Soft tissue image reconstruction using cone-beam computed tomography combined with laser scanning: a novel method to evaluate the masticatory mucosa.

OBJECTIVE: To construct a 3-D model of the masticatory mucosa to measure the thickness of the facial/lingual gingiva and palatal mucosa. STUDY DESIGN: Maxillofacial regions of 8 volunteers were scanned using cone-beam computed tomography to generate 3-D maxillary and mandibular models. Digital models were obtained by laser scanning of the impressions. Models were constructed using global data registration and Boolean subtraction. Accuracy was assessed by comparison against control patients with a periodontal pack around their gingival boundaries. Inter- and intra-observer variability were determined. RESULTS: Masticatory mucosa models (in stereolithography format) showed the gingival and mucosal contours. The gingival thickness of the 3-D models and controls were not significantly different (P > .05). The interclass correlation coefficient and Kappa values indicated good intra-observer and inter-observer agreement, respectively. CONCLUSIONS: Cone-beam computed tomography combined with laser scanning can be reliable for visualizing and measuring the thickness of the masticatory mucosa.

Prospects application of polypyrrole-based immunosensor to Porphyromonas gingivalis quantification in subgingival plaque samples.

BACKGROUND: Periodontitis still poses a serious threat to oral and systemic health condition of humans. The proportion of the main pathogenic bacteria change in localized sites was associated with the initiation of the disease process. However, the limitations of microbiological diagnostic aids rendered the diagnosis of active periodontitis status point-of-care or chair-side based on microbiological data difficult. METHODS: Porphyromonas gingivalis, a major putative etiological agent in the initiation and progression of chronic periodontitis, was used as the experimental subject. An immunosensor based on polypyrrole-coated interdigitated array microelectrodes was developed to quantify Porphyromonas gingivalis in pure culture, gingival crevicular fluid and saliva samples. The regression equation for the normalized impedance change (NIC) versus Porphyromonas gingivalis concentration (C) was measured. The correlation between results of the immunosensor and quantitative real-time PCR method in quantifying Porphyromonas gingivalis in subgingival plaque samples was evaluated. RESULTS: Results of the study revealed that the lowest detection limits of the immunosensor was 1.9 x 10(4), 2.7 x 10(5), and 2.7 x 10(6) cells/mL in pure culture, gingival crevicular fluid, and saliva samples respectively. The values determined using the immunosensor strongly correlated with those obtained using quantitative real-time PCR method (R2 = 0.91, p < 0.05). The immunosensor did not require any labels and amplification steps, and the total detection time from sampling to measurement was less than one hour. CONCLUSIONS: The immunosensor developed in the present study offered some insight into monitoring the change in the number of periodontal bacteria chair-side during routine clinical practice.

Response of human periodontal ligament cells to baicalin.

BACKGROUND: Periodontitis is the most common cause of tooth loss in adults. Periodontal ligament cell (PLC)-based therapy is considered one of the most promising methods in periodontal tissue regeneration. The traditional Chinese medicine baicalin has been shown to possess antimicrobial and anti-inflammatory activities and enhance cell proliferation and alkaline phosphatase activity. The aim of this study is to investigate the response of human PLCs (HPLCs) to baicalin. METHODS: The effect of baicalin on cultured HPLC proliferation was measured with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The effect of baicalin on the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), core binding factor α1 (Cbfα1), and osteocalcin (OC) was determined by quantitative real-time polymerase chain reaction and immunodetection. RESULTS: Baicalin at a concentration of 0.01 µg/mL promoted HPLC proliferation, upregulated OPG messenger RNA (mRNA) and protein expression, and downregulated RANKL mRNA and protein expression. In addition to reducing the RANKL/OPG expression ratio significantly, it also increased Cbfα1 and OC mRNA and protein expression. CONCLUSION: Baicalin showed multifaceted regulation of genes with important roles in tissue growth and differentiation, and thus it has the potential to be a promising candidate for HPLC-based periodontal regeneration therapy.

Effect of icariin on cell proliferation and the expression of bone resorption/formation-related markers in human periodontal ligament cells.

Periodontitis is a common destructive inflammatory disease that leads to changes in the tooth-supporting tissues. Human periodontal ligament cells are essential in periodontal tissue regeneration. The traditional Chinese medicine icariin promoted bone formation, stimulated the osteogenic differentiation of preosteoblastic cells and inhibited osteoclast differentiation and bone resorption. Thus, in the present study, the effect of icariin on cell proliferation and the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), core binding factor α1 (Cbfa1) and osteocalcin (OC) was investigated in human periodontal ligament cells, by an MTT assay, qPCR and western blot analysis. The results demonstrated that icariin promoted cell proliferation in a dose- and time-dependent manner, upregulated OPG, Cbfa1 and OC expression, and downregulated RANKL production and the RANKL/OPG expression ratio. This suggested the potential value of icariin in treating alveolar bone resorption and promoting periodontal tissue regeneration, due to its ability to stimulate the proliferation and osteogenic differentiation of human periodontal ligament cells and inhibit osteoclast differentiation.

