The Early Adhesion Effects of Human Gingival Fibroblasts on Bovine Serum Albumin Loaded Hydrogenated Titanium Nanotube Surface.

The soft tissue sealing at the transmucal portion of implants is vital for the long-term stability of implants. Hydrogenated titanium nanotubes (H2-TNTs) as implant surface treatments were proved to promote the adhesion of human gingival fibroblasts (HGFs) and have broad usage as drug delivery systems. Bovine serum albumin (BSA) as the most abundant albumin in body fluid was crucial for cell adhesion and was demonstrated as a normal loading protein. As the first protein arriving on the surface of the implant, albumin plays an important role in initial adhesion of soft tissue cells, it is also a common carrier, transferring and loading different endogenous and exogenous substances, ions, drugs, and other small molecules. The aim of the present work was to investigate whether BSA-loaded H2-TNTs could promote the early adhesion of HGFs; H2-TNTs were obtained by hydrogenated anodized titanium dioxide nanotubes (TNTs) in thermal treatment, and BSA was loaded in the nanotubes by vacuum drying; our results showed that the superhydrophilicity of H2-TNTs is conducive to the loading of BSA. In both hydrogenated titanium nanotubes and non-hydrogenated titanium nanotubes, a high rate of release was observed over the first hour, followed by a period of slow and sustained release; however, BSA-loading inhibits the early adhesion of human gingival fibroblasts, and H2-TNTs has the best promoting effect on cell adhesion. With the release of BSA after 4 h, the inhibitory effect of BSA on cell adhesion was weakened.

A dual role for ß1 integrin in an in vitro Streptococcus mitis/human gingival fibroblasts co-culture model in response to TEGDMA.

AIM: To evaluate the effect of TEGDMA on human gingival fibroblasts (HGFs) in vitro co-cultured with Streptococcus mitis, focusing on the signalling pathways underlying cell tissue remodelling and inflammatory response processes. METHODOLOGY: ß1 integrin expression was evaluated by means of imaging flow cytometry. The Western blot technique was used to investigate the expression of protein kinase C (PKC), extracellular signal-regulated kinase (ERK), matrix metalloproteinase 9 (MMP9) and 3 (MMP3). RT-PCR was performed to quantify nuclear factor-kb subunits (Nf-kb1, ReLa), IkB kinase ß (IkBkB), cyclooxygenase II (COX-2) and tumour necrosis factor-α (TNF-α) mRNA levels. Statistical analysis was performed using the analysis of variance (anova). RESULTS: When HGFs are co-cultured with S. mitis, ß1 integrin intensity, phosphorylated PKC (p-PKC), activated ERK (p-ERK), IkBkB mRNA level and MMP9 expression increased (for all molecules P < 0.05 HGFs versus HGFs co-cultured with S. mitis). A higher level of MMP3 in HGFs treated with TEGDMA was recorded (P < 0.05 HGFs versus HGFs exposed to TEGDMA). COX-2 inflammatory factor mRNA level appeared higher in HGFs exposed to 1 mmol L(-1) TEGDMA (P < 0.01 HGFs versus HGFs exposed to TEGDMA), whereas TNF-α gene expression was higher in HGFs co-cultured with S. mitis (P < 0.05 HGFs versus HGFs co-cultured with S. mitis). CONCLUSIONS: ß1 integrin triggered the signalling pathway, transduced by p-PKCα and involving ERK 1 and 2 and MMPs. This pathway resulted in an unbalanced equilibrium in tissue remodelling process, along with inflammatory response when HGFs are exposed to bacteria or biomaterial alone. On the contrary, the TEGDMA/S. mitis combination restored the balance between extracellular matrix deposition and degradation and prevented an inflammatory response.

Alpha-mangostin suppresses IL-6 and IL-8 expression in P. gingivalis LPS-stimulated human gingival fibroblasts.

