A cross-sectional evaluation of knowledge among Chinese dentists regarding the treatment of traumatic injuries in primary teeth.

BACKGROUND/AIM: Injuries to the primary dentition affect children's esthetics, function, and mental health. They may also affect the development of the permanent teeth. The knowledge of dentists about deciduous tooth trauma is rarely evaluated. The aim of this study was to evaluate the knowledge and attitude of dentists in China regarding traumatic dental injuries to primary teeth. MATERIAL AND METHODS: A self-administered online questionnaire containing questions on demographic data and knowledge based on a clinical scenario was given to a purposive sample of dentists, recruited by a non-probability convenience sampling method. The chi-square test was used for statistical analysis, with the significance level set at P <.05. RESULTS: A total of 394 out of 409 dentists provided valid data. There was no significant difference in demographic data. Questions about the treatment of hard dental tissue injuries in primary teeth presented a correct-response rate of 66.4%, with the highest correct-response rate for enamel fracture (n = 368, 93.4%) and lowest for complicated crown-root fracture with pulp exposure (n = 104, 26.4%). Questions about treatment of luxation injuries in primary teeth presented a correct-response rate of 66.6%, with subluxation presenting the highest correct-response rate (n = 391, 99.2%). Factors associated with higher correct-response rates were specialist disciplines, educational qualifications, workplaces, experience of injured teeth treated, and educational experience about primary tooth trauma. No significant differences were found in the correct-response rates of dentists with different years of work experience. Lack of cooperation from children was considered a major obstacle for treatment. Special lectures and Internet courses were the most preferred methods of obtaining knowledge. CONCLUSION: The results suggest that it is necessary to enhance dental trauma education for dentists in China. More attention needs to be paid to trauma in primary dentition to ensure adequate treatment for traumatized primary teeth.

Worldwide tendency and perspectives in traumatic dental injuries: A bibliometric analysis over two decades (1999-2018).

BACKGROUND/AIMS: Traumatic dental injuries (TDIs) are considered to be a public dental health problem worldwide. The aim of the current study was to provide the worldwide tendency and perspectives in TDIs in the last two decades via bibliometric analysis. METHODS: ''Tooth injuries'' was searched as the Medical Subject Headings term within PubMed with the date range from 1999 to 2018. Two investigators perused information in the articles according to the inclusion and exclusion criteria. The articles were independently categorized according to the following aspects: (a) annual scholarly output; (b) leading countries or regions; (c) leading journals; (d) productive authors; (e) citations; (f) study design; (f) distribution of topics; and (g) the type of dentition and TDIs. VOSviewer 1.6.7 and Citespace 5.2 were used for analyzing and visualizing bibliometric networks. RESULTS: A total of 2627 articles about traumatic dental injuries were published and indexed in PubMed during the two decades, and the number of publications on traumatic dental injuries was rising in general. The research outputs were mainly concentrated in developed countries and affiliated hospitals of universities. Brazil was the most productive country. The journal Dental Traumatology had the most contributions to the scientific research of traumatic dental injuries. "Case report" was the most frequent type of article (36.50%), followed by cross-sectional studies (19.57%) and case-control studies (13.67%). Most studies focused on the treatment of TDIs (38.94%), especially for avulsion (21.01%), crown fracture (9.71%), and intrusion (5.25%). Permanent teeth (66%) were the dominant dentition. CONCLUSION: There is a lack of high-quality well-designed studies such as cohort studies. The number of publications on prevention and the primary dentition is disproportionate in relation to their significance.

Deferoxamine-Induced Migration and Odontoblast Differentiation via ROS-Dependent Autophagy in Dental Pulp Stem Cells.

BACKGROUND/AIMS: As a vital degradation and recycling system, autophagy plays an essential role in regulating the differentiation of stem cells. We previously showed that iron chelator deferoxamine (DFO) could promote the repair ability of dental pulp stem cells (DPSCs). Here, we investigated the effect of DFO in autophagy and the role of autophagy in regulating the migration and odontoblast differentiation of DPSCs. METHODS: Transmission electron microscopy, immunofluorescence staining and western blotting were performed to evaluate the autophagic activity of DPSCs. Transmigration assay, alkaline phosphatase staining/activity, alizarin red S staining and quantitative PCR were performed to examine the migration and odontoblast differentiation of DPSCs. Reactive oxygen species (ROS) levels and the effects of ROS scavenger in autophagy induction were also detected. Autophagy inhibitors (3-MA and bafilomycin A1) and lentiviral vectors carrying ATG5 shRNA sequences were used for autophagy inhibition. RESULTS: Early exposure to DFO promoted the mineralization of DPSCs and increased autophagic activity. Autophagy inhibition suppressed DFO-induced DPSC migration and odontoblast differentiation. Furthermore, DFO treatment could induce autophagy partly through hypoxia-inducible factor 1α/B cell lymphoma 2/adenovirus E1B 19K-interacting protein 3 (HIF-1α/BNIP3) pathway in a ROS-dependent manner. CONCLUSION: DFO increased DPSC migration and differentiation, which might be modulated through ROS-induced autophagy.

