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.

Does vestibular incision improve the outcomes of vestibular incision subperiosteal tunnel technique: A randomized clinical trial for treatment of multiple adjacent type 1 gingival recession.

OBJECTIVE: The purpose of this study was to compare the clinical outcomes of vestibular incision subperiosteal tunnel technique (VISTA) and tunnel approach combined with connective tissue graft (CTG) for treatment of type 1 (RT1) multiple gingival recession. MATERIALS AND METHODS: Twenty-four patients with a total of 59 nonmolar recession teeth were randomly allocated to VISTA + CTG or Tunnel + CTG group. Recession depth and width, probing depth, clinical attachment level, width of keratinized tissue, gingival thickness, flap tension, mean root coverage (MRC), complete root coverage (CRC), patient-centered, and esthetic outcomes (root coverage esthetic scores, RES) were assessed at baseline and 12 months after surgery. RESULTS: At 12 months, MRC of 91.13 ± 16.96% and 91.40 ± 13.53%, CRC of 70.97% and 67.86% were observed for VISTA + CTG and Tunnel + CTG group respectively, with no significant difference between the two groups (p > 0.05). High RES of 8.52 ± 1.46 and 8.82 ± 1.44 was obtained in VISTA + CTG and Tunnel + CTG group respectively, without showing a significant difference (p = 0.245), while less scar formation was observed in Tunnel + CTG group (p < 0.01). CONCLUSIONS: Both procedures were effective for root coverage in RT1 multiple gingival recession at 12 months. Better esthetic result with less scar formation was obtained in tunnel approach combined with CTG without vestibular incision. (Registration number: ChiCTR-INR-16007845, registered on 19/12/2015, http://www.chictr.org.cn). CLINICAL SIGNIFICANCE: VISTA + CTG and Tunnel + CTG were both effective for root coverage in RT1 multiple gingival recession, with satisfying esthetic outcomes. However, it is suggested in critical esthetic areas, treatment options of making vertical incisions should be carefully considered.

Role of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 6 in activation of inflammation in human umbilical vein endothelial cells stimulated by Porphyromonas gingivalis-an in vitro study.

Background/purpose: Porphyromonas gingivalis (P. gingivalis) could induce the activation of vascular endothelial cells and promote the formation of atherosclerosis. Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing (NLRP) 6 could recognize P. gingivalis, but its role in atherosclerosis was unknown. The purpose of this study is to investigate the role of NLRP6 in the activation of inflammation in human umbilical vein endothelial cells (HUVECs) stimulated by P. gingivalis. Materials and methods: The expression level of NLRP6 in HUVECs with or without P. gingivalis-challenge was observed. Down-regulating the expression of NLRP6 in HUVECs, the expression levels of interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein (MCP)-1 were detected. Then, the HUVECs with NLRP6-overexpressed were stimulated by P. gingivalis, the levels of inflammatory cytokines above were examined and compared with those in HUVECs triggered by P. gingivalis only. To evaluate the effect of NLRP6 on bacterial immune escape, the NLRP6 was overexpressed, and the colonies of P. gingivalis that survived in HUVECs were calculated. Results: NLRP6 was expressed in HUVECs and decreased after P. gingivalis stimulation. Downregulation of NLRP6 decreased the expression levels of IL-1ß, IL-6, IL-8, TNF-α and MCP-1 in HUVECs. Those cytokines above in NLRP6-overexpressed HUVECs with P. gingivalis-stimulation significantly increased than in the cells with P. gingivalis-stimulation only. Furthermore, over-expression of NLRP6 decreased the colonies of P. gingivalis survival in HUVECs. Conclusion: NLRP6 regulated the activation of inflammation in HUVECs triggered by P. gingivalis and played an important role in P. gingivalis survival in endothelial cells.

Role of immune-related lncRNAs--PRKCQ-AS1 and EGOT in the regulation of IL-1ß, IL-6 and IL-8 expression in human gingival fibroblasts with TNF-α stimulation.

