Application of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) for dental age assessment on orthopantomograms.

OBJECTIVES: This study aimed at exploring a new tooth development evaluation method for age assessment and investigating the dynamic alteration and potential trend of tooth development by orthopantomograms (OPGs), in order to provide references for tooth development prediction and forensic purpose. MATERIALS AND METHODS: A total of 132 OPGs of children aged 3-8 years were collected. The developmental stages of the permanent mandibular second molar (M2)were evaluated by experienced examiners according to the Nolla method and Mimics software, respectively. Quantitative analysis of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) in different stages, ages, sexes and quadrants were evaluated and compared via descriptive statistics and Spearman's correlation coefficient analysis. RESULTS: There was a strong, positive correlation between the examiners' evaluation and mimics analysis results. With the age increased, the Nolla stage of M2 observed by OPGs increased, and the RCA/DF showed increased trends both in males and females. There were significant differences of the RCA/DF of the M2 at various ages. The tooth calcification development of female was 9.08% earlier than that of male between 3 and 8 years old. However, teeth of male seemed to develop faster than that of female during this period. There was no significant difference between left and right quadrant either according to the Nolla stage or RCA/DF. CONCLUSIONS: The RCA/DF value obtained from OPGs of the developmental mandibular second permanent molars could be used as a reliable indicator for tooth maturity and age estimation in children aged 3-8 years. CLINICAL RELEVANCE: Age assessment based on radiographs is considered as a reliable and efficient indicator for judging different types of malocclusion, making suitable orthodontic treatment plan, deciding the extraction time of retained deciduous teeth in clinic practice.

Unveiling the Differences in Biological Properties of Dental Pulp Stem Cells from Normal and Inflamed Pulp: A Comprehensive Comparative Study.

BACKGROUND The aims of the study were to comprehensively compare the morphology, immunophenotype, proliferation, migration, and regeneration potential of normal dental pulp stem cells (DPSCs) versus inflammatory dental pulp stem cells (iDPSCs). MATERIAL AND METHODS Healthy pulp or inflamed pulp tissue was used to isolate and culture DPSCs and iDPSCs, respectively. These cell populations were characterized by flow cytometry, colony formation assay, transwell assay, and multi-directional differentiation in vitro. RESULTS No difference was observed in the morphology, cell-surface markers, or cell migration between DPSCs and iDPSCs. DPSCs showed a higher colony-forming capacity, proliferative viability, and osteo/dentinogenesis ability compared with iDPSCs. However, iDPSCs demonstrated enhanced neurogenesis, angiogenesis, adipogenesis, and chondrogenesis capacities in comparison to DPSCs. CONCLUSIONS Our data revealed the differences of biological properties between DPSCs and iDPSCs. The highly angiogenic and neurogenic potential of iDPSCs indicate their possible use in the regeneration of the dentin-pulp complex and support the critical role of angiogenesis and neurogenesis in pulp regeneration.

Effect of acidic culture conditions on the proliferation, apoptosis, and migration ability of human tongue squamous cell carcinoma cells and its related mechanism.

OBJECTIVES: This study aims to explore the effect of acidic culture conditions on the proliferation, apoptosis, and migration ability of human tongue squamous cell carcinoma SCC15 and CAL27 cells and its potential molecular mechanism. METHODS: After acidic culture for different periods, methyl thiazolyl tetrazolium (MTT) method was adop-ted to detect the cell proliferation of SCC15 and CAL27. Flow cytometry was employed to detect the apoptosis level of SCC15 and CAL27 cells. The migration ability of SCC15 and CAL27 after acidic culture was detected by scratch hea-ling test. Real-time fluorescence quantitative polymerase chain reaction (FQ-PCR) was used to detect the mRNA expression of cyclooxygenase 2 (COX-2) and survivin in SCC15 and CAL27 cells after acidic culture. RESULTS: After culture for 24 h under acidic microenvironment, SCC15 and CAL27 cells grew rapidly and reached the stationary phase after adjustment for 3 days. The apoptosis levels of SCC15 and CAL27 cells decreased after acidic culture, but the most significant reduction occurred after 6 h of acidic culture. The scratch healing rates of SCC15 and CAL27 cells increased after acidic culture. The results of FQ-PCR showed that the mRNA expression levels of COX-2 and survivin in SCC15 and CAL27 cells increased after acidic culture. CONCLUSIONS: Extracellular acidic microenvironment can inhibit the apoptosis of tongue squamous carcinoma cells, promote their migration, and induce more adaptable and malignant tongue squamous carcinoma cells. The mechanism may be related to COX-2 and survivin and their signal pathways.

