Investigation of peri-implant diseases prevalence and related risk indicators in patients with treated severe periodontitis over 4 years after restoration.

Background/purpose: History of periodontitis is a well-documented risk indicator of peri-implantitis. However, the influence of severity of periodontitis is still unclear, especially for severe periodontitis. This study was aimed to investigate the prevalence of peri-implant disease and analyze the risk indicators in patients with treated severe periodontitis. Materials and methods: A total of 182 implants from 88 patients (44 males and 44 females) with severe periodontitis with a mean fellow-up period of 76.5 months were enrolled in this study. Patient and implant information, and periodontal and peri-implant conditions were collected to evaluate the prevalence of peri-implant disease and risk indicators. Results: The prevalence of peri-implantitis was 9.1% and 6.6% at the patient-level and implant-level. The prevalence of peri-implant mucositis was 76.1% and 51.1% at the patient-level and implant-level. Risk indicators of peri-implantitis included older age (OR: 1.132), poor proximal cleaning habits (OR: 14.218), implants in anterior area (OR: 10.36), poor periodontal disease control (OR: 12.76), high peri-implant plaque index (OR: 4.27), and keratinized tissue width (KTW)＜2 mm (OR: 19.203). Conclusion: Implants in patients with severe periodontitis after periodontal treatment and maintenance show a low prevalence (9.1%) of peri-implantitis and a relatively high prevalence (76.2%) of peri-implant mucositis. Patient age, peri-implant proximal cleaning habits, implant position, periodontal disease control, peri-implant plaque index, and KTW are associated with prevalence of peri-implantitis.

The expression levels of chemotaxis-related molecules CXC chemokine receptor 1, interleukin-8, and pro-platelet basic protein in gingival tissues.

Background/purpose: Excessive host immune response is thought to be an important cause of periodontal tissue damage during periodontitis. The potent chemotaxis produced by locally released chemokines is the key signal to trigger this response. Here, we aimed to investigate the expression of CXC chemokine receptor 1 (CXCR1), and chemokines interleukin-8 (IL-8) and pro-platelet basic protein (PPBP) in human inflammatory gingival tissues compared with healthy tissues. Materials and methods: A total of 54 human gingival tissues, 27 healthy and 27 inflammatory samples, were collected. Fifteen specimens of each group were employed for quantitative reverse transcription polymerase chain reaction to determine the mRNA levels of CXCR1, IL-8, and PPBP. Six samples of each group were used for Western blotting to investigate the protein expression of CXCR1 and for enzyme-linked immunosorbent assay to evaluate the protein levels of IL-8 and PPBP, respectively. Results: The mRNA levels of chemokine receptor CXCR1, chemokine IL-8, and PPBP in inflammatory gingival tissues were significantly higher than those in healthy controls (P < 0.05). The protein levels of CXCR1, IL-8, and PPBP in inflammatory gingival tissues were also significantly higher than those in healthy gingival tissues (P < 0.05). Conclusion: When compared to healthy gingival tissues, the expression of CXCR1, IL-8, and PPBP in inflammatory gingival tissues is higher.

Subgingival Microbial Profiles of Young Chinese Adults with Stage I/II Periodontitis, Gingivitis and Periodontal Health Status.

OBJECTIVE: To analyse the subgingival microbiota of Stage I/II periodontitis, gingivitis with different degrees of severity, and periodontal health in subjects in a Chinese young adult population. METHODS: Subgingival plaque samples were collected from 15 Stage I/II periodontitis patients, 38 gingivitis patients and 15 periodontally healthy individuals, all aged from 18 to 21 years. Gingivitis patients were divided into two subgroups according to the Bleeding Index (BI) of their sampled teeth: gingivitis with above median BI (G-HBI) and below median BI (G-LBI). The subgingival plaque samples were collected from teeth 16, 26, 36, 46, 11 and 31 according to FDI notation. The V3-V4 region of the 16S rRNA gene of all the samples was sequenced and analysed. RESULTS: The Stage I/II periodontitis, gingivitis and periodontal health groups showed distinct subgingival microbiota profiles. When the gingivitis patients were stratified into two subgroups, the community structure of G-HBI showed no significant difference from early-stage periodontitis, but differed from G-LBI and the healthy group. Most periodontitis-related taxa were most abundant in Stage I/II periodontitis, followed by G-HBI, G-LBI and the periodontally healthy group. Porphyromonas gingivalis, Filifactor alocis, Tannerella forsythia, Saccharibacteria TM7 G-5 356, Lachnospiraceae G-8 500, Peptostreptococcaceae spp. and Syntrophomonadaceae VIIIG-1 435 were associated with Stage I/II periodontitis. Porphyromonas 275, Leptotrichia 417 and Saccharibacteria TM7 G-2 350 were associated with gingivitis. Porphyromonas gingivalis was significantly more abundant in G-HBI than in G-LBI. CONCLUSION: Within the limitations of this preliminary study, gingivitis and early-stage periodontitis were associated with an increased degree of dysbiosis in the subgingival microbiota in a Chinese young adult population.