Background/purpose: It was reported that lncRNAs have an effect on immune-related diseases, however, their roles in periodontitis remain to be investigated. The aim of this study was to look for immune-related lncRNAs in periodontitis, and to preliminarily explore their function in vitro. Materials and methods: CIBERSORT was used to analyze abundance of immune cell in the periodontal tissue. Correlation between the expression profile of lncRNAs and abundance of immune cell was calculated and immune-related lncRNAs were identified. The expressions of immune-related lncRNAs identified were validated by RT-qPCR with 15 periodontitis and 15 healthy gingival tissues. The expressions of PRKCQ-AS1 and EGOT in HGFs were detected under the stimulation of different concentrations of TNF-α (0, 10, 15, 20, 30 ng/mL) and different duration (0, 12, 24 and 48 h). Then, siRNA was used to silence PRKCQ-AS1 and EGOT in HGFs. The expression level of IL-1ß, IL-6, IL-8 of the HGFs after stimulated by 15 ng/mL TNF-α, and the activation of NF-κB pathway was observed. Results: PRKCQ-AS1 and EGOT were identified as top 2 immune-related lncRNAs in periodontal tissues. The expressions of PRKCQ-AS1 and EGOT were significantly up-regulated in inflamed periodontal tissue and in HGFs under TNF-α stimulation. After knock-down of PRKCQ-AS1 and EGOT, expression level of IL-1ß, IL-6, and IL-8 in HGFs with TNF-α stimulation were decreased, and activation of NF-κB pathway was inhibited. Conclusion: PRKCQ-AS1 and EGOT were firstly identified as immune-related lncRNAs in periodontal tissue, and they regulate the expression of IL-1ß, IL-6, and IL-8 of HGFs through the NF-κB pathway.

Assessment of a developed pig cadaver model for teaching crown lengthening surgical procedures.

Background: Information regarding using a pig cadaver model for teaching purposes in dentistry is limited, especially for periodontal surgery procedures. The aim of this study was to assess the feasibility and efficacy of teaching crown lengthening surgical procedures using a prepared pig cadaver model. Methods: Mandibles of slaughtered pigs with subgingival crown fracture defects on two premolars and two molars on each side were prepared as periodontal surgery teaching cases. A resident group (n = 20) and an instructor group (n = 18) participated in assessing the efficacy of the model by completing questionnaires before and after training sessions. Data was either assessed descriptively or analyzed statistically with Wilcoxon signed-rank test with the significance level at α = 0.05. Results: Results revealed that all the knowledge points showed statistically significant improvements (p < 0.05) except for the procedure to determine the quantity of bone removal during osteotomy procedures. Most residents rated the efficacy of the model obtained with 9.0 out of 10 scale. The data of effectiveness of the pig cadaver model from the instructor group ranged from 7.4 ± 1.4 to 9.0 ± 1.0. Conclusion: Results of this study support feasibility in using prepared pig cadaver models to teach crown lengthening surgical procedures to postgraduates.

LOX-1 Regulates P. gingivalis-Induced Monocyte Migration and Adhesion to Human Umbilical Vein Endothelial Cells.

Porphyromonas gingivalis (P. gingivalis) is one of the main periodontal bacteria. This pathogen was reported to enhance monocyte migration and adhesion to endothelial cells in atherosclerosis. The scavenger receptor lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays a pivotal role in atherogenesis. The aim of this study was to investigate whether LOX-1 modulates P. gingivalis-mediated monocyte migration and adhesion to endothelial cells and how it works. The results showed that the migration and adhesion of monocytic THP-1 cells to human umbilical vein endothelial cells (HUVECs) were significantly enhanced when HUVECs or THP-1 cells were challenged with P. gingivalis. Meanwhile, the expression level of LOX-1 in both HUVECs and THP-1 cells were also significantly increased by P. gingivalis stimulation. It is well known that ligand/receptor pairs monocyte chemoattractant protein-1 (MCP-1)/CC chemokine receptor 2 (CCR2), selectins/Integrins, and cell adhesion molecules (CAMs)/Integrins mediate monocyte migration and adhesion to endothelial cells. In this study, LOX-1 was demonstrated to be crucially involved in P. gingivalis-induced THP-1 cell migration and adhesion to HUVECs, by regulating expression of ligands MCP-1, intercellular adhesion molecule-1 (ICAM-1) and E-selectin in HUVECs and that of their receptors CCR2 and Integrin αMß2 in THP-1 cells. The nuclear factor-kappa B (NF-κB) signaling pathway was proved to be involved in this process. In conclusion, LOX-1 plays a crucial role in P. gingivalis-induced monocyte migration and adhesion to endothelial cells. This result implies LOX-1 may act as a bridge in linking periodontitis to atherosclerosis.

