Introduction: The endodontic treatment of root canals with large apical sizes is considered one of the most complex challenges for clinicians. This case series evaluated the clinical outcome of single-cone (SC)obturation technique with iRoot SP in root canals with large apical sizes in chronic apical periodontitis(CAP). Case description: The teeth with large apical sizes and CAP were treated. After access preparation and establishing apical patency, root canal preparation and disinfection were performed. IRoot SP(Innovative Bioceramix Inc., Vancouver, Canada)assisted gutta percha tip filling root canal. Radiography was performed to check the root canal obturation. The access cavity was sealed with GIC or composite resin. The treated teeth were followed up for at least two years. Discussion: Clinical evaluation during the follow-up period revealed the significant healing of periapical lesions. After 2 years, teeth were asymptomatic and tested negatively in all clinical tests. Radiographs showed no further progression of resorption and healing of the periapical tissues. Conclusion/clinical significance: Cases in this report show the effectiveness of SC with iRoot SP for treating large apical sizes in permanent teeth with chronic apical periodontitis.

Circular RNAs (circRNAs) are a large class of widely expressed RNAs with covalently closed continuous structures. However, it is currently unknown if circRNAs shows allele-specific expression, as are the consequences of genetic variation on their circularization efficiency and subsequent biological function. Here, we propose a novel pipeline, ASE-circRNA, to accurately quantify both circRNA and their related linear RNA for each allele, and then assess the allele-specificity of the expression of a circular RNA. We identified and analyzed allele-specific circRNAs from human tissue, as well as brains from reciprocal crosses between pairs of highly divergent strains of both mice and pigs by next generation sequencing. Droplet digital PCR (ddPCR) was used to confirm the circularization efficiency measured by next generation sequencing. We found that variation in intron sequences affect the circularization efficiency of circRNAs. Furthermore, we demonstrate that a circRNA, circHK1, regulates the expression of POLR2A to influence the rate of cell proliferation. Our study provides new insight into the molecular mechanisms impacted by variation in genome sequence in the origin of human disease and phenotype.

OBJECTIVES:The objective of this study was to assess the impact of immediate and delayed post- space preparation on the push-out bond strength (PBS) of fiber posts by employing two root canal obturation techniques: continuous wave of condensation (CWC) and single-cone (SC) obturation. MATERIALS AND METHODS:Forty-eight human maxillary premolar teeth were instrumented, and the samples were divided into four groups according to the obturation technique and the time of post-space preparation. SC and CWC underwent immediate post-space preparation; and CWC and SC underwent delayed post-space preparation. The smear layer and dentine tubules from the apical, middle, and cervical regions of the samples were observed via scanning electron microscopy (SEM) and the %VoidsVol of the medium 4-mm fiber posts of each group was calculated via micro-computed tomography (CT). Each post space of the root was subsequently cut into slices, resulting in three 1-mm slices at 3 different depths (apical to the cervical region) and subjected to a push-out test. The failure mode was assessed. The data were analysed via the Shapiro-Wilk test, one-way analysis of variance and Bonferroni correction tests. RESULTS:In terms of depth from the apical to the cervical region, SC following immediate post-space preparation exhibited greater bond strength than did CWC following delayed post-space preparation. SEM images revealed that the smear layer was completely visible. In the SC with immediate post-space preparation group, the smear layer could be partially removed from the apical, middle and cervical regions of the samples and the outlines of the dentine tubules were visible. The percentage volume of the voids of the medium 4-mm fiber posts of the four groups and the samples in the three directions were not significantly different. No significant differences were observed in the CWC or SC obturation technique regardless of the time of post-space preparation or in immediate or delayed post-space preparation with different obturation techniques. CONCLUSIONS:SC followed by immediate post-space preparation provided better bond strength of fiber posts to intraradicular dentine than did CWC followed by delayed post-space preparation.