This study aims to investigate the effect of alpha-mangostin on interleukin (IL)-6 and IL-8 expression in human gingival fibroblasts (HGFs). HGFs were challenged with Porphyromonas gingivalis LPS and then treated with various concentrations of alpha-mangostin. The cytotoxicity was determined using MTS assay and cytokine expressions were evaluated by Real-time PCR and ELISA. The results showed that 5 µg/ml P. gingivalis LPS and alpha-mangostin at 1 µg/ml or less did not affect the viability of HGFs. Alpha-mangostin reduced IL-6 and IL-8 mRNA and protein in P. gingivalis LPS-stimulated HGFs. These findings suggested that alpha-mangostin might be used as an adjunct to the periodontal therapy.

Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications.

Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol-gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior.

Comparison of the osteogenic potential of fibroblasts from different sources.

OBJECTIVE: With the growing interest in the role of fibroblasts in osteogenesis, this study presents a comparative evaluation of the osteogenic potential of fibroblasts derived from three distinct sources: human gingival fibroblasts (HGFs), mouse embryonic fibroblasts (NIH3T3 cells), and mouse subcutaneous fibroblasts (L929 cells). MC3T3-E1 pre-osteoblast cells were employed as a positive control for osteogenic behavior. DESIGN: Our assessment involved multiple approaches, including vimentin staining for cell origin verification, as well as ALP and ARS staining in conjunction with RT-PCR for osteogenic characterization. RESULTS: Our findings revealed the superior osteogenic differentiation capacity of HGFs compared to MC3T3-E1 and NIH3T3 cells. Analysis of ALP staining confirmed that early osteogenic differentiation was most prominent in MC3T3-E1 cells at 7 days, followed by NIH3T3 and HGFs. However, ARS staining at 21 days demonstrated that HGFs produced the highest number of calcified nodules, indicating their robust potential for late-stage mineralization. This late-stage osteogenic potential of HGFs was further validated through RT-PCR analysis. In contrast, L929 cells displayed no significant osteogenic differentiation potential. CONCLUSIONS: In light of these findings, HGFs emerge as the preferred choice for seed cells in bone tissue engineering applications. This study provides valuable insights into the potential utility of HGFs in the fields of bone tissue engineering and regenerative medicine.

Photothermal modulation of gingival fibroblasts via polydopamine-coated zirconia: A novel approach for promoting peri-implant soft tissue integration.

Achieving robust soft tissue integration around dental implants is crucial for long-term clinical success, as it forms a protective biological seal against bacterial invasion. However, the soft tissue attachment to implants is relatively deficient compared to natural teeth, particularly in the connective tissue region lacking sufficient gingival fibroblasts and collagen fiber alignment. This study proposed an innovative strategy to enhance peri­implant soft tissue integration by modulating gingival fibroblast behavior via photothermal conversion. Zirconia surfaces were coated with polydopamine (PDA), a melanin-like polymer exhibiting near-infrared (NIR) absorption for photothermal conversion. Under NIR irradiation, the PDA coating enabled mild hyperthermia (42-43 °C) on the zirconia surface. Remarkably, this mild photothermal stimulation significantly promoted human gingival fibroblast proliferation, adhesion, and collagen production compared to unmodified zirconia in vitro. By utilizing the photothermal properties of PDA coatings to modulate cellular behaviors beneficial for connective tissue formation, this approach provides a promising avenue to achieve improved soft tissue integration and long-term stability of dental implants. The findings highlight the innovative potential of combining biomaterial surface engineering with photothermal therapy for applications in implant dentistry.

TNF-α promotes expression of inflammatory factors by upregulating nicotinamide adenine dinucleotide phosphate oxidase-2 expression in human gingival fibroblasts.