[Study of the effect of different methods on the removal of calcium hydroxide in root canal by micro-computed tomography in vivo].

PURPOSE: To establish molar root canal model with micro-computed tomography (Micro-CT) and evaluate the removal efficiency of calcium hydroxide by different methods. METHODS: Eight molar teeth (24 root canals) extracted from the Department of General Dentistry, Shanghai Ninth People's Hospital from October 2023 to February 2024 were collected. Root canal preparation was instrumented by M3 according to standard root canal treatment procedures, then calcium hydroxide was injected into the root canal. One week later, the samples were randomly divided into 3 groups according to different irrigation methods(n=8): lateral opening syringe group, ultrasonic group and sonic vibration group. Micro-CT was used to reconstruct the root canal system before and after irrigation, and independent root canals were marked with different colors. The root canals were divided into upper root segment, middle root segment and apex segment. The volume of calcium hydroxide in each canal was calculated, and the clearance rate of calcium hydroxide was compared among the groups. SPSS 19.0 software package was used for statistical analysis. RESULTS: None of the three methods could completely remove calcium hydroxide from the root canal. When sodium hypochlorite was used as the flushing solution, the removal effect of ultrasonic group and sonic vibration group was significantly better than that of lateral opening syringe group(P＜0.05). The removal efficiency of calcium hydroxide by ultrasonic group and sonic vibration group was similar, and the difference was not statistically significant(P＞0.05). The removal rate of calcium hydroxide in apical segment was low. CONCLUSIONS: Micro-CT can reconstruct the molar root canal model efficiently for evaluating the removal effect of calcium hydroxide. The removal efficiency of calcium hydroxide in ultrasonic group and sonic vibration group is similar, and both are better than that in lateral syringe group.

Gallium Metal-Organic Nanoparticles with Albumin-Stabilized and Loaded Graphene for Enhanced Delivery to HCT116 Cells.

Background: Gallium (III) metal-organic complexes have been shown to have the ability to inhibit tumor growth, but the poor water solubility of many of the complexes precludes further application. The use of materials with high biocompatibility as drug delivery carriers for metal-organic complexes to enhance the bioavailability of the drug is a feasible approach. Methods: Here, we modified the ligands of gallium 8-hydroxyquinolinate complex with good clinical anticancer activity by replacing the 8-hydroxyquinoline ligands with 5-bromo-8-hydroxyquinoline (HBrQ), and the resulting Ga(III) + HBrQ complex had poor water solubility. Two biocompatible materials, bovine serum albumin (BSA) and graphene oxide (GO), were used to synthesize the corresponding Ga(III) + HBrQ complex nanoparticles (NPs) BSA/Ga/HBrQ NPs and GO/Ga/HBrQ NPs in different ways to enhance the drug delivery of the metal complex. Results: Both of BSA/Ga/HBrQ NPs and GO/Ga/HBrQ NPs can maintain stable existence in different solution states. In vitro cytotoxicity test showed that two nanomedicines had excellent anti-proliferation effect on HCT116 cells, which shown higher level of intracellular ROS and apoptosis ratio than that of cisplatin and oxaliplatin. In addition, the superior emissive properties of BSA/Ga/HBrQ NPs and GO/Ga/HBrQ NPs allow their use for in vivo imaging showing highly effective therapy in HCT116 tumor-bearing mouse models. Conclusion: The use of biocompatible materials for the preparation of NPs against poorly biocompatible metal-organic complexes to construct drug delivery systems is a promising strategy that can further improve drug delivery and therapeutic efficacy.

[Effect of recombinant connective tissue growth factor on proliferation and odontogenic differentiation of dental pulp cells].

PURPOSE: To analyze the effect of recombinant connective tissue growth factor(rCTGF) on proliferation and differentiation of human dental pulp cells(hDPCs). METHODS: Human dental pulp cells were cultured in vitro and treated with rCTGF at different concentrations (0, 1, 10, 100 ng/mL). The proliferation of dental pulp cells was detected by CCK8 assay. The formation of mineralized nodules was determined by alizarin red staining and half-quantitative alizarin Red S assay. qRT-PCR was utilized to detect the expression of odontogenic differentiation related genes DMP-1, DSPP and OC, and the phosphorylation level of ERK1/2 signaling pathway was detected by Western blot. The data were analyzed with SAS 9.3 software package. RESULTS: High concentration of rCTGF(100 ng/mL) could promote proliferation of dental pulp cells. After mineralization induction, 10 g/mL rCTGF had the best effect on promoting the formation of mineralized nodules in dental pulp cells, and calcium ion deposition was the most obvious(P<0.05). The expression of odontogenic differentiation related genes DMP-1 and DSPP was significantly up-regulated(P<0.05). Western blot results showed that hDPCs stimulated by 10 ng/mL rCTGF could increase the expression of p-ERK1/2. CONCLUSIONS: rCTGF may promote the proliferation and differentiation of human dental pulp cells through activating ERK1/2 signaling pathway.

[Evaluation of the efficacy of two kinds of NiTi retreatment instruments for removing filling material during root canal retreatment].