Subgingival Microbiome of Gingivitis in Chinese Undergraduates.

OBJECTIVE: To analyse the microbiome composition of health and gingivitis in Chinese undergraduates with high-throughput sequencing. METHODS: Sequencing of 16S rRNA gene amplicons was performed with the MiSeq system to compare subgingival bacterial communities from 54 subjects with gingivitis and 12 periodontally healthy controls. RESULTS: A total of 1,967,372 sequences representing 14 phyla, 104 genera, and 96 species were detected. Analysis of similarities (Anosim) test and Principal Component Analysis (PCA) showed significantly different community profiles between the health control and the subjects with gingivitis. Alpha-diversity metrics were significantly higher in the subgingival plaque of the subjects with gingivitis compared with that of the healthy control. Overall, the relative abundance of 35 genera and 46 species were significantly different between the two groups, among them 28 genera and 45 species showed higher relative abundance in the subjects with gingivitis, whereas seven genera and one species showed a higher relative abundance in the healthy control. The genera Porphyromonas, Treponema, and Tannerella showed higher relative abundance in the subjects with gingivitis, while the genera Capnocytophaga showed higher proportions in health controls. Porphyromonas gingivalis, Prevotella intermedia and Porphyromonas endodontalis had higher relative abundance in gingivitis. Among them, Porphyromonas gingivalis was most abundant. CONCLUSION: Our results revealed significantly different microbial community composition and structures of subgingival plaque between subjects with gingivitis and healthy controls. Subjects with gingivitis showed greater taxonomic diversity compared with periodontally healthy subjects. The proportion of Porphyromonas, especially Porphyromonas gingivalis, may be associated with gingivitis subjects aged between 18 and 21 years old in China. Adults with gingivitis in this age group may have a higher risk of developing periodontitis.

Proposing a Novel, Three-level Definition of Periodontitis using Probing Depth, Clinical Attachment Loss and Bleeding on Probing: Analysis of a Rural Chinese Population.

OBJECTIVE: To propose a novel, three-level (severe, moderate, mild) case definition using probing depth (PD), clinical attachment loss (CAL) and bleeding on probing (BOP) for epidemiologic studies on periodontitis. METHODS: Case definitions (DEF) 1-30 with PD, CAL and BOP were made. Based on data from epidemiologic research in Chengde (Hebei Province, China) in 1992, prevalence of periodontitis by DEF1-30 was calculated and compared with a reference (definitions by Centers for Disease Control and Prevention/American Academy of Periodontology in 2012). Sensitivity, specificity, Youden Index, Cohen's kappa coefficient (CKC) and the area under the receiver operator characteristic curve (AUC) were calculated for the definitions selected. RESULTS: DEF1 and DEF18 for periodontitis, DEF2, DEF3, DEF19 for moderate and severe periodontitis, and DEF5, DEF13, DEF14, DEF21 and DEF25 for severe periodontitis, which were similar for estimation of periodontitis prevalence compared with the reference, were selected. DEF18 for periodontitis, DEF19 for moderate and severe periodontitis, and DEF5 for severe periodontitis were selected because they showed higher values for the Youden Index, CKC and AUC, and formed a three-level definition. CONCLUSION: A novel three-level case classification of periodontitis using three parameters of PD, CAL and BOP was proposed. The estimated periodontitis prevalence according to the novel proposed definition is close to the prevalence according to the CDC/AAP definition.