[Comparison of biological characteristics of human gingival junctional epithelial cells and oral epithelial cells].

OBJECTIVE: To isolate P-cadherin positive and negative oral gingival epithelial cells, and to compare the biological characteristics with junctional epithelial cells. METHODS: Human oral gingival epithelial cells and junctional epithelial cells were cultured. P-cadherin positive and negative cells were isolated from oral gingival epithelial cells. The cellular adhesion, proliferation and migration were measured and compared. RESULTS: The P-cadherin positive cells accounted for 20% of oral gingival epithelial cells. Compared with juctional epithelial cells, P-cadherin positive oral gingival epithelial cells showed similar properties of adhesion and migration, and stronger proliferation ability (0.72 ± 0.06 vs. 0.60 ± 0.05, P<0.05). P-cadherin negative oral gingival epithelial cells showed weaker ability of adhesion (48% ± 6% vs. 87% ± 11%, P<0.05), proliferation (0.36 ± 0.04 vs. 0.60 ± 0.05, P<0.05) and migration (10.3 ± 2.7 vs. 23.4 ± 4.8, P<0.05). CONCLUSION: P-cadherin positive oral gingival epithelial cells showed some similar but different biological characteristics, compared with juctional epithelial cells, which suggested that during the process of transforming oral gingival epithelial cells into juctional epithelial cells, complex gene and protein changes were involved instead of simply cellular migration.

[Evaluation of the in vitro quantitative measurement of II degree furcation involvements in mandibular molars by cone-beam computed tomography].

OBJECTIVE: To evaluate the accuracy of measurement of II degree furcation involvements in molars of dry mandibles by cone-beam computed tomography (CBCT). METHODS: Twenty molars with II degree furcation involvements in dry mandibles were examined directly and measured by CBCT. Eight parameters were selected to describe the exact appearance of each II degree furcation involvements, including vertical defect dimensions, horizontal defect dimensions and furcation entrance dimensions. The results were compared with the corresponding data obtained by probing and periapical radiograph. RESULTS: All furcation involvements could be correctly classified by CBCT. For 5 of 8 parameters, no significant difference was found between the data obtained by CBCT and probing measurements (P>0.05). The distances from furcation entrance to alveolar crest, to bottom of bone pocket, and to the deepest site of horizontal bone defect measured by CBCT were less than those probed directly (P<0.05), but the differences were less than 0.5 mm (0.21, 0.24, 0.35 mm, respectively). The localization of furcation entrance may cause the differences. Two out of 20 furcation involvements could not be detected on periapical radiographs, and only 2 of 8 parameters could be measured on periapical radiographs. CONCLUSION: CBCT could provide precise and detailed 3D images of II degree furcation involvements in vitro.

Improved biological characteristics of poly(L-lactic acid) electrospun membrane by incorporation of multiwalled carbon nanotubes/hydroxyapatite nanoparticles.

Significant effort has been devoted to fabricating various biomaterials to satisfy specific clinical requirements. In this study, we developed a new type of guided tissue regeneration (GTR) membrane by electrospinning a suspension consisting of poly( l-lactic acid), multiwalled carbon nanotubes, and hydroxyapatite (PLLA/MWNTs/HA). MWNTs/HA nanoparticles were uniformly dispersed in the membranes, and the degradation characteristics were far improved. Cytologic research revealed that the PLLA/MWNTs/HA membrane enhanced the adhesion and proliferation of periodontal ligament cells (PDLCs) by 30% and inhibited the adhesion and proliferation of gingival epithelial cells by 30% also, compared with the control group. After PDLCs were seeded into the PLLA/MWNTs/HA membrane, cell/membrane composites were implanted into the leg muscle pouches of immunodeficient mice. Histologic examinations showed that PDLCs attached on the membranes functioned well in vivo. This new type of membrane shows excellent dual biological functions and satisfied the requirement of the GTR technique successfully in spite of a monolayer structure. Compared with other GTR membranes on sale or in research, the membrane can simplify the manufacturing process, reduce the fabrication cost, and avoid possible mistakes in clinical application. Moreover, it does not need to be taken out after surgery. PLLA/MWNTs/HA membranes have shown great potential for GTR and tissue engineering.

[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.