Phenotypic changes in nonfimbriated smooth strains of Aggregatibacter actinomycetemcomitans grown in low-humidity solid medium.

Aggregatibacter actinomycetemcomitans is the primary etiologic agent of localized aggressive periodontitis. In vitro, it can undergo fimbriated rough to nonfimbriated smooth phenotypic transition, accompanied by an increase in invasive ability and a decrease in adhesive ability. No opposite direction phenotypic transition was reported. To better understand its pathogenicity, the authors studied the morphological changes of nonfimbriated smooth strains induced by growth environmental humidity. Transmission electron microscopy was used to identify fimbriae expression change. It was found that the lower medium humidity, the more fimbriae reexpressed. In conclusion, the smooth strain of A. actinomycetemcomitans can reexpress the fimbriae in lower humidity environment.

Osteogenic differentiation of human periodontal ligament stem cells expressing lentiviral NEL-like protein 1.

NEL-like protein 1 (NELL1) is a newly identified secreted protein involved in craniosynostosis and has been found to promote osteogenic differentiation of mesenchymal stem cells. The objective of this study was to investigate the effect of NELL1 on osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and the potential underlying mechanism. hPDLSCs underwent lentivirus-mediated NELL1 transfection (Lenti-NELL1) and markers of osteogenesis were assessed [alkaline phosphate (ALP), osteocalcin (OCN) and calcium deposition] to evaluate the effect of NELL1 on the differentiation of these cells. Quantitative polymerase chain reaction (qPCR) was employed to measure the mRNA expression of Msx2 and Runx2, and Lenti-enhanced green fluorescent protein (EGFP) served as a control. Western blot analysis and qPCR analyses confirmed that Lenti-NELL1-transfected hPDLSCs could express NELL1. Compared with the Lenti-EGFP group, ALP, OCN, calcium deposition and Msx2 mRNA expression were markedly increased (P<0.01), but there was no significant difference in Runx2 mRNA expression between the two groups (P>0.01). hPDLSCs can be transfected by Lenti-NELL1 and can stably express NELL1. NELL1 is able to promote the osteogenic differentiation of hPDLSCs, which may be related to the downregulation of Msx2 expression. Lenti-NELL1 transfection can be used during in vitro gene therapy for periodontal regeneration.

An open CAM system for dentistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and industrial CAM software.

China-made 5-axis simultaneous contouring CNC machine tool and domestically developed industrial computer-aided manufacture (CAM) technology were used for full crown fabrication and measurement of crown accuracy, with an attempt to establish an open CAM system for dental processing and to promote the introduction of domestic dental computer-aided design (CAD)/CAM system. Commercially available scanning equipment was used to make a basic digital tooth model after preparation of crown, and CAD software that comes with the scanning device was employed to design the crown by using domestic industrial CAM software to process the crown data in order to generate a solid model for machining purpose, and then China-made 5-axis simultaneous contouring CNC machine tool was used to complete machining of the whole crown and the internal accuracy of the crown internal was measured by using 3D-MicroCT. The results showed that China-made 5-axis simultaneous contouring CNC machine tool in combination with domestic industrial CAM technology can be used for crown making and the crown was well positioned in die. The internal accuracy was successfully measured by using 3D-MicroCT. It is concluded that an open CAM system for dentistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and domestic industrial CAM software has been established, and development of the system will promote the introduction of domestically-produced dental CAD/CAM system.

An Open CAM System for Dentistry on the Basis of China-made 5-axis Simultaneous Contouring CNC Machine Tool and Industrial CAM Software / 华中科技大学学报（医学）（英德文版）

China-made 5-axis simultaneous contouring CNC machine tool and domestically developed industrial computer-aided manufacture (CAM) technology were used for full crown fabrication and measurement of crown accuracy,with an attempt to establish an open CAM system for dental processing and to promote the introduction of domestic dental computer-aided design (CAD)/CAM system.Commercially available scanning equipment was used to make a basic digital tooth model after preparation of crown,and CAD software that comes with the scanning device was employed to design the crown by using domestic industrial CAM software to process the crown data in order to generate a solid model for machining purpose,and then China-made 5-axis simultaneous contouring CNC machine tool was used to complete machining of the whole crown and the internal accuracy of the crown internal was measured by using 3D-MicroCT.The results showed that China-made 5-axis simultaneous contouring CNC machine tool in combination with domestic industrial CAM technology can be used for crown making and the crown was well positioned in die.The intemal accuracy was successfully measured by using 3D-MicroCT.It is concluded that an open CAM system for dentistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and domestic industrial CAM software has been established,and development of the system will promote the introduction of domestically-produced dental CAD/CAM system.