Background/purpose: Periodontitis is a chronic infectious disease. The oxidative stress environment can cause or exacerbate the inflammation in periodontitis. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) may be the most important source of reactive oxygen species (ROS) in periodontal tissues. The pathological mechanism of periodontitis may be related to the increased ROS caused by enhanced NOX activity. The purpose was to investigate the effect of tumor necrosis factor (TNF-α) on inflammatory cytokines and ROS, and the role of NOX-2 in human gingival fibroblasts (HGFs). Materials and methods: HGFs were cultured and divided into the normal control group (NC group) and the inflammatory model group (TNF-α group) induced by 10 ng/ml TNF-α. Thereafter, NOX-2 siRNA was used to knock down NOX-2 gene expression. Quantitative real-time PCR was applied to detect IL-6, MCP-1, and NOX-2 mRNA levels. The levels of IL-6 and MCP-1 protein were examined by ELISA. The level of NOX-2 was evaluated by Western blot. ROS expression was measured by the fluorescence microplate. Results: The mRNA and protein expression levels of IL-6, MCP-1, and NOX-2 were significantly increased, and the expression of ROS was significantly elevated in response to 10 ng/ml TNF-α. Compared with the si-NC group, the mRNA and protein expression levels of IL-6 and MCP-1 were significantly down-regulated and ROS expression was significantly decreased in the si-NOX2 group stimulated by 10 ng/ml TNF-α. Conclusion: TNF-α promotes the expression of NOX-2 in human gingival fibroblasts and enhances the expression of inflammatory factors and ROS in human gingival fibroblasts through the upregulation of NOX-2 partly.

Influence of clinical zirconia surface treatments on microscopic characteristics and adhesion-proliferation behavior of human gingival fibroblasts.

Zirconia is favored in dental implant applications due to its biocompatibility, mechanical properties, and esthetic appeal, particularly in its interaction with soft oral tissues such as the gingiva. To optimize zirconia for clinical use, surface treatments like sanding and polishing are essential. The aim of this study was to investigate the effects of clinical surface treatments on the microscopic characteristics of zirconia and the adhesion and proliferation of human gingival fibroblasts (HGFs). Scanning electron microscopy (SEM) and fluorescence microscopy were utilized to examine the microscopic morphology and roughness resulting from various clinical surface treatment procedures on zirconia and to assess their impact on the microscopic appearance and behavior of HGFs. The results showed that the application of surface treatment procedures, particularly polishing treatments, resulted in the formation of a regular shallow groove morphology and a significant reduction in roughness in zirconia. This was accompanied by improved cell proliferation, cell adhesion, and the expression of integrin ß1 in HGFs. The results suggest that smoother zirconia surfaces promote better cell-material interactions, potentially improving the clinical success of dental implants. This research contributes to our understanding of the optimal surface roughness for soft tissue adhesion and the effect of different micro-morphologies on HGF attachment.

Weighted gene co-expression network analysis (WGCNA) to explore genes responsive to Streptococcus oralis biofilm and immune infiltration analysis in human gingival fibroblasts cells.

The correlation between oral bacteria and dental implants failure has been reported. However, the effect and mechanism of bacteria during dental implants is unclear. In this study, we explored key genes and candidate gene clusters in human gingival fibroblasts (HGF) cells in response to Streptococcus oralis biofilm through weighted gene co-expression network analysis (WGCNA) and differential genes analysis using gene expression matrix, GSE134481, downloaded from the Gene Expression Omnibus (GEO) database. We obtained 325 genes in the module significantly associated with S. oralis infection and 113 differentially expressed genes (DEGs) in the S. oralis biofilm; 62 DEGs indicated significant correlation with S. oralis injury. Multiple immune pathways, such as the tumor necrosis factor (TNF) signaling pathway, were considerably enriched. We obtained a candidate genes cluster containing 12 genes - IL6, JUN, FOS, CSF2, HBEGF, EDN1, CCL2, MYC, NGF, SOCS3, CXCL1, and CXCL2; we observed 5 candidate hub genes associated with S. oralis infection - JUN, IL6, FOS, MYC, and CCL2. The fraction of macrophage M0 cells was significantly increased in biofilm treatment compared with control; expression of FOS and MYC was significantly positively correlated with macrophage M0 cells. Our findings present a fierce inflammation changes in the transcript level of HGF in response to S. oralis.

TAS2R16 Activation Suppresses LPS-Induced Cytokine Expression in Human Gingival Fibroblasts.