The Application of a Case-Based Social Media-Assisted Teaching Method in Cariology Education：Comparative Study.

BACKGROUND: Current cariology education based on the traditional teaching method faces a lot of challenges. Meanwhile, the COVID-19 pandemic caused an unprecedented disruption in medical education and health care systems worldwide. Innovation in the teaching mode of cariology education is required to change the situation. OBJECTIVE: The goal of the research was to evaluate the application effects of a case-based social media-assisted teaching method in cariology education. METHODS: Dental students of class 2019 were enrolled into the experimental group, while students of class 2018 served as control. A case-based social media-assisted teaching method was used in the experimental group, which included preclass activity via social media, additional discussion and practice process record in class, and questions and answers on the platform after class. The traditional teaching method, which consisted of conventional preparation before class, traditional lectures and demonstrations followed by students practice in class, and questions and answers step after class, was used in the control group. The teaching materials were the same in both groups. At the end of the program, students from both groups took cavity preparation skill evaluation tests. Questionnaires were tested on the case-based social media-assisted teaching group students anonymously. All data were analyzed using SPSS statistical software (version 22.0, IBM Corp). RESULTS: The mean student cavity preparation skill evaluation scores was 82.51 (SD 6.82) in the experimental group and 77.19 (SD 5.98) in the control group (P<.05). The questionnaire response rate was 100%. Of those, 94.3% (100/106) of the students recommended the case-based social media-assisted teaching method in cariology education. The majority of the participants agreed that it helped them memorize the theoretical knowledge of cariology, facilitated in-depth discussion, improved their enthusiasm and initiative in learning, and enhanced the relationship between teachers and students (104/106, 98.1%). They also recognized that the classroom atmosphere was active (94/106, 88.7%). CONCLUSIONS: The case-based social media-assisted teaching method was beneficial in terms of learning, as demonstrated by the statistically significant improvement of the cavity preparation skill evaluation scores and satisfaction from attending students. This method could be used to supplement the teaching of cariology.

Effects of different aperture-sized type I collagen/silk fibroin scaffolds on the proliferation and differentiation of human dental pulp cells.

This study aimed at evaluate the effects of different aperture-sized type I collagen/silk fibroin (CSF) scaffolds on the proliferation and differentiation of human dental pulp cells (HDPCs). The CSF scaffolds were designed with 3D mapping software Solidworks. Three different aperture-sized scaffolds (CSF1-CSF3) were prepared by low-temperature deposition 3D printing technology. The morphology was observed by scanning electron microscope (SEM) and optical coherence tomography. The porosity, hydrophilicity and mechanical capacity of the scaffold were detected, respectively. HDPCs (third passage, 1 × 105 cells) were seeded into each scaffold and investigated by SEM, CCK-8, alkaline phosphatase (ALP) activity and HE staining. The CSF scaffolds had porous structures with macropores and micropores. The macropore size of CSF1 to CSF3 was 421 ± 27 µm, 579 ± 36 µm and 707 ± 43 µm, respectively. The porosity was 69.8 ± 2.2%, 80.1 ± 2.8% and 86.5 ± 3.3%, respectively. All these scaffolds enhanced the adhesion and proliferation of HDPCs. The ALP activity in the CSF1 group was higher than that in the CSF3 groups (P < 0.01). HE staining showed HDPCs grew in multilayer within the scaffolds. CSF scaffolds significantly improved the adhesion and ALP activity of HDPCs. CSF scaffolds were promising candidates in dentine-pulp complex regeneration.