AFM and fluorescence imaging of nanomechanical response in periodontal ligament cells.

Most biologists think that AFM has only a limited use in biological research due to its inability to study other than surface structures. Therefore, a BIO-AFM system has been developed to combine both AFM imaging and fluorescence detection, which acts as a powerful tool for a better understanding of dynamic cell processes. In this study, based on a custom-made BIO-AFM system, the elasticity and ultrastructure of living periodontal ligament cells (PDLCs) were investigated. The cantilever probe with a micron-sized bead was used to exert nano-loading force onto the PDLCs. The related signal of NO was then recorded simultaneously. The results show that PDLCs hold strong networks of stress fibers as well as high elastic modulus value, exhibiting the ability for better counteracting the external forces. In the mechano-transduction studies, an initial increase and subsequent drop in intracellular NO response was found. Furthermore, NO may diffuse from a stimulated cell to adjacent cells. In conclusion, our single-cell nano-mechanical study provides a significant advancement in elucidating the magnitude, location, time scale, and biomolecular mechanisms underlying cell mechano-transduction.

Detection of bacterial cells by impedance spectra via fluidic electrodes in a microfluidic device.

In this study, a novel method for detecting bacterial cells in deionized (DI) water suspension is presented by using fluidic electrodes with a hydrodynamic focusing technique. KCl solution was utilized as both sheath flow and fluidic electrodes, and the bacterial suspension was squeezed to form three flowing layers with different conductivities on a microfluidic chip. An impedance analyzer was connected with the KCl solution through two Ag/AgCl wires to apply an AC voltage to fluidic layers within a certain frequency for impedance measurements. Porphyromonas gingivalis and Escherichia coli were detected and linear relationships were found between the impedance and the logarithmic value of the bacterial concentration in certain cell concentration ranges. It is demonstrated that bacterial detection using the microdevice is rapid and convenient, with a chip made of simple flow channels, and the detection sensitivity of cell counting can be tuned by varying the width of the sample flow layer through changing input velocities, showing a detection limit of 10(3) cells mL(-1).

[Study on reference value of healthy teeth mobility of youth].

OBJECTIVE: This study aimed to establish the reference value range of healthy teeth mobility in Chinese youth. METHODS: 200 right side teeth of Han nationality of Chinese youths were measured so as to get the range of the parameters. RESULTS: All parameters of 14 teeth were achieved. The parameter of TM in mandibular incisor was the highest and in mandibular first molar lowest. CONCLUSION: It is very significant to get and quantify the healthy teeth's parameter range. Because they can be served as the healthy contrast when dentists diagnose the mobility. It also reflects the fact that lower the TM parameter is, firmer the tooth will be.

[Primary culture of human periodontal ligament fibroblasts by explants with enzymatic digestion].

OBJECTIVE: To increase the success rate of primary culture of human periodontal ligament fibroblasts (HPLF), and to establish an experimental model for studying HPLF in vitro. METHODS: The primary cells were isolated from human periodontal ligament by explants with enzymatic digestion method. Morphological analysis and immunocytochemical staining were used to characterize the cell lineage, and growth curve assay to evaluate the biological features of HPLF. RESULTS: The success rate of primary culture of HPLF was 77.8%. Cultured cells were spindle-shaped, and had a positive reaction to antibodies against vimentin, and a negative reaction to antibodies against keratin. Their morphological and biological characteristics were similar to those of typical HPLF. Growth of HPLF obtained by this method was satisfactory. CONCLUSION: The success rate of primary culture of HPLF is significantly increased by explants combined with enzymatic digestion. The method is simple and feasible.

Effect of human serum albumin on cell attachment of human gingival epithelial cells.

OBJECTIVE: To investigate the effect of human serum albumin (HSA) on cell attachment of human gingival epithelial cells (HGE). METHODS: HGE were primary cultured with keratinocyte serum-free medium (KSFM) and dispase. The cultured cells were immunohistochemically stained by monoclonal anti-pan cytokeratin. MTT test was employed to investigate the influence of HSA on the cell attachment on polystyrene surface. The cell growth curve of HGE which were cultured in KSFM with 50 g/L HSA was observed. RESULTS: The results showed significant decrease in cell numbers within 8 hours after HGE were inoculated, in which the polystyrene surface was preincubated with 50 g/L HSA. But it did not prove to be the case from 10 hours to 24 hours after HGE were inoculated. There were no significant difference within 24 hours in cell numbers between cultured in KSFM with 50 g/L HSA and control. The cell numbers in cell growth curve of HGE in KSFM with and without 50 g/L HSA did not show significant difference. CONCLUSIONS: HSA preincubation on polystyrene were produce inhibitory effect of HGE attachment in early stage.