSiO₃, broadened the light-absorption range, and gave it a good photothermal conversion ability in response to near infrared. Invitro experiments showed that the modified CaSiO₃ could promote the formation of hydroxyapatite on the tooth surface, thereby promoting the remineralization of teeth and improving the teeth hardness. Moreover, it had photothermal antibacterial properties and no cytotoxicity. CONCLUSIONS Defect-modified black calcium silicate has multiple functions, such as promoting tooth remineralization and photothermal bacteriostatic. When combined with the infrared luminescent toothbrush, it can simply and effectively treat tooth enamel erosion and oral bacteriostatic diseases caused by the excessive consumption of carbonated beverages and other daily bad living habits. This combination is expected to achieve the synergic treatment effect of tooth remineralization and oral bacteriostatic through daily cleaning is expected.
Calcium Compounds/pharmacology* ; Silicates/pharmacology* ; Humans ; Staphylococcus aureus/drug effects* ; Tooth Remineralization ; Escherichia coli/drug effects* ; Anti-Bacterial Agents/pharmacology* ; Keratinocytes/drug effects* ; Microscopy, Electron, Scanning

OBJECTIVE: To explore the effects of two methods of smear layer removal on the surface properties of dentin. METHODS: Sixty extracted sound third molars were collected in this study, and were prepared as uniform dentin specimens with smear layer. All specimens were randomly divided into three groups: Control group, ultrasonic treatment (UT) group and etched treatment (ET) group. Scanning electron microscope (SEM) were used to observe the surface micromorphology of all three groups. Then, the surface elements, mineral phases and functional groups were analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and flourier transformed infrared spectrometer (FTIR) respectively. The mechanical properties, hydrophilicity and biocompatibility were also further evaluated. RESULTS: It was revealed that dentin tubules of UT and ET groups were exposed, but lots of dentin debris piled up on the surface of the control one which covered up dentin tubules on the surface. The EDX results should that the weaker peak value of calcium and phosphorus in ET group than control and UT groups. Characteristic peaks of hydroxyapatite could be seen by XRD in all of the three groups, but lower distinctive peaks of amide Ⅰ, Ⅱ and Ⅲ bands of collagen of the dentin surface in control group than in ET and UT groups. The microhardness results showed that ET group was lower than control and UT groups, the difference was significant (P < 0.05). Better hydrophilicity of ET group was investigated (P < 0.05) than control group and UT group. Cells could be observed to adhere normally to dentin surface of each group which meant that all of the three groups had good biocompatibility. CONCLUSION Both UT and ET could effectively remove the smear layer on the surface of dentin and had no adverse effect of the dentin micromorphology and biocompatibility. The ultrasonic removal of the smear layer did not influence the mineral structure, hydrophilicity and mechanical properties of dentin surface. Although ET can effectively improve the hydrophilicity of dentin but decreased mechanical properties and the content of calcium and phosphorus.
Dentin/ultrastructure* ; Humans ; Surface Properties ; Smear Layer ; Molar, Third ; Microscopy, Electron, Scanning ; Dental Etching/methods*

OBJECTIVES: Verrucous epidermal nevus (VEN), seborrheic keratosis (SK), verruca plana (VP), verruca vulgaris (VV), and nevus sebaceous (NS) are common verrucous proliferative skin diseases with similar clinical appearances, often posing diagnostic challenges. Dermoscopy and reflectance confocal microscopy (RCM) can aid in their differentiation, yet their specific features under these tools have not been systematically described. This study aims to summarize and analyze the dermoscopic and RCM features of VEN, SK, VP, VV, and NS. METHODS: A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled. Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions. RESULTS: Under dermoscopy, the 5 diseases displayed distinct characteristics: VEN typically showed gyriform structures; SK was characterized by gyriform structures, comedo-like openings, and milia-like cysts; VP and VV featured dotted vessels and frogspawn-like structures; NS presented as brownish-yellow globules. RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases. Specific features included gyriform structures and elongated rete ridges in VEN; pseudocysts and gyriform structures in SK; evenly distributed ring-like structures in VP; vacuolated cells and papillomatous proliferation in VV; and frogspawn-like structures in NS. CONCLUSIONS These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM. The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.
Humans ; Dermoscopy/methods* ; Diagnosis, Differential ; Microscopy, Confocal/methods* ; Male ; Female ; Adult ; Middle Aged ; Adolescent ; Keratosis, Seborrheic/pathology* ; Young Adult ; Warts/diagnosis* ; Child ; Aged ; Skin Diseases/pathology* ; Nevus, Sebaceous of Jadassohn/diagnosis* ; Skin Neoplasms/diagnosis* ; Child, Preschool