Assessing Maxillary Molar Furcation Involvement by Cone Beam Computed Tomography.

OBJECTIVE: To evaluate the reproducibility of four parameters for quantitatively assessing maxillary molar furcation involvement (FI) by cone beam computed tomography (CBCT). METHODS: Thirty-nine sites with degree II FI, classified by probing of 21 maxillary molars, were investigated. Degrees of FI in these sites were assessed based on CBCT data. In these samples, four parameters for quantitatively assessing FI in CBCT images were measured. The parameters included horizontal bone loss at furcation entrance level (HBL), maximum HBL (HBL-max), maximum vertical bone loss (VBL-max) and root trunk length (RT). The reproducibility of the measurements was evaluated. RESULTS: Amongst the 39 degree II FI classified by probing, only 17.9% were confirmed by CBCT. The other 46.2% were 'through and through' defects, 15.4% were fused roots and 20.5% were degree I FI in the CBCT image. The intraobserver repeatability for all four parameters was high, with intraclass correlation coefficients (ICC) of 0.960 for HBL, 0.992 for HBL-max, 0.987 for VBL-max and 0.983 for RT. The ICCs for two observers was also high (ICCs: 0.873 to 0.947). The parameters and related methods of measurements proposed in the study showed high reproducibility. CBCT images provided more details in assessing maxillary molar FI. CONCLUSION: The parameters and related methods of measurements developed in this study showed high reproducibility. CBCT images provide more details in assessing maxillary molar FI.

Radiographic and Clinical Outcomes of Ridge Augmentation in Molar Extraction Sockets with Severe Bone Wall Defect.

OBJECTIVE: To describe a technique for socket augmentation in molar extraction sockets with severe bone wall defect. METHODS: Five teeth in four patients were included in this study. Each tooth had buccal and/ or lingual bone loss identified by bone sounding and periapical radiographs before removal. After a flapless, minimally invasive tooth extraction, the socket was grafted with deproteinized bovine bone mineral with or without a collagen membrane. At the buccal and/or lingual bone defect area, the buccal and/or lingual gingival walls may act as holders, to support the materials. Finally, colloidal silver gelatin sponge was packed gently on top of the graft or membrane to avoid graft or membrane exposure, without attempting to achieve primary closure of the soft tissue. Six months after augmentation, changes in ridge width, ridge height and keratinised tissue were measured on clinical photographs or radiographs. RESULTS: The alveolar bone widths observed at implant surgery were all greater than 6 mm. All patients showed bone augmentation in terms of ridge height. Keratinised tissue width showed increased or minor reductions. CONCLUSION: Treated with this technique, the deficient socket was re-established in the molar area. Clinically, the quantity and quality of the bone obtained in the grafted sockets allowed for successful implant placement.

Comparison of Measurements on Cone Beam Computed Tomography for Periodontal Intrabony Defect with Intra-surgical Measurements.

OBJECTIVE: To explore the relationship between cone beam computed tomography (CBCT) measurements and direct measurements during the surgery to correct intrabony defects. METHODS: Forty-four patients with 44 intrabony defects who finished initial periodontal therapy and were considered for periodontal surgery were recruited. Digital periapical radiography and CBCT was performed before the surgery. The distance from the bottom of the defect to the cementoenamel junction (CEJ-BD), the depth and mesio-distal width of the defect were measured on CBCT, periapical radiographs and during the surgery. The buccal-lingual width of the defect was only recorded on CBCT and during the surgery. Lastly, intra-surgical linear measurements were compared with measurements of radiographs and CBCT, respectively. RESULTS: The means of the intra-surgical CEJ to BD, the depth of the defect, the mesio-distal (M-D) width and the buccal-lingual (B-L) width of the defect were 8.90 mm, 5.52 mm, 3.35 mm and 7.40 mm, respectively. Between CBCT measurements and surgical measurements the differences for the CEJ to BD (0.76 ± 1.40 mm) and the depth of the defect (0.63 ± 1.67 mm) were statistically significant, but the differences for the M-D width (-0.17 ± 0.67 mm) and the B-L width (-0.16 ± 0.65 mm) of the defect were not statistically significant. CONCLUSION: CBCT could provide relatively accurate measurements of the M-D width of the defect and additionally showed accurate measurements of the B-L width of the defect which periapical radiographs could not show. However, for vertical measurements of the intrabony defect (CEJ to BD and depth of the defect), when compared with measurements during the surgery, CBCT showed no advantages over periapical radiographs. A new method should be developed for accurately measuring the periodontal intrabony defects using CBCT in the future.