PURPOSEThe underlying mechanism of how topographic cues of artificial scaffolds regulate cell function remains poorly understood. Yes-associated protein (YAP) and β-catenin signaling have both been reported to play important roles in mechano-transduction and dental pulp stem cells (DPSCs) differentiation. We investigated the effects of YAP and β-catenin in spontaneous odontogenic differentiation of DPSCs induced by topographic cues of a poly(lactic-co-glycolic acid) (PLGA) membrane.METHODSThe topographic cues and function of a fabricated PLGA scaffold were explored via scanning electron microscopy (SEM), alizarin red staining (ARS), reverse transcription-polymerase chain reaction (RT-PCR), and pulp capping. Immunohistochemistry (IF), RT-PCR, and western blotting (WB) were used to observe the activation of YAP and β-catenin when DPSCs were cultured on the scaffolds. Further, YAP was inhibited or overexpressed on either side of the PLGA membrane, and YAP, β-catenin, and odontogenic marker expression were analyzed using IF, ARS, and WB.RESULTSThe closed side of the PLGA scaffold promoted spontaneous odontogenic differentiation and nuclear translocation of YAP and β-catenin in vitro and in vivo compared to the open side. The YAP antagonist verteporfin inhibited β-catenin expression, nuclear translocation, and odontogenic differentiation on the closed side, but the effects were rescued by LiCl. YAP overexpressing DPSCs on the open side activated β-catenin signaling and promoted odontogenic differentiation.CONCLUSIONThe topographic cue of our PLGA scaffold promotes odontogenic differentiation of DPSCs and pulp tissue through the YAP/β-catenin signaling axis.

AbstractBackgrounds: Sodium hypochlorite (NaOCl) has been the most widely used chemical auxiliary substance in endodontics owing to its effective antimicrobial action and excellent tissue-dissolving properties. To date, the ideal concentration of NaOCl has not been established, since potential complications are still controversial. NaOCl is routinely used in endodontics, the aim of the present study is to answer the following question: Does the concentration of NaOCl have effects on postoperative pain in endodontic treatment of permanent teeth? Methods Electronic databases, including PubMed, EMBASE, Web of Science and Cochrane Library, were searched for randomized controlled trials published from their start dates to March 2021 using strict inclusion and exclusion criteria, and reviewed following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Only randomized controlled trials that compared the effects of NaOCl with different concentrations on endodontic postoperative pain during chemomechanical preparation of permanent teeth with endodontic infection were included. Two reviewers respectively assessed the eligibility for inclusion, extracted data and assessed the quality using the risk of bias tool. Results From 1638 studies that resulted from the initial search, 22 articles were included for full-text appraisal; five articles met the inclusion criteria for quantitative synthesis. A single meta-analysis was performed to compare the effects of NaOCl with different concentrations on endodontic postoperative pain in endodontic treatment of permanent teeth. The forest plot of endodontic postoperative pain indicated that there was no difference in incidence of endodontic postoperative pain between low concentration and high concentration of NaOCl (odd ratio [OR]: 0.60; 95% confidence interval [CI], 0.20–1.74; P = 0.34). Conclusions This review has been the first analysis to compare the incidence of endodontic postoperative pain after irrigation of NaOCl between low concentration group and high concentration group of permanent teeth so far. Based on the present limited evidence, the study suggested that there was no difference in incidence of endodontic postoperative pain between low concentration and high concentration of NaOCl in permanent teeth with endodontic infection. Trial registration: PROSPERO (CRD42021241829).

Background During the obturation procedure, sealer extrusion occurs in some cases. iRoot SP is a kind of bioceramic sealer with superior physicochemical and biological properties. This article reports the outcome of iRoot SP extrusion in root canal treatment and the potential factors associated with the outcome. Methods Ninety-nine patients and one hundred and eighty-five teeth treated between 2014 and 2020 were included in this retrospective study. All of the cases were filled with a single-cone technique and the iRoot SP sealer. The minimum follow-up visit period was 1 year. The outcome was evaluated by clinical examination and radiographic examination at recall and was classified as healed, healing (success), or not healed (failure). Results The overall success rate of all teeth was 96.8%. The success rate of adequately filled teeth was 97.3%, while that of iRoot SP extrusion was 95.8%; the difference was not statistically significant. Factors such as gender, age, tooth position, follow-up visit period, size of periapical lesion, treatment type and extruding sealer amount had no influence on the outcome of iRoot SP extruded teeth. Conclusions The results suggested that iRoot SP extrusion has no adverse effect on the outcome of root canal treatment, which may contribute to the endodontic treatment.

