Research progress in the pathogenesis mechanism of dental fluorosis / 中华口腔医学杂志

Dental fluorosis is a developmental disturbance of dental enamel caused by excessive fluoride intake during tooth development, leading to the changes in morphology, structure and function of tooth enamel, which can affect the aesthetics and function of teeth. There are many factors which may account for the occurrence of dental fluorosis. However, the pathogenesis mechanism underlying dental fluorosis has not been fully clarified.In recent years, researches in the fields of fluoride-induced stress response pathways, signaling pathways and apoptosis at the molecular and genetic level had provided extensive knowledge of dental fluorosis. This article focuses on the latest research progress in the mechanism of dental fluorosis, which include the effects of fluoride on ameloblasts and enamel matrix proteins, genetic polymorphism and dietary nutrients, in order to provide new references for the targeted prevention and treatment of dental fluorosis.

Applications of digital medical techniques for dental dysplasia / 中华口腔医学杂志

Dental dysplasia are abnormalities in teeth structure, morphology, number and eruption caused by genetic and environmental factors during dental development. Digital medical techniques, as the current hot spot of medical research, bring great challenges and opportunities to modern stomatology. The applications of digital techniques, such as digital diagnosis method, digital virtual simulated design, three-dimensional printing, static and dynamic guidance and artificial intelligence, can provide a more accurate, efficient, automatic and intelligent modern concepts and patterns for epidemiology, diagnosis, multidisciplinary treatment and outcome assessment of dental developmental anomalies.

Application and prospect of static/dynamic guided endodontics for managing pulpal and periapical diseases / 中华口腔医学杂志

Root canal therapy and endodontic surgery are conventional treatments for pulpal and periapical diseases. Compared with naked-eye operations, the application of dental operating microscope has enhanced the procedural accuracy and prognosis efficiently. However, root canals with pulp calcification/obliteration, apical lesions with thick cortical bone or adjacent to important anatomic structures are even challenging for experienced operators to achieve predictable clinical outcomes. Recently, with the advances in the field of digitalized information sciences, the above mentioned complicated endodontic cases can be solved under static and dynamic guidance. Before the treatment begins, virtual path is designed from data collected by cone-beam CT and oral image scanning using guidance software. Afterwards, root canal therapy and endodontic surgery can be performed precisely under the assistance of three-dimensional printed guide or dynamic guidance system. The present review describes the classification, features and clinical applications of the guided endodontics.

Effect of Repetitive Transcranial Magnetic Stimulation Combined with Conventional Rehabilitation on Upper Extremity Function for A Patient with Complex Regional Pain Syndrome I after Distal Radius Fracture / 中国康复理论与实践

Objective:To summarize the development of a patient with complex regional pain syndrome (CRPS) after distal radius fracture and the effect of repetitive transcranial magnetic stimulation (rTMS) combined with conventional rehabilitation on it. Methods:One patient with CRPS after left distal radius fracture was treated with rTMS combined with conventional rehabilitation for three weeks. The pain degree was evaluated with Visual Analogue Score (VAS), the edema was assessed with volume of hand and circumference of finger, and motion of joint was measured with passive range of motion. The activities of daily living was assessed with modified Barthel Index (MBS). Results:Before treatment, the VAS score was 8, the volume of left hand was 330 ml, the temperature of skin was 36.8 ℃. The activity of flexion and extension of left elbow joint, pronation and supination of left forearm, the flexion, extension, ulnar deviation and temporal deviation of left wrist, and metacarpophalangeal joints (MCP), proximal interphalangeal joint (PIP) and distal interphalangeal joint (DIP) of left hand were all limited. The circumference of left finger was larger than right finger, and the score of MBI was 85. After three weeks of treatment, the VAS score was 2, the volume of the left hand was 310 ml, the temperature of the skin was 33.8 ℃. The activities of left elbow joint, left wrist joint and left MCP, PIP, and DIP were better than before. The score of MBI was 100. Conclusion:rTMS combined with conventional rehabilitation is effective on CRPS after distal radius fracture, in the range of motion and edema of upper extremity, and activities of daily living.