[Molecular mechanism involved in adhesion of monocytes to endothelial cells induced by nicotine and Porphyromonas gingivalis-LPS].

OBJECTIVE: To investigate molecular mechanism involved in nicotine in combination with Porphyromonas gingivalis (P.g) caused monocyte-endothelial cell adhesion. METHODS: The effect of nicotine, P.g-lipopolysaccharide (P.g-LPS) and their combination on the proliferation of U937 cells was determined by CCK-8 method. Interleukin-6 (IL-6) expression was investigated by real-time PCR after U937 cells were treated with nicotine, P.g-LPS and their combination. In human umbilical vein endothelial cells (HUVECs), the expressions of monocyte chemoattractant protein CCL-8 and adhesion molecules including vascular cell adhesion molecule 1 (Vcam-1), very late antigen 4 alpha (VLA4α), tumor necrosis factor receptor superfamily member 4 (OX40) and OX40 ligand (OX40L) were detected by real-time PCR or Western blotting assays after HUVEC cells were treated with nicotine, P.g-LPS and their combination. Adhesion of monocytes to endothelial cells was detected after the HUVECs and U937 cells were stimulated with nicotine, P.g-LPS and their combination, respectively. RESULTS: P.g-LPS did not affect the proliferative ability of nicotine in U937 cells. However, the ability of P.g-LPS induced IL-6 expression was inhibited by 100 µmol/L nicotine in U937 cells. In HUVECs, the expressions of CCL-8, Vcam-1, VLA4α, OX40 and OX40L were significantly up-regulated by nicotine and P.g-LPS combination compared with nicotine alone, P.g-LPS alone and the untreated control. Adhesion of monocytes to HUVECs results showed that the two types of cells treated with nicotine in combination with P.g-LPS could markedly increase the adhesion ability of monocytes to HUVECs. CONCLUSION: P.g-LPS in combination with nicotine could recruit monocytes to endothelial lesion through up-regulation of CCL-8, and promote adhesion of monocytes to endothelial cells through enhancement of Vcam-1/VLA4α and OX40/OX40L interactions, which could be involved in the initiation and development of atherosclerosis.

Hydrogen sulfide synergistically upregulates Porphyromonas gingivalis lipopolysaccharide-induced expression of IL-6 and IL-8 via NF-κB signalling in periodontal fibroblasts.

OBJECTIVES: The periodontal pathogen Porphyromonas gingivalis produces hydrogen sulfide (H2S). H2S in the oral cavity is positively correlated with periodontitis but the mechanism by which H2S contributes to periodontal diseases is obscure. We investigated the effect of H2S in combination with P. gingivalis lipopolysaccharide (LPS) on expression of the pro-inflammatory cytokines interleukin (IL)-6 and IL-8 in periodontal fibroblasts and the underlying mechanism of action. MATERIAL AND METHODS: Gingival fibroblasts (GFs) and periodontal ligament cells (PDLCs) were treated with different concentrations of the H2S donor NaHS in the presence/absence of P. gingivalis LPS for different time periods. Expression of IL-6 and IL-8 was detected by real-time PCR and ELISA. The activity of nuclear factor-kappa B (NF-κB) signalling was investigated using western blotting, EMSA and pathway blockade assays. RESULTS: Real-time PCR and ELISA results showed that H2S not only upregulated expression of IL-6 and IL-8 at mRNA and protein levels in a dose- and time-dependent manner, but also aggravated P. gingivalis LPS-induced expression of IL-6 and IL-8 in GFs and PDLCs. Western blotting and EMSA showed that NF-κB signalling was activated by NaHS, P. gingivalis LPS, and both, which was in accordance with the expression levels of IL-6 and IL-8 in GFs and PDLCs. These results were confirmed using a NF-κB pathway blockade assay. CONCLUSIONS: H2S synergistically upregulated P. gingivalis LPS-induced expression of IL-6 and IL-8 in GFs and PDLCs via activation of NF-κB signalling, which could promote the development of periodontitis.