FUN14 domain-containing 1 (FUNDC1) is a receptor that has been previously reported to activate hypoxia-induced mitophagy. However, the potential role of FUNDC1 in the pathophysiology of dental pulp diseases remains unknown. Therefore, present study first collected tissue specimens from patients with pulpitis and from healthy individuals. The results of reverse transcription-quantitative PCR and immunohistochemical staining revealed markedly increased FUNDC1 and hypoxia-inducible factor-1 alpha expression in pulpitis tissue specimens compared with those from healthy individuals. To provide a theoretical basis for the study of the occurrence, development and reparative mechanisms in the dental pulp after tissue injury, the present study then investigated the role of hypoxia-induced mitophagy in the regulation of proliferation, migration and odontoblastic differentiation in human dental pulp cells (HDPCs), in addition, to the possible involvement of FUNDC1. The surface markers and multipotent differentiation capabilities of HDPCs were performed by flow cytometry (surface markers), alizarin red (osteogenic capabilities), alcian blue (chondrogenic capabilities) and oil red O (adipogenic capabilities). Following culture under hypoxia conditions (1% O-2) for varying time periods, the proliferation, migration and odontoblastic differentiation of HDPCs were measured using Cell Counting Kit-8, wound healing and Transwell migration assays, alkaline phosphatase staining and activity tests and western blotting (runt-related transcription factor 2, collagen I, osterix and osteopontin), respectively. Immunofluorescence and western blotting were performed to measure the expression levels of hypoxia-inducible factor-1 alpha, pro-fission dynamin-related protein 1, mitochondria-related proteins translocase of inner mitochondrial membrane 23 and translocase of outer mitochondrial membrane 20, in addition to those of autophagy markers (p62, LC3II, Beclin-1 and autophagy-related 5). Transmission electron microscopy was also used to image the autophagosomes and mitochondrial morphology. In addition, to study the functional role of FUNDC1, its expression was silenced by liposome-mediated transfection with small interfering RNA into HDPCs. Compared with those in HDPCs cultured under normoxic conditions (21% O-2), the ability of autophagy in HDPCs cultured under hypoxic conditions for 18 h was markedly increased, whilst the proliferation, migration and odontoblastic differentiation were also enhanced. Increased numbers of autophagosomes could also be observed in the hypoxic group. However, FUNDC1 knockdown in HDPCs reversed the aforementioned effects. Overall, data from the present study suggest that hypoxia can promote the proliferation, migration and odontoblastic differentiation of HDPCs, where the underlying mechanism may be associated with the activation of mitophagy downstream of FUNDC1.

Abstract BackgroundAs promising seed cells of periodontal tissue regeneration, dental follicle cells (DFCs) can differentiate into cementoblasts, osteoblasts and fibroblasts upon the regulation of signaling pathways. Emerging evidence shows that circular RNA (circRNA) may participate in tooth regeneration, however its effect on DFCs remains unclear. Our early research found that the expression of circFgfr2 was significantly up-regulated when the rat DFCs were incubated by mineral induction medium for 4 weeks, while the expression of miR-133 was down-regulated. It has been widely reported that circRNA may exert as a miRNA sponge to target genes. Therefore, the function of circFgfr2 in osteogenesis of rDFCs was further identified in this study.MethodsCircFgfr2 was identified by Sanger sequencing and agarose gel electrophoresis. The intracellular location of circFgfr2 in rDFCs was analyzed by fluorescence hybridization (FISH). Furthermore, we constructed circFgfr2 overexpressed rDFCs via pLC5-ciR plasmid. RNA high-throughput sequencing was carried out to investigate the differently expressed messenger RNA (mRNAs) between circFgfr2 overexpressed (OE) groups and control groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to further explore the role of circFgfr2 in rDFCs. Moreover, the binding sites of miR-133a-3p and miR-133a-5p with circFgfr2 were predicted by bioinformatics and detected by dual-luciferase reporter (DLR) assay and Chromatin Isolation by RNA Purification (ChIRP). Bioinformatics analysis and the luciferase reporter assay were also performed to investigate the interaction between miR-133a-3p, miR-133a-5p and Distal-Less Homeobox 3 (DLX3). We also constructed miR-133a-3p overexpressed rDFCs via miR-133a-3p mimics. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to examine their expression of circFgfr2, miR-133a-3p, miR-133a-5p and bone-related genes including bone morphogenetic protein2 (BMP2), BMP6, Runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), Osterix (OSX) and distal-less homeobox DLX3. Alkaline phosphatase (ALP) activity detection and staining along with Alizarin red staining and were performed to evaluate the mineralization ability of rDFCs. Western blot were performed to analyse RUNX2 protein expression.ResultsCircFgfr2 primarily had a cytoplasmic location. The mRNA sequencing results illustrated that 361 and 391 mRNAs were upregulated and downregulated respectively. GO and KEGG analysis indicated several pathways and processes which are important for osteogenic differentiation. Furthermore, circFgfr2 acted as a molecular sponge for miR-133a-3p which inhibited DLX3 expression. Overexpression of circFgfr2 increased expression levels of markers of osteogenesis including RUNX2, OCN, OSX, BMP2, BMP6 and DLX3 and decreased the expression of miR-133a-3p and miR-133a-5p. In addition, miR-133a-3p was shown to decrease mineralization in rDFCs. Moreover, circFgfr2 protected DLX3 and Runx2 from miR-133a-3p mediated suppression. ConclusionWe demonstrated that circFgfr2 promoted the osteogenic differentiation of rDFCs via circFgfr2 / miR-133a-3p / DLX3 / RUNX2 axis. CircFgfr2 has the potential to be the molecular target for the bone tissue engineering.