Expression of wingless-type MMTV integration site family member 3 in rat dental follicle tissues and cells undergoing osteogenic differentiation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of wingless-type MMTV integration site family, member 3 (Wnt3) in rat dental follicles and its protein level in dental follicle cells (DFC) undergoing osteogenic induction and to discuss the effects of Wnt3 on the differentiation of DFC.</p><p><b>METHODS</b>Rats at postnatal days 1, 3, 5, 7, 9, 11 and 13 were executed, then the mandibles were immediately removed and immunohistochemistry was performed to detect the expression of Wnt3 in dental follicles of postnatal rats. The expression and distribution of Wnt3 in DFC were determined by immunofluorescence. Alizarin red-S staining was performed to assess the mineralization of DFC. Western blotting was used to evaluate Wnt3 and β-catenin protein levels after stimulated by osteogenic medium for 1, 2 and 3 weeks, respectively.</p><p><b>RESULTS</b>Immunohistochemistry revealed that the expression of Wnt3 in rat dental follicles began at day 5 and sustained to day 13. On day 1 and 3, the expression of Wnt3 in dental follicles was negative.Wnt3 was expressed in the cytoplasm of DFC. Alizarin red-S staining indicated that the osteogenic medium stimulated the differentiation of DFC into osteoblastic lineage.Western blotting demonstrated that the Wnt3 protein levels were significantly up-regulated after stimulated with osteogenic medium for 1 weeks compared with the control (2.60 ± 0.04 vs.1.00 ± 0.00, P < 0.05). Then the levels of Wnt3 protein were declined, and at the 3rd week, no significant difference was observed between osteo-induced group and the control (1.00 ± 0.05 vs.1.00 ± 0.00, P > 0.05). The levels of β-catenin were increased in osteo-induced groups compared with the control (1.95 ± 0.05 vs.1.00 ± 0.00, P < 0.05; 9.77 ± 0.65 vs.1.00 ± 0.00, P < 0.05;1.75 ± 0.21 vs.1.00 ± 0.00, P < 0.05). Furthermore, the expression of β-catenin reached to a peak on the 2nd week (9.77 ± 0.65), and then declined.</p><p><b>CONCLUSIONS</b>Wnt3 was expressed in the rat dental follicles both in vivo and in vitro and up-regulated during early phase of osteoblast differentiation in DFC.Wnt3 may be involved in early phase of osteoblast differentiation.</p>

Effects of immA and immB coding putative bacteriocin immunity proteins on the antimicrobial sensitivity in planktonic Streptococcus mutans and biofilm formation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of putative bacteriocin immunity proteins on the growth mode of Streptococcus mutans (Sm). To observe the differences of antimicrobial sensitivity in planktonic Sm wild-type strains and mutant strains caused by the inactivation of bacteriocin immunity proteins and their influence on the biofilm formation.</p><p><b>METHODS</b>Sm wild-type strains (WT) and its knockout mutants defective in immA and immB (ΔimmA(-) and ΔimmB(-) mutants) coding putative bacteriocin immunity proteins were cultured in brain heart infusion (BHI) and selected by erythromycin at the concentration of 10 mg/L. Optical density was detected by spectrophotometer every hour and growth curve was drawn. WT, ΔimmA(-) and ΔimmB(-) mutants were treated with ampicillin (0.04, 0.05, 0.06, 0.07, 0.08 mg/L), sodium fluoride (50, 100, 150, 200, 250 mg/L) and sodium hypochlorite (0.078%, 0.156%, 0.313%, 0.625%, 1.250%) for 24 hours. Optical density was detected by multifunctional micro plate reader. WT and the mutants were cultured in MBEC(TM) P&G Assay for 24 hours. The minimum biofilm eradication concentration (MBEC) of chlorhexidine against Sm was determined by serial dilution method. Confocal laser scanning microscopy (CLSM) was used to visualize the biofilm architecture, depth and ratio of live to dead bacteria.</p><p><b>RESULTS</b>Growth curve showed that it took about 3 hours to reach exponential phase and about 7 hours to stationary phase for WT, while 4 hours to exponential phase and 8 hours to stationary phase for mutants. Optical density of mutants were lower than WT in the presence of various antimicrobial agents (P < 0.01). In 0.06 mg/L ampicillin group, optical density value of WT, ΔimmA(-) and ΔimmB(-) mutants were 0.334 ± 0.016, 0.027 ± 0.016 and 0.047 ± 0.018. In 150 mg/L sodium fluoride group, optical density value of WT and mutants were 0.254 ± 0.018, 0.129 ± 0.011 and 0.167 ± 0.010. In 0.313% sodium hypochlorite group, optical density value of WT and mutants were 0.467 ± 0.008, 0.017 ± 0.006 and 0.050 ± 0.006. The MBEC of chlorhexidine against Sm WT, ΔimmA(-) and ΔimmB(-) mutants were 6.25, 1.57, and 3.13 mg/L. The results by CLSM showed a noticeable difference in biofilm architecture. The depth of WT biofilm was higher than the mutants biofilm (P < 0.01). The ratio of live to dead bacteria of WT biofilm was higher than ΔimmA(-) mutants in all layers (P < 0.05) and ΔimmB(-) mutants in the outer and intermedium layer (P < 0.01). There is no significant different between the inner layers of WT and ΔimmB(-) mutants (P = 0.191).</p><p><b>CONCLUSIONS</b>Putative bacteriocin immunity proteins have influence on the growth mode of Sm. The antimicrobial sensitivity of planktonic Sm can be up-regulated by the inactivation of immA or immB. The MBEC of chlorhexidine against ΔimmA(-) and ΔimmB(-) mutants is lower than WT. The inactivation of immA or immB affects the biofilm formation.</p>

