Publications by authors named "Yongchun Gu"

To investigate the association between impacted mandibular third molars (IMTMs) and the prevalence of distal caries in adjacent mandibular second molars (MSMs) in a Chinese population, a retrospective analysis was conducted using cone-beam computed tomography (CBCT) images obtained from routine dental practice for various diagnostic purposes. The impaction patterns of the mandibular third molars were recorded using Winter's classification and Pell and Gregory's classification. The occurrence and severity of distal caries in MSMs were also documented.

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Objectives: The C-shaped mandibular second molars (MSMs) may pose an endodontic challenge. The aim of this study was to develop a convolutional neural network (CNN)-based deep learning system for the diagnosis of C-shaped MSMs on panoramic radiographs.

Materials And Methods: Panoramic radiographs and cone beam computed tomographic (CBCT) images were collected from a hospital in China and subsequently divided into two groups.

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Background: To investigate the anatomic features of the root furcation of permanent mandibular first molars.

Methods: A total of 50 extracted mandibular first molars (25 two-rooted and 25 three-rooted) were collected and scanned using micro-computed tomography. The digital models of teeth and root canal systems were reconstructed three-dimensionally.

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Surface-enhanced Raman spectroscopy (SERS) is widely utilized in bacterial analyses, with the dominant SERS peaks attributed to purine metabolites released during sample preparation. Although adenosine triphosphate (ATP) and nucleic acids are potential molecular origins of these metabolites, research on their exact contributions remains limited. This study explored purine metabolite release from E.

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Background: Methylenetetrahydrofolate reductase (MTHFR) is essential for the metabolism of folic acid and homocysteine. The MTHFR C677T polymorphism is associated with several disorders. Our study aims to explore the geographical distributions of the MTHFR C677T polymorphism of women in China and how migration affected the polymorphism in Suzhou.

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Purpose: To explore the cytotoxic effect of a menthol-favored E-liquid on human periodontal ligament stem cells (hPDLSCs), as well as the underlying mechanism of electronic cigarette (E-cig)-induced cell apoptosis.

Methods: PDLSCs were isolated and cultured from periodontal ligament tissues of healthy premolars extracted for orthodontic reasons. Cells in passage 3 were used to detect the surface markers of stem cells by flow cytometry.

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Background: The preparation of the middle mesial (MM) canal of mandibular molars represents a challenge because it is often curved, narrow, and close to the root concave. The purpose of this study was to evaluate the ex vivo shaping ability of 3 nickel-titanium (NiTi) rotary systems in the MM canal using 3D printed resin tooth replicas.

Methods: A permanent mandibular first molar with a MM canal was acquired from a pool of extracted teeth and reproduced by a 3D printer.

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Background: In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients' root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors.

Methods: A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 μm.

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Background: Sebaceous glands (SGs) synthesize and secret sebum to protect and moisturize the dermal system via the complicated endocrine modulation. Dysfunction of SG are usually implicated in a number of dermal and inflammatory diseases. However, the molecular mechanism behind the differentiation, development and proliferation of SGs is far away to fully understand.

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Electronic cigarettes have rapidly gained acceptance recently. Nicotine-containing electronic cigarette liquids (e-liquids) are prohibited in some countries, but are permitted and simply available online in others. A rapid detection method is therefore required for on-site inspection or screening of a large amount of samples.

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Background: Comprehensive understanding of the root canal system complexity is critical important for successful root canal therapy. A double root canal system may be present in permanent mandibular incisors with a variable incidence in different ethnic populations. Ignorance or improper management of this canal variation can lead to treatment failure.

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The potential toxicities and threats of electronic cigarettes (E-cigs) on periodontal health remain elusive. Gingival mesenchymal stem cells (GMSCs) and periodontal ligament stem cells (PDLSCs) contribute to cell differentiation and regeneration for periodontium as well as inflammatory modulation. However, the effects of E-cig exposure on periodontal tissues, particularly GMSCs and PDLSCs, and the underlying epigenetic mechanisms remain largely unknown.

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JAK/STAT pathway has been widely acknowledged in the development of human cancers. However, the role of different phosphorylated STAT proteins translocating into nucleus in transcription activation of target genes is not fully understood. In present research, ChIP-seq was carried on to investigate the genome-wide distribution of the activated STAT1, STAT2, STAT3, STAT5 and STAT6 in colorectal cancer HCT-116 cells.