Dental pulp stem cells (DPSCs) and their exosomes (Exos) are effective treatments for regenerative medicine. Hypoxia was confirmed to improve the angiogenic potential of stem cells. However, the angiogenic effect and mechanism of hypoxia-preconditioned DPSC-Exos are poorly understood. We isolated exosomes from DPSCs under normoxia (Nor-Exos) and hypoxia (Hypo-Exos) and added them to human umbilical vein endothelial cells (HUVECs). HUVEC proliferation, migration and angiogenic capacity were assessed by CCK-8, transwell, tube formation assays, qRT-PCR and Western blot. iTRAQ-based proteomics and bioinformatic analysis were performed to investigate proteome profile differences between Nor-Exos and Hypo-Exos. Western blot, immunofluorescence and immunohistochemistry were used to detect the expression of lysyl oxidase-like 2 (LOXL2) in vitro and in vivo. Finally, we silenced LOXL2 in HUVECs and rescued tube formation with Hypo-Exos. Hypo-Exos enhanced HUVEC proliferation, migration and tube formation in vitro superior to Nor-Exos. The proteomics analysis identified 79 proteins with significantly different expression in Hypo-Exos, among which LOXL2 was verified as being upregulated in hypoxia-preconditioned DPSCs, Hypo-Exos, and inflamed dental pulp. Hypo-Exos partially rescued the inhibitory influence of LOXL2 silence on HUVEC tube formation. In conclusion, hypoxia enhanced the angiogenic potential of DPSCs-Exos and partially altered their proteome profile. LOXL2 is likely involved in Hypo-Exos mediated angiogenesis.

目的 通过回顾性分析,研究iRoot SP辅助单尖充填法及多种预后因素对根管治疗临床效果的影响.方法 从2014—2018年于中山大学附属口腔医院接受根管治疗且能追踪复查的患者中,选择使用iRoot SP辅助单尖充填后且复诊时间为1年以上患者的110颗患牙纳入分析.根据每颗患牙复诊时临床和影像学检查结果,将患牙的预后分为成功和失败两组.使用连续性修正卡方检验和Fisher精确检验,对术前是否存在根尖阴影、术前根尖阴影的直径大小和有无封闭剂超充等8项可能影响iRoot SP单尖充填临床效果的预后因素进行统计分析.结果 110颗接受iRoot SP单尖充填治疗的患牙总体成功率为95.5％.其中,83颗术前有根尖阴影患牙的治疗成功率为96.4％,68.7％为已愈合;27颗术前无根尖阴影患牙的治疗成功率为92.6％.术前有根尖阴影和无根尖阴影患牙的治疗成功率差异无统计学意义(χ2=0.084,P=0.772).术前根尖阴影直径小于或等于5 mm的患牙共53颗,治疗成功率为98.1％;而阴影直径大于5 mm的患牙共30颗,治疗成功率为93.3％.两组患牙治疗成功率的差异无统计学意义(χ2=0.259,P=0.611).44颗封闭剂超充患牙的治疗成功率为97.7％,患牙有无iRoot SP超充的治疗成功率差异也无统计学意义(χ2=0.218,P=0.640).结论 iRoot SP单尖充填法是可行的根管充填技术.