OBJECTIVES: Papular dermatoses commonly affecting the female vulva, such as molluscum contagiosum, syringoma, lymphangioma, folliculitis, verruca vulgaris, ectopic sebaceous glands, and bowenoid papulosis, often present with similar clinical appearances and are frequently misdiagnosed. This study aims to explore the clinical diagnostic value of reflectance confocal microscopy (RCM) in differentiating these conditions. METHODS: A retrospective analysis was conducted on RCM imaging and histopathological findings from lesion sites in 172 female patients with vulval papular dermatoses. RCM characteristics confirmed by biopsy were summarized and diagnostic clues were explored. RESULTS: RCM diagnosis was consistent with histopathological diagnosis in 147 out of 172 cases (85.47%). Molluscum contagiosum, syringoma, lymphangioma, and folliculitis all exhibited cystic-like structures under RCM, differing in the location of the structures, wall characteristics, internal contents, and reflectivity. Verruca vulgaris, ectopic sebaceous glands, and bowenoid papulosis lacked such structures. Verruca vulgaris showed distinctive low-refractive vacuolated cells in the spinous layer; bowenoid papulosis exhibited mild cytologic atypia in the spinous layer; ectopic sebaceous glands were characterized by moderately to low-refractive, fish roe-like sebaceous lobules within the dermis. CONCLUSIONS RCM enables noninvasive, real-time, and dynamic visualization of key diagnostic and differential features of common vulvar papular dermatoses in women, offering high diagnostic value.
Humans ; Female ; Microscopy, Confocal/methods* ; Retrospective Studies ; Adult ; Vulvar Diseases/diagnosis* ; Middle Aged ; Young Adult ; Aged ; Adolescent ; Diagnosis, Differential ; Child ; Skin Diseases/pathology* ; Molluscum Contagiosum/diagnosis*

Dynamic changes in the physiochemical, structural, and flavor characteristics of ginger-juice milk curd were explored by texture analysis, scanning electron microscopy, rheometry, electronic tongue, and gas chromatography-mass spectrometry (GC-MS). Protein electrophoresis showed that ginger juice could hydrolyze α_s-, β-, and κ-casein. Curd formation was initiated at 90 s, marked by significant changes in intensity detected via intrinsic fluorescence. The contents of soluble protein and calcium decreased rapidly during coagulation, while the caseinolytic activity, storage moduli, loss moduli, hardness, adhesiveness, and water-holding capacity increased, resulting in a denser gel structure with smaller pores and fewer cavitations as observed by scanning electron microscopy. Electronic tongue analysis indicated that milk could neutralize the astringency and saltiness of ginger juice, rendering the taste of ginger-juice milk curd more akin to that of milk. Approximately 70 volatile components were detected in ginger-juice milk curd. α‍-Zingiberene, α‍-curcumene, β‍-sesquiphellandrene, and β‍-bisabolene were the predominant volatile flavor compounds, exhibiting an initial decrease in content followed by stability after 90 s. Decanoic acid, γ-elemene, and caryophyllene were identified as unique volatile compounds after mixing of milk and ginger juice. Understanding the dynamic changes in these characteristics during coagulation holds significant importance for the production of ginger-juice milk curd.
Zingiber officinale/chemistry* ; Milk/chemistry* ; Animals ; Taste ; Gas Chromatography-Mass Spectrometry ; Caseins/chemistry* ; Microscopy, Electron, Scanning ; Rheology ; Flavoring Agents