FKBP11 promotes cell proliferation and tumorigenesis via p53-related pathways in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is one of the causes of cancer-related death worldwide. The abnormal proliferation ability of OSCC has become one of the major reasons for its poor prognosis. FK-506 binding protein 11 (FKBP11) is abnormally expressed in malignant tumors and affects many biological processes. The purpose of this study is to investigate the effect of FKBP11 on cell proliferation in OSCC and explore the possible regulatory mechanism. The expression of FKBP11 was detected by western blotting (WB) and/or real-time PCR in OSCC and paracancerous normal tissues in tongue squamous cell carcinoma (TSCC) cell lines, revealing high expression in OSCC and CAL-27 cells. Furthermore, FKBP11 knockdown inhibited the proliferation of CAL-27 cells by CCK-8 and colony formation assays. G2/M arrest and induction of apoptosis were observed using flow cytometry, Hoechst 33258 and Calcein-AM/PI staining, accompanied by changes in some cell cycle- and apoptosis-related proteins, including CDK1, Cyclin B1, p21, p27, p53, Bax, Bcl-2 and Caspase-3. Additionally, the expression of these proteins can be reversed by the use of pifithrin-α (PFT-α), a p53 inhibitor. An in vivo xenograft model further confirmed that FKBP11 enhanced OSCC progression. In conclusion, FKBP11 could promote cell proliferation by regulating G2/M phase and apoptosis via the p53/p21/p27 and p53/Bcl-2/Bax pathways, respectively, which suggests that it may be a new candidate target for the treatment of OSCC.

Cyclic mechanical stimulation inhibits rheumatoid arthritis fibroblast-like synoviocytes proliferation via cell cycle arrest.

The imbalance between proliferation and apoptosis of fibroblast-like synoviocytes (FLSs) has been the main cause of rheumatoid arthritis (RA) synovial hyperplasia. Our previous study confirmed that the cyclic mechanical stimulation (CMS) inhibited the proliferation of RA FLSs, but the underlying mechanisms are still unclear. This study aimed to investigate these underlying mechanisms. The in vitro cultured human RA FLSs were subjected to CMS (6%, 1.0 Hz). Cell cycle was detected by flow cytometry. The expression of cyclin D1, cyclin E1, CDK-2 and p27 was detected by reverse transcription-polymerase chain reaction (RT-PCR). MTS assay was used to detect cell viability. Cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) levels in RA FLSs were detected by western blotting and enzyme-linked immunosorbent assay (ELISA), respectively. The results showed that CMS significantly inhibited the cell cycle transformation of RA FLSs from G1 phase to S phase, which significantly decreased the cell proliferation index. Meanwhile, both cyclin E1 and CDK-2 gene expressions were significantly decreased, p27 gene expression was increased, and no significant change was observed in the expression of cyclin D1. The inhibition of COX-2/PGE2 pathway in RA FLSs by celecoxib treatment showed no effect on the inhibition of RA FLSs proliferation by CMS. In conclusion, CMS inhibited the proliferation of RA FLSs by modulating the expression of cell cycle-related molecules such as cyclin E1, CDK2 and p27 to arrest cell cycle transformation, which is independent of COX-2/PGE2 signaling pathway.

Mapping the amelogenin protein expression during porcine molar crown development.

INTRODUCTION: Amelogenin (AMEL) plays critical roles during enamel and dentin matrix deposition and mineralization. Most studies focused on the expression patterns of AMEL through the bud, cap, and bell stages. The spatial-temporal expression of AMEL protein during different mineralization stages, especially from presence of crypts to crown completed stages, remains unknown. Thus, the distribution pattern of AMEL in tooth crown formation from Nolla Stage 1 to 6 was investigated. METHODS: Porcine mandibular molar tooth germs from Nolla Stage 1 to 6 were obtained. The dynamic morphologic changes of tooth germs were examined by X-ray and surgical operating microscope. The AMEL protein expression was evaluated immunohistochemically, then analyzed semi-quantitatively, and further visualized via heat map. RESULTS: Tooth germs continuously increased in size from Nolla Stage 1 to 6. AMEL expression in the newly formed enamel kept negative, but presented intensively positive in the previously formed enamel from Stage 1 to 3. The adjacent enamel-dentin junction (EDJ) was strongly positive during the whole process. In predentin, AMEL was weakly seen at Stage 1 and then dramatically up-regulated from Stage 2 to Stage 3, then down-regulated but was still apparently seen in the whole process. AMEL expression in dentin was decreased during dentin matrix secretion and mineralization. CONCLUSIONS: This study identified the dynamic distribution of AMEL during porcine tooth crown formation. Semi-quantitative analysis and heat map emerged as reliable indicators in demonstrating AMEL distribution pattern.