Excessive numbers of osteoclasts are responsible for inflammation-induced osteolysis. Identification of osteoclast-targeting agents may facilitate the development of a novel therapeutic approach for the treatment of pathological bone loss. Seven-amino acid truncated (7ND) protein, a mutant form of monocyte chemoattractant protein-1 (MCP-1), functions as a competitive inhibitor of MCP-1. However, the effects of 7ND protein on osteoclast differentiation remain unknown. Therefore, in the present study, the effects of 7ND protein on osteoclast differentiation induced by tumour necrosis factor superfamily member 11 were investigated. In the present study, 7ND protein inhibited the osteoclast differentiation of peripheral blood mononuclear cells without influencing cell proliferation. Furthermore, to evaluate the effects of 7ND protein in vivo, a lipopolysaccharide (LPS)-induced calvarial bone erosion animal model was established. The 7ND protein remarkably attenuated LPS-induced bone resorption, as assessed by micro-computed tomography and histological analysis. Taken together, the present results suggested the feasibility of local delivery of 7ND protein to mitigate osteoclast differentiation and LPS-induced osteolysis, which may represent a potential approach to treat inflammatory bone destruction.

牙髓治疗,特别是牙髓再生治疗后出现牙齿内源性着色是临床治疗经常遇到的问题.牙髓治疗过程中出现在髓室内的血液,残留于髓室的根管消毒药物、根管充填用封闭剂及冲洗剂等均可能导致牙齿内源性着色.本文对牙髓治疗后硅酸盐水门汀、抗生素、次氯酸钠、乙二胺四乙酸和氢氧化钙等材料引起牙齿内源性着色的具体机制、预防方法和内源性着色后处理的研究现状作一综述.

The alterations in expression and function of circular RNA (circRNA) in human dental pulp cells (hDPCs) during odontogenic differentiation were investigated. To induce odontogenic differentiation, hDPCs (passage 3) were cultured for 14 days in odontogenic induction medium. circRNA high-throughput sequencing was performed using Illumina HiSeqseq (TM) 2000. Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were used to evaluate the bio-functions of the identified circRNAs. To validate the results of circRNA sequencing, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed for two selected differentially expressed circRNAs. The RNA sequencing results revealed that 1,314 and 1,780 circRNAs were upregulated and downregulated, respectively, during odontogenic induction. Their predicted target miRNAs and genes are involved in several biological functions and signaling pathways, including the mitogen-associated protein kinase signaling pathway. The RT-qPCR results of the two selected circRNAs (hsa_circ_0015260 and hsa_circ_0006984) were consistent with the expression trend obtained using high-throughput sequencing. The results of the present study add to the current understanding of the regulatory mechanisms underlying hDPCs differentiation.

Circular RNAs (circRNAs) are novel noncoding RNAs and play crucial roles in various biological processes. However, little is known about the functions of circRNAs in osteogenic differentiation. The current study aimed to investigate the differential expression of circRNAs in rat dental follicle cells (rDFCs) during osteogenic differentiation, identified by RNA high‐throughput sequencing and quantitative real‐time polymerase chain reaction. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to further explore the biofunctions of circRNA biofunctions. Two hundred sixty‐six differentially‐expressed circRNAs that are involved in several important signaling pathways, including mitogen‐activated protein kinases (MAPK) and transforming growth factor‐β (TGF‐β) signaling pathways were revealed. Among these, circFgfr2 and its predicted downstream targets, miR‐133 and BMP6 (bone morphogenetic protein‐6), were identified both in vivo and in vitro. For further validation, circFgfr2 was overexpressed in rDFCs, the results showed that the expression of miR‐133 was downregulated and the expression of BMP6 was upregulated. Taken together, the results revealed the circRNA expression profiles and indicated the importance of circRNAs of rDFCs. In addition, circFgfr2 might promote osteogenesis by controlling miR‐133/BMP6, which is a potential new target for the manipulation of tooth regeneration and bone formation.