[Intracellular mechanisms of Porphyromonas gingivalis induced interleukin-8 upregulation in endothelial cells].

OBJECTIVE: To find out the mechanisms by which Porphyromonas gingivalis (P. gingivalis) regulates interleukin (IL)-8 expression in endothelial cells. METHODS: P. gingivalis was applied to infect human umbilical vein endothelial cells (HUVECs), and the expressions of nucleotide binding oligomerization domain (NOD) 1, NOD2 and IL-8 were detected at mRNA and protein levels. Then the NOD1/NOD2 gene was silenced by RNA interference targeting NOD1 or NOD2 mRNA, followed by P. gingivalis treatment in the HUVECs, and the expression levels of NOD1/NOD2 and IL-8 were examined by real-time PCR, Western-blot or ELISA. In order to confirm the relationship between NOD1/NOD2 and IL-8 in the HUVECs, the agonists for NOD1 and NOD2, DAP and MDP were used in this study. RESULTS: P. gingivalis was activated the expressions of NOD1 and NOD2 in the HUVECs. Meanwhile, IL-8 expression level was also upreguated after P. gingivalis treatment (P<0.01). Knocking down of NOD1 or NOD2, the expression level of NOD1 or NOD2 was decreased, and P. gingivalis-induced IL-8 expression was attenuated in the HUVECs (P<0.01). Compared with normal cells, the NOD1 and NOD2 agonists, DAP and MDP, successfully increased IL-8 expression respectively (P<0.05). CONCLUSION: NOD1 and NOD2 play an important role in the inflammation of HUVECs caused by P. gingivalis in the expression of IL-8.

[Translational Medicine and its application in stem cell research for periodontal regeneration].

Translational Medicine is an evolutional concept that encompasses the rapid translation of basic research for use in clinical disease diagnosis, prevention, treatment and finally in public health promotion. It follows the idea "from bench to bedside and back", and hence relies on cooperation between laboratory research and clinical care. Translation process is a complex process that requires both research and non-research activities. During the past ten years, there has been intense interest in the development of new clinical procedures, therapeutic molecules, and prototypes based on translational medicine concept including dentistry. Periodontitis is a globally prevalent inflammatory disease that causes the destruction of the tooth supporting apparatus. Current methods to reconstitute lost periodontal structures have been shown to have limited and variable outcomes. Stem cell therapy can be used for periodontal regeneration and it is also one of the hot topics in translational regenerative medicine. In this article, recent advances and current status of translational medicine in stem cell therapy in periodontal regeneration field were reviewed. However, a number of biological, technical and clinical hurdles must be overcome before stem cell therapy could be used in clinics.

Effect of non-surgical periodontal therapy on serum levels of TNF-a, IL-6 and C-reactive protein in periodontitis subjects with stable coronary heart disease.

OBJECTIVE: To evaluate the effects of periodontal non-surgical therapy on serum levels of the inflammatory cytokines in chronic periodontitis subjects with stable coronary heart disease. METHODS: Seventy-five subjects with both chronic periodontitis (CP) and stable coronary heart disease (CHD) were enrolled in the study. Forty subjects received periodontal nonsurgical treatment including oral hygiene instruction, scaling and root planing, whereas 35 subjects received oral hygiene instruction only. At baseline and 3 months after completion of periodontal treatment, clinical periodontal parameters were recorded. Serum levels of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and C-reactive protein (CRP), lipid profile markers and white blood cell count were assayed. Pearson's correlation analysis was applied to examine the correlation between the change of TNF-α, IL-6 and CRP levels and the change of periodontal parameters after non-surgical periodontal treatment. RESULTS: At baseline, there were no statistical differences in all clinical, biochemical parameters and cytokine levels between these two groups. Three months later in the treatment group, all clinical parameters improved significantly and the serum levels of TNF-α, IL-6, and CRP reduced significantly. Reduction of TNF-α was significantly positively correlated with the reduction of bleeding index and plaque index; reduction of IL-6 was significantly positively correlated with the reduction of clinical attachment loss; reduction of CRP was significantly positively correlated with the reduction of clinical attachment loss and plaque index. CONCLUSION: Non-surgical periodontal therapy decreased serum TNF-α, IL-6 and CRP levels in CP subjects with stable CHD, which could help to reduce the inflammatory burden of stable coronary heart disease subjects.