Comparison of actual porcine tooth crown development stages and computer image analysis.

Tooth developmental stage evaluation is important in dental and chronological age estimation, and it is important for accurate diagnoses and appropriate treatment in dental practice. It is routinely assessed by clinical observations and radiographic techniques. This study aimed at ascertaining tooth developmental stage judgments made by examiners and Mimics software according to the Nolla method with radiographs. Meanwhile, the true tooth developmental stages would be explored with histological analysis. Twenty freshly slaughtered porcine heads were collected and hemisected, and both the left and right mandibular samples were numbered. The developmental stages of the second and third permanent molars (M2 and M3) were evaluated by examiners and Mimics software analysis. The ratio of the radiopaque calcified area to the dental follicle (RCA/DF) at different stages was calculated. Both non-decalcified and decalcified samples were processed for histologic observation. The results showed significant differences between RCA/DF ratios from different developmental stages. There was a high positive correlation between the examiners' evaluation results and Mimics analysis results. Radiograph judgments and histology observation results were consistent from Stages 2-6. However, radiograph images of Stage 1 samples showed only crypts present, while under a surgical operating microscope, a bell-shaped tooth germ was observed. This was also confirmed by normal and hard tissue histology. In conclusion, radiograph judgments made by either examiners or Mimics software were both reliable. Mimics analysis can be a useful tool in evaluating tooth developmental stages. However, judgments need to be made cautiously in early developmental stages.

Frequency and Influencing Factors of Rubber Dam Usage in Tianjin: A Questionnaire Survey.

Objective. To investigate the frequency and influencing factors of rubber dam usage for endodontic procedures among general dentistry practitioners and specialized practitioners (endodontist) in Tianjin. Methods. Three hundred questionnaires were distributed among practitioners from 3 different types of medical institutions in Tianjin. Data were collected and analysed using Chi-square tests. Results. There were 63.3% of respondents who have used rubber dam (response rate 82.7%, valid response rate 76.3%). However, only 0.4% and 3.1% of them recognized using rubber dam "every time" during caries direct restoration and root canal therapy, respectively. There was no significant difference in rubber dam usage between male and female practitioners. Among the respondents, practitioners with working experience between 5 and 10 years showed the highest usage rate (76.3%), while practitioners working more than 20 years showed the lowest (53.2%). The endodontists gained the highest and the most frequent usage rate and the best rubber dam technique mastering skills. Practitioners working in those stomatological departments of general hospitals showed the lowest rubber dam usage rate. Conclusions. The prevalence of rubber dam usage in Tianjin city is still low. The practitioner's gender, years of professional experience, general or specialized field, and the type of dental setting they work for are the factors that need to be considered during making policy and executing training.

Palladium-catalyzed oxidative cyclization of tertiary enamines for synthesis of 1,3,4-trisubstituted pyrroles and 1,3-disubstituted indoles.

A novel and efficient palladium-catalyzed intramolecular oxidative cyclization of tertiary enamines for the synthesis of 1,3,4-trisubstituted pyrroles and 1,3-disubstituted indoles has been developed. Trifluoroacetic acid plays an important role in the reaction. A series of pyrroles and indoles with substitution patterns that are not easily accessible by traditional routes were synthesized in good yields under mild conditions.

Oxidation of 2-arylindoles for synthesis of 2-arylbenzoxazinones with oxone as the sole oxidant.

A novel and efficient method for the oxidation of 2-arylindoles to synthesize 2-arylbenzoxazinones utilizing oxone as the sole oxidant has been developed. The reaction tolerates a wide range of functional groups and allows quick and atom-economical assembly of a variety of valuable 2-arylbenzoxazinones in high yields.