Macrophage migration-inhibitory factors expression and its effects on proliferation in human dental pulps / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of macrophage migration-inhibitory factors (MIF) in clinically healthy and inflamed human pulp tissues and the effects of rhMIF on the proliferation of human dental pulp cells (HDPC).</p><p><b>METHODS</b>Immunohistochemistry was used to detect the localization of MIF expression in clinically healthy pulp and inflamed pulp tissues. Quantitative real-time polymerase chain reaction (PCR) was performed to evaluate the mRNA levels of MIF in pulp specimens. In addition, the culture supernatants of HDPC were collected after HDPC was stimulated by lipopolysaccharide (LPS) for 24 h, and then the MIF levels were assayed by quantitative sandwich enzyme-linked immunosorbent assay. Meanwhile, the effects of rhMIF on the proliferation of HDPC at different concentrations for 24 and 48 h were observed by cell counting kit-8 (CCK-8).</p><p><b>RESULTS</b>MIF was mainly distributed in odontoblasts of healthy pulp tissue, however, in inflamed pulp tissue, it was widely detected in fibroblasts, inflammatory infiltrates and endothelial cells as well as odontoblasts. Quantitative real-time PCR showed that there was no significant difference in MIF mRNA levels between inflamed pulps and healthy pulps (P > 0.05). Additionally, the secretion of MIF was significantly increased by stimulation with LPS at the concentration of 0.1 and 1.0 mg/L [(1772.58 ± 495.05), (1692.58 ± 337.45) ng/L] (P < 0.05), and the concentration was (1048.53 ± 161.81) ng/L in control group. rhMIF stimulated the HDPC's proliferation at the concentration of 10, 30, 60 µg/L for 24 and 48 h.</p><p><b>CONCLUSIONS</b>MIF was expressed in pulp tissue and its expression was increased after stimulation by LPS. rhMIF increased the proliferation of HDPC. These results suggest that MIF may be involved in the process of pulpal inflammation.</p>

Application and prospect on the resin-dentin adhesion in the root canal therapy / 华西口腔医学杂志

The application of adhesive root canal filling materials is the tendency in root canal obturation. The orientation is to develop the adhesive core material and sealer making a whole structure. In this review, we summarized the researches on the resin-dentin adhesion in the root canal obturation.

