Global Research Trends in Dental Stem Cells: A Bibliometric and Visualized Study.

Dental stem cells (DSCs) are mesenchymal stem cell-like populations with self-renewal and multidifferentiation potential. These cells have been studied in regenerative medicine and tissue engineering. Despite rapid progress in the past two decades, there has been no bibliometric analysis of DSC research. Here, we performed a comparative study using bibliometric methods for DSCs. A total of 5498 articles were included. Our results showed that the United States was the leader in international cooperation and numbers of citations and was the largest contributor. The Journal of Endodontics published the largest number of articles. The author with the greatest contribution was Songtao Shi. The keywords were mainly related to the fields of tissue engineering and regenerative medicine. Relative research interest and the number of publications increased yearly worldwide. The hotspots of DSC research were transiting from basic research to clinical regenerative medicine. Impact statement Dental stem cells (DSCs) are stem cells with self-renewal and multidirectional differentiation potential. Research in this field is attracting increasing attention. This study aimed to understand the current research status of DSCs and to predict promising keywords and trends. We found the global trend of DSCs and their application in the field of regenerative medicine and tissue engineering. Our study makes a significant contribution to the literature because it will help researchers to understand the research trends and directions in this field.

[Cytotoxicity of a novel endodontic treatment material iRoot BP Plus to human gingival fibroblasts].

PURPOSE: To compare the cytotoxicity of a novel endodontic treatment material iRoot BP Plus and mineral trioxide aggregate (MTA) to human gingival fibroblasts in vitro. METHODS: Cultured human gingival fibroblasts were exposed to multiple concentrations of material elutes (no dilution, 1:2 dilution, and 1:5 dilution). The test material samples were immersed and incubated in the culture medium for 1, 3 or 7 days at 37 degrees centigrade. The proliferation rate was evaluated using methylthiazol tetrazolium (MTT) assay. Cell relative growth rates were presented as x±s. The data was statistically analyzed by factorial design ANOVA using SPSS 20.0 software package. RESULTS: Cell relative growth rates of the eluates of iRoot BP Plus and MTA in different concentrations ranged from 77.31% to 113.82%. The cytotoxicity grade of both materials was 0 or 1 (no cytotoxicity). There was no significant difference in the relative growth rate in different concentrations of iRoot BP plus and MTA eluates under different elution times (F(concentration×time×material)=1.393, P=0.256). CONCLUSIONS: Both iRoot BP Plus and MTA exhibit minimal level of cytotoxicity.

Histologic comparison between platelet-rich plasma and blood clot in regenerative endodontic treatment: an animal study.

INTRODUCTION: In regenerative endodontic treatment (RET) for immature permanent tooth, better treatment results could be obtained by applying platelet-rich plasma (PRP) as the scaffold rather than the blood clot. The goal of this study was to compare the histologic differences between using PRP and blood clot in RET. METHODS: Three 6-month-old beagles each carrying 9 premolars with double root canals were randomly assigned to the PRP group, blood clot group, or negative control group. All experimental teeth suffered apical periodontitis, and RET was performed. In the blood clot group, bleeding was induced from the periapical tissues to fill the canal space. In the PRP group, autologous PRP was injected into each root canal. The animals were sacrificed 3 months later. Histologic sections were stained with hematoxylin-eosin. Statistical analysis was performed by the Fisher exact test, with the significance set at 0.05. RESULTS: With the ingrowth of cellular cementumlike tissues, the canal wall was thickened, and the apical apex was closed in both the PRP and blood clot groups. Cementocytelike cells were present in the newly formed tissues. Meanwhile, no statistical difference was found in both experimental groups for the average percentage of apical closure, new tissue formation, and pulplike tissue formation. Noticeably, a large number of inflammatory cells were present in some root canals in both groups although the postoperative radiograph revealed the disappearance of periapical radiolucency. CONCLUSIONS: PRP application could be an option for clinical cases in which little or no bleeding were found when irritating the apical tissue during RET.

Regenerative endodontic treatment of an immature permanent tooth at an early stage of root development: a case report.

INTRODUCTION: Regenerative endodontic treatment (RET) has been used in treating nonvital immature permanent tooth whose root formation ranged from approximately two-thirds of the full root length to almost completely developed root with open apex at least 1.1 mm in diameter according to the reported cases. However, this case report was to introduce RET in an affected tooth at an early stage of root development. METHODS: The premolar #29 in an 8-year-old girl had pulpal necrosis and apical periodontitis caused by the fracture of dens evaginatus. Its root was at the beginning of formation. Copious hemorrhagic drainage was observed after preparing of an access cavity. The canal was irrigated with 3% NaOCl solution, sterile normal saline, and chlorhexidine. Root dressing with triple antibiotic was then performed and left for 4 weeks. We used a K-file to create bleeding into the canal after flushing and drying the root canal. Mineral trioxide aggregate was carefully placed over the formed blood clot. RESULTS: Clinical examination at 1, 3, 6, 9, and 12 months revealed an asymptomatic tooth. Radiographic examination revealed resolution of periapical radiolucency, increased thickening of the canal wall, and lengthening of the root, which demonstrated the continual development of the tooth root. Noticeably, the first-month postoperative radiograph showed radiopaque image in the root canal like an isolated island, which was gradually obvious during follow-up. Cone-beam computed tomography revealed that the calcification was attached with dentin wall in buccolingual direction, and the root canal was not completely obliterated. CONCLUSIONS: RET is feasible for a tooth at an early stage of root development that has necrotic pulp and periapical lesion.

[Expression of ß-catenin in the apical papilla and dental pulp tissues of human permanent teeth].

PURPOSE: The expression of ß-catenin at the level of mRNA and protein in the apical papilla and dental pulp tissues of human permanent teeth were compared to explore the possible relationship between ß-catenin and the development of pulp-dentin complex. METHODS: Forty-eight healthy permanent teeth in need of extraction for orthodontic treatment were obtained. The apical papilla and dental pulp tissues were isolated immediately when the teeth were extracted. All the samples were divided into 3 groups: group1, apical papilla of immature permanent teeth; group 2, dental pulp tissues of immature permanent teeth; group 3, dental pulp tissues of mature permanent teeth. RT-PCR and Western blot techniques were used to examine the expression of ß-catenin at the level of mRNA and protein respectively. Meta Morph software was used to measure the gray value of the positively expressed bands. Two-sample t test was performed to analyze the expression intensity (gray value) of ß-catenin by use of SPSS 11.0 software package. RESULTS: ß-catenin was positively expressed at both mRNA level and protein level in all the samples investigated. The expression intensity of ß-catenin in the dental pulp tissues of human immature permanent teeth was higher than that in the apical papillary tissues and that in the dental pulp tissues of human mature permanent teeth as well. The differences were statistically significant (P<0.05). CONCLUSIONS: ß-catenin was expressed in both the apical papilla and dental pulp tissues of immature and mature permanent teeth, but the expression intensity was different. It indicated that ß-catenin may play an important role in the development of pulp-dentin complex and in the reparative process after the dental pulp injury.