Sustained and non-resolved inflammation is a characteristic of periodontitis. Upon acute inflammation, gingival fibroblasts release cytokines to recruit immune cells to counter environmental stimuli. The intricate regulation of pro-inflammatory signaling pathways, such as NF-κB, is necessary to maintain periodontal homeostasis. Nonetheless, how inflammation is resolved has not yet been elucidated. In this study, 22 subtypes of taste receptor family 2 (TAS2Rs), as well as the downstream machineries of Gα-gustducin and phospholipase C-ß2 (PLCß2), were identified in human gingival fibroblasts (HGFs). Various bitter agonists could induce an intensive cytosolic Ca2+ response in HGFs. More importantly, TAS2R16 was expressed at a relatively high level, and its agonist, salicin, showed robust Ca2+ evocative effects in HGFs. Activation of TAS2R16 signaling by salicin inhibited the release of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines, at least in part, by repressing LPS-induced intracellular cAMP elevation and NF-κB p65 nuclear translocation in HGFs. These findings indicate that TAS2Rs activation in HGFs may mediate endogenous pro-inflammation resolution by antagonizing NF-κB signaling, providing a novel paradigm and treatment target for the better management of periodontitis.

Co-implantation of magnesium and zinc ions into titanium regulates the behaviors of human gingival fibroblasts.

Soft tissue sealing around implants acts as a barrier between the alveolar bone and oral environment, protecting implants from the invasion of bacteria or external stimuli. In this work, magnesium (Mg) and zinc (Zn) are introduced into titanium by plasma immersed ion implantation technology, and their effects on the behaviors of human gingival fibroblasts (HGFs) as well as the underlying mechanisms are investigated. Surface characterization confirms Mg and Zn exist on the surface in metallic and oxidized states. Contact angle test suggests that surface wettability of titanium changes after ion implantation and thus influences protein adsorption of surfaces. In vitro studies disclose that HGFs on Mg ion-implanted samples exhibit better adhesion and migration while cells on Zn ion-implanted samples have higher proliferation rate and amounts. The results of immunofluorescence staining and real-time reverse-transcriptase polymerase chain reaction (RT-PCR) suggest that Mg mainly regulates the motility and adhesion of HGFs through activating the MAPK signal pathway whereas Zn influences HGFs proliferation by triggering the TGF-ß signal pathway. The synergistic effect of Mg and Zn ions ensure that HGFs cultured on co-implanted samples possessed both high proliferation rate and motility, which are critical to soft tissue sealing of implants.

Eldecalcitol Inhibits LPS-Induced NLRP3 Inflammasome-Dependent Pyroptosis in Human Gingival Fibroblasts by Activating the Nrf2/HO-1 Signaling Pathway.

PURPOSE: Periodontitis is a major chronic oral disease that is accelerated by activation of the NLRP3 inflammasome and the resulting pyroptosis. According to recent studies, active vitamin D and its analogs have been reported to have great anti-inflammatory effects. However, the anti-inflammatory mechanism of a newly found vitamin D analog, eldecalcitol (ED-71), is still unclear. This study investigates whether ED-71 could protect human gingival fibroblasts (HGFs) from LPS-induced pyroptosis and, if so, determine its underlying mechanism. METHODS: After HGFs were treated with LPS alone or with LPS and ED-71, their viability was measured by CCK8 assay. The degrees of inflammation and pyroptosis were measured via LDH assay, H2O2 assay, fluorescent staining, flow cytometry, and Western blots. Intracellular ROS, Hoechst 33,342, and PI stains were assessed with a fluorescence microscope. ROS inhibitor NAC, NLRP3 inhibitor MCC950, and Nrf2 inhibitor ML385 were added to further clarify the mechanism. RESULTS: LPS induced cytotoxicity in HGFs, as shown by CCK8 assay. LPS also increased intracellular ROS, H2O2 levels, release of LDH, and expression of the pyroptosis-related proteins NLRP3, caspase-1, and IL-1ß. NAC and MCC950 reduced LPS-induced NLRP3, caspase-1, and IL-1ß. Pretreatment with ED-71 effectively inhibited the LPS-induced pyroptosis and was associated with activation of the Nrf2/HO-1 signaling pathway. This beneficial effect of ED-71 was suppressed by ML385. CONCLUSION: This study demonstrates the therapeutic effect of ED-71 on LPS-induced NLRP3 inflammasome-dependent pyroptosis in HGFs and further reveals that ED-71 can inhibit pyroptosis by activating the Nrf2/HO-1 pathway. Our results thus suggest that ED-71 is a potential candidate for the treatment of periodontitis.