A micro-computed tomographic study of the isthmus in the root canal system of mandibular first molar / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence and configuration of the isthmuses in the apical 6 mm of the mesial and distal roots of Chinese mandibular first molar by means of micro-computed tomography.</p><p><b>METHODS</b>Thirty-six extracted human mandibular first molars were selected. Specimens were subject to micro-CT and a slice thickness of 30 microm was obtained in the apical 6 mm of the roots examined. The number of sections showing isthmuses at each apical level was recorded. Three-dimensional images of isthmuses of mandibular first molars were reconstructed and observed.</p><p><b>RESULTS</b>The mesial roots of human mandibular first molars had a high incidence of isthmus. The isthmus incidence was greatest 4-6 mm from the apex in human mandibular first molar, with prevalence figures of 49.5%-66.1% and 17.3%-17.8% in mesial and distal roots, respectively. The chi-square test indicated a significant difference in the distribution of isthmuses between the two roots (P < 0.01).</p><p><b>CONCLUSIONS</b>The mesial roots of human mandibular first molars have a high incidence of isthmus, which may have clinical implications especially when surgical endodontics is performed on the mesial roots of mandibular molars.</p>

Clinical evaluation of periapical endodontic surgery for endodontic failure / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical outcome of periapical endodontic surgery for teeth that can't be treated by nonsurgical endodontic methods.</p><p><b>METHODS</b>Sixty-two affected teeth were chosen for surgical endodontic treatment, of which 31 teeth underwent periapical curettage and the others were treated by root-end resection, retrograde preparation and filling. A radiography was taken immediately after surgery and was compared with those taken at 12 and 24 months. The results of two groups were analyzed using the chi2 test.</p><p><b>RESULTS</b>The success rate for retrograde filling was higher (85% after 12 months, 88% after 24 months) compared with that of periapical curettage (52% after 12 months, 45% after 24 months). The difference in success rate between the two groups was statistically significant.</p><p><b>CONCLUSIONS</b>Ultrasonic root-end preparation and retrograde filling is a good choice of treatment when the teeth can't be treated appropriately by nonsurgical treatment.</p>

A proteomic analysis of human dental pulp cells undergoing odontoblast differentiation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the difference in protein profiles between human dental pulp cells (DPC) and odontogenic differentiated DPC by using proteomic approach.</p><p><b>METHODS</b>Human DPC were induced to odontoblast differentiation and total proteins in the cell lysates before and after induction were prepared. Proteins spots were isolated by two-dimensional gel electrophoresis. DeCyder V6.0 software was applied to gel image analysis. Differential protein spots were identified by peptide mass fingerprinting technique.</p><p><b>RESULTS</b>Forty-six protein spots were determined to be differentially expressed with twenty identified protein spots. Expression changes of the identified proteins revealed the involvement of various regulation mechanisms in odontoblast differentiation, such as cell cycle, cellular energy regulation and signal transduction.</p><p><b>CONCLUSIONS</b>The proteomic approach is a high throughput method to screen the candidate proteins involved in odontoblast differentiation of DPC.</p>

A differential expression proteomic study of human periodontal ligament cell during osteogenic differentiation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To obtain regulating proteins during human periodontal ligament cell (hPDLC) osteogenic differentiation and investigate its underlying molecular mechanism.</p><p><b>METHODS</b>Two-dimension difference in gel electrophoresis (2D-DIGE) coupled with matrix-assisted laser adsorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis was used to identify regulating proteins during hPDLC osteogenic differentiation.</p><p><b>RESULTS</b>A differently expressed protein profile was obtained 7 days after osteogenic induction, and 61 protein spots with significant differences, 29 protein spots were identified by MALDI-TOF-MS, including cytoskeleton, cell membrane-bounding, nuclear regulation, matrix synthesis, and metabolic enzymes and signal transduction and other proteins. A functional class of cytoskeleton proteins showed co-regulation, these proteins were intimately involved in the reorganization of the cytoskeleton, cytokinesis and migration during PDLC differentiation.</p><p><b>CONCLUSIONS</b>A database of differently displayed proteins during hPDLC osteogenic differentiation was established, which may be helpful to understand and further study molecular mechanism of PDLC osteogenic differentiation.</p>

Expression and biological roles of heat shock protein 25 in rat dental follicle cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the expression of heat shock protein 25 (HSP-25) in dental rat follicles in vivo and in vitro in order to investigate the possible effect of HSP-25 on cell proliferation and alkaline phosphatase (ALP) activity.</p><p><b>METHODS</b>The expression of HSP-25 in mandibles of postnatal rats from day 1, 3, 5, 7, 9, 11 was examined by immunohistochemistry in vitro, the expression of HSP-25 in the dental follicle cells was detected by the indirect immunofluorescence method. Methyl thiazolyl tetrazolium (MTT) assay, flowcytometry and ALP assay were used to detect the effect of HSP-25 on rat dental follicles.</p><p><b>RESULTS</b>HSP-25 expression was absent or weak in rat dental follicle cells at early postnatal stage and present from day 5 till day 11. HSP-25 was detected in the cytoplasm of cultured dental follicle cells. MTT results showed no effect could be detected on dental follicle cell proliferation after stimulation of different concentrations of HSP-25 on day 1, 2, 3. Flowcytometry results also exhibited no difference in cell cycles after stimulation of HSP-25 at 0 microg/L and 100 microg/L. HSP-25 at a concentration of 50 microg/L and 100 microg/L could up-regulate the ALP activity on day 9.</p><p><b>CONCLUSIONS</b>Expression of HSP-25 increases chronologically in the rat dental follicle cells. HSP-25 locates in the cytoplasm of cultured rat dental follicle cells. HSP-25 has no effect on the proliferation of dental follicle cells, however it can up-regulate the ALP activity.</p>

Clinical observation on the characteristics of occlusion and tooth abrasion in patients with cracked tooth / 中华口腔医学杂志

<p><b>OBJECTIVES</b>To investigate the occlusal characteristics and the condition of tooth abrasion in patients with cracked tooth and to discuss the etiology of the cracked tooth and the relationships between occlusal disorder, tooth abrasion and cracked tooth.</p><p><b>METHODS</b>Twenty-seven patients with cracked tooth were selected. The occlusal courses were recorded by T-ScanIII system in intercuspal position, protrusive movement and lateral movement. Teeth with cracked tooth were regarded as the cracked tooth group, and the healthy adjacent teeth as the control group. The distribution of premature contact, occlusal interference, the center of occlusal force were examined. The abrasive conditions of the two groups were recorded according to the Smith tooth wear index and compared.</p><p><b>RESULTS</b>There were more teeth with occlusal interference in cracked tooth group (20 teeth) than in the control group (6 teeth), which was significantly different (OR = 5.67, chi(2) = 8.45, P = 0.003). In 24 patients with single affected tooth, the center of occlusal force (COF) located in the inside and outside ellipse were 6 teeth (25%) and 18 teeth (75%) respectively, Z test showed that there were statistical differences between the cracked tooth group and normal people. In cracked tooth group, the proportion of the teeth with abrasion was higher in teeth with occlusal interference than those without occlusal interference (chi(2) = 4.79, P = 0.029).</p><p><b>CONCLUSIONS</b>The formation of the cracked tooth was related to the occlusal disorder and associated with the tooth abrasion.</p>

Expression of matrix extracellular phosphoglycoprotein in human dental pulp cells undergoing odontoblastic differentiation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of matrix extracellular phosphorylated protein (MEPE) in human dental pulp cells (hDPC) undergoing odontogenic induction and explore the role of MEPE in odontoblast-like differentiation.</p><p><b>METHODS</b>hDPC were isolated by enzymatic digestion and preceded to odontogenic induction for 7, 14 and 21 days respectively. hDPC before induction served as controls. The expressions of MEPE, dentin sialophosphoprotein (DSPP)/dentin sialoprotein (DSP), bone sialoprotein (BSP) and collagen type I were determined by quantitative real-time RT-PCR and Western blotting.</p><p><b>RESULTS</b>The mRNA levels of MEPE, DSPP, BSP and type I collagen were increased in a time-dependent manner as hDPC were induced along odontoblastic lineage. Statistical differences were detected for MEPE and BSP mRNA expressions in induced hDPC compared with control group (P < 0.001). For DSPP and type I collagen, the mRNA levels in the induced groups were (12 943.33 + or - 3805.73) and (250.55 + or - 31.86) respectively, which were significantly higher than those in control group on days 21 (P < 0.05). Western blotting also revealed the increased expressions of MEPE, DSP, BSP and type I collagen in the induced DPC.</p><p><b>CONCLUSIONS</b>hDPC showed analogously temporal expressions of MEPE, DSPP/DSP, BSP and collagen type I while differentiating along odontoblast lineage. MEPE may play an important role in the odontogenic differentiation of hDPC and may be a potential marker of odontoblast-like differentiation.</p>

HSP25 affects the proliferation and differentiation of rat dental follicle cells / 国际口腔科学杂志·英文版

<p><b>AIM</b>To detect the expression of HSP25 in rat dental follicles both in vivo and vitro, and explore the underlying mechanism of HSP25 on the proliferation and differentiation of rat dental follicle cells (DFCs).</p><p><b>METHODOLOGY</b>Immunohistochemistry was performed to detect the expression of HSP25 in mandibles of postnatal rats on days 1, 3, 5, 7, 9 and 11 in vivo. In vitro, the expression of HSP25 in DFCs was detected by an indirect immunofluorescence assay. Thiazolyl blue tetrazolium bromide (MTT) assay, flow cytometry and alkaline phosphatase (ALP) assay were used to identify the time-course effect mediated by different concentrations of recombinant murine HSP25 of 0, 1, 10, 50 and 100 ng/mL on rat DFCs.</p><p><b>RESULTS</b>Expression of HSP25 was not detected in dental follicles of the rats until day 5 after birth, but became up-regulated in a time-dependent manner till day 11. HSP25 was detected in the cytoplasm of cultured rat DFCs. No significant difference could be observed in the proliferation of DFCs after stimulation with different concentrations of HSP25 on days 1, 2 and 3 (P > 0.05). HSP25 at concentrations of 50 ng/mL and 100 ng/mL up-regulated the ALP activity of DFCs on day 9 (P < 0.05).</p><p><b>CONCLUSION</b>HSP25-immunoreactivity increased chronologically during the development of dental follicles. The protein had no significant effect on cell proliferation but may play a role in cementoblast/osteoblast differentiation of DFCs.</p>

The surface antigen expression of periodontal ligament cells and dental pulp cells in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of surface antigen of human periodontal ligament cells (PDLCs) and dental pulp cells (DPCs) and the impact of ex vivo expansion to the expression of surface antigen. To provide basis of proper surface antigen for further selection of homogenous stem cell subpopulation from PDLCs and DPCs.</p><p><b>METHODS</b>PDLCs and DPCs were isolated and cultured by collagenase type I and dispase. The expression of surface antigen was analyzed by immunohistochemistry and flow cytometry.</p><p><b>RESULTS</b>Positive expression of STRO-1 and CD146 were observed in PDLCs and DPCs by immunocytochemistry. Similar to DPCs, PDLCs expressed mesenchymal stem cell markers STRO-1, CD146, CD29, CD44 and CD106, and displayed negative expression for CD34 at passage 1 by flow cytometry. There were no significant difference of STRO-1, CD29 and CD44 expression level between PDLCs and DPCs (P > 0.05). PDLCs expressed significantly higher level of CD106 and significantly lower level of CD146 than DPCs (P < 0.001). The proportion of STRO-1 and CD146 positive cells decreased steadily with passages in PDLCs and DPCs.</p><p><b>CONCLUSION</b>PDLCs have some similar surface antigen as DPCs, and the stem cells properties of PDLCs and DPCs decreased steadily with passages.</p>

Expression and significance of stromal cell-derived factor-1alpha and its receptor CXCR4 in human dental pulp cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of CXCR4 in cultured human dental pulp cells (HDPC) in vitro and the corresponding ligand SDF-1alpha level of HDPC supernatants stimulated by lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha), and to explore the role of SDF-1alpha on the proliferation and the migration of HDPC.</p><p><b>METHODS</b>The expression of CXCR4 in HDPC was detected by immunocytochemistry technique and indirect immunofluorescence technique. The culture supernatants of HDPC were collected after HDPC had been simulated by LPS and TNF-alpha of different concentrations for 48h and then the SDF-1alpha level was assayed by quantitative sandwich ELISA. Meanwhile, the effects of recombinant human SDF-1alpha (rhSDF-1alpha) on the proliferation and the migration of HDPC at different concentrations were observed by MTT and Boyden Chamber Assay.</p><p><b>RESULTS</b>CXCR4 was expressed in cytomembrane of HDPC and SDF-1alpha was secreted into their normal cell supernatants with a concentration of (4513.55 +/- 962.92) ng/L. The secretion of SDF-1alpha was both significantly decreased by stimulation with LPS and TNF-alpha (P < 0.05). In addition, rhSDF-1alpha stimulated the HDPC proliferation at the concentrations of 50, 100, 200 microg/L (P < 0.01) and increased the chemotactic migration of HDPC significantly after 9h's incubation with the concentrations of 50, 100 microg/L (P < 0.05).</p><p><b>CONCLUSIONS</b>SDF-1alpha accelerated the proliferation and the migration of HDPC which expressed CXCR4. SDF-1-CXCR4 axis may play a role in repair of pulp injury.</p>

Clinical management of mandibular incisors with multiple root canals using dental operating microscope / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the role of dental operating microscope in clinical treatment of lower incisors with multiple root canals.</p><p><b>METHODS</b>143 mandibular incisors in 128 patients were treated endodontically. Two kinds of preoperative radiographs were taken for each tooth, using straight projection and eccentric projection. The root canal morphology was recorded according to Vertucci's classification. Under dental operating microscope, the teeth with multiple root canals were shaped using Ni-Ti rotary instruments Hero 642, cleaned using sodium hypochlorite, and obturated with vertical condensation technique. The following information was recorded: The number of teeth that were found to have multiple canals in two kinds of preoperative radiographs, and when using and without using microscope. The efficiency of preparation and obturation was analyzed with radiographs before, during and after operation.</p><p><b>RESULTS</b>The mandibular central incisor with one canal was 73.53% and multiple canals was 26.47% in treated teeth. The mandibular lateral incisor with one canal was 70.67% and multiple canals was 29.33% in treated teeth. By eccentric projection radiograph and treatment using microscope, more teeth with multiple canals were found. No complication was found during root canal preparation. 134 teeth were well filled and 9 showed slight over-filling.</p><p><b>CONCLUSION</b>With dental operating microscope, the mandibular incisors with multiple root canals could be treated well in combination with rotary instrumentation and vertical condensation technique.</p>

Morphological characteristics of the mandibular first premolars in people from Pearl River Delta region in Guangdong province / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the morphological characteristics of the mandibular first premolars in people from Pearl River Delta region in Guangdong province using three techniques, including periapical radiographs, the radiographs with files inserted the canals and the clearing technique.</p><p><b>METHODS</b>A total of 363 extracted mandibular first premolars were collected and numbered. Two preoperative radiographs were taken in buccolingual and mesiodistal directions respectively. After access opening, the files were placed in the canals and two other radiographs were taken. The mandibular first premolars with multi-canal system were selected and observed under dental operating microscope (DOM). The mandibular first premolars were made transparent and were categorized using the Vertucci's classification.</p><p><b>RESULTS</b>There were different results among the three approaches. Periapical radiographs could be used to distinguish only between one and multiple canals systems. The incidence of multiple canals was 33.33% from the radiographs with file. The mandibular first premolars had a high frequency (34.44%) of multi-canal system by clearing method. The root canal morphology of the mandibular first premolars showed great variance. The canal orifices of the mandibular first premolars with one or two canal distributed in a buccolingual line. The floor of pulp chamber of the mandibular first premolars with three or four canals was a plat form.</p><p><b>CONCLUSION</b>The mandibular first premolars have a high frequency multi-canal system and could be classified in many categories. Using DOM and radiographs with file is a useful way in judging the canal numbers and categories.</p>