Gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting promotes cell adhesion and proliferation of human dental pulp cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the cytotoxicity of gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting in human dental pulp cells (HDPCs) and compare the cell adhesion and proliferation of the cells seeded in the biomaterial using two different methods.</p><p><b>METHODS</b>HDPCs isolated by tissue block culture and enzyme digestion were cultured and passaged. Gelatin/alginate hydrogel scaffolds were printed using a bioplotter, and the cytotoxicity of the aqueous extracts of the scaffold material was tested in the third passage of HDPCs using cell counting kit-8. Scanning electron microscopy and trypan blue were used to assess the adhesion and proliferation of the cells seeded in the scaffold material at a low or high concentration.</p><p><b>RESULTS</b>The aqueous extract of the scaffolds at different concentrations showed no obvious cytotoxicity and promoted the proliferation of HDPCs. The scaffolds had a good biocompatibility and HDPCs seeded in the scaffold showed good cell growth. Cell seeding at a high concentration in the scaffold better promoted the adhesion of HDPCs and resulted in a greater cell number on the scaffold surface compared with low-concentration cell seeding after a 5-day culture (P<0.05).</p><p><b>CONCLUSION</b>Gelatin<alginate hydrogel scaffolds prepared by 3D bioprinting has a good biocompatibility and promotes the proliferation of HDPCs, and can be used as a scaffold material for tooth regeneration. Cell seeding at a high concentration can better promote cell adhesion to the scaffold material.</p>

Six degree-of-freedom acquisition and analysis of jaw opening and closing with motion capture system / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the six degrees of freedom of jaw opening and closing movement with motion capture and analysis system to establish a quantitative method for studying mandibular movement and a digital basis for virtual reality study of mandibular movement.</p><p><b>METHODS</b>In a male adult with normal dentition without temporomandibular joint disorders, 3 fluorescent markers were pasted in the upper dentition and 4 in the lower dentition. Six cameras of the motion capture system were arranged in a semi-circular fashion. The subject sat in front of the camera at an 80-cm distance with the Frankfort plane kept parallel to the horizontal plane. The degree-of-freedom (3 linear displacement and 3 angular displacement) of jaw opening and closing movement was obtained by collecting the marker motion.</p><p><b>RESULTS</b>Six degrees of freedom of jaw opening and closing were obtained using the motion capture system. The maximum linear displacements of X, Y and Z axes were 5.888 089 cm, 0.782 269 cm, and 0.138 931 cm, and the minimum linear displacements were -3.649 83 cm, -35.961 2 cm, -5.818 63 cm, respectively. The maximum angular displacements of X, Y and Z axes were 0.760 088°, 2.803 753°, and 0.786 493°, with the minimum angular displacements of -2.526 18°, -0.625 94°, and -25.429 8°, respectively. Variations of linear displacements during jaw opening and closing occurred mainly in the Y axis, and those of angular displacement occurred mainly in the Z axis.</p><p><b>CONCLUSION</b>The six degree-of-freedom of mandibular movement can be accurately obtained with the motion capture system to allow quantitative examination of the mandibular movement.</p>

Application of three-dimensional laser scanning-based maxillofacial soft tissue reconstruction in orthodontic treatment / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a convenient and rapid method for constructing a digital model of the maxillofacial soft tissue based on three-dimensional laser surface scanning to allow direct and accurate observation of the soft tissue changes in the course of orthodontic treatment.</p><p><b>METHODS</b>The point cloud data of three-dimensional laser scanning of the maxillofacial region were acquired from a healthy woman with Angle Class I occlusion, who maintained a horizontal Frankfort plane during scanning with the scanner placed at a distance of 80 cm. The scanning was repeated twice after wearing the dental cast for an Angle Class I occlusion. The three-dimensional digital model of the maxillofacial soft tissue was constructed based on the point cloud using GeoMagic10.0 software.</p><p><b>RESULTS</b>The high-resolution three-dimensional model of the maxillofacial soft tissue reconstructed allowed accurate observation of the distinct facial anatomical landmarks and represented directly the soft tissue changes in the process of orthodontic treatment by merging the models. Using the analytic tool provided by the software, this model also allowed direct quantitative measurement of the nasolabial angle and the distances from the esthetic plane to the upper lip, labral inferior, and mentolabial sulcus, which were 111.86°, -3.57 mm, -2.54 mm, and 3.95 mm before orthodontic treatment as compared to 114.31°, -2.73 mm, -1.06 mm, and 3.46 mm during treatment, and 116.53°, -0.15 mm, 0.64 mm, and 3.11 mm after the treatment, respectively.</p><p><b>CONCLUSION</b>Three-dimensional laser surface scanning enables accurate and rapid construction of the digital model of the facial soft tissues, which may provide valuable assistance in orthodontic treatment.</p>

Detection of Helicobacter pylori in oral cavity of patients with recurrent aphthous ulcer / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the association of recurrent aphthous ulcer (RAU) with Helicobacter pylori (Hp) infection and digestive diseases.</p><p><b>METHODS</b>Saliva samples were collected from 82 patients with RAU and 74 healthy volunteers for Hp detection with PCR.</p><p><b>RESULTS</b>The positivity rates of HP differed significantly between RAU patients and healthy volunteers (43.9% vs 16.2%, P<0.001). In the 82 RAU patients, 22 (26.82%) were identified to have gastritis and peptic ulcer, whereas only 7 out of the 74 healthy volunteers (10.45%) had such digestive diseases, showing significant difference between them (P<0.01).</p><p><b>CONCLUSION</b>Hp might in some way associate with RAU, which in turn is associated with an increased incidence of digestive diseases.</p>