Influence on proliferation and adhesion of human gingival fibroblasts from different titanium surface decontamination treatments: An in vitro study.

OBJECTIVES: To investigate the effects of different decontamination treatments on microstructure of titanium (Ti) surface as well as proliferation and adhesion of human gingival fibroblasts (HGFs). MATERIAL AND METHODS: Ti discs with machined (M) and sand blasted, acid etched (SAE) surfaces were treated with five different decontamination treatments: (1) stainless steel curette (SSC), ultrasonic system with (2) straight carbon fiber tip (UCF) or (3) metal tip (UM), (4) rotating Ti brush (RTB), and (5) Er:YAG laser (30 mJ/pulse at 30 Hz). Surface roughness was analyzed under optical interferometry. HGFs were cultured on each disc. Proliferation and adhesive strength were analyzed. qRT-PCR and ELISA were performed to detect the RNA and protein expression of FAK, ITGB1, COL1A1, and FN1 respectively from different Ti surfaces. RESULTS: Surface roughness increased on M surface. Proliferation, adhesive strength and gene expression were higher on M surface than SAE surface. Decontamination treatments affected surface parameters significantly (P < 0.001), making M surface less smooth while SAE surface became less rough. SSC, UCF, UM and RTB decreased proliferation on M surfaces significantly (P < 0.05). UCF, RTB and laser increased proliferation on SAE surface significantly (P < 0.05). UM decreased adhesive strength on M surface significantly and laser increased adhesive strength on SAE surface significantly (P < 0.05). Gene expression increased with time and was altered by decontamination treatments significantly (P < 0.001). CONCLUSIONS: Decontamination treatments influence surface roughness and cell behavior of HGFs. Laser might be an optimal decontamination treatment which has the least negative effect on M surface and the most positive effect on SAE surface.

An RNA-seq screen of P. gingivalis LPS treated human gingival fibroblasts.

BACKGROUND: In gingival tissues, lipopolysaccharide (LPS) from Porphyromonas gingivalis (P. gingivalis) is the most critical stimulator for inducing inflammatory response. Human gingival fibroblasts (HGFs) are the major constituents of gingival connective tissues. The aim of this study was to investigate P. gingivalis LPS induced whole transcriptional profile in HGFs and the potential crosstalk between microRNAs (miRNAs) and inflammatory cytokines. METHODS: RNA-seq was performed on HGFs with and without P. gingivalis LPS treatment. The gene expression of selected inflammatory cytokines and miRNAs induced by LPS at different time points was evaluated by quantitative RT-PCR. The protein expression of chemokines was further confirmed by ELISA. RESULTS: Interestingly, most of the significantly changed genes (198/204) were up-regulated at 4 h after 10 µg/ml LPS stimulation, including inflammatory cytokines and miRNAs. Confirmed by quantitative RT-PCR, the mRNA levels of IL-1ß, IL-6 and IL-8 showed single up-regulation peak (4 h/6 h) after 1 µg/ml and 10 µg/ml LPS treatment. Similarly, 1 µg/ml LPS induced single up-regulation peak (8 h) of miRNA-146a, -146b and -155 expression. However, 10 µg/ml LPS induced the increased expression of miRNA-146a and -155 at both early stage (2 h/4 h) and late stage (24 h). CONCLUSION: Taken together, we investigated P. gingivalis LPS induced whole transcriptional profile, and the different behaviors of miRNA expression induced by different doses of LPS in HGFs.

Promotion of cells to close gaps and encourage cell coverage, by radio frequency glow discharge treatment.