The effect of root canal therapy is closely related to the root canal sealers, and extrusion of sealers occurs to part of cases. iRoot SP, which is a kind of bioceramic root canal sealers, attracts clinical operators′ attentions due to its superior biocompatibility, sealing and antibacterial properties. At the meantime, clinicians come to a question of whether over-obturated iRoot SP affects the tooth prognosis. This article summarized the features of iRoot SP, the research progress of sealer extrusion and several follow-up case reports, in order to analyze the prognosis of iRoot SP over-obturation. Key words: Root canal filling materials; Root canal obturation; Prognosis; iRoot SP

Objectives The aim of this study was to investigate the accuracy of minimally invasive endodontic cavity preparation with the guidance of cone-beam computed tomography (CBCT) and three-dimensional printed templates through analyzing distance deviation and angle deviation. Methods Forty extracted human single-rooted maxillary first premolars with double root canals were selected. Preoperative CBCT scanning of all specimens was used for designing access cavities. All teeth were numbered and assigned into two groups according to the random number table. There were twenty teeth including forty root canals in each group. The minimally invasive endodontic cavity was designed as Truss access cavity. Preparation for access cavities in group A was guided by three-dimensional printed templates which were fabricated according to the CBCT images. Access cavities in group B were prepared according to the marks on occlusal surface after the analysis of CBCT images. Distance deviations and angle deviations in buccopalatal and mesiodistal directions as well as the areas of access cavities at occlusal and pulp horn levels were measured and calculated in the CBCT images. Statistical analysis for the data was performed by SPSS 20.0. Results The data were analyzed with Mann-Whitney U test, since they were not satisfied with the normal distribution and the homogeneity of variance. No statistic difference was observed between the two groups in the areas of access cavities at occlusal level [group A: (1.34 ± 0.18) mm2, group B: (1.30 ± 0.15) mm2; U=0.876, P=0.393] or at pulp horn level [group A: (1.74 ± 0.20) mm2, group B: (1.67 ± 0.24) mm2; U=1.290, P=0.194]. The mesiodistal distance deviations at occlusal level in group B [ (0.37 ± 0.26) mm] were less than that in group A [ (0.52 ± 0.30) mm], which had significant difference (U=2.237, P=0.024) . There was no significant difference between the two groups in the buccopalatal distance deviations of occlusal level [group A: (0.45 ± 0.40) mm, group B: (0.41 ± 0.28) mm; U=0.385, P=0.697], the buccopalatal distance deviations of pulp horn level [group A: (0.32 ± 0.25) mm, group B: (0.41 ± 0.30) mm; U=1.290, P=0.199], the mesiodistal distance deviations of pulp horn level [group A: (0.38 ± 0.24) mm, group B: (0.35 ± 0.26) mm; U=0.905, P=0.500], as well as the buccopalatal angle deviations [group A: (4.76 ± 3.04) °, group B: (4.72 ± 3.61) °; U=0.404, P=0.679] or the mesiodistal angle deviations [group A: (3.04 ± 1.97) °, group B: (3.05 ± 2.45) °; U=0.467, P=0.637]. Conclusions CBCT scanning was able to accurately guide the preparation of the minimally invasive endodontic cavities for the teeth with normal root canal anatomy. The guidance of CBCT scanning with templates did not significantly enhance the accuracy of access cavities, compared to that of CBCT scanning alone. Moreover, no significant difference was detected in the actual sizes of Truss access cavities prepared with the guidance of the two approaches. Key words: Endodontics, minimally invasive; Dental cavity preparation; Cone-beam computed tomography; Printing, three-dimensional; Deviation