Lipoprotein-associated phospholipase A2 and serum lipid levels in subjects with chronic periodontitis and hyperlipidemia.

OBJECTIVE: To evaluate the relationships between clinical periodontal parameters and levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and lipid profile markers in subjects with or without hyperlipidaemia. METHODS: Forty chronic periodontitis (CP) subjects with hyperlipidaemia (CP/HPL group), 40 systemically healthy CP subjects (CP group) and 20 systemically and periodontally healthy subjects (control group) were enrolled. The clinical periodontal parameters, the serum concentrations of Lp-PLA2, lipid profiles including total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c) and white blood cell (WBC) counts were determined and compared between different groups. Linear regression analysis was performed to identify the contributing factors of Lp-PLA2. RESULTS: Serum Lp-PLA2 level in the CP/HPL group and the CP group was significantly higher than in the healthy group. TC and TG levels in the CP/HPL group were higher than in the CP and control groups. No difference was observed for levels HDL-c and LDL-c and WBC counts among the groups. Linear regression analysis showed that the serum level of Lp-PLA2 was positively associated with bleeding on probing and WBC counts. CONCLUSION: Elevated level of Lp-PLA2 is associated with periodontal inflammation, indicating that periodontal treatment could reduce the risk of cardiovascular disease in CP subjects with hyperlipidaemia.

[Effect of initial periodontal therapy on chronic periodontitis patients with stable coronary heart disease].

OBJECTIVE: To investigate the clinical results of initial periodontal therapy on chronic periodontitis patients with stable coronary heart disease. METHODS: Thirty-two chronic periodontitis patients with stable coronary heart disease were included in this prospective study. All subjects received oral hygiene instruction, scaling and root planing and clinically monitored for 3 months. The clinical parameters, including plaque index (PLI), probing depth (PD), attachment loss (AL) and bleeding index (BI), were recorded at baseline and 3 months after treatment. Serum levels of high-sensitivity C-reactive protein (hs-CRP), cholesterol (CHO), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL) and glucose (GLU) were also measured. RESULTS: At 3 months after initial periodontal therapy, the mean PD of patients reduced from (3.95 +/- 0.15) mm to (2.93 +/- 0.21) mm (P < 0.01), the mean AL from (3.08 +/- 0.43) mm to (2.43 +/- 0.37) mm (P < 0.01), the percentage of sites with PD > or =5 mm from (22.37 +/- 6.88)% to (3.00 +/- 1.80)% (P < 0.01). hs-CRP significantly decreased at 3 months after treatment compared with baseline [(2.71 +/- 2.69) mg/L vs. (1.99 +/- 2.14) mg/L, P < 0.05]. CHO,TG, HDL, LDL and GLU decreased slightly (P > 0.05). CONCLUSIONS: Initial periodontal therapy is effective for chronic periodontitis patients with stable coronary heart disease. After initial periodontal therapy, periodontal parameters improved significantly and serum levels of hs-CRP decreased.

[The effect of extracellular protein from Porphyromonas gingivalis ATCC 33277 on viability of bovine aortic endothelial cells].

PURPOSE: To evaluate the effect of extracellular protein from Porphyromonas gingivalis on the viability of bovine aortic endothelial cells (BAECs). METHODS: Extracellular protein was extracted from the culture supernatant of P. gingivalis ATCC 33277 by salt induced precipitation. In the experimental group, BAECs were treated by extracellular protein in different concentrations (200, 300, 400, 500, 600 mug/mL) for 24 hours. In the control group, BAECs were cultured without extracellular protein. Furthermore, BAECs were exposed to 400 mug/mL extracellular protein for 6, 12, 24 and 36 hours, while BAECs in the control group were also cultured for 6, 12, 24 and 36 hours. Cell viabilities in both groups were determined by trypan blue staining. All the results were analyzed by non-paired t test with SPSS 10.0 software package. RESULTS: The viability of BAECs in the experimental group was significantly lower than that of the control group (P<0.05), which mean that the viability of BAECs decreased when cells treated with extracellular protein. As the concentration of extracellular protein increased, cell viability was reduced gradually. With the lapse of time (within 36 hours), the viability of BAECs in both groups declined. However, cell viability in the experimental group decreased significantly than that of the control group (P<0.05). The reduction of cell viability caused by extracellular protein was in a time dependent manner. CONCLUSIONS: Extracellular protein from P. gingivalis reduces the viability of bovine aortic endothelial cells in a dose and time dependent manner.