Exposure of dental abutments to cleaning and sterilizing Radio Frequency Glow Discharge Treatment (RFGDT) triggered greater degrees of human gingival fibroblast (HGF) attachment and spreading over their surfaces. Enhanced cell growth and metabolic activity of such HGFs were found which might lead to improved cellular margins in the smile-revealing "esthetic zone". This investigation, approved by the Institutional Review Board, employed in vitro studies of HGFs to support in vivo clinical applications of differentially treated titanium healing abutments to demonstrate the possible improvements for tissue growth around dental implants. Harvested commercially pure titanium (cpTi) abutments from three clinical cases per group revealed that separation of the abutments from the human gingival tissues occurred mainly intercellularly rather than directly from the tissue, suggesting that placement of an RFGDT permanent abutment would trigger tissue-integration more completely than noted with usual alcohol-cleaned abutments. This work confirmed and extended observations of prior studies that RFGDT materials have mitogenic effects that might be captured for stimulating desired tissue growth around implanted biomaterial appliances. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 169-177, 2017.

Caffeic acid phenethyl ester attenuates lipopolysaccharide-stimulated proinflammatory responses in human gingival fibroblasts via NF-κB and PI3K/Akt signaling pathway.

Periodontal diseases often begin with chronic gingival inflammation, which causes the destruction of periodontal tissues. Inflammatory immune responses from host cells to bacteria, such as Porphyromonas gingivalis (P. gingivalis), cause periodontal degradation. Human gingival fibroblasts (HGFs) are the major cells in periodontal soft tissues. When stimulated by lipopolysaccharide (LPS), HGFs could secrete several pro-inflammatory cytokines and chemokines, such as interleukins (ILs) IL-6, IL-8, inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2). Caffeic acid phenethyl ester (CAPE) is the main active component of propolis, which is collected by honeybees from different plants and known for its anti-inflammatory effects. The anti-inflammatory effects of CAPE on the LPS-induced HGFs were demonstrated in this study. HGFs were pretreated with CAPE (10, 20, and 30µm) for 1h, followed by LPS stimulation (1µg/ml) for 24h. Enzyme-linked immunosorbent assay, Western blot analysis, and immunofluorescence staining were used to evaluate the production of IL-6, IL-8, iNOS, and COX-2, as well as the activation of TLR4-mediated NF-κB, PI3K/AKT, and MAPK signaling pathways. The results indicated that CAPE inhibits LPS-induced IL-6, IL-8, iNOS, and COX-2 production in a dose-dependent manner. Moreover, CAPE suppresses LPS-induced TLR4/MyD88 and nuclear factor kappa B (NF-κB) activation. In addition, phosphatidylinositol 3 kinase (PI3K) and protein kinase B (AKT) phosphorylation was inhibited by CAPE. These results demonstrated that CAPE could be effective for treating of periodontal diseases.

Human Dental Pulp Stem Cells and Gingival Fibroblasts Seeded into Silk Fibroin Scaffolds Have the Same Ability in Attracting Vessels.

Neovascularization is one of the most important processes during tissue repair and regeneration. Current healing approaches based on the use of biomaterials combined with stem cells in critical-size bone defects fail due to the insufficient implant vascularization and integration into the host tissues. Therefore, here we studied the attraction, ingrowth, and distribution of blood vessels from the chicken embryo chorioallantoic membrane into implanted silk fibroin scaffolds seeded with either human dental pulp stem cells or human gingival fibroblasts. Perfusion capacity was evaluated by non-invasive in vivo Magnetic Resonance Imaging while the number and density of blood vessels were measured by histomorphometry. Our results demonstrate that human dental pulp stem cells and gingival fibroblasts possess equal abilities in attracting vessels within silk fibroin scaffolds. Additionally, the prolonged in vitro pre-incubation period of these two cell populations favors the homogeneous distribution of vessels within silk fibroin scaffolds, which further improves implant survival and guarantees successful healing and regeneration.

Inducing bioactivity of dental ceramic/bioactive glass composites by Nd:YAG laser.