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This study aimed to find appropriate nickel-titanium instruments for lingual canals in mandibular first premolars with two canals. Forty-two extracted mandibular first premolars with lingual canals (Vertucci type V) verified by micro-CT scanning were selected. The teeth were randomly divided into three groups, and their lingual canals were instrumented by M3, HyFlex CM and XP-endo Shaper, respectively.

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Background: To investigate the anatomic features of three-rooted deciduous mandibular second molars (DMSMs) in Chinese children by using cone-beam computed tomography (CBCT).

Methods: A total of 247 CBCT scans of Chinese children were selected and retrospectively analyzed. The occurrence, gender and side predilection of three-rooted DMSMs were examined.

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Background: This study evaluated and compared the shaping ability of four advanced single-file nickel-titanium (NiTi) systems during the preparation of curved second mesiobuccal (MB2) canals in maxillary first molar replicas fabricated by three-dimensional (3D) printing via micro-computed tomography (Micro-CT) imaging.

Methods: A total of 60 3D-printed maxillary first molar replicas were constructed from one extracted tooth, with an angle of curvature ranging from 15° to 25°. The MB2 canals from these 60 replicas were divided into 4 groups of 15 replicas according to the canal instrumentation system used, namely, Waveone gold (WOG), Reciproc blue (RCB), XP-endo shaper (XPS) and M3-L.

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Purpose: To explore the effects of high-concentration fluoride(F) on apoptosis of human periodontal ligament stem cells (PDLSCs).

Methods: PDLSCs were isolated from periodontal ligament tissues of extracted third molars, and treated with different concentrations (0-40 ppm F) of NaF for indicated period of time. CCK-8 assay was performed to detect cell viability.

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Objectives: To investigate the root canal morphology of mesiobuccal (MB) roots in maxillary first molars, and to assess the presence of a second mesiobuccal canal (MB2) according to the location of the main MB canal.

Materials And Methods: A total of 72 extracted permanent maxillary first molars were collected from dental clinics and were scanned with micro-CT and reconstructed three-dimensionally. The root canal systems were recorded according to Vertucci's classification, and the occurrence of accessory canals was also recorded.

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The aim of this study was to evaluate the shaping characteristics of Protaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), Hero Shaper (HS; MicroMega, Besacon, France) and Hyflex CM (HCM; Coltene-Whaledent, Allstetten, Switzerland) nickel-titanium systems with various apical sizes and tapers in second mesiobuccal (MB2) canal instrumentation using micro-computed tomographic imaging. A total of 27 maxillary first molars with independent patent MB2 canals were selected and randomly assigned to three groups according to the 3-dimensional morphologic aspects obtained from preoperative micro-computed tomographic scans. Canals were first negotiated with a size 8 K-file and finally prepared to F1, F2, and F3 with PTU and to sizes 20.

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Nicotine-containing electronic cigarette liquid (e-liquid) is prohibited in many countries, creating requirements for rapid detection approaches for on-site inspection or screening for large amounts of samples. Here, we demonstrate a simple way to identify nicotine using surface-enhanced Raman scattering (SERS) with substrates made of silver nanoparticle arrays imbedded in anodic aluminum oxide nanochannels (Ag/AAO). Compared with the reported colloidal nanoparticle-based SERS, that required serial dilutions to enable colloid aggregation in the viscous e-liquid, a small amount of undiluted e-liquid sample can be directly added onto our solid-phase Ag/AAO substrate without any pre-treatment.

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The aim of this study was to establish an effective method of locating and negotiating the lingual canal in mandibular first premolars with two canals during root canal preparation. A total of 125 mandibular first premolars with radicular grooves were collected, and after micro-computed tomography scanning, 50 mandibular first premolars with a Vertucci V/III canal form were selected based on the inclusion criteria. Access cavities were prepared, and the lingual canals (LCs) were searched in four following steps: step 1 direct vision and a straight K-file; step 2 stereomicroscopy and a straight K-file; step 3 stereomicroscopy and a pre-curved K-file; and step 4 a long-neck bur.

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Periodontitis is a chronic inflammatory disease that can lead to the loss of periodontal bone tissue. The osteogenic potential of periodontal ligament stem cells (PDLSCs) is significantly decreased in periodontitis microenvironment. However, the mechanism is still unclear.

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The aim of this study was to prepare a promising biomaterial for dental pulp tissue repair and regeneration. The ultrasmall superparamagnetic iron oxide (USPIO)-labeled hydroxyapatite (HA)/silk fibroin (SF) scaffold loaded dental pulp stem cells (DPSCs) was designed. The odontogenic differentiation of DPSCs was investigated, and USPIO was used as magnetic resonance imaging (MRI) contrast agent.

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