PURPOSE: To compare the efficacy of Mtwo R and Reciproc with that of hand files in removing filling material during root canal retreatment. METHODS: The root canals of forty-five human extracted mandibular central incisors were cleaned and shaped to a size 40 and filled with gutta-percha and sealer using a lateral compaction technique. The teeth were divided into 3 groups. The filling material was removed with hand files, Mtwo R and Reciproc, respectively. The debris extruded out of the apical foramen was collected and weighted. The working time was recorded. Then the teeth were split longitudinally, observed under microscope, and evaluated. The data were statistically analyzed with SPSS 13.0 software package. RESULTS: There was no significant difference among 3 groups for debris extrusion (P>0.05). Removal of filling material with Mtwo R and Reciproc consumed less time (P<0.05). CONCLUTIONS: NiTi retreatment instruments can not remove all filling material during root canal retreatment, but can reduce working time.

Effects of deferoxamine on the repair ability of dental pulp cells in vitro.

INTRODUCTION: In previous studies, we found that hypoxia promoted the mineralization of dental pulp cells (DPCs). However, the clinical application of hypoxia as a therapy is questionable or unfeasible. Deferoxamine (DFO), a medication for iron overload, has also been shown to induce hypoxia. The purpose of this study was to investigate the effects of DFO on the repair ability of DPCs. METHODS: DPCs were obtained by using a tissue explant technique in vitro and were treated with different concentrations of DFO or hypoxia culture for 2 days. The viability, proliferation, migration, and odontogenic differentiation of DPCs were assayed and analyzed. The expression of hypoxia-inducible factor 1-alpha (HIF-1α) was assessed through Western blotting. RESULTS: Ten micromolars of DFO enhanced the expression of HIF-1α similarly to hypoxia and did not affect the viability of DPCs for 2 days. Furthermore, the proliferation, migration, and odontogenic differentiation of DPCs were promoted by DFO. CONCLUSIONS: These results suggest that DFO might improve the repair ability of DPCs by HIF-1α.

Hydrogen peroxide induces apoptosis in human dental pulp cells via caspase-9 dependent pathway.

INTRODUCTION: Reactive oxygen species are a group of metabolic intermediates produced during oxidative metabolism in eukaryotic cells. They include superoxide anion (O2(-)), hydrogen peroxide (H2O2), hydroxyl radical (·OH), and (1)O2. Of these intermediates, H2O2 is the most stable. Dental pulp cells can be invaded by tooth bleaching, laser radiation, and dental materials. This can influence the intracellular level of reactive oxygen species. Apoptosis, which is the best-known form of programmed cell death, is pivotal to tissue development and regeneration. Little information is available regarding the relationship between H2O2 and apoptosis of human dental pulp cells (hDPCs). The purpose of this study was to investigate whether H2O2 can induce apoptosis in hDPCs and its signaling way. METHODS: HDPCs were obtained by using a modified tissue explant technique in vitro and cultured at 37°C, 20% O2 (5% CO2, 95% air) in Dulbecco modified Eagle medium. Cell viability was investigated by methyl-thiazol-tetrazolium assay. Cell apoptosis was detected by using the annexin V-fluorescein isothiocyanate/propidium iodide apoptosis assay and flow cytometry. Expression of activated caspase-3, cleaved caspase-9, and ß-actin was analyzed by using Western blot. RESULTS: Cell viability of hDPCs decreased more in treated groups than in the control group from days 1 to 7. The relative number of apoptotic cells and the expression of activated caspase-3 and cleaved caspase-9 were much higher in groups exposed to 20 and 50 µmol/L H2O2. CONCLUSIONS: These results imply that low concentrations of H2O2 are cytotoxic to hDPCs and induce apoptosis in hDPCs in a caspase-9-dependent way.

[Detection of reactive oxygen species of human dental pulp cells by flow cytometry].

PURPOSE: To establish a method for detection of reactive oxygen species(ROS) of human dental pulp cells(HDPCs) by flow cytometry. METHODS: HDPCs were obtained using tissue explant technique in vitro. The subcultured cells were exposed to peroxide oxygen(H2O2) of different concentrations from 50 µmol/L to 400 µmol/L for 30 minutes, then incubated with two different concentrations of 2',7'-dichlorofluorescein diacetate (DCFH-DA), which were 10 µmol/L and 20 µmol/L for 20 minutes at 37 degrees centigrade in dark. The fluorescence intensities of intracellular dichlorofluorescein(DCF) were detected by flow cytometry. Statistical analysis was carried out by SPSS 13.0 software software. RESULTS: The positive rate varied with different concentrations of detectors. The fluorescence intensities remained insignificant difference among samples incubated with the same concentration of detector and H(2)O(2),and increased by rising of the incubating concentration of H(2)O(2). CONCLUSIONS: The detector with concentration of 20 µmol/L shows higher detector loading rate(positive rate). The intracellular ROS level changes as the H(2)O(2) treatment concentration rising from 50 to 400 µmol/L. The application of flow cytometry to measure the ROS in HDPCs is simple, reliable and stable.