Dental caries, pulpitis and periapical diseases are the most common diseases in the Endodontics. Correspondingly, the effective treatment is to remove the structure of caries or infections in time and to fill or restore them with aseptic methods strictly. On the basis of stopping the development of the disease, the healthy tooth tissues will be preserved as much as possible to improve the long-term preservation rate of the affected teeth. With the innovation of modern diagnostic and therapeutic equipments, the application of new materials and the study of basic research on vital pulp therapy, together with the application of this minimally invasive theory in the field of vital pulp therapy have been further realized. This article reviews the minimally invasive theory in the vital pulp therapy by briefly introducing these three parts: the diagnosis of dental pulp under the guidance of the new concepts and methods, the treatment strategies for the vital pulp, the evaluation and prognosis of vital pulp therapy. Key words: Dental carries; Dental pulp; Periodontal diseases; Minimally invasive treatment; Vital pulp therapy; Preservation of tooth structure

Objective The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the sealing ability of two root canal obturation techniques by using micro-computed tomography imaging and a push-out test. Methods The root canals of 40 human maxillary premolar teeth were instrumented and divided into four groups: (A) single cone (SC) followed by immediate post space preparation, (B) continuous wave of condensation (CWC) followed by immediate post space preparation, (C) SC followed by delayed post space preparation, and (D) CWC followed by delayed post space preparation. Micro-CT scans were performed for volumetric analysis of voids and filling materials in the apical 4-mm portion. A push-out test was performed, and failure modes (adhesive, cohesive, or mixed) were assessed. Data were analyzed using the Kruskal-Wallis test and one-way analysis of variance. Results No significant differences were observed among the four groups in terms of the percentage volume of voids of the apical 4mm or the bond strength of apical gutta-percha. Conclusions The percentage volume of voids and bond strength of apical gutta-percha were similar and were not significantly influenced by the timing of post space preparation or the obturation technique.

AIM:To investigate the role of Lipopolysaccharide (LPS) in the odontoclast differentiation of MDPC-23 cells. It was hypothesized that MDPC-23 odontoblast-like cells may function as odontoclasts under the influence of LPS. METHODOLOGY:MDPC-23 cells were cultured in the presence of 0.1 or 1 μg mL-1 LPS for 6 days. Cell viability was determined using the CCK8 assay. TRAP staining, dentine resorption assay and ROS detection by confocal laser scanning microscope were used to test the odontoclast-like function of the induced cells. In additional, the related protein expression was confirmed by Western blotting and ELISA. An unpaired Student's t-test and one-way anova were used in statistical analysis. RESULTS:TRAP-positive cells, which are multinucleated, on the dentine slice were significantly increased in 1 μg mL-1 LPS-induced cells (P < 0.05). Osteoclast-specific proteins such as TRAP cathepsin K and Rac1 were upregulated in the 1 μg mL-1 LPS-treated cells (P < 0.05), whilst the expression of marker proteins of the RANKL-RANK signalling pathway (RANKL, RANK and TRAF6) in the induced cells was not significantly changed (P > 0.05). ROS production was observed in the 1 μg mL-1 LPS treatment group (P < 0.05), but no significant differences were observed in the level of RANKL in the cell supernatant between the LPS-treated group and the control group (P > 0.05). CONCLUSIONS:A known value of 1 μg mL-1 LPS might induce odontoblast-like MDPC-23 cells to generate odontoclast-like cells or to function as odontoclasts. The data might provide a new explanation for the precursors of odontoclasts and root resorption.

Objective To investigate the effect of dental pulp cell derived exosomes(DPC-Exos) on human umbilical vein endothelial cells(HUVECs)migration in vitro. Methods Exosomes were isolated from the supernatant of DPCs cell culture by ultracentrifugation and characterized by transmission electron microscope(TEM),western blotting.The effect of DPC-Exos on HUVECs migration was examined by wounding healing assay and transwell assay in vitro. Two independent samples t test was used to statistically analyze the migration rate and number of migration cells by SPSS 20.0 software.Results The bi-layer membrane and "saucer-like" appearance of DPC-Exos were examined by transmission electron microscopy(TEM).Western blotting revealed that CD63 was expressed in the DPC-Exos.Wound-healing assay showed significantly reduced migration ability by 26% in HUVECs after treated with DPC-Exos(t=6.534,P<0.001).Transwell assay results indicated that DPC-Exos treatment could significantly reduced migration ability of HUVECs by 32%(t=5.846,P<0.001).Conclusion DPC-Exos could significantly suppress the migration of HUVECs.