OBJECTIVES: Aims of this study were to investigate the optimal conditions of laser irradiation of a novel Bioactive Glass/Dental Ceramic-BP67 composite for acceleration of hydroxyapatite-HA formation and to assess cellular responses on the precipitated HA region. METHODS: BP67 (Bioactive Glass: 33.3%, Dental Ceramic: 66.7%) was fabricated by the sol-gel method. A laser assisted biomimetic-LAB process was applied to BP67 sintered specimens immersed in 1.5-times concentrated simulated body fluid-1.5×-SBF. The effect of various energy densities of pulsed nanosecond Nd-YAG (1064nm) laser and irradiation exposure times (30min, 1 and 3h) were evaluated for HA precipitation. The HA film was characterized by FTIR, XRD, SEM and micro Raman techniques. ICP-AES was used for revealing changes in chemical composition of the 1.5×-SBF during irradiation. Cell viability and morphological characteristics of periodontal ligament fibroblasts-PDLFs, human gingival fibroblasts-HGFs and SAOS-2 osteoblasts on the HA surface were evaluated by MTT assays and SEM. RESULTS: At optimal energy fluence of 1.52J/cm2 and irradiation time for 3h followed by immersion in 1.5×-SBF at 60°C, a dense HA layer was formed on laser-irradiated BP67 within 7 days. The resulting HA film was tightly bonded to the underlying substrate and had mineral composition similar to cementum. MTT assay showed a consistent reduction of cell proliferation on the HA layer in comparison to conventional control ceramic and BP67 for all 3 cell lines studied. SIGNIFICANCE: These findings suggest LAB is an effective method for acceleration of HA formation on materials with low bioactivity, while cellular responses need further investigation.

Characterization of Human Gingival Fibroblasts on Zirconia Surfaces Containing Niobium Oxide.

It was indicated that tetragonal zirconia polycrystal (TZP) containing yttria (Y2O3) and niobium oxide (Nb2O5) ((Y,Nb)-TZP) could be an adequate dental material to be used at esthetically important sites. The (Y,Nb)-TZP was also proved to possess its osteogenic potential comparable with those conventional dental implant material, titanium (Ti). The objective of the current study was to characterize cellular response of human gingival fibroblasts (HGFs) to smooth and rough surfaces of the (Y,Nb)-TZP disc, which were obtained by polishing and sandblasting, respectively. Various microscopic, biochemical, and molecular techniques were used to investigate the disc surfaces and cellular responses for the experimental (Y,Nb)-TZP and the comparing Ti groups. Sandblasted rough (Y,Nb)-TZP (Zir-R) discs had the highest surface roughness. HGFs cultured on polished (Y,Nb)-TZP (Zir) showed a rounded cell morphology and light spreading at 6 h after seeding and its proliferation rate significantly increased during seven days of culture compared to other surfaces. The mRNA expressions of type I collagen, integrin α2 and ß1 were significantly stimulated for the Zir group at 24 h after seeding. The current findings, combined with the previous results, indicate that (Y,Nb)-TZP provides appropriate surface condition for osseointegration at the fixture level and for peri-implant mucosal sealing at the abutment level producing a suitable candidate for dental implantation with an expected favorable clinical outcome.

Cytotoxicity of ammonium hexafluorosilicate on human gingival fibroblasts.

Ammonium hexafluorosilicate (SiF), which is claimed to significantly improve occlusion of dentinal tubules, was proposed as a novel desensitizer for dentine hypersensitivity (DH). However, the cytotoxicity of SiF on oral cells is lacking. The purpose of this study was to investigate the cytotoxicity of SiF on human gingival fibroblasts (hGFs) under different dosages (0.001%, 0.01%, 0.1%, and 1%) and treatment durations (1, 5, 10, and 30min). Cell proliferation, mitochondrial membrane potential (MMP) and cell cycle were tested by MTT assay, JC-1 staining and flow cytometry, respectively. Glutathione (GSH) depletion was analyzed to further investigate the underlying mechanism of SiF-induced cytotoxicity. MTT assay showed that there was significantly lower number of viable cells when the hGFs were treated with 0.01% (10min), 0.1% (10 and 30min) and 1% (5, 10, and 30min) SiF than the control group (p<0.05). MMP decreased and GSH depletion increased dramatically along with higher concentrations (0.1% and 1% SiF) and prolonged times (10 and 30min). DNA synthesis [S (%)] of cells treated with 0.1% and 1% SiF (5, 10, and 30min) was significantly lower than the control group (p<0.05). Our results indicate exposure to up to 0.01% SiF for less than 5min causes low or no cytotoxicity in vitro.