Association between periodontal disease and coronary heart disease.

There were increasing studies on the association of periodontal diseases with coronary heart disease (CHD) in the recent 20 years. This article reviewed the evidence supporting the association between periodontal disease and CHD, the possible mechanisms explaining the association, and the possible effect of periodontal treatment on the risk of CHD. In general, it is suggested that periodontal disease especially, periodontitis is modestly associated with CHD. Besides there are some common risk factors, such as smoking, stress, elder age, male gender and low socioeconomic status, between these two diseases, long chronic periodontal infections by periodontal pathogens, the systemic acute-phase response and host immuno-inflammatory response to the exposures of periodontal infection appear to be the important mechanisms for connecting the periodontal disease and CHD. Periodontal treatment can decrease the infection of periodontal pathogens and therefore, reduce the systemic inflammatory burden. It was observed in some studies that periodontal treatment could reduce the serum inflammatory biomarkers such as C-reactive protein and improve endothelial function. Even though the studies on effect of periodontal interfere on CHD are still limited now, it appears hopeful that periodontal treatment could reduce the risk of CHD and therefore become one of the preventing strategies for CHD.

[The effect of different concentrations of platelet-rich plasma on human periodontal ligament cells in vitro].

PURPOSE: To assess the effect of different concentrations of platelet-rich plasma (PRP) on cell proliferation and alkaline phosphatase (ALP) activity of human periodontal ligament cells (hPDLCs) in vitro. METHODS: PRP was obtained from volunteer donors using two-step centrifugation. TGF-beta1 and PDGF-AB levels in activated PRP, PRP and plasma were evaluated by enzyme-linked immunosorbent assay. hPDLCs were exposed to various concentrations of PRP (2%,5%,10% and 20%) and DMEM (negative control), respectively. After 24 and 72 hours, cell proliferation was evaluated using Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) activity of hPDLCs was evaluated by a p-nitrophenyl phosphate disodium assay. Statistical analysis was performed using one-way ANOVA and Student's t test in SPSS10.0. RESULTS: TGF-beta1 and PDGF-AB levels were highest in activated PRP. The effect of various concentrations of PRP on cell proliferation and ALP activity was significantly greater than that of negative control (P<0.001). The effect of PRP was significantly greater at 72-hour compared with that at 24-hour (P<0.01), with significantly difference among various PRP concentrations (P<0.001). Cell proliferation and ALP activity increased when the concentration of PRP increased from 2% to 10%. The maximum effect on cell proliferation was achieved with 10% PRP; 20% PRP resulted in a reduced cell proliferation. However, ALP activity was greatest with 20% PRP. CONCLUSION: PRP preparations exert a dose-dependent effect on hPDLCs proliferation and ALP activity in a certain extent in vitro at 24-hour and 72-hour. Supported by the Capital Medical Development Fund (Grant No. 2005-2007).

[Construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds and dog periodontal ligament cells].

OBJECTIVE: To investigate the construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds (beta-TCP/col) and dog periodontal ligament cells (PDLCs). METHODS: Dog PDLCs were isolated, cultured and identified. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of beta-TCP/col on the proliferation of PDLCs. The cells were seeded onto porous beta-TCP/col scaffolds. The cellular capability of adhesion and growth on porous beta-TCP/col surface was investigated visually by scanning electron microscopy (SEM). RESULTS: The cytotoxicity assay indicated that there was no significant difference between beta-TCP/col and the control during the 7 days (P>0.05). SEM showed cells successfully adhered to porous beta-TCP/col scaffolds and spread extensively. Matrix secretions were found on the cell surface. CONCLUSION: Porous beta-tricalcium phosphate/collagen scaffolds were of good biocompatibility to the dog periodontal ligament cells, and were potential ideal candidates for periodontal tissue engineering.