Comparison and analysis of human dentin matrix protein 1 promoter activity in three different cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe and compare the luciferase activities of different length segments of human dentin matrix protein 1 promoter in human dental pulp stem cells (HDPSC), osteoblasts (OC) and Hela cells.</p><p><b>METHODS</b>The differentlength desired DNA segments were obtained from 2 195 bp Dmp1 promoter cloned by PCR method. The amplified promoter segments with different length were cloned into luciferase report gene vector pGL3-Basic, the correct orientation of those inserts was verified by cutting with two different restrict enzymes. The luciferase activity was observed after different pGL3-PDmp1 vectors were transfected transiently into those three different-type cells.</p><p><b>RESULTS</b>6 Dmp1 promoter segments with different-length were obtained successfully, and luciferase report gene vectors with different promoter segments were successfully constructed after identified by restriction enzymes cutting. They had different luciferase activities when they were transfected transiently into HDPSC, and the region of -505(-)-193 bp and -935(-)-505 bp could be regarded as the specific promoters of Dmp1 promoter for HDPSC and OC respectively, which could include the basic regulatory elements.</p><p><b>CONCLUSION</b>The correct clone of the upstream of human Dmp1 promoter segments with different length had been obtained, and they had strong luciferase activities in HDPSC and OC, but very low in Hela cell. These results will make an important basis for studying mineralized tissue-specific transcriptional regulation mechanisms of Dmp1.</p>

Reconstruction of dentin-pulp complex structure by tissue engineering technology / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the possibility of reconstruction of dentin-pulp complex by tissue engineering technology.</p><p><b>METHODS</b>Rat dental pulp stem cells were seeded into HA-TCP scaffold and incubated for 20 hours in vitro. Then the cell-scaffold complex was implanted subcutaneously into the dorsal side of nude mice. 8 weeks postimplantation, the samples were extracted for histological and immunohistochemical examinations.</p><p><b>RESULTS</b>Three strata of tissue were observed in the hole of HA-TCP scaffold. They were dentin-like tissue, predentin-like tissue and pulp-like tissue respectively from the inner surface of the pore to the center. Dentin tubules were obvious in predentin-like and dentin-like tissue lining from the pulp-like tissue through predentin-like tissue and dentin-like tissue. Cells localized along the edge of pulp-like tissue were dense and polarized, resembling odontoblasts. Immunohistochemical study demonstrated DSP and DMP1 expression in these odontoblast-like cells and in the area of predentin-like tissue.</p><p><b>CONCLUSIONS</b>Tissue-engineered rat dentin-pulp complex was reconstructed by seeding HA-TCP scaffold with rat dental pulp stem cells.</p>

Expression of GBD gene of Streptococcus mutans glucan binding protein A in mammalian cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the expression of recombinant plasmid pcDNA3.1/GBD of glucan binding protein of Streptococcus mutans in mammalian cells COS-7.</p><p><b>METHODS</b>Eukaryotic plasmid carrying encoding gene of GBD of Streptococcus mutans gbpA was constructed and the plasmid was introduced into COS-7 cells by Lipofectamine reagent. The transient expressed protein in COS-7 cells was detected by immunochemistry technique.</p><p><b>RESULTS</b>The positive expression was detected in plasma of the cells which were transfected with recombinant plasmid pcDNA3.1/GBD. The cells which were transfected with pcDNA3.1 were negative.</p><p><b>CONCLUSION</b>GBD can translate and express in COS-7 cells after transfected with recombinant plasmid pcDNA3.1/GBD. The expressed protein locates in the plasma and the protein is able to combine with anti-GbpA antibody. The expressed protein has the antigenicity and is a candidate gene vaccine.</p>

Characterization of Notch gene involved in genetic regulatory networks in dental pulp stem cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the characterization of Notch gene involved in genetic regulatory networks in dental pulp stem cells.</p><p><b>METHODS</b>The pulp tissue was separated from mouse teeth and digested by collagenase type I. Single-cell suspensions of dental pulp were seeded into 6-well plates with alpha modification of Eagle's medium supplemented with ES cell qualified Fetal Bovine Serum. Colony-forming efficiency was assessed in 14ds culture. Transcripts for Notch were detected by reverse transcription-PCR by using total RNA isolated from cells.</p><p><b>RESULTS</b>There were clonogenic cells in dental pulp cell and the incidence of colony-forming cells derived from mouse dental pulp cells was 1.6-2.5 colonies/10(4) plate. Mouse-specific Notch mRNA expressed in colony-forming cells.</p><p><b>CONCLUSION</b>Notch mRNA expressing in colony-forming cells provided a more detailed understanding of mouse dental pulp stem cell biology.</p>

Cbfa1 induces the expression of the mineral-related proteins in human dental papilla cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explicit whether the expression of the mineral-related proteins is regulated by cbfa1 in human dental papilla cells.</p><p><b>METHODS</b>Human dental papilla cells were cultured in vitro and transfected with pcDNA3-cbfa1 recombinant plasmids. After selected with G418 sulfate, a cell clone named PC-3, which could stably express the cbfa1 mRNA and protein, was proved by PCR and western blot. Then the amount of ALP and OC and the expression of OPN, BSP, ON, DMP1, DSP and DSPP were detected by immunohistochemistry, Western blot and PCR methods.</p><p><b>RESULTS</b>We established the human dental papilla cells model PC-3 which could stably express the cbfa1 mRNA and protein. Compared with normal cells, a lot of mineral-related proteins such as ALP, OC, OPN, BSP, ON, DMP1 were upregulated in PC-3 cells.</p><p><b>CONCLUSIONS</b>In human dental papilla cells, cbfa1 can induce the expression of most mineral-related genes and proteins. It may implicate that cbfa1 must play a key role during tooth development